OASIS SUPPLEMENTARY MONOGRAPH #1 B I O L O G I C A L E V O L U T I O N AN OVERVIEW
OASIS SUPPLEMENTARY MONOGRAPH #1
B I O L O G I C A L E V O L U T I O N
AN OVERVIEW OF MECHANISMS AND EVIDENCE
J. Richard Wakefield
CONTENTS:
~~~~~~~~~
INTRODUCTION
PART ONE:
Natural Selection
Speciation: Mechanisms and Evidence
Rates of Evolutionary Changes
PART TWO:
Emergence of Evolutionary Novelties
PART THREE:
Filling those Gaps --Fossil Transitions
PART FOUR:
Taxonomic Classification --A Theory of Lineages
CONCLUSION:
REFERENCES:
===========================================================================
"Our confidence that evolution occurred centers upon three general
arguments. First, we have abundant, direct, observational evidence of
evolution in action, both from the field and laboratory. It ranges from
countless experiments on change in nearly everything about fruit flies
subjected to artificial selection in the laboratory to the famous British
moths that turned black when industrial soot darkened the trees upon which
they rest. ...
The second and third arguments --the case for major changes-- do not involve
direct observation of evolution in action. They rest upon inference but are
no less secure for that reason. ...
The second argument strikes many people as ironic, for they feel that
evolution should be most elegantly displayed in the nearly perfect adaption
expressed by some organisms...
Evolution lies exposed in the imperfections that record a history of
descent. Why should the embryos of whalebone whales develop teeth only to
reabsorb them later, unless they evolved from toothed ancestors? ...
The third argument relies upon transitions in the fossil record. Preserved
transitions are not common, and should not be according to our understanding
of evolution..., but they are not entirely wanting as creationists often
claim."
Stephen Jay Gould, "Evolution as Fact and Theory",
Science and Creationism, Edited by Ashley Montagu, (1984).
INTRODUCTION
~~~~~~~~~~~~
Creationists charge that major changes in structures of animals are
impossible to evolve. How did the wing evolve? How could the hard egg shell
evolve? How could a lung evolve? How could the complex eye have possibly
evolved? We do not see half a bird, or half an elephant in the fossil
record. All structures found in fossil forms are fully functional and
complete. Creationists also argue that part of a wing, or eye, would be of
no value to an organism. An attribute must be fully functional or how
could it be of a selective advantage? These, and many others, are common
creationist attacks on evolution.
Creationists even go so far as to quote prominent evolutionists who appear
to support the position that evolution does not work. These selectively
lifted quotes are nothing more than a desperate attempt to discredit
evolution. Dr. Ed Friedlander investigated creationist literature for such
misquotation. In a small monograph Friedlander shows a photocopy from Dr.
Duane Gish's book Evolution. The Fossils Say No! where a lifted quote
appears and a photocopy from the original source. The difference makes one
wonder about the true reason for Gish's crusade. Friedlander notes at the
beginning:
"A review of Dr. Gish's use of honest scientific articles reveals a
consistent pattern of deception. Whenever Dr. Gish cites evidence, it is
either out of date or incomplete. In every case, Dr. Gish withholds key
information that would discredit his case. When this has been pointed out
to his audiences, Dr. Gish has shifted to vicious personal attacks."
Friedlander, who himself is a Christian, after giving his evidence for
deception, concludes:
"Whatever Christians understand to be the doctrine of creation,
we all agree that lying is a sin. Many honest scientists have
faith that God had a hand in our biological origins. But
charlatans like Dr, Gish have done much to make scientists, and
other educated people, believe that Christianity is archaic and
dishonest. Dr. Gish has not only done harm to science education,
he has done serious harm to what he claims to be his own faith
--Christianity."
The extent of the scientific damage done by Gish and his colleagues at ICR
is evident simply by listening to ordinary Christians who follow them. The
thrust of this paper will be to help you explain, in terms easily
understandable, these charges with specific examples. You will quickly
discover, that not only is the literature full of examples and explanations,
but that creationists have distorted the evolutionists position and erected
strawman arguments, or they have not done their homework. Presenting this
case in front of a creationist is tricky. Creationists quickly learn how to
create ad hoc arguments whenever evolutionary evidence is presented. One
must first force the individual to admit that within the bounds of
creationism an item should not exist, then bring forth the item. I will
give hints here as to how to do that with the arguments and evidence
presented here.
This work is not to be considered a complete treatise of the subject --far
from it. Excellent books abound that explain bio-evolution in detail. We
would like to make sure that when you charge creationists that they do not
know what they are talking about, that at least you can say you do a bit. I
recommend that you at least read the references listed below prior to
attempting to defending evolution.
To use this monogaph properly, when confronting a creationist, you must have
the following on hand: Ruse (1986), Strahler (1988), Carrol (1988), Montagu
(1984), Godfrey (1983), McGowan (1984) and the Creation/Evolution Journal
as starters. Having also Dawkins (1985) , Mayr (1976), Strickberger (1990)
for some basic introductions and evidence would be most helpful to you.
Check out periodicals such as Evolution, Theoretical Biology, Evolutionary
Biology, to name a few, and photocopy some articles. (If creationists
claim there is no evidence for evolution, then what do they think is
published in these journals?)
This monograph is a supplement to these fine works. I have attempted to
assimilate the important major points and explain them in terms you can use
against creationist assaults.
The first of four parts will be on the mechanisms and evidence for natural
selection and speciation. Creationists argue that they accept "variation
within created kind", but this to them is not evolution. The rate of
evolution will also be discussed since creationists totally misrepresent
punctuated equilibrium.
The second part will be specific mechanisms and examples of the evolution of
major body parts. I will show how structures do indeed have a selective
advantage even though they are not fully functioning. Organisms entering a
new environment and undergoing evolutionary changes will show a mosaic of
characteristics of old structures and new structures. These are the true
intermediates.
The third section is on transitions in the fossil record and how
creationists have either distorted the evidence or do not understand how to
read it. Indeed there is ample evidence of fossils bridging major gaps.
These will be reviewed and explained.
The final part is taxonomic classification. Is it just pigeon holing, or is
it a theory of organic relationships? Again, creationists misunderstand
what classification is.
PART ONE
~~~~~~~~
NATURAL SELECTION:
==================
The best definition for natural selection is found in Endler (1986):
"Natural selection can be defined as a process in which:
a. variation among individuals in some attribute or trait: variation;
b. a consistent relationship between that trait and mating ability,
fertilizing ability, fertility, fecundity, and, or, survivorship: fitness
differences;
c. a consistent relationship, for that trait, between parents and their
offspring, which is at least partially independent of common environmental
effects: inheritance.
Then:
1. the trait frequency distribution will differ among age classes or
life-history stages, beyond that expected from ontogeny;
2. if the population is not at equilibrium, then the trait distribution of
all offspring in the population will be predictably different from that of
all parents, beyond that expected from conditions a and c alone.
[55, p.4]"
Essentially Endler is saying that if you have an isolated population of
reproducing individuals and there is a shift in the environmental pressures,
then subsequent offspring will differ --the gene frequency within the
population will shift-- in response to the changing forces acting on the
phenotype (physical characteristics) of each individual.
Some examples of selective pressures include rain, wind, soil type,
temperature, water, mate selection, predation, and food supply. Essentially
any and all encounters an individual of a population has with the world
around it will either select for, or against, or have no effect, on an
individual's phenotype. Selective pressures are on individuals in a
population, not on populations collectively.
Natural selection is not absolute. That is, fitness of a particular trait
does not guarantee reproductive success. Natural selection is statistical.
On a statistical basis a fit trait has a greater chance of propagating
through the gene pool than a lower fit trait.
The notation of "fitness" is greatly misunderstood by creationists, and the
rest of the public for that matter. The term is thought to denote brute
strength. But how a tree can have brute strength is beyond me! Instead the
term fitness is a genetic expression of how well the genotype, expressed as
the phenotype, is suitable for the environment that the individual lives in
[3, 45, 46, 75, 92]. The different variations within members of a
population will mean that different responses to the same selective
pressures will occur.
The fitness of an organism is in retrospect to the contribution a mating
pair leaves to subsequent generations. Thus you can only determine if a
mating pair were fit if their genes are still found in some members of the
population several generations later.
Most often, it is just one or two characteristics that will be left. Thus
one mating pair would leave their genes for toe length, other pairs for hair
length, and so on. Each member who produces offspring leaves different
contributions to the overall fitness of the population.
The importance of fitness to the survival of the individual can be seen in
the reproductive rates and strategies of various species. Organisms produce
far more offspring than can possibly survive. Take for example, a stable
population size --that is, the frequency at which a population size
fluctuates is low. Add to that a mating pair of birds producing 4 offspring
per year for 10 years. Since the population size is stable, 38 of the 40
offspring produced from that pair must perish before they can reproduce.
Another example, or reproductive strategy, is a shot-gun approach. A sea
urchin would produce millions of potential offspring during its life. But
again all but 2 must perish. (Realistically the rate of survival for
individual families will vary, these are average survivals over the whole
population.)
What governs the elimination? Obviously selection pressures the environment
inflicts on the population.
Now take an unstable population where most of the reproducing members die
off due to an atypical stress, leaving behind very few atypical members.
More of their offspring will survive perpetuating their atypical genes into
a new population (see Figure 1).
---------------------------------------------------------------------------
FIGURE 1: Example of a population (black outline) of organisms isolated by
various geographic conditions. This organism must live in grassland and is
not very mobile, say some sort of insect. On the right is an ocean. On the
left is a high cliff. Below is dense forest and above a river separating
the population from available niches.
Members at location "C" will be the "type" members under uniform selection
pressures while those individuals at the periphery will be influenced by
different selection pressures. Those at the sea margin (location B to E)
will be under different stress than those members at location "A" at the
waterfall. Gene flow from the interior will keep the peripherals from
becoming too variable.
If, for example, a small peripheral group invades the islands of the delta
(location B), or even gets to the other side of the river, and becomes
reproductively isolated from the rest of the population, then the differing
selective pressures would select for different traits producing a new
species.
Small populations produce large variability for selection to act upon.
---------------------------------------------------------------------------
The statistical basis for selection cannot be overstated. For example, in a
herd of deer the dominant male mates with all the females. Rival younger
males are driven off each year in combat with the dominant male. However
much he controls the gene pool being exclusive male contributor, the male's
dominance is usually short lived --a few seasons. There are instances where
while the dominant males is defending his property against another male, a
third male can slip in un-noticed and fertilize a female. Who is more fit?
The dominant male with his physical strength, or the smart third party who
takes advantage of the situation and quickly mates unseen? Also the
dominant male may succumb to an accident and die prematurely. Thus natural
selection is statistical in nature.
Creationists charge that natural selection, which some admit does exist, can
only confine organisms to maintain their "pureness", and cannot produce new
species [14]. However true this is in a stable environment, it most
definitely is not true in an environment that is changing.
One of the best examples of natural selection changing a population under a
changed environment is the peppered moth Biston betularia. Most of us know
the story: Prior to industrialization in England the moths which spent the
day elighted on tree trunks were the same colour as the lichen growing on
the tree --gray. Predatory birds cannot see the moths and hence leave them
to carry on reproducing grey moths. However, a small mutation frequently
occurs where a black or darkened morph of the moth arises and would have
been quite obvious, and become a quick meal --obviously selected against.
Now, with pollution having killed off the lichen and the trunks of the trees
darkened, these dark morphs find themselves at a selective advantage. The
light ones, which were the population's dominant colour, are quickly gobbled
up by the birds.
During the change over we would have seen a collapse in the population size
as the light moths were consumed, the dark ones being the only survivors.
Theoretically the population size of the birds must have increased with a
short interim of abundant food supply. Theoretically during the collapse
in food supply, the bird population would have had a collapse in numbers.
Slowly over subsequent generations, the black morphs increase the population
of moths back to its original equilibrium with its food supply. The bird
population would have recovered to its original population size prior to the
industrial pollution. Actually, this is far too simplistic an explanation,
since there was the surrounding countryside providing new gene influx of the
light morph [16].
All this seems so logical that even creationists are forced to agree. But
to them it is not evolution. Creationist Gary Parker states:
"Well, the peppered moths do seem to provide strong evidence of natural
selection. But is that evidence of evolution? Notice I've changed the
question. That's a key point. First I asked if there was any evidence that
Darwin was correct about natural selection. The answer quite simply is
'Yes, there is.' But now I'm asking a radically different question, 'Is
there any evidence for evolution?' Many people say, 'Isn't that the same
question? Aren't natural selection and evolution the same thing?' Answer:
NO, absolutely not. ... The answer really depends on what the person means
by evolution. In one sense, evolution means 'change'. ... But change
isn't the real question, of course. Change is just as much a part of the
creation model as the evolution model. The question is, what kind of change
do we see: change only within type (creation) or change from one type to
others (evolution).
... After 100 years of natural selection, what did we end up with? Dark
and light varieties of the peppered moth, species Biston betularia. All
that changed was the percentage of moths in two categories --that is, just
variation within type. [98, p.48]"
Clearly Parker accepts Darwinism! But is evolution natural selection, or
natural selection part of evolution?
In our Spring 1990 Issue of OASIS Newsletter we published the accepted
definition of evolution as found in [48, p. 8]. Change, any change at all
in a population as a result of the influences of the environmental
pressures, is evolution --period. Natural selection is one of three
components of the mechanism by which evolution occurs. The other two being
micromutation and reproduction. Let's look at these others in some detail.
MUTATION: This is mutation in the DNA during cell division --called
micromutation. It is important for evolution during sex cell division
(miosis). Contrary to what creationists will tell you, micromutations are
mostly neutral, they have no net effect on the individual's ability to
produce offspring, or have no net effect on the population. What mutations
do provide is variation amongst individuals in a population. The amount to
which new genes from mutations will effect the evolution of a population
depends upon the size of the population. The larger the population, the
less chance a mutation will flow through the population. The smaller the
population, or even peripheral regions of a large population, the larger the
frequency with which a mutation will become prominent in a population, or
peripheral region.
Occasionally mutations may have a beneficial effect on the population. For
example, prior to human habitation, a population of mosquitoes would have
produced individuals resistent to DDT, but back then the mutation producing
the trait would have been neutral. Now when DDT is used, only those in the
population who have the trait live to produce offspring. Thus that mutation
did have a positive, for the mosquito, ramification when the environment
changed due to the introduction of DDT. Did the mosquito know that DDT
would have been used against it and unconsciously mutate to resist?
Obviously not. Are populations of mosquitoes intrinsically resistant to any
and all pesticides? Again, obviously not. But insect population sizes
coupled with micromutation occurring in high and fast offspring production
will obviously be a strategy for insects to cope with changes in their
environment. That would explain why insects far out number all other
species constituting some 80%!
Positive genes flow quickly over subsequent generations. Mayr states
"...genes accumulate in a population, independently of each other, in
accordance with the contribution they make to fitness. [86, p.216]"
Is this positive contribution of mutations reproducible in the lab? Yes it
has been. For example, two isolated populations of fruitflies --one
subjected to low dose radiation, the other kept normally-- were subjected to
the same reproductive stress forces --artificial selection. After
successive generations which do you suppose produced the better surviving
population? The irradiated one! Why? Simple. The introduction of
radiation produced more micromutations which provided more variability for
selection to choose from. The reference is [5].
Micromutations alter only the chemical sequence of the proteins' amino
acids, but rarely altering the protein's function. A protein is a wrapped
ball of amino acids coded from the DNA. It is the structure, NOT the
chemical make up, of a protein that determines the function a protein will
do. Only part of the outer structure does the function. Thus a small
mutation in the coding for that protein will only slightly, if at all,
change the outer structure, which in most cases would not alter the normal
function. It could, however, give the protein a new function as well as
the old one.
SEXUAL REPRODUCTION: The second component of evolution is sexual
reproduction. Sexual reproduction allows these variable traits in
individuals to be passed on to others in the population. Also much
alteration of the genetic code takes place. You are not the average of the
traits of your parents, nor are you the sum of the traits. You have some
traits from each of your parents, while your siblings may have different
traits from your parents. Such is the case with my own kids. But on the
other hand, you certainly have seen where all the kids in the family look
like only one of the parents --dominant traits.
NATURAL SELECTION: Natural selection can alter a population in response
to directional pressure, or maintain a population in a static environment.
Creationists charge that evolution is a random chance event. They will
charge that the animal world shows purposeful design, as if the "designer"
which is God, knew what he was doing. Make them be specific about this.
Have them commit themselves into saying that animals cannot evolve by
chance, and evolution is a chance event. Make sure you confine the argument
to the evolution of organisms, and leave the origin of life as a separate
matter.
Indeed mutation and sexual reproduction are chance events --in most cases.
For example, where mutations will occur before and during sex cell division
appears to be random. Who one mates with is random (except in the case of
sexual selection in some species). Which sperm fertilizes which egg is also
random. Had your parents decided not to have sex the day you were
conceived, you would not be here. On the other side, because they missed
contraception that day you are here! There definitely is chance in these
two components of evolution. Creationists cannot deny this.
Natural selection is quite different. It is directional and anti-chance.
Certain physical characteristics are forced to be propagated throughout
generations due to the discriminating function of natural selection.
However, there still are chance events which interfere with natural
selection, such as a meteorite impact's mass extinction. Thus, even though
natural selection is directional, it is blind to the future [45], which is
why diversity evolved.
Thus if there is purposeful design at work in nature, one must explain, or
add a qualifier, that the "designer" used, and still uses, random chance in
the creation.
There are two possible results of the effects of natural selection on a
population --extinction or speciation. Extinction is the most radical and
final environmental influence on a population. Speciation is the more
interesting for evolution. Speciation is when a single population is split
into two or more reproductively isolated populations. Let us now look at
the evidence for speciation.
SPECIATION: MECHANISMS AND EVIDENCE:
====================================
There are two ways speciation can occur. The first is geographic speciation
also called allopatric speciation. This is when a portion of a population
is physically cutoff from the rest of the population, or the rest of the
population becomes extinct. This, Mayr argues, is the way most speciation
takes place [76]. That is most speciation takes place when a small
population colonizes a new niche --called a founder population.
Creationists who argue that speciation does not take place will have trouble
with you after this. Ask them what they would demand as undeniable and
acceptable evidence for one species to become two. After they give you what
would satisfy them, then give them these next examples.
Specific examples of allopatric speciation can be found in [53]. Here is
one such case : A Central American fish, Xiphoporus maculatus, that lives
in rivers up the east coast exibits various stages of speciation, from
simple diversity of a single population, to subspecies, to full isolated
species. Mayr [86, p.281] points out "Here then we have a series of
related, allopatric populations showing every stage from the local genetic
race, to the ordinary subspecies, to the almost specifically distinct
subspecies ([X.] xiphidium), to the full species (couchianus)."
Three phenomena give evidence for geographic speciation. They are:
1) Levels of speciation: That is a range of degrees of isolation of various
populations.
2) Geographic variation of species characters dependent upon differing
habitats the population blankets.
3) Borderline cases and distribution patterns. That is, isolated
sub-populations that show some characteristics of species, but retains old
characteristics. Isolating mechanisms are not completely operative.
Another more striking example of speciation occurred in the Australian
mallee thickhead Pachycephala. In the first stage a wide ranging population
became split into two due to changes in the vegetation of southern
Australia. Eventually, the two populations were allowed to come into
contact, but were reproductively isolated from each other --two new species
[74] (see Figure 2).
The second way speciation can take place is called sympatric speciation.
This is when speciation --reproductive isolation-- takes place within a
large population. There was some difference of opinion amongst scientists
if this could actually occur. Until, that is, specific examples were
observed.
A case well documented by Bush [24] is the fruit fly Rhagoletis infestation
on cherry trees. The western cherry fruitfly R. indifferens normally
infests the cCalifornian native cherry Prunus enarginata in August. The
plant grows at altitudes over 400 meters and fruits from August to October.
But when a domesticated orchard of P. avium or P. cerasus (introduced from
Europe) are grown within the upper boundary of the wild cherry there is
occasional out-break of infestation by R. indifferens races. The cherries
are never infested at the lower altitudes.
On Mt. Shasta there is an interogression zone of wild and domesticated
cherries at altitudes between 1050 and 1500 meters. During the last two
weeks in July R. indifferens can shift from the native Prunus to the
introduced species. The different growth period of the Europian cherry
selected for a small number of early rising flies in a race of Rhagoletis.
If not for the Europian cherries, these early rising flies would have been
selected against due to the absence of cherries.
Now this race has infested the domesticated cherries, and because of the
offset fruiting, we have a new species of fly. They both occupy the same
area, but inflict cherries of differing fruiting times --late June for the
domesticated cherry, August for the wild cherry. Speciation at the same
locality, but isolated by a shift in breeding and egglaying by an atypical
group of the fly population.
These are a clear examples of speciation, and there is no way creationists
can argue that they are the same species. They do indeed look the same,
but their life-cycles are now so divergent that there is no way of testing
for inbreeding --they are truly isolated and by definition separate species.
It is reproductive isolation that is important. Mayr discusses at length
each of the required modes of isolation for a new species to be distinct
from the ancestral [88].
1. PREMATING ISOLATION: Mechanisms that prevent interspecific cross breeding
a) Potential mates do not come into contact either due to seasonally or
geographically different habitats. For example, Lake Victoria in Africa
3,500 years ago was much higher than now. A reduction in the level of the
lake isolated smaller lakes, like Lk. Nabugabo, in which the cichlid fish
became isolated and diverged independently from the ancestral population.
Five new species evolved [86]. The case of the cherry tree fly is an
example of seasonal isolation.
b) Potential mates occupy the same geographic areas, but do not recognize
each other as mating partners. This is the case with song birds and many
insects. The song birds occupy the same geographic area but it is the
difference in their songs which attracts the correct mate. Frogs are the
same. In the case of insects, it is the chemical equivalent of the song,
their pheremones, which attracts the correct mate.
c) Attempted mating by two individuals fails due to differing mechanical
parts preventing sperm transfer. In the case of insects, the mechanical
parts are very complex and specific to each species. For example there is a
mimic firefly, Photuris, where the female is capable of flashing the code of
another species of firefly, Photinus. The male of the other species comes
to what he expects is the flashing code of a female of his own species, but
instead when he attempts to mate becomes a meal [126]. While consuming one
male if another male Photinus arrives and attempts to mate with the female
mimic then differing mechanical parts prevents sperm transfer between the
two different species.
2. POSTMATING ISOLATION: Mechanisms that reduce success of crossbreeding.
a) Sperm cannot fertilize egg. Either the sperm cannot enter the egg, or
the genetic makeup is different. This would be true for certain members of
the wolf and fox family [36, 42, 78]. The number of chromosomes are
different and so even if mating does occur, then there will be no offspring.
b) Zygote dies after fertilization.
c) Hybrid inviability and death after birth. The best case here is the
mule being a crossbreed between a horse and a donkey. The mule is
infertile.
d) Hybrid lives but is partly or fully infertile, or produces an inviable
second hybrid.
---------------------------------------------------------------------------
FIGURE 2: Example of geographic speciation in the bird Pachycephala. The
original population (1) became split due to arid conditions isolating the
vegetation and the bird population into two groups (2). Different
environmental conditions selected the two groups in different directions(3 &
4). Subsequent invasion of the western population into the eastern's range
(5) showed reproductive isolation had occurred (6). From Keast 1961.
FIGURE 3: Example of sympatric speciation in the wild cherry fruitfly
Rhagoletis indifferens. Infestation in the wild cherry fruit occurs during
August when the flies lay their eggs in the fruit. Introduction of a
domesticated cherry with a June fruiting time allowed a small number of
early egglying flies to be selected for and propagate into a new species of
flies.
FIGURE 4: How speciation looks in the three dimensions of space, time, and
phenotypic variation. X is phenotypic variation of all characteristics of
all members of the population. Y is time or number of generations. Z is
geographic location or selection variation.
Populations --defined by the X and Z axis-- are dynamic objects, constantly
fluctuating during successive generations. Budding off of peripheral
members of the population can result in extinction for that sub-population,
or a new species depending upon environmental pressures.
Three important factors exist for recognizing geographic speciation: 1)
Different degrees of speciation occurring, 2) geographic variation of
species characters, and 3) borderline cases and distribution patterns.
FIGURE 5: Two examples of how speciation works. A static environment
produces a static population where atypical members (the stippled sides of
the bell graph) are selected against each generation, to be replaced with
new atypical members upon gene mutations. "Scenario A" has the parent
population completely dying off due to a selection barrier, like DDT
introduction, except for a small peripheral atypical group. That new group
later becomes the dominant type. "Scenario B" is when a small atypical
peripheral group becomes geographically isolated from the parent group due
to some small change in the environment.
--------------------------------------------------------------------------
Creationists will charge that if an artificial mating of two species shows
fertility, then really they are not separate species, and that they could
have diverged after the ark landed. One example Taylor gives is the horse
and zebra [117]. I doubt that Taylor would agree that they are actually the
same species. It is not just the criterion of hybridability of two species,
but the other isolating mechanisms too. If any of these mechanisms above
prevent hybridization, then we have separate species --period. As for
hybridization of two separate species under artificial conditions only shows
that the two species have yet to become phenotypically divergent enough for
the second set of mechanisms to kick in, in addition to the first set.
It is the time separation and the effects of directional selection which
would determine when the species would be hybrid isolated.
Creationists will argue that what to them is a separate "kind" is whether or
not cross-breeding can take place. Ask them, then, if they would think it
possible for a series of populations which, at their contact with other
populations of the same species, interbreed. But at the two extreme ends
there can be no inbreeding possible. For example, a series of populations:
A, B, C, D, E, F, G. A breeds with B, B with C and so on. But A cannot
breed with G. Ask them if that would fit their "model".
Clines, as they are called, do indeed occur. For example, Endler [53] gives
many examples where the gradual change in environmental conditions over a
distance, for example latitude or up the side of a mountain, will select for
different characteristics within the same species. Each successive
population over the gradient has slightly different averages for the
population's phenotype, until the morphology is so great that interbreeding
between the extreme distant populations is impossible.
RATES OF EVOLUTIONARY CHANGES:
==============================
Classical Darwinism is portrayed as saying that species change gradually
over time. Unfortunately the fossil record does not support that totally.
There are gaps in the record, and creationists do their best to use that
against us. They claim that these gaps are proof of the "abrupt appearance"
of organisms. This is nothing more than their supernatural creation. But
still the creationists have a fallacy here. They are claiming that a lack
of evidence is evidence itself. False. A lack of evidence says nothing at
all.
But the gaps are real, so what do they represent? Fossilization is a very
rare event, especially so when there are no conditions for it to occur. But
the low probability of fossilization coupled with the large numbers of
fossils found attests to one thing --large population sizes. Large
populations are stable, and resist changes from selection pressures due to
the large numbers of genes flowing through the population.
On the other hand in small isolated peripheral populations, where the real
part of evolution --speciation-- is taking place, one would expect not to
find any fossils. Unless, that is, even the peripheral population is large
enough, or is living in ideal fossilization habitats.
Niles Eldredge found the test case with his work on the trilobite Phacops
rana [51]. He was trying to find a continuous gradual evolutionary pattern
in this trilobite found in the Middle Devonian seas, 380 million years ago.
From several locations around Ohio, Southwestern Ontario and Michigan,
Eldredge sampled several successive layers of the shales and limestones for
these trilobites. In looking at specimens from different horizons he could
see no difference in the morphology across a geological boundary that should
have indicated a gradual evolutionary change.
He eventually discovered something quite remarkable in the trilobite eyes
that would set the stage for his theory of "Punctuated Equilibrium".
Creationists have greatly distorted punctuated equilibrium. They will tell
you that it is the same as what the evolutionist Richard Goldschmidt
postulated --that a reptile laid an egg and a bird flew out! (Creationists
have also misrepresented, or not understood, Goldschmidt's "hopeful monster"
theory. Since his saltationist view of new species is rejected and has no
real evidence we can dispense with it here.)
Gould, obviously outraged by the blatant misrepresentation of punctuated
equilibrium by creationists, said this
"Since we proposed punctuated equilibria to explain trends, it is
infuriating to be quoted again and again by creationists --whether by design
or stupidity, I do not know-- as admitting the fossil record includes no
transitional forms. The punctuations occur at the level of species;
directional trends (on the staircase model) are rife at the higher level of
transitions within major groups. ...
"Continuing the distortion, several creationists have equated the theory of
punctuated equilibrium with a caricature of Goldschmidt's belief that major
transitions are also accomplished suddenly by means of 'hopeful monsters.'
(I am attracted to some aspects of the non-caricatured version, but
Goldschmidt's theory has nothing to do with punctuated equilibrium[61]."
Punctuated Equilibrium basically states that if the environment does not
change over long periods of time then the animal forms that are in
equilibrium with that environment will not be changed either. However, if
the environment starts to change, the population can absorb a bit of that
change, but eventually the stress becomes too large and then radical and
rapid evolutionary changes can occur. Small peripheral populations selecting
for few atypical members are the only ones capable of coping --the rest
dying off.
The time in which this "rapid" change can occur is dependent on several
factors such as population size and reproductive rates. This change can take
place in only a few hundred of thousands of years --a mere instant in
geological time. The small population and short time interval for the
event, makes the possibility of fossilization very remote. But is there any
evidence to support this?
Eldredge may have found the test case for this in the evolution of trilobite
eyes. Trilobites had eyes similar to insects, with some major differences.
The particular trilobites he was studying had eyes arranged in columns of
lenses. A typical eye would have 18 columns with having from 1 to 7 or more
lenses in each column.
What he discovered in the Mid-west was that below a disconformity the
trilobites had 18 rows. Directly above that rock unit, above a
disconformity, the trilobites had 17 rows. What happened?
A disconformity is a distinct break between two horizontally successive
sedimentary rock units. It is an erosional surface. The shallow sea that
was covering the continent in that area dried up for an unknown period of
time. Later, the sea reinvaded the dry land and the lush marine animals
returned, except these trilobites had one less column of lenses in their
eyes!
In a remote small quarry in New York Eldredge found a sequence of rocks that
also contained his trilobites. This unit is parallel in time to the lower
unit which had the 18 columns. What he found were a very few trilobites,
that had a variation of columns of lenses from 18 to 17. That is, the first
column had different number of lenses in individuals in the population.
Small population --high variability.
What he was apparently seeing was two populations of trilobites. One, with
18 columns of lenses, living in the large shallow continental ocean. The
other, a much smaller peripheral population with a variation in columns from
18 to 17 (that is containing lenses from one to several), living in a near
shore environment at the base of the growing Appalachian Mountains to the
east.
It appears that when the continental sea dried up a small pocket of water,
with the smaller population, was left and they continued to flourish. When
the sea reinvaded the land the trilobites with the 17 columns found
themselves a nice uninhabited environment to live in. Eldredge was able to
determine that the interlude lasted about 8 million years.
Further up the rock column in the Mid-west Eldredge noticed a second "event"
where the 17 columns were overlain by a rock unit that had trilobites with
only 15 columns. Looking back in New York he found in another small pocket
of rocks a population of trilobites with variation in columns from 17 down
to 15, that is having 15 1/2, 16, 16 1/2 etc. columns of eyes. A repeat of
the previous event. These transitions are true transitions. Exactly what
the creationist hoped would never be found (see Figure 6).
Creationists will charge that this is a very small change and can easily be
incorporated into just variation within "created kind." However, they have
missed the boat on this. These are found in what the creationists would
claim are rocks from Noah's Flood. Ask them how such a cataclismic and
violent an event as the Flood is supposed to have been, could have neatly
deposited the trilobites so that only those with 18 columns lie togther,
then a break and all the 17 columned together, and another break and finally
the 15 columned trilobites together. Ask them how a small pocket of
transitions could have come to lie togther during the Flood, in what looks
like a perfect evolutionary sequence.
What this really shows us is that evolution, when it occurs, takes place in
unusual places, during unusual circumstances. This has been Eldredge and
Gould's position all along:
The essential idea here is that new species --new reproductive communities--
tend to bud off in some isolated region from a more widely spread ancestral
species [Eldredge, 51, p.189].
In summary, most evolutionary change is concentrated in events of
speciation; speciation tends to occur rapidly in very small subpopulations
isolated at the periphery of their ancestor's range [Gould, 62, p. 24]."
When one finds a gap in the rock record, the transitions should be found in
another location -where evolution took place. Add to that periodic mass
extinctions, and one can see why explosive radiation of organisms can, and
did, occur.
Creationists have been away off base in their accusation that Gould and
company have completely destroyed Darwinism. Punctuated equilibrum is only
at the level of species; "Punctuated equilibrium is a model for the level
of speciation alone [62, p.24]" and is in perfect harmony with Darwinism:
"What needs to be said now, loud and clear, is the truth: that the theory of
punctuated equilibrium lies firmly within the neo-Darwinian synthesis. It
always did. It will take time to undo the damage wrought by the overblown
rhetoric, but it will be undone [Dawkins, 45, p. 251]."
Thus "Punk Ek", as it is abreviated, is nothing more than an expression of
the rate at which speciation and overall evolution takes place.
Once evolved, species tend to remain unchanged --stasis-- until there is a
change in the environment, then only a small peripheral sub-population
survives. This new population is small in size, but rapid in filling vacant
niches. The transitions occur during this rapid phase of evolution, on the
order of hundreds of thosands of generations. This is far too short for
fossilization to record, unless the organism lives in ideal conditions, such
as Eldredge's trilobites.
---------------------------------------------------------------------------
FIGURE 6: Example of punctuated equilibrium as seen in the evolution of
trilobite eye columns. The important point of "Punk Ek" is that the
speciation events take place at different localities than the parent
population. This is an example of what is shown in Scenario A of Figure 5.
---------------------------------------------------------------------------
PART TWO
~~~~~~~~
MECHANISMS FOR THE EMERGENCE
OF EVOLUTIONARY NOVELTIES:
============================
Mayr (1976) [88] is a classic collection of essays on evolutionary thought.
In an essay entitled, "The Emergence of Evolutionary Novelties" Mayr gives
specific examples of how various body plans evolve. Firstly, one must
define what an evolutionary novelty is. Mayr states:
"Tentatively, one might restrict the designation "evolutionary novelty" to
any newly acquired structure or property that permits the assumption of a
new function. This working definition must remain tentative until it is
determined how often it is impossible to decide whether or not a given
function is truly "new." [88, p.89]"
Any appearance of a new structure in a population is what the creationists
consider impossible to evolve (See Table 1 for examples of new structures
which arose in various taxa). The reasons they give, mostly, is that a
partial structure is not sufficiently functional, and would be quickly
selected against because they feel that natural selection is a negative
force eliminating the unfit [14, 98]. They also argue that there are no
intermediates to show how these new structures evolved. We leave that for
Part 3.
---------------------------------------------------------------------------
Features associated with the origin of vertebrates:
--emergence of the cordate body plan
--development of the neural crest and its derivatives
--origin of the brain and paired sense organs
--origin of bone (which occurred separately in
several lineages)
Features associated with the origin of gnathostomes
--origin of jaws
--origin of teeth with regular replacement pattern
--origin of paired fins
--origin of swimbladder in osteichthyes
Features associated with the origin of tetrapods
--origin of limbs in amphibians
--origin of the amniote egg
--origin if an impedance-matching ear in squamates,
archosaurs, turtles, and mammals
--loss of limbs in aistopods, caecilians and snakes
--secondary aquatic adaptation of mesosaurs,
ichthyosaurs, nothosaurs, placodonts, mosasaurs,
whales, and sirenians
Features associated with the origin of flight
--Origin of wings in pterosaurs, birds and bats
--Elaboration of the avian respiratory system
--echolocation in bats
Features associated with the origin of mammals
--endothermy
--hair
--mammary glands
--precise tooth occlusion and the tribosphenic molar
--trophoblast of placentals
TABLE ONE: List of evolutionary novelties that gave rise to the vertebrates
as listed by Carroll [ 31] page 579. The list is not complete, as feathers
and endothermy in birds and dinosaurs could be included.
---------------------------------------------------------------------------
Mayr argues that the notion of natural selection as a negative force biases
one into thinking that natural selection cannot have a positive influence on
a structure to make it better. Natural selection can indeed select FOR a
structure which only partly works in an organism's favour. Each stage in
the selection of a structure will be better able to cope than previous
stages. Thus those individuals with better abilities will, on average,
produce more surviving offspring, and selecting for the structure involved.
Each step in the selection for a structure will be more superior than
previous steps, until the optimum configuration of the structure is
obtained.
The evolution of lungs in the early bony fish, for example, seems to have
been the result of oxygen being absorbed through the mouth region, as well
as the gills [106]. This ability of some fish would have had a selective
advantage over those fish which did not have this feature when the
environment changed into drought conditions. Any individuals in the
population with more surface area, due to population variability, to absorb
atmospheric oxygen would have a selective advantage under drought
conditions. Each stage in the evolution of producing a sack to give more
surface area would be more advantageous than previous stages and hence is
selected for under high environmental pressures, eventually producing the
lung found in vertebrates.
Let us look at the specific mechanisms by which new structures can arise by
natural selection as listed by Mayr.
1) Pleiotropic By-Product:
It may occur that a minor structure or function would be selectively neutral
at first, and may be the result of accidental, or of a by-product of another
structure, which later obtains an advantage. Mayr argues, incorrectly, that
"...it is very probable that neutral genes do not exist,...". In fact
neutral genes do exist [45], and this passage is now outdated, but he also
argues that phenotypic (structural) characteristics can be selectively
neutral for the normal niche the organism lives in, to later have a
selective advantage, or even disadvantage, when the environment changes [45,
88].
2) Intensification of Function:
Mayr claims that this is the major mechanism for the origin of new
structures. He argues that:
Most differences [in the vertebrates] are merely shifts in proportions,
fusions, losses, secondary duplications, and similar changes that do not
materially affect what the morphologist calls the "plan" of the particular
type [88p.96]
Carroll echoes the same with a specific example:
Many different lineages of aquatic crocodiles evolved from terrestrial or
semiaquatic ancestors, and numerous intermediate forms are known. The
transitions between terrestrial sphenodontids and aquatic pleurosaurs and
between varanoid lizards and mosasaurs involve little more than progressive
changes in proportions [31].
Many examples are given, such as glands, which are the result of
specialization of a few cells in a specific region of the body to produce a
requires product. Mammalian breasts are one good example. The Monotremes
do not have breasts or nipples, but instead the skin in the pouch region
simply excretes milk which the young must lick up [97]. Not very efficient,
not a "perfect" design, but it works.
The eye is also an example of a new function arising due to intensification
of a function. Any light sensitive tissue will be of advantage to an
organism, and the more light receptive cells, the better the organism will
be. A perfectly functioning eye is not necessary, as shown by the large
number of organisms which do not have "perfect" vision, but still do very
well. It even appears that the eye evolved more than once.
You will, no doubt, hear the creationist charge that even Darwin "admitted"
that the eye could not have evolved by citing this:
"To suppose that the eye...could have been formed by natural selection,
seems, I freely confess, absurd in the highest degree [88, p.186]."
The problem with this is that it is only a partial quote, the rest states:
"...the difficulty ceases to be very great in believing that natural
selection may have converted the simple apparatus of an optic nerve, coated
with pigment and invested by transparent membrane, into an optical
instrument as perfect as is possessed by any member of the Articulate Class
[88, p.188]."
Clearly Darwin understood how, through intensification of function, natural
selection evolved the eye, and other structures. Mayr points out that "Once
one admits that the possession of such photosensitivity may have a selective
value, all else follows by necessity [88, p.96]." This is true for all
structures which arise by this mechanism. Once a characteristic attains the
smallest advantage, natural selection will eventually modify it to where it
will have the greatest advantage for the environment the organism lives in.
3) Change of Function:
The change in function is the interesting evolutionary strategy to producing
a new structure. This occurs when one structure which is used for one
function, can take on another function. That is, one structure does more
than one function, with the secondary function later becoming dominant, and
the primary function may eventually be lost. Many clear cut examples exist
showing stages in the movement from dominant primary function, to a dominant
secondary function:
--The Steamer Duck. It uses its wings primarily for flying, but secondarily
for paddling across the surface of the water. It is rather clumsy at it
too, but the wings still work well enough. If the selective pressure for
paddling is strong enough, and the use of flying low enough, the wings could
become dominant paddling structures.
--Penguins. Wings were once used for flying (otherwise why would they be
wings?), but now used for swimming. Why would the penguin be created with
wings, when fins are much more efficient for swimming? The reason is that
the wings were the only structure this bird had in which to take advantage
of an aquatic life. The penguin is a clear case of evolution using whatever
there is to fulfill a function. As a creation it is a ridiculous design.
Poorly adapted to land, and only reasonably adapted to life in the water.
It's design is so incomplete that it is restricted to certain habitats in
the south. Why are there no penguins in the Arctic?
Evolution's answer is logical, they have not been able to migrate from their
original grounds, their phenotype cannot compete with tropical organisms to
get to the arctic.
There can also be a change in the function that is so radical that the
structure is no longer used. Cave dwelling organisms that lose colouration
and have functionless eyes are one good example [11, 84]. But the
flightless birds are the best example.
There are stages in the reduction of wings in flightless birds from the
Kakapo (which is a flightless parrot of New Zealand) to the Kiwi which has
nothing but stubs for wings. Structures that are no longer functioning are
quickly selected against, or become selectively neutral. If the structure
consumes large amounts of energy, or becomes a hinderance to the organism,
then there will be a selection pressure to truly degenerate the wings, for
example, into nothing but stubs.
Change in function for the evolutionist is important because these
structures preserve the evolutionary lineage the structures or organism came
from. Flightless birds are birds! Why? Because they have feathers and
wings, even though the wings are functionless. (Imagine creating a
structure, like wings on flightless birds, that does not do what it was
designed to do!)
Change in function also shows that there is more than one way of solving
problems of function. Swimming can be achieved either by horizontal fins
(whales), vertical fins (fish), modified wings (penguins), or even webbed
feet (otters). In some cases there are two structures in a single organism
which do the same function, but in different ways (Lungs and skin of
amphibians both transfer metabolic gases).
4) Preadaption:
Preadaption is when a structure can perform a new function without
modification or interference with its primary function. One example is the
lung of early fish preadapted to being used as a hydrostatic organ in living
fishes. Another is your hand. You use it to hold objects, but it can also
be used for swimming, albeit not very good, but still useful. Dogs use
their feet for running, for holding down bones while eating, or for digging
holes. The mudskipper fins were designed for swimming, but also work well
enough out of water to climb trees! The mudskipper is such a beautiful
example of evolution in action. It is a fish, but it lives the life of an
amphibian!
Summarizing the mechanisms of the evolution of a new structure, we have four
ways organisms can use parts of their bodies to exploit new environmental
shifts, or bettering their performance in the current niche. An organism
undergoing a shift in structure configuration will be a mosaic of
structures. That is, it will retain old structures, preserving its original
lineage, and will have modified new structures to function in the new
environment. Many examples abound of mosaic structures, both fossil and
extant. Living organisms include the Monotremes, where they still lay eggs,
but are close to being a Mammal; the panda bear where a bone in the wrist
acts like a thumb (for details read Gould, 1988); and the flightless birds,
where some, like the Kiwi, have lost most of their wings down to a stub,
and the others find their wings more of a hinderance, than useful. One
must ask why would God create a flightless bird with stubs for wings!
Evolution can perfectly account for them. They evolved in isolation where
predators were absent and flight became a wasteful luxury quickly selected
against.
The best example of evolutionary pathways are in the imperfect designs found
in nature. There are organisms who use imperfectly "designed" organs to
perform a function. Creatonists can't give a reasonable answer to imperfect
design, just "God wanted it that way", or they will claim that it is a
degenerative state of a created organism [117]. This is such absurdity.
What mechanism drove an organism to be "degenerative"? It must have
"de=evolved" but how, what mechanism if not by natural selection? In the
case of the flightless birds, it is indeed degeneration, but by known
evolutionary mechanisms. In the case of the panda, with its sixth "finger",
it is a case of evolution using what ever structure is available to move
into a new niche.
If it is a creationist "degeneration", then how can it survive, since by
their own admission, organisms must be perfectly designed or they would not
survive?
PART THREE
~~~~~~~~~~
FILLING THOSE GAPS
--FOSSIL TRANSITIONS:
=====================
Creationists claim there are no intermediates, and that there are huge gaps
in the fossil record, gaps which cannot be closed between the major groups
of animals. They will quote people like S.J. Gould to the tune of "All
paleontologists know that the fossil record contains precious little in the
way of intermediate forms; transitions between major groups are
characteristically abrupt [112].", or "The extreme rarity of transitions in
the fossil record persists as the trade secret of paleontology [112]."
If creationists are so confident that major transitions do not exist then
ask them if you were to show just one transition would they admit to major
evolutionary trends. Force them to make that commitment first, then proceed
to show the following.
Despite what Gould has been, incorrectly, quoted as saying, there are
intermediate forms and Gould knows them very well. Could it be that Gould
has been, again, misrepresented?
Inasmuch as specific lineages have not been established (how could it with
the scant fossil record) intermediates between the major taxa do indeed
exist. They are organisms which have both new and old characteristics.
That is, the organisms linking mammals and reptiles will have both reptilian
and mammalian characteristics occurring in the same fossil. There should
also be found occasional character traits which will be in the middle of the
two taxa.
This is what it means to be an intermediate. It is a mosaic of
characteristics. The creationist argument of half winged birds should be
found in the fossil record is a strawman argument. Creationists have
defined away transitions.
Cuffey's article "Paleontological Evidence and Organic Evolution" [44] notes
that there are categories of transitions found in the fossil record. They
range from bridging species gaps to bridging class gaps. Simpson [110,
p.397] notes a specific example of elephant speciation where fossils trace
one species, Elephas planifrons, to another species, E. meridionalis in a
single lineage.
Gingerich [58] noted speciation in the mammal Hyopsodus strictly by the
fossil teeth that were found in abundance (see Figure 7).
But this is not the major creationist charge. They charge that the gaps
between the classes (birds, amphibians, reptiles etc) cannot be bridged. To
them these are separate creations, and by their own definition, transitions
cannot exist. But in fact they do.
Carroll notes
"During the past 20 years, our knowledge of fossil vertebrates has increased
immensely. Entirely new groups of jawless fish, sharks, amphibians, and
dinosaurs have been discovered, and the major transitions between amphibians
and reptiles, reptiles and mammals, and dinosaurs and birds have been
thoroughly studied [31, p.xii]"
Two things must be understood at the start. One, the organisms
paleontologists consider as intermediates are not the actual organisms that
blazed the trail. For example, Archaeopteryx is not the ancestor to all
birds, but a representative of the group of organisms which did give rise to
birds. They contain the features one would expect to see in organisms
moving into new adaptive zones.
Two, getting into anatomical details is essential for understanding how and
why transitional organisms are intermediates. A thorough understanding of
skeletal anatomy of fish, amphibians, reptiles, and mammals is required to
know what paleontologists are talking about when, for example, two bones
fuse in the move from fish to amphibians. Some character trait differences
between taxa can be as simple as the number of holes in the skull, or the
location of the articulation of the jaw bone. But to understand how they
work requires understanding in detail the bones themselves as found in
different organisms.
Then there are those long and complex sounding names. The horrendously
complex names for fossils that paleontologists use can make one's head spin,
but the paleontologist requires this for accuracy and understanding. "Cat"
and "Dog" are meaningless to a paleontologist. Which Felis, which Canis?
It is precisely this complication that creationists have managed to con
their lay followers.
When dealing with a creationist, you will need to have a paleontology book
with you, Robert Carroll's [31] is the best and up to date. Tough, jargon
filled, terminology will be kept to a minimum here, but can't be totally
avoided. Let us now look at specific examples of intermediate fossils.
[*] Fish to Amphibians: The major change in body traits required to move
onto the land would need to be in supporting the body under gravity,
feeding, respiration, locomotion, water balance, sensory input, and
reproduction. Quite a bit of changes! But not all appeared at once.
The group which bridges this gap is the Leptospondyls which appear to have
been derived from the Rhipidistian fish, of which the famous Coelacanth is
an extant representative. Though no specific fossils making the transition
have been found, they mark the changes that took place. They had paired
limbs for walking like an amphibian, but a finned tail like a fish. They
had large ribs to hold the internal organs (viscera) out of the buoyancy of
the water, but retained a fish vertebral column. The brain case bones were
solidified like the amphibians, but other features of the skull are
rhipidisian. Carroll notes: "Aside from these changes, there are
relatively few differences between the pattern of the dermal bones of the
skull of early amphibians and rhipidistians such as Osteolepis and
Eusthenopteron. Nearly all the bones can be directly and unquestionably
homologized [31, p.160]." Ichthyostega is the "type" transition, not the
actual transitional organism, but a very close representative of the actual
transition.
Two groups of primitive amphibians emerged, the Labyrinthodonts, which still
contained many rhipidistian characteristics, and the specialized
Leptospondyls. Labyrinthodonts, Solenodosaurids, Limnoscelids and
Tseajiids, share many characteristics with primitive reptiles. Details of
these transitions can be found on pages 158-191 of [31].
Carroll concludes
"Paleozoic amphibians form a phylogenetic link between the rhipidistian fish
and more advanced tetrapods. The earliest amphibians, the Upper Devonian
ichthyostegids, retain many primitive features of the skull, vertebrae, and
girdles from their fish ancestors but have fully developed limbs for
terrestrial locomotion. [31, p. 188]"
[*] Amphibians to Reptiles: It is interesting that on page 193 of [31]
Carroll writes "In sharp contrast with the fossil record of amphibians,
modern amniotes are linked to their Paleozoic ancestors by a relatively
complete sequence of intermediate forms." The fossils which are half
reptile, half amphibian are Hylonomus and Paleothyris. Details of this can
be found on pages 192-239 of [31].
It is also interesting that Romer, who Gish used for his book against
transitions, wrote
Primitive Paleozoic reptiles and some earliest amphibians were so similar in
their skeletons that (as was seen in the case of Seymouria and Diadectes) it
is almost impossible to tell when we have crossed the boundary between the
two classes. The true test, of course, is the type of egg the animal laid;
but direct evidence for this is practically impossible of attainment in the
case of extinct forms. The ties between primitive reptiles and
anthracosaurian amphibians are so many and so clear that it is reasonable to
believe that the reptiles stem from that group [104 ,p. 102]
How did Gish miss that! The emergence of the shelled egg may have been a
quick evolutionary adaption by an atypical population that was able to
occupy new niches and propagate themselves further inland.
[*] Reptiles to Mammals: In Gish's book Evolution. The Fossils Say No!
[60]
he complains that the evolutionist cannot explain how the reptile evolved
into a mammal. The jaw bone articulation at the skull is different.
Reptiles have three bones comprising the lower jaw, while mammals have only
one. The articulation with the skull on the reptile is with different bones
than the mammal. Complicating matters is that reptiles have one ear bone
to transmit sound, while mammals have three. Gish maintains there are no
fossils to show how that complex change from reptile to mammal happened.
McGowan gives details of exactly that [90]. The reader is encouraged to get
a copy and use it. Also Strahler [ 115] recapitulates McGowan. The point
made here is that indeed there is a nice sequence of fossils which show the
change from the reptilian condition to the mammalian condition. They are
called the mammal-like reptiles. They are organisms which retain reptilian
characteristics, but have new mammalian characteristics. McGowan tables
these traits on page 138 of [90].
Carroll gives full details on page 392 to 397 of [31]. Of one fossil in
particular he notes:
"In Probainognathus, the surangular and dentary extend back to the squamosal
to form a second jaw articulation. As the dentary is further elaborated, we
can recognize two functional jaw joints, a medial reptilian joint, which
consists of the articular and quadrate, and a lateral mammalian joint, which
is formed by the dentary and squamosal. Both are retained in early mammals
[31, p. 395]"
Sounds complex, but the gist of the argument is clear: THIS FOSSIL HAS BOTH
A REPTILIAN JAW JOINT AND A MAMMALIAN JAW JOINT OPERATING AT THE SAME TIME!
The front cover shows a drawing of this very fossil. Note in the overhead
view, that the skull looks rather mammalian in its wide appearance, but the
brain case is still very small showing the reptilian condition.
So here is how the shift from three bones (reptile) to one bone (mammal) of
the lower jaw evolved. The other two bones of the lower jaw became
incorporated into the middle ear for sound transmission (see Figure 8a & b).
Not only is this shift seen in the fossils, but it occurs during fetal
development of marsupials! "During their development in the pouch, the
maleus and incus retain the reptilian role of the articular and quadrate.
Only when the young leave the pouch do these bones separate from the lower
jaw and enter the middle ear [31,p. 395]"
[*] Reptile to Dinosaur: The new understanding of dinosaurs as not being
true reptiles is now filtering through to the public. Robert Bakker's
excellent book Dinosaur Heresies [7] gives specific details of why they are
not reptiles, but are a group of their own. Dinosaurs did not walk with
legs out to the side, but more like the mammalian condition of propping up
the body from beneath. Trackways found, of which there are more than
actual fossils, shows these organisms moved with mammal like agility, than
reptilian sluggishness.
Predator-prey relationships seem to indicate, as well as other anatomical
features, that dinosaurs were warm-blooded to some degree.
The exact lineage for the dinosaurs is not precisely known, but trends do
point the way especially in the change in ankle joints to allow for the
dinosaurian posture. Carroll sums it up:
Archosaurs include the living crocodiles, dinosaurs, pterosaurs, and a
primitive assemblage from the Triassic, the thecodonts. Archosaurs may
share a common ancestry in the late Paleozoic with rhynchosaurs,
protorosaurs, and trilophosaurs. Together, these groups constitute the
Archosauromorpha. They share a similar specialization of the ankle that
facilitates a more upright posture [31 ,p.283].
The subsequent complex radiation of the dinosaurs is, unfortunately, beyond
what can be put here. The reader is directed to both Bakker [7] and Carroll
[31] for details.
[*] Dinosaurs to Birds: Most creationists, such as those at the ICR, still
regard Archaeopteryx as just another bird. It had asymmetrical feathers,
and that settles it (Taxonomists use feathers as the sole criteria for
placing an organism into the Class Aves.). The fact it has teeth, or that
it has a tail and separate finger bones on the wing, does not matter to
them. It is a bird --period.
A small number of creationists still cling to the notion perpetrated by
Hoyle and company that Archaeopteryx is just a small dinosaur with feather
impressions placed there by someone --in other words a hoax.
The latter charge has been thoroughly discredited, especially in the
discovery of a sixth specimen. Details of this fiasco can be found in [35,
63]. This hoax notion fails also on other counts, because it is not just
the feathers that make Archaeopteryx intermediate to the birds and
dinosaurs.
Birds are living dinosaurs, according to Robert Bakker. The similarities
between the small carnivorous dinosaurs and birds is just too close.
Archaeopteryx, the famous mosaic of bird and dinosaur features, is the
representative that bridges this gap. Also, there are others which come
between the dinosaurs and Archaeopteryx. Pages 298 to 322 of [7] explain in
detail the origin of birds through Archaeopteryx. (see also [90, 96]).
At one point Bakker describes John Ostrom's [96] investigation into the
origin of birds. One specimen in particular that Ostrom described in
detail was a carnivorous dinosaur called Deinonychus, a rather fearsome
looking beast of man height with a large sickle claw on the hind feet for
disembowelment of its prey.
When Ostrom carefully examined a specimen of Archaeopteryx, he discovered
that the hand bones were merely small hands of Deinonychus. Bakker wrote:
"Alternating images flashed before [Ostrom's] mind's eye as he scrutinized
the Dutch [Archaeopteryx] specimen. He recognized the bony hands with their
three long, clawed fingers as belonging to Archaeopterx. But he also
recognized in that hand a miniature version of Deinonychus's. Archaeopteryx
had been pigeon-sized, its hand four inches long; Deinonychus had been as
heavy as an average man and could stretch its hand a full nine inches. Yet
the small bird hand and the dinosaur were virtually identical in shape.
Each finger and wrist bone had been molded to the same peculiar
biomechanical pattern, and adaptive plan totally unknown anywhere in the
animal kingdom outside the Dinosauria. There was an important message on
this Dutch slab, and Ostrom read it correctly. Archaeopteryx and
Deinonychus had been very closely related. And birds were indeed the direct
descendants of the dinosaurs [7, p. 312]."
Figure 9 is how the shape of the various organism's finger bones are
related. It is interesting to note that the arm bone articulation of
Deinonychus and the ranges of movement are virtually identical to
Archaeopteryx. That is, Deinonychus moved its arms in the same flapping
manner as a bird! Why? Simple, it was a strategy that evolved for
capturing its prey and holding it firmly. Thus flight was a simple shift of
function for Archaeopteryx. The motion for capturing prey was preadapted to
gliding and flapping.
And it was not just the fingers, but other anatomical similarities between
Archaeopteryx and Deinonychus, such as the shape and configuration of the
ankle, hip, shoulder and a virtually identical coracoid bone placement
unique amongst the dinosaurs. Deinonychus had no ossified breastbone (it
may have had a cartilaginous one), but Oviraptor, Segisaurus and
Velociraptor, all small dinosaurs, do [96]. Breastbones in birds are not
unique to birds!
Thus, the dinosaurian features of Archaeopteryx are well founded it is not
"just a bird". At the same time definite bird features, feathers and
perching feet, are well founded.
Creationists claim that having clawed wings on Archaeopteryx is not unique
to birds --the South American Hoatzin has them. Notice on the figure that
the Hoatzin chick still retains not only the claws, but the unfused finger
bones, only later to be fused and the claws reabsorbed. That is proof of
evolution, not against it! Bakker noted: "Hoatzin's ancestors never lost
the genetic blueprint for producing Archaeopteryx-style clawed fingers [7,
p.316]."
But what of the origin of these complex feathers? Carroll describes in
detail flight and feathers on pages 340 to 342. Of interest is:
"Developmentally, feathers and reptilian scales are homologous structures.
In contrast to hair, which is strictly epidermal in origin, feathers and
scales incorporate mesodermal tissue as well. Either feathers or scales can
develop in a particular area of the skin but not both. This phenomenon is
readily seen on the legs of birds such as the domestic fowl, where the
relative extent of the two tissues vary considerably [31, p.341]"
[*] The Origin of the Diversity of Mammals: It seems a vast amount of more
literature is written about mammal radiations and fossils than any other
group. This is due mostly to the large number of fossils, and the
relatively shorter time since they existed. Of course, this is great for
establishing phylogenies for the various mammals, including us.
One of the orders of mammals creationists have the most trouble with are the
whales. Strahler [115] gives some excellent descriptions of fossil whale
intermediates, and Carroll describes the details on pages 522 to 523.
Specifically he notes
"The skulls of Eocene whales bear unmistakable resemblances to those of
primitive terrestrial mammals of the early Cenozoic. Early genera retain a
primitive tooth count with distinct incisors, canines, premolars and
multirooted molar teeth. Although the snout is elongate, the skull shape
resembles that of the mesonychids, especially Hapalodectes, a small Eocene
genus with particularly narrow shearing lower molars [31, p.522]"
For a summary of the evolution of whales read pages 1 to 19 of
Creation/Evolution Journal Fall 1982 [38, 79]+.
You will find that creationists will attack the phylogeny of the horse. For
preparation read McGown [90] pages 142 to 148, Carroll [31] pages 527 to 536
and Creation/Evolution Journal Vol. 5, No. 2, pages 4 to 30 (93]
In concluding this very brief expose of the fossil intermediate forms, it
must be emphasized that the creationists will claim that these above are not
transitions, but fully functioning organisms. The only way to deal with
that is to inform them that they have it wrong as to what a transition
should look like.
One way to point this out would be to take a series of transitions, like of
the horned dinosaurs, and ask the creationists what would satisfy them as to
an evolutionary order. You can do this by photocopying the phylogenetic
tree on page 7 of Creation/Evolution Summer 1982 [48]. Then starting with
Psittacosaurus (because it is at the bottom of the record) ask them to
arrange the fossils in an order they will accept. Remember to emphasize
that they must place them in the correct stratigraphic sequence as they are
found in the rocks. Guess what? They will come to the same conclusion as
the paleontologists! Then ask the creationists how the Great Flood
deposited these fossils in a nice evolutionary sequence, that even they
accept!
The preceding examples are some of the organisms which paleontologists
consider transitions, and the justification as to why they are so regarded.
If the creationists disagree, then let them give physical evidence as to why
they are not. Don't let them get away with quoting so-and-so evolutionist
who says they are not. Chances are the quote is a misrepresentation. Get
the physical data from them. You will find that they can't provide it.
Then reinforce to them that these are indeed the intermediates creationists
are looking for.
--------------------------------------------------------------------------
FIGURE 7: Fossil evidence for speciation in the mammal Hyopsodus. Graph
shows the variation in tooth size through time. H. loomisi became larger
and diverse enough to be classed as separate species H. latidens and H.
simplex. The former evolved into H. minor and H. miticulus. The latter in
turn evolved into H. lysitensis and H. powellianus and so on. From
Gingerich 1976 [58]
FIGURE 8a: Relationship of the bones found in the jaw joint region of the
mammal-like reptile Probainognathus. This organism has both a reptilian jaw
joint and a mammalian jaw joint opperating at the same time. This is
possible because the reptilian articulation between the quatrate (q) and
articular (art), and the mammalian articulation between the squamosal (sq)
and dentary (d), and the ear bone --stapes-- are all found in the same
immediate region. The quadrate and articular became the mammalian ear bones
malleus and incus respectively. See McGowan [90] page 139 for details.
FIGURE 8b: Sequence of events for the change from the reptilian jaw region
to the mammalian condtion. a) Dimetrodon, b) advanced therocephalian, c)
Thrinaxodon, d) Probainognathus, e) Jurassic mammal Morganucodon, and f) a
hypothetical Jurassic panthothere. The articular became detached from the
dentary and reduced to become the malleus of the mammal ear bones. Both
from Carroll [ 31], pages 390 & 394.
FIGURE 9: The evolution of the hand bones from reptiles at the bottom, to
birds at the top. Notice how Deinonychus, Archaeopteryxs and the Hoatzin
chick have essentially the same hand. From Bakker [7, p. 313]
---------------------------------------------------------------------------
+ The July 22, 1990 Toronto Star reported on a 40 million year old whale
fossil found in Egypt which has a full set of hind legs.
--------------------------------------------------------------------------
PART 4
~~~~~~
TAXONOMIC CLASSIFICATION
--A THEORY OF LINEAGES
========================
To make our discussion of evolution more complete we need to look at the
origin of the higher taxa. But before we can do this we need to understand
what the higher taxa are. Thus we need to look at the criteria upon which
animal classification is based.
Is classification merely pigeonholing? Or is it a theory of evolutionary
relationships? A purely pigeonhole type of classification is one commonly
used in classifying inanimate objects, like types of houses or buildings.
Such a classification is used merely for our convenience and simplicity. In
some cases more than one type of classification can be used depending upon
the reasons for classifying.
Organisms can also be classed this way. Thus, for example, all animals that
fly (beetles, butterflies, birds, bats, etc.) could be one class of
organisms. All those that swim are classed as another. All those who
burrow in the ground another, and so on.
If the creationists are firm that all living organisms are unrelated
creations then this type of classification would be just as valid, and just
as arbitrary, as any other method used.
But biologists see things quite differently. They see a lineage of descent,
and thus the classification system used should reflect that. In fact,
classification of organisms should be a theory of descent with predictive
powers. Another way of looking at classification is that it is not at all
arbitrary, but evolution itself sets the classification rules. Discovering
those rules, however, is definitely not an easy task, and arbitrary
conditions are often forced onto the system so that classification can even
occur.
Ironically for creationists to use the current system of classification of
organisms means they must accept the evolutionary process without realizing
it. In fact, the whole argument about what a "created kind" means shows
that creationists desperately wish to remove themselves from the
evolutionary classification. As hard as they have tried to deal with this,
creationists still have not come up with a workable model of classification
based upon created kinds, and they never will.
Taxonomists have three basic methods of classification. The first is
phenetics. That is, organisms are classed into groups based upon shared
similarities. This was the pre-Darwinian way of classifying organisms. All
traits which were used to lump organisms together had the same degree of
importance.
The second way of classifying was strictly by "recency of common descent",
or cladistics. This took into account strictly traits that were derived
from other organisms. The third way of classification takes into account
both the shared similarities --but weighs some traits more important than
others-- and the derived characteristics, or evolutionary trial, those
traits show. Even this method has its problems when applied to the natural
world (see Mayr [88] pages 423 to 476 for discussions as to why.) For us
here all we are concerned with is how large scale classification is related
to the origin of the higher taxa.
In the creationist publication Origin's Research, I had quite a discussion
about this. The point creationist Art Battson was driving home was that no
new taxa evolved since the Cambrian [14, 123, 124]. To him, if evolution
were true, we should see new phyla arise at any time in the past. He
expected that new phyla could evolve if evolution was true, and since there
are no new phyla after the Cambrian then evolution must not be true. This
shows a fundamental misunderstanding of evolution and phylogeny (not
surprising).
All that exists in nature are species, all that has ever existed in nature
are species. If one could travel into the past and look at the organisms,
all one would find are still species. Regardless of when you looked that
is all you would find. Classifying these populations at different times is
a different matter altogether.
The grouping of organisms into high taxa has been very difficult and
originally largely based upon extant organisms. On the scene came the
fossils and the system required overhaul in some cases. For example the
mammal-like reptiles or cynodonts. Are they mammals or reptiles? If you
were there when the cynodonts lived what would you classify them as? What
is even worse is that if you did not know that mammals were to evolve some
time down the road would that make a difference as to how you classify them?
Merely a strange looking reptile?
Today it is even harder to place the cynodonts since specific traits to
mammals (hair, mammary glands, etc) are not preserved. Only the
configuration of the skeleton can be used. But in this case there is no way
of determining because of the truly intermediate traits. Taxonomists, then,
force themselves into assigning an arbitrary fixed line and over it the
organism is a mammal, and before it, it is a reptile. Thus the cynodonts,
for example, are artificially assigned to the reptiles. Creating a false
dichotomy.
Bird and dinosaur classification is an example of how traditional ways of
looking at organisms reflects an incorrect lineage. Remember that
classification should have predictive value. But observe: reptiles are
assigned as a class --Reptilia. Dinosaurs are a subclass of the Reptilia.
However, birds are assigned to the rank of class, supposedly equal in rank
to the reptiles. But birds are derived from the lower subclass of
dinosaurs!
Bakker advocates that the reptiles are not a natural group and should not be
ranked as class [7]. The dinosaurs should be elevated to class Dinosauria
and birds a Subclass of them. This would make far more sense especially
since dinosaurs were as diverse and as dominant then as mammals are today.
But tradition is long in changing (I personally advocated such a change to
my systematics prof in 1976). The only way to change it is to just forcibly
use the better system. Clearly the ranking of higher taxa needs to be
overhauled to reflect the understanding of the fossil record. Other
discussions of how fossils have changed the taxonomic classification can be
found in [47, 99].
Despite these traditional short falls, classification is very important in
our understanding of the relationships amongst organisms. This is the
important part for us here. The higher taxa are based upon major shared
traits that are really not very different from each other. These traits
evolved at a specific time in the past, probably in some atypical
population, that later flourished into a totally new group of organisms.
Table two shows the criteria used to separate the phyla. Notice that for
the most part it is only one trait, a minor trait, that distinguishes a
separate phyla. That trait is shared, no matter how diverse the phyla, by
all members of that phyla. That trait evolved very early on in the fossil
record.
Note that the trait evolves through time, but that we are still looking at
only species regardless of the time frame. The classification system is
based upon these traits in a hierarchal manner. That is, one trait
distinguishes the phyla, within that phyla are other traits that distinguish
classes and another for order and so on. The more traits that are observed
for grouping organisms the more taxonomic levels are required. For example,
many more levels of classification are required for insects than for
mammals. The reason is the greater diversity and related traits that groups
them together. In insects we have Infraclass, Superfamily, Subfamily, Tribe
to name a few of the divisions these organisms must be classed as.
So what is the origin of the higher taxa then? Figure 10 shows a
hypothetical set of organisms through time. If one were to go back into the
Cambrian, one would see only populations, and a very diverse and bizarre set
at that [64]. One could not classify these organisms into class, order or
phyla. There is not enough time in the evolution of these organisms.
-------------------------------------------------------------------------
FIGURE 10: A simplified hypothetical model for the origin of higher taxa.
If one could go back into time to take snapshots (horizontal planes) one
would only find species. The further back into time, the more
diversification of major body plans one would find [64]. Classification
depends upon shared and unique characteristics. The greater the divergence
and survival of ancestral traits, the more taxonomic levels one needs to use
in classifying extant species.
At a time near the beginning of the emergence of a unique body plan (say the
Cambrian "explosion") all one has are species which contain minor
variations. Each of the populations found during that time are denoted by
the 24 letters of the alphabet (enlargement at the bottom right). Each
population has a small, but unique character trait and are reproductively
isolated from the other populations. These character traits evolved due to
speciation via natural selection. This is what is found, for example, in
the Burgess Shale deposit. One cannot classify these organisms into phylum,
class, or order. There has not been enough time or restriction of body
plans.
Next a major extinction takes place where most of the populations are
eliminated (enlargement bottom left) except some small and very atypical
populations. This sets the stage for passing their unique characteristics
onto subsequent generations. A snapshot later on (middle plane) shows that
the original restricted populations have diversified and occupied all the
niches left vacant. Still all one has are species, but they can be
arranged according to the ancestoral characteristics into slightly higher
taxa than species. Due to newly arrived characteristics via speciation,
new traits emerge. These new traits are now denoted by numbers (middle
right enlargement) from 1 to 25. A letter-number combination shows
ancestoral and new characteristics respectively for each species found.
Another mass extinction sets the stage for futher restrictions of original
traits (top left enlargement). One entire trait "J" becomes totally
extinct. A final snapshot (present day) again has only species found, but
can be arranged into a hierarchal classification based upon ancestoral and
new character traits. Letter-number-letter combinations shows long time and
short time ancestoral traits, and newly derived traits respectively for each
species found.
Of the original 24 populations found in the first snapshot, only 3 have had
some of their traits filter through to the present. Of the 25 number
traits which evolved in the "T" line, only 4 passed on traits to the present
populations. Due to these traits one can classify the many species found
today into phyla and class. For example, species "T21A" would be classed as
belonging to Phyla "T", and Class "21". "T21B" belongs to the same phyla
and class, but is a separate species. "T3A" belongs to the same phyla, but
different class. "D9A" belongs to a different phyla.
Under this model one can see that no new phyla can ever emerge again, since
the stage for the critera of phyla was set in the past. One can also see
that other than species, the other taxa are not real entities upon which
evolution can select. They are the consequences of restriction of certain
character traits which get passed down through time. They are body plans
which were so successful, or "fit", that they perpetuated through successive
speciation events to emerge as a major body plan. The "gaps" between body
plans disappears when the phylogeny of the trait is traced through time.
---------------------------------------------------------------------------
Of the millions of diverse populations, only a few have survived to produce
all the organisms of today. The reason is that mass extinction restricted
that once diverse ecosystem. Only a few of the species survived, and their
unique traits set the stage for classification into higher categories. For
example, some organism in the Cambrian set the stage for the vertebrates by
passing down the notochord to subsequent generations and became the
"backbone" of the vertebrate plan (pun intended). We do not know what
organism that was, but back then it would have been nothing more than one
strange looking beast amongst many. It was not a phylum then, only a
species. But it set the stage for the classification of phyla because it
left that one trait to many millions of years of organisms to follow.
The next stage saw the organisms proliferate filling the vacant niches.
Their unique traits were passed on, as well as new traits evolving. At that
time the notochord found in the populations separating by speciation would
have allowed only the classification of them as a family of notochords
amongst other families of non-notochords, nothing more.
Later, as the diversity continued, new traits emerged, such as ossification
of parts for support. Some populations had it, some did not. Those
populations which had some bone emerging would have been oddities, and
nothing more. Another large extinctions cleared the way for the
notochord/bony organisms to proliferate. Now we classify again and we have
two major criteria, one nested within another, to help in organizing body
plans that are emerging. Still no phyla, but now classes (those with
notochords, those without), and orders (those with notochords and bone and
those with notochords and no bone). Still as one looks at the total biota,
we still only have species, nothing more.
Finally in this long story, we have come to today, where enough
characteristics have evolved to lump organisms into a complex hierarchial
system, but the basic plan that sets the Phylum Cordata apart from the other
30 phyla is only the presence of the notochord, which evolved first in the
Cambrian.
Thus no new phylum, or class, or order will ever evolve again. As time
continues into the millions of years in the future, intelligent beings will
need even more levels of classification to fill the diverse but highly
restricted organisms. Who knows what penguins could evolve into should the
niches open up for them, a whole "class" of diversity!
But on the side of "created kinds" one would not expect to see the
evolutionary style of character traits emerging. Organisms would be totally
independent of each other. Even automobiles show descent with
modification! Once a plan (such as the internal combustion engine) works it
is passed on through subsequent generations. But the creationists' all at
once creations can't be classed that way. They would have to classify in
such a bizarre manner as to be something from Alice in Wonderland. All
traits would be just as equal in the criteria for lumping as any other
trait. Such a system, phenetics, has already shown to not work [88].
But no fear, such a system based on "created kinds" will never emerge, the
biota won't allow for it!
--------------------------------------------------------------------------
SUBKINGDOM: Protozoa
Phylum 1 >(not multicellular)
SUBKINGDOM: Metazoa
===Branch A Metazoa
Phylum 2 >Metazoa (Cellular animals with the organization plan of an
outer layer and an inner reproductive group of cells)
===Branch B Parazoa (Cellular animals with several kinds of interior
cells, no mouth or internal organs)
Phylum 3 >Porifera (Sponges)
===Branch C Eumetazoa (Cellular animals with tissue and organs, mouth and
digestive tract)
GRADE I. Radiata (radial symetry derived from embryonic symetry,
GRADE II. Bilateria (Bilateral mesoderm, high degree of cellular
specialization) symetry, organ systems, mesoderm)
Phylum 4 >Cnideria Phylum 5 >Ctenophora (Comb jellies)
DIVISION A Protostomia. (Bilateria, mouth from blastopore)
SUBDIVISION 1: Acoelomates
Superphylum Acoelomata (bilateral no coelom)
Phylum 6 >Platyhelminthes (flatworms)
Phylum 7 >Nemertina
SUBDIVISION 2: Pseudocoelomates
Phylum 8 >Acanthocephala
Phylum 9 >Entoprocta
Superphylum Aschelminths
Phylum 10 >Rotifers
Phylum 11 >Gastrotricha
Phylum 12 >Kinorhyncha
Phylum 13 >Nematoda
Phylum 14 >Nematomorpha
SUBDIVISION 3: Coelomates (With a body cavity, the coelom, lined with
peritoneum appearing in the mesoderm)
Superphylum Inarticulata (unsegmented)
Phylum 15 >Priapula
Phylum 16 >Sipuncula
Phylum 17 >Mollusca (Clams, snales, squids, octopus)
Phylum 18 >Echiura
Superphylum Articulata (segmented)
Phylum 19 >Annelida
Phylum 20 >Tardigrada
Phylum 21 >Onychophora
Phylum 22 >Pentastoma
Phylum 23 >Arthropoda (crabs, lobsters, spiders, mites, insects,
millipedes, centipedes)
DIVISION B Deuterostomia (Bilateral, mouth not from blastopore; coelom
arising from primative gut)
Superphylum Tentaculata
Phylum 24 >Phoronida
Phylum 25 >Ectopracta
Phylum 26 >Brachiopoda
The following deuterostomes cannot be arranged into a wholly
satisfactory superphyla
Phylum 27 >Echinodermata (Secondary radial symmetry and a water
vascular system)
Phylum 28 >Chaetognatha (Permanently bilateral; with no gill
slits or endoskeleton; with a digestive tube)
Phylum 29 >Pogonophora (Permanently bilateral; with no gill slits
or endoskeleton; no digestive tube)
Phylum 30 >Hemicordata (Permanently bilateral; adults with gill
slits, endoskeleton or both; embryos no notochord)
Phylum 31 >Chordata (Permanently bilateral; adults with gill
slits, vertebra or both; embryos with notochord)
TABLE 2 (Left): Hierarchial classification of the 31 phyla of the animal
world. Notice that the criteria for separating various groups of organisms
is small, especially in the case of separating the Subkingdom Metazoa into
three branches. All that has been accomplished is various degrees of
cellular specialization easily attained by intensification of function of
parts of the organism. Within the Eumetazoa, the two Grades differ only in
being radially or bilaterally symetrical. Within Subdivision 3, the
Coelomates, the only difference in the two Superphylum is that the
Inarticulata are unsegmented. In the Articulata the segmented organisms
have the same organs in each segment, except in the arthropods where
speciallization has occurred in the segments. The only difference between
Phylum 27 to 31, is whether digestive tubes, gills, endoskeleton, or
notochords exist in any stage of development. Adapted from Meglitsch, 1972
[91].
---------------------------------------------------------------------------
CONCLUTION
~~~~~~~~~~
We have discussed much in the past 21 pages. To a non-biologist this may
have been too much in one reading. Again, the reader is encouraged to read
some of the material cited earlier.
We have covered natural selection and evidence for speciation. We have seen
that indeed natural selection can be a positive force in selecting for new
structures. Two major methods of speciation --allopatric and sympatric--
indeed do occur, usually in small peripheral subpopulations. For more
eamples read off the names of the following references [9, 11, 13, 15, 17,
18, 22, 23, 25, 26, 32, 33, 34, 37, 52, 53, 55, 70, 72, 73, 74, 78, 80, 81,
82, 83, 85, 89, 95, 100, 114, 118, 119, 120, 121, 122, 125]. We also
discussed that fitness is not about survival of the individual, but about
the genetic contribution a mating pair of organisms leaves to subsequent
generations.
The second section discussed and clarified how new body parts can evolve
from a shift in function of old body parts. Specific examples where used
to show that a mosaic of character traits is important for understanding how
an organism can function in a totally atypical environment.
The third section exemplified the second section by showing specific
examples of transitions in the fossil record. When these organisms lived
they would have looked like out of place and bizarre like our extant
organisms the panda, bat, whale, mudskipper, flying squirrel, etc. Two
detailed examples of bridges between major taxa, the reptile/mammal
transition and the dinosaur/bird transition were shown. The point was that
creationists have a misunderstanding of what a transition is.
The last section explained that taxonomic classification, though not perfect
and burdened with tradition and arbitrary restraints, is still a theory of
evolutionary descent with predictive powers. Species are the only units of
reality, and evolution only acts upon individuals of populations. The
origin of the higher taxa, like phylum and class, are a consequence of
extinction restricting a diverse set of organisms into a few traits that are
used today to justify classification into distinct groupings. Thus the
higher taxa are time dependent, not absolute but relative, to the amount of
diversification taken place after major restrictions. No new phylum or
class can ever originate again.
In this discussion many items were left out that show unequivocal evolution.
These included geographic distribution of organisms. The distribution of
the marsupials on all major continents, and then a restriction to
essentially Australia, where no placentals were endemic, shows isolation
caused by plate tectonics and subsequent evolution.
Another topic not discussed is the biochemical comparison work. This work
is showing relationships of extant organisms based upon DNA and protein
similarities. Phylogenetic trees can be constructed to show these
relationships. Though still in its infancy, the amount of understanding
already pouring out is a phenomenal vindication of evolution. I suspect
that one day it will actually predict the fossil record.
Inasmuch as all of these topics that show evolutionary descent do have their
flaws, upon which creationists exploit and overblow, all of them do point in
the same direction --evolution. They may all have their problems and
assumptions, but not all of them can be that much wrong.
Evolution is a fact --period. Organisms, over successive generations, do
change in responce to environmental pressures. The theory of evolution is
the mechanism by which the process takes place --the interaction of
micromutation, reproduction and natural selection.
The creationist charge that evolution can no more create new kinds than a
doghouse can evolve into a house fails because inanimate objects are not
reproducing populations --organisms are.
One thing also not discussed here is the reason for environmental changes.
Plate tectonics is the major reason for environmental changes, but such a
discussion would require a monograph of its own. Another charge of
creationists, that evolution violates the second law of thermodynamics would
also require a separate monograph, though discussions have already shown
that the creationists are wrong.
One final point. Creationists will argue until they are blue in the face
that to accept evolution means that you must be atheistic. No believer in a
God would accept evolution since that flies in the face of what the Bible
says. This is their OPINION only. There is no underlying reason to reject
that God created through evolution. Some argue that such a creation makes
God more powerful and life more of a miracle. They also argue that a God
who creates through evolution is a lot smarter than a god who creates as if
evolution took place.
I thank Jack Lord and my wife, Dorothy, for their proofreading and comments.
"Creationism is a counsel of despair as far as this aspect of biology is
concerned. It encourages the scientist to abandon all research into the
question because he has no hope of answering it in traditional terms. Such
a negative policy can hardly be described as part of an active scientific
program. In fact, no area of science would be able to progress if every
difficulty were treated as an excuse to give up research because the problem
might be impossible to solve. Creationism is not a scientific approach to
the origin of species; it is a call to give up scientific research into that
particular question." Bowler, P.J. Evolution. History of an Idea, p. 359
REFERENCES
~~~~~~~~~~
This is obviously only a tiny, partial listing of references dealing with
the items in this monograph. Skipping over such long lists of references is
easy to do, but the reader should be urged to read through the titles,
especially aload to a creationist, to get some grasp of the nature of the
published material on evolution. Ask creationists what they think is
published in these references if not specific evidence for evolution!?
[ 1] Andrews, S.M., Miles, R.S. and Walker, D. (19xx) Problems In
Vertebrate Evolution: Academic Press, 411p.
[ 2] Antonovics, J. (1971) The effects of a herterogeneous environment on
the genetics of natural populations, American Scientist. 59:593-599.
[ 3] Arnold, S.J. (1983) Morphology, performance and fitness,Americal
Zoologist 23:347-361.
[ 4] Ashlock, P.D. (1980) An Evolutionary Systematist's View of
Classification, Systematic Zoology 28:441-450.
[ 5] Ayala, F.J. (1969) Evolution of Fitness. V. Rates of evolution in
irradiated populations of Drosophila, Proceedings of the National Acadamy of
Science USA 63:790-793.
[ 6] Awbrey, F. (1981) "Defending 'Kinds' --Do Creationists Apply a Double
Standard?" Creation/Evolution: Issue V, Summer 1981, pp.1 - 6.
[ 7] Bakker, R.T. (1986) The Dinosaur Heresies: William Morrow and Co.
481p.
[ 9] Barber, J.S.F. and East, P.D. (1980) Evidence for selection following
perturbation of allozyme frequencies in a natural population of Drosophila,
Nature 284:166-168.
[ 10] Barghusen, H.R. (1972) "Origin of the Mammalian Jaw Apparatus" in
Morphology Of The Maxillo- mandibular Apparatus: edited by G.H. Schumacher,
Leipzig: Thieme, pp.26-32.
[ 11] Barr Jr., T.C. and Holsinger, J.R. (1985) "Speciation in Cave Faunas"
in Annual Review Of Ecology And Systematics: Vol. 16, pp.318 - 338.
[ 12 ] Barton, N.H. (1983) Multilocus Clines, Evolution, 37:454-471
[ 13] Barton, N.H. and Charlesworth, B. (1984) "Genetic Revolutions Founder
Effects, and Speciation" in Annual Review Of Ecology And Systematics: Vol.
15, pp.133-164.
[ 14] Battson III, A.L. (1986) "The Paradox of Natural Selection" in Origins
Research Vol. 9, No. 2. Fall/Winter 1986, pp.1, 3, 6
[ 15] Benson, W.W. (1972) Natural selection for Mullerian mimicry in
Heliconius erato in Costa Rica. Science 176:936-939.
[ 16] Bishop, J.A. and Cook, L.M. (1975) Moths, Melanism and Clean Air,
Scientific American, Jan. 1975,
[ 17] Boag, P.T. and Grant, P.R. (1981) Intense natural selection in a
population of Darwin's finches (Geospizinae) in the Galapagos, Science
214:82-85.
[ 18] Bock, W.J. (1959) Preadaption and multiple evolutionary pathways,
Evolution 13:194-211.
[ 19] Bookstein, F.L., Gingerich, P.D. and Kluge, A.G. (1978) Hierarchial
linear modeling of the tempo and mode of evolution, Paleobiology 4:120-134.
[ 20] Bowler, P.J. (1989) Evolution. The History of an Idea, Revised
Edition, University of California Press, Berkeley, 432p.
[ 21] Brady, R.H. (1979) Natural Selection and the criteria by which a
theory is judged, Systematic Zoology 28:600-621.
[ 22] Brown, L.N. (1965) Selection in a population of house mice containing
mutant individuals, Journal of Mammalogy 46:461-465.
[ 23] Bush, G.L. (1975) "Modes of Animal Speciation" in Annual Review Of
Ecology And Systematics, Vol. 6, pp.339 - 360
[ 24] Bush, G.L. (1975) "Sympatric Speciation in Phytophagous Parasitic
Insects" in Evolutionary Strategies of Parasitic Insects and Mites, edited
by Price, P.W., Plenum Press, N.Y.
[ 25] Bush, G.L., Wilson, S.M., and Patton, J (1977) Rapid Speciation and
Chromosomal Evolution in Mammals, Proceedings of the National Acadamy of
Sciences USA 74:3942-3946
[ 26] Calhoun, J.B. (1947) The role of temperature and natural selection in
relation to the variation of the size of the English Sparrow in the United
States, American Naturalist 81:203-228.
[ 27] Caplan, A.L. (1977) Tautology, circularity, and biological theory.
American Naturalist 111:390-393
[ 28] Castrodeza, C. (1977) Tautologies, beliefs, and emperical knowledge
in biology, American Naturalist 111:393-394
[ 29] Carroll, R.L. (1969) Problems of the Origins of Reptiles, Biological
Review 44:393-432.
[ 30] Carroll, R.L. (1982) "Early Evolution of Reptiles" in Annual Review of
Ecology and Systematics: Vol. 13, pp.87-110
[ 31] Carroll, R.L. (1989) Vertebrate Paeontology and Evolution, W.H
Freedman. 698p.
[ 32] Carson, H.L. (1970) Chromosome Tracers of the Origin of Species,
Science 168:1414-1418.
[ 33] Carson, H.L. (1983) "Speciation as a Major Reorganization of Polygenic
Balances" in Mechanisms of Speciation, Barigozzi, C. editor, pp.411-433, New
York
[ 34] Carson, H.L. and Templeton, A.R. (1984) "Genetic Revolutionsin
Relation to Speciation Phenomena: The Founding of New Populations" in Annual
Review Of Ecology And Systematics: Vol. 15, pp.97 - 131.
[ 35] Charig, A.J. et al (1986) Archaeopteryx Is Not a Forgery, Science
232:622-626
[ 36] Clarke, B.C. (1975) The contribution of ecological genetics to
evolutionary theory: Detecting the direct effects of natural selection on
particular polymorphic loci, Genetics (supplement) 79:101-113.
[ 37] Clarke, C.A. and Sheppard, P.M. (1960) The Evolution of Mimicry in the
Butterfly Papilio dardanus. Heredity 14:163-173.
[38] Conrad, E.C. (1982) "True Vestigal Structures in Whales and Dolphins"
in Creation/Evolution: issue X, pp.8-13.
[ 39] Cooper, W.S, and Kaplan, R.H. (1982) Adaptive "coin-flipping": A
descusion-theoretical examination of natural selection for random individual
variation, Journal of Theoretical Biology 94:135-151.
[ 40] Cooper, W.S. (1984) Expected time to extinction and the concept of
fundamental fitness, Journal of Theoretical Biology 107:603- 639
[ 41] Cracraft, J. (1983) "Systematics, Comparative Biology, and the Case
against Creationism" in Scientists Confront Creationism edited by Godfrey,
L., W.W.Norton, pp.162-192
[ 42] Cracroft, J. and Eldredge, N. (1979) Phylogenic Analysis And
Paleontology Columbia University Press, 233p.
[ 43] Crompton, A.W. and Jenkins Jr., F.A. (1972) "Mammals from Reptiles: A
Review of Mammalian Origins" in Annual Review of Earth and Planetary
Sciences: Vol. 1, pp.131-156
[ 44] Cuffey, R.J. (1984) "Paleontological Evidence and Organic Evolution"
in Science and Creationism, edited by Montagu, M., pp.255-281 (lists nearly
100 references to intermediate fossils)
[ 45] Dawkins, R. (1987) The Blind Watchmaker: W.W.Norton, 332p.
[ 46] Dobzhansky, T., Ayala, F.J., Stebbins, G.L., Valentine, J.W. (1977),
Evolution: W.H. Fredman and Co. 572p.
[ 47] Donoghue, M.J, Doyle, J.A., Gauthier, J., Kluge, A.G. & Rowe, T.
(1989) "The Importance of Fossils in Phylogeny Reconstruction" in Annual
Review Of Ecology And Systematics Vol. 20, pp.431-460.
[ 48] Edwords, F. (1982) "The Delimma of the Horned Dinosaurs"
Creation/Evolution: issue IX, pp.1-11.
[ 49] Eldredge, N. and Cracroft, J. (1980) Phylogenetic Patterns And The
Evolutionary Process Columbia University Press, 349p.
[ 50] Eldredge, N. (1981) "Do Gaps in the Fossil Record Disprove Decent with
Modification?" Creation/Evolution: Issue IV, Spring 1981. pp.17-19.
[ 51] Eldredge, n. (1986) Time Frames. The Rethinking of Darwinian
Evolution and the Theory of Punctuated Equilibria: Simon and Schuster, 240p.
[ 52] Endler, J.A. (1973) Gene flow and population differentiation.
Science 179:243-250.
[ 53] Endler, J.A. (1977) Geographic Variation, Speciation, and Clines.
Princeton University Press, Princeton, N.J.
[ 54] Endler, J.A. (1980) Natural selection on color patterns in Poecilia
reticulata, Evolution 34:76-91.
[ 55] Endler, J.A. (1986) Natural Selection in the Wild. Princeton
University Press, Princeton, N.J.
[ 56] Friedlander, E. (1986) Private monograph examining Duane T. Gish's
quotation usage, Johnson City, TN, USA.
[ 57] Gillespie, D.H. (1986), "Rates of Molecular Evolution" in Annual
Review Of Ecology And Systematics Vol. 17, pp. 637 - 665.
[ 58] Gingerich, P.D. (1976) Paleontology and Phylogeny: Patterns of
Evolution at the Species Level in Early Tertiary Mammals, American Journal
of Science 276:1-28.
[ 59] Gingerich, P.D. (1980) "Evolutionary Patterns of Early Cenozoic
Mammals" in Annual Review Of Earth And Planetary Sciences: Vol 8,
pp.407-424
[ 60] Gish, D. (1979) Evolution? The Fossils Say No!, 3rd edition, Creation
Life Publishers, San Diego.
[ 61] Gould, S.J. (1984a) "Evolution as Fact and Theory" in Science And
Creationism edited by Montagu, A., Oxford University Press. pp. 117-125.
[ 62] Gould, S.J. (1984b) "Toward the Vindication of Punctuational Change"
in Catastrophies and Earth History. The New Uniformitarianism, edited by
Berggen, W.A. and Van Couvering, J.A., Princeton University Press,
Princeton, N.J.
[ 62] Gould, S.J. (various dates) [a series of essays which appeared in
Natural History and consolidated in a series of books: Ontogeny And
Phylogeny, Ever Since Darwin, The Panda's Thumb, The Mismeasure Of Man,
Hen's Teeth And Horse's Toes, and The Flamingo's Smile: W.W.Norton & Co.]
[ 63] Gould, S.J. (1986) The Archaeopteryx Flap, Natural History, Sept.
1986, pp.16-25.
[ 64] Gould, S.J. (1989) Wonderful Life. W.W.Norton & Co.
[ 65] Heffer, J. (1969) Speciation in Amazonian Forest Birds, Science
165:131-137.
[ 66] Hallam, A. editor, (1977) Patterns Of Evolution, As Illustrated By
The Fossil Record, Elsevier, 591p.
[ 67] Halstead, L.B. (1984) "Evolution --The Fossils Say Yes!" in Science
And Creationism, edited by Montagu, A., pp.240-254
[ 68] Harper, C.W. (1976) "Phylogenetic Inference in Paleontology", Journal
of Paleontology 50:180-193
[ 69] Hecht, M.K., Goody, P.C. and Hecht, B.M. editors, (1977) Major
Patterns In Vertebrate Evolution, Plenum Press, 908p.
[ 70] Hedberg, O. (1969) Evolution and Speciation in a Tropical High
Mountain Flora, Biological Journal of the Linnean Society 1:135-148.
[ 71] House, M.R. editor (1979) The Origin Of Major Invertebrate Groups,
Academic Press, 515p.
[ 72] Johnston, R.F. et al (1972) Hermon Bumpus and Natural Selection in the
House Sparrow Passer Domesticus Evolution: 26:20-31.
[ 73] Kaneshiro, K.Y. (1980) Sexual Isolation, Speciation and the Direction
of Evolution, Evolution 34:437-444.
[ 74] Keast, A. (1961) Bird Speciation on the Australian Continent, Bulletin
of the Museum of Comparative Zoology 123:305-495
[ 75] Keller, E.F. (1987) Reproduction and the Central Project of
Evolutionary Theory, Biology and Philosophy, 2:383-396
[ 76] Kitts, D.H. (1974) "Paleontology and Evolution Theory", Evolution
28:458-472.
[ 77] Kluge, A.G. and Strauss, R.E. (1985) "Ontogeny and Systematics" in
Annual Review Of Ecology And Systematics Vol. 16, pp.247-268
[ 78] Koref Santibanez, S. and Waddington, C.H. (1958) The Origin of Sexual
Isolation Between Different Lines Within a Species, Evolution 12:485-493.
[79] Landau, M. (1982) "Whales: Can Evolution Account for Them?",
Creation/Evolution: Issue X, Fall 1982, pp. 14-19.
[ 80] Lande, R. (1976) Natural Selection and Random Genetic Drift in
Phenotypic Evolution, Evolution 30:314-334.
[ 81] Lande, R., (1980) Genetic Variation and Phynotypic Evolution During
Allopatric Speciation, American Naturalist 116:463-479.
[ 82] Lande, R. (1982) Rapid Origin of Sexual Isdolation and Character
Divergence in a Cline, Evolution 36:213-223.
[ 83] Lewis, H. (1962) Catastrophic Selection as a Factor in Speciation,
Evolution 16:257-271.
[ 84] Loftin, R.W. (1988) "Caves and Evolution", Creation/Evolution, Issue
XXIII, Spring 1988, pp.21-27.
[ 85] Maynard Smith, J. (1966) Sympatric Speciation, American Naturalist
100:637-650.
[ 86] Mayr, E. (1963), Populations, Species, And Evolution Harvard
University Press. 453p.
[ 87] Mayr, E. (1969) Principles of Systematic Zoology: McGraw-Hill, 428p.
[ 88] Mayr, E. (1976) Evolution and the Diversity of Life, Harvard
University Press, 721p.
[ 89] Mayr, E. (1982) Processes of Speciation in Animals, Mechanisms of
Speciation, Barigozzi, C. editor, pp. 1-19
[ 90] McGowan, C. (1984) In the Beginning... A Scientist Shows Why the
Creationists are Wrong: Prometheus Books, 208p.
[ 91] Meglitsch, P.A. (1972) Invertebrate Zoology, Oxford University Press,
N.Y.
[ 92] Mishler, B.D. and Brandon, R.N. (1987) Individuality, Pluralism and
the Phylogenetic Species Concept, Biology And Philosophy 2 (4):397-414.
[ 93] Monroe, J.S. (1985) "Basic Created Kinds and the Fossil Record of
Perissodactyls" in Creation/Evolution: Issue XVI, PP.4-30.
[ 94] Nelson, G.J. (1974) "Classification as an Expression of Phylogenetic
Relationships", Systematic Zoology: 22:344-359
[95] Nevo, E. (1982) "Speciation in Subterranean Mammals" in Mechanisms of
Speciation, Barigozzi, C. editor, pp.191-218, New York
[ 96] Ostrom, J.H. (1974) "The Origin of Birds" in Annual Review Of Earth
And Planetary Sciences: Vol. 3, pp.55-77
[ 97] Page, G. (1990) Australia: Island Continent, Nature, PBS series
[ 98] Parker, G. & Morris, H. (1982) What is Creation Science?, Creation
Life Publishers, Ca.
[ 99] Patterson, C. (1981) "Significance of Fossils in Determining
Evolutionary Relationships" in Annual Review Of Ecology And Systematics:
Vol. 12, pp.195-223
[100] Patton, J.L. & Sherwood, S.W. (1983) "Chromosome Evolution and
Speciation in Rodents" in Annual Review Of Ecology And Systematics: Vol.
14, pp.139-158.
[101] Raup, D.M. (1983) "The Geological and Paleontological Arguments of
Creationism" in Scientists Confront Creationism, edited by Godfrey,L.,
pp.147-162
[102] Raup, D.M. (1986) The Nemesis Affair: W.W.Norton & Co. 220p.
[103]Rensch, B., (1960) Evolution Above the Species Level, Columbia
University Press, N.Y., 419p.
[104] Romer, A.S. (1966) Vertebrate Paleontology: University of Chicago
Press, 468p.
[105] Romer, A.S. (1967) Notes And Comments On Vertebrate Paleontology,
University of Chicago Press, 304p.
[106] Romer, A.S. & Parsons, T.S. (1977) The Vertebrate Body, W.B. Saunders
Co., Toronto.
[107] Ruse, M. (1982) Darwinism Defended: Addison-Westley Publishing Co.,
356p.
[108] Schaeffer, B., Hecht, M.K. and Eldredge, N. (1972) Phylogeny and
Paleontology, Evolutionary Biology: 6:31-46
[109] Sims, R.W., Price, J.H., and Whalley, P.E.S. editors (1983) Evolution,
Time and Space: The Emergence of the Biosphere, Academic Press, N.Y.
[110] Simpson, G.G. (1953) The Major Features of Evolution, Columbia
University Press, 434p.
[111] Simpson, G.G. (1961) Principles Of Animal Taxonomy, Columbia
University Press 247p.
[112] Smith, K. (1988) The Accuracy of The Quote Book, Private publication,
University of Queensland, Australia.
[113] Sonleitner, F.J. (1987) "The Origin of Species by Punctuated
Equilibria" Creation/Evolution: Issue XX, Spring 1987, pp. 25-30.
[114] Standly, S.M. (1979) Macroevolution: Pattern and Process, W.H.
Freedman, San Fransico, 332p.
[115] Strahler, A. (1989) Science and Earth History, Prometheus Books,
Buffalo
[116] Strickberger, M.W. (1990), Evolution,Jones and Bartlett Publishers
[117] Taylor, I.T. (1984) In the Minds of Men, TFE Publishing, Toronto
[118] Templeton, A.R. (1980) The Theory of Speciation via the Founder
Principle, Genetics 94:1011-1038
[119] Templeton, A.R. (1980) Modes of Speciation and Inferences Based on
Genetic Distances, Evolution 34:719-729
[120] Templeton, A.R. (1981) "Mechanisms of Speciation --A Population
Genetic Approach" in Annual Review Of Ecology And Systematics: Vol. 12,
pp.1-22.
[121] Templeton, A.R. (1982) "Adaption and the Integration of Evolutionary
Forces", in Perspectives on Evolution, Milkmann, R. editor, pp.15-31,
Sinauer, Mass.
[122] Templeton, A.R. (1982) "Genetic Architectures of Speciation", in
Mechanisms of Speciation, Barigozzi, C. editor, pp.105-121, New York
[123] Wakefield, J.R. with reply by Battson III, A.L. (1987) "Plate
Tectonics and Paradox" (Letter to the Editor) in Origins Research: Vol. 10,
No. 1, p.4
[124] Wakefield, J.R. and Battson III, A.L. (1987) "The Role of Natural
Selection in Macro-evolutionary Theory (A dialogue)" in Origins Research:
Vol. 10, No. 2, pp.6-7
[125] White, M.J.D. (1978) Modes of Speciation, W.H. Freedman, San Fransico.
[126] Wickler, W. (1968) Mimicry in Plants and Animals, McGraw-Hill,
Toronto.
[127] Young, J.Z. (1981) The Life Of The Vertebrates: Clarendon Press,
645p.
Last Words:
Creationists are fond of quoting various evolutionists as if they are
opposed to evolution. Here, then, are the very same people who, quoted
correcty, are actually in full support of evolution, both large and small
scale, and thus were the victims of misrepresentation and misquotation by
the creationist authors. Use these as often as possible.
Gould, S.J.: "The essence of Darwinism lies in its claim the natural
selection creates the fit. Variation is ubiquitous and random in direction.
It supplies the raw material only. Natural selection directs the course of
evolutionary change. It preserves favorable variants and builds fitness
gradually."
Eldredge, N.: "Well, Darwinism is by no means passe. Creationism is a wolf
in sheep's clothing, biblical literalism simply (and clumsily) cloaked in
the garb of science to evade consititutional injunctions that preclude
religion in public-scool curricula. And within science, Darwin's argument
that life has had a history --has evolved-- remains intact as a profoundly
solid idea."
Dawkins, R.: "To explain the origin of the DNA/protein machine by invoking a
supernatural Designer is to explain precisely nothing, for it leaves
unexplained the origin of the Designer. You have to say something like 'God
was always there', and if you allow yourself that kind of lazy way out, you
might as well just say 'DNA was always there', or 'Life was always there',
and be done with it."
Dawkins, R.: "The myth that mammals, for instance, form a ladder or 'scale',
with 'lower' ones being closer to fish than 'higher' ones, is a peice of
snobbery that owes nothing to evolution."
Bowler, P.J.: "Not all modern evolutionists have adopted the agnostic or
humanist perspective. Some have tried to incorporate the idea of evolution
into an explicitly religious framework, preserving traditional spiritual
values by reinterpreting the message of science."
Popper, Sir Karl: "I have always been extremely interested in the theory of
evolution, and very ready to accept evolution as a fact."
Ayala, F.J.: "The process of evolution has two dimentions: phyletic
evolution and speciation. Phyletic evolution is the gradual changes that
occur with time in a single lineage of descent; as a rule the changes result
in greater adaption to the environment and often reflect environmental
changes. Speciation occurs when a lineage of descent splits into two or
more new lineages and is the process that accounts for the great diversity
of the living world."
Cracraft, J.: "Indeed, from the manner in which creationists have discussed
[fossil transitions], one can only conclude that either the creationists
have consciously adopted the tactic of outright distortion or they are so
abysmally ignorant of the scientific arguments and data that their apparent
distortions are only accidental, not purposeful."
Cracraft, J.: "While professional biologists struggle with the enormous
complexity of the systematic relationships of organisms, their distribution
patterns, and the correlation of those patterns with hypotheses about earth
history, creationists take the easy road to 'knowledge' and simply force a
biblical interpretation on nature."
Godfrey, L.R.: "In many cases, the problem is not a lack of intermediates
but the existence of so many closely related intermediate forms that it is
notoriously difficult to decipher true ancestral-descendant relationships.
In a very real sense, the fossil record is far better testimony to
evolutionary change than Darwin, in his later years, probably imagined
possible."
===========================================================================
[Jan. 12, 1991. NOTE TO OR BBSer's: This monograph was a supplement to the
Ontario Association for the Support of Integrity in Science Education's
newsletter for the Summer 1990, Vol. 3.2, No. 9. Obviously the graphics
could not be included. If you want a hard copy of the monograph please
write to me at 385 Main Street, Beaverton, Ont. Canada. L0K 1A0. The cost
is a modest $5.00. Also write if you have any comments you wish to make on
E-Mail Fredric L. Rice / The Skeptic Tank