Many organisms show features of appallingly bad design. This is because evolution via natu

Many organisms show features of appallingly
bad design. This is because evolution via natural selection
cannot construct traits from scratch; new traits must be mod-
ifications of previously existing traits. This is called
historical constraint. A few examples of bad design imposed
by historical constraint:

 In parthenogenetic lizards of the genus _Cnenidophorus_,
only females exist. Fertility in these lizards is increased when
another lizard engages in pseudomale behaviour and attempts to
copulaMany organisms show features of appallingly
bad design. This is because evolution via natural selection
cannot construct traits from scratch; new traits must be mod-
ifications of previously existing traits. This is called
historical constraint. A few examples of bad design imposed
by historical constraint:

 In parthenogenetic lizards of the genus _Cnenidophorus_,
only females exist. Fertility in these lizards is increased when
another lizard engages in pseudomale behaviour and attempts to
copulaMany organisms show features of appallingly
bad design. This is because evolution via natural selection
cannot construct traits from scratch; new traits must be mod-
ifications of previously existing traits. This is called
historical constraint. A few examples of bad design imposed
by historical constraint:

 In parthenogenetic lizards of the genus _Cnenidophorus_,
only females exist. Fertility in these lizards is increased when
another lizard engages in pseudomale behaviour and attempts to
copulaMany organisms show features of appallingly
bad design. This is because evolution via natural selection
cannot construct traits from scratch; new traits must be mod-
ifications of previously existing traits. This is called
historical constraint. A few examples of bad design imposed
by historical constraint:

 In parthenogenetic lizards of the genus _Cnenidophorus_,
only females exist. Fertility in these lizards is increased when
another lizard engages in pseudomale behaviour and attempts to
copulafingers are made of. The thumb is con-
structed by enlarging a few bones that form the wrist in other
species. The muscles that operate it are "rerouted" muscles
present in the hand of vertabrates (see S.J. Gould book "The
Panda's Thumb" for an engaging discussion of this case). Again,
this is not good design.

 In addition, organisms betray their history (phylogeny)
in their development (ontogeny). All mammals (including humans)
go through a stage were gills begin to form. Many organisms
contain fingers are made of. The thumb is con-
structed by enlarging a few bones that form the wrist in other
species. The muscles that operate it are "rerouted" muscles
present in the hand of vertabrates (see S.J. Gould book "The
Panda's Thumb" for an engaging discussion of this case). Again,
this is not good design.

 In addition, organisms betray their history (phylogeny)
in their development (ontogeny). All mammals (including humans)
go through a stage were gill