Answering the Challenge of the Fossil Record
The lack of intermediates showing tooth reduction has more to do with the lack of fossils and the
way evolution operates than with any lack of such intermediates in the history of the birds. The
number of Jurassic and Cretaceous bird fossils number only a few dozen at best. It is not
surprising that such intermediates are not represented. However, as has been pointed out
previously the expectation of finding such smooth intermediates is fallacious.
"Advanced" and "primitive" carry certain connotations. Biologists now use 'derived' for
"advanced" and 'ancestral' for "primitive". However, what are considered derived characters for
one group cannot be used to decide what are derived characters in another group. For instance,
derived characters in snakes are (in order of appearence); reduction of limbs, loss of limbs and
reduction from two to one lung, acquisition of fangs, acquisition of sensory pits. Thus from the
point of view of snake evolution, humans, with their retention of limbs, retention of two lungs,
absence of fangs and absence of sensory pits, are ancestral, or "primitive". As can be seen from
this example what is sauce for the snake is certainly not sauce for the human! The absence of
teeth is considered a derived character
, it is of little importance when deciding which
characters are "advanced"
in other groups
. Thus the claim that, "the duck-billed platypus and
the spiny anteater, mammals that do not have teeth, should be considered more advanced or
highly evolved than man" is ludicrous, and Dr Gish should know this.
"Evolutionists have long maintained that contemporaries could not have an ancestral-descendant
relationship but if related, they must have evolved from a common ancestor sometime in the
past." (p. 116)
This is only true for
, not for species in general. A population can be described as a
(usually) reproductively isolated group of individuals which comprise a specific gene pool.
Changes to that gene pool over time (the death of individuals, the birth of new individuals,
mutations, etc.) all conspire to alter the genetic composition of the population so that the
descendant population represents the
population plus the sum of the changes over time.
Thus the descendant population cannot coexist with the ancestral population because the
the ancestral population, plus the sum of the changes over time.
However, in the vast majority of cases, one population does not comprise the entire species.
There are usually multiple populations spread out geographically, some interact, some do not.