CREATION
SCIENCE: True Homology - an endangered concept
Since 1859,
the principle of homology has been quoted as the singularly most powerful
argument in favour of organic evolution. The biological world had been
grouped into classes. Organisms within each class exhibit very similar
characteristics. Despite being used for rather different purposes, the
various organs of the reptile, amphibian and mammal show remarkable uniformity
in its organisation or design. Evolution was born out of the belief that
such homologous attributes indicate that all these life forms descend
from a common ancestor.
Homology
in nature can also be explained through faith in the same Creator creating
all things. This idea lost favour in the latter part of the 19th
century. Believing that our universe was miraculously born became eroded
as scientists developed the theory of evolution and began to study nature
in the hope of finding evidence to support the theory. Scientists, in
general, did not necessarily have this as their agenda, but became engrossed
in the study efforts as evolutionary ideas became more popular. Some Christians
accept the concept of a common ancestor and see the creative/evolutionary
process as the ‘miracle’ - hence theistic evolution.
Recent studies
in embryological and genetic research have started to undermine the principle
of homology. Homologous organisms exhibiting ‘unity of type’, would be
expected to show homologous genes and homologous patterns of embryological
development. Such evidence would further support the common ancestor theory.
What is being discovered however, are non homologous genetic structures
and different embryological development patterns. Once again this is not
very common or popular knowledge.
In terms
of embryological development, research is beginning to show how homologous
structures are arrived at by different routes. From the first cell divisions,
the sequence of events in the formation of the blastula in reptiles, amphibians
and mammals are obviously different. The blastula itself in all three
classes is clearly not identical. The next phase of development is embryo
formation or gastrulation. The resulting gastrula in all vertebrates are
homologous, however the cells giving rise to the different germ layers
and their migration patterns are markedly dissimilar.
After gastrulation,
homologous structures (such as the kidney and alimentary canal for example),
develop from different sites in the different vertebrate classes. Through
research on the common frog, it was discovered that the optic cup was
itself the organiser which induced the epidermis layer to form the lens
of the eye. By cutting the optic cup of the embryo, no lens developed
at all. With an evolutionary mindset, this led scientists to conclude
that all vertebrate lenses form in this manner. However, when the optic
cup was altogether removed from the embryo of the closely related edible
frog, the lens developed all the same. The lenses of the frogs are as
homologous a structure as you will find, yet they are formed by completely
different mechanisms.
This is
clearly a case where Romans 1:20 comes into play; that homologous structures
arise out of a multiplicity of methods is testimony to the omnipotence
of God. It is interesting that it can be seen so differently depending
on the accepted worldview adhered to.
The previous
paragraphs discussed the principle of homology as the interpretation that
similar characteristics or design in various species indicate that all
life evolved from a common ancestor. It was shown how embryological research
has however, revealed that homologous attributes in the different classes
of vertebrates (or even within the same species) are arrived at by different
(non-homologous) routes from non-homologous sites in the embryo. The comment
was made that this is a remarkable testimony to God’s omnipotence.
Similar
discoveries have been made in the plant and animal kingdoms. Different
species boasting incredibly homologous characteristics, achieve this homology
via different mechanisms. This is ironic when you consider Darwin’s definition
of homology in the ‘The Origin of Species’: Homology is…that "relationship
between parts which results from their development from corresponding
embryonic parts." As recent research is beginning to discover, this
is precisely what homology is not.
As for genetic
research, evidence to support the theory of common ancestry is threadbare.
For example, many genes appear to affect homologous structures as well
as features specific to that particular species. These are called pleiotropic
genes in that they serve a multitude of functions. One would expect that
the genes associated with homologous structures are exclusive to only
homologous features if common ancestry were correct. A mutation in a gene
affecting the feathers of a bird also affects the skull of the bird. The
skull being homologous to all vertebrates and the feathers not.
There are
also many cases of homologous design that cannot possibly be credited
to common ancestry. Yet no-one questions the biased logic. The similar
pentadactyl design in the forelimbs of all terrestrial vertebrates is
uncanny. However, the forelimb and the hindlimb of all vertebrates also
follow the same pentadactyl design. No scientist would dare suggest that
the forelimb evolved from the hindlimb (or vice versa) as it is accepted
that these evolved independently from the pectoral and pelvic fins of
the fish. And this by random accumulations of tiny advantageous mutations.
It is hard to believe that there is some adaptive necessity in the pentadactyl
design. And if there was, that random mutations could hit on it more than
once. There is still no satisfactory scientific explanation for ‘unity
of type’.
The fish-like
appearance of the whale resulted in its original classification as a fish.
This is a classic example of how analogy can so easily be mistaken for
homology. Modern advances in embryology and genetics are dwindling the
number of cases of true homology implicating the uniqueness of species.
Sometimes a special creation is more credible than the alternative. Or
as Michael Denton puts it…
…The
same deep homologous resemblance which serves to link all the members
of one class together into a natural group also serves to distinguish
that class unambiguously from all other classes. Similarly, the same
hierarchic pattern which may be explained in terms of a theory of
common descent, also, by its very nature, implies the existence of
deep division in the order of nature. The same facts of comparative
anatomy which proclaim unity also proclaim division; while resemblance
suggests evolution, division, especially where it appears profound,
is counter-evidence against the whole notion of transmutation.
Becky Conolly
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For
more information and resources contact:
AFRICA CHRISTIAN ACTION
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