Another branch of comparative anatomy studies structures in humans
(and other so called ‘higher’ forms of life) that were believed by
evolutionists to be the remains of structures that were required or
useful in ‘lower’, less evolved and less complex ancestral forms, but
that now no longer are necessary.
In this case, the homologous organ in the more advanced animal is less developed, or even deemed useless. Such homologous structures or organs are referred to as vestigial,
with most examples being assumed remnants that resulted from the loss
of an earlier, better developed structure. Evolutionists used to proudly
point to over a hundred such structures in humans, but the number has
decreased consistently as anatomical knowledge has increased.
Today, only a couple of examples at most are usually
mentioned (and there is no doubt that even the few examples usually
mentioned are useful and not vestigial). As Howitt28 noted, the
celebrated German anatomist, Wiedersheim, listed 180 vestigial organs in
the human body, but with the increase of knowledge it has been found that every one of them has an important function, although the functions of some organs is presently viewed as minor, or as serving a back-up capacity.
Moreover, if some vestigial organs can be proven to
exist, they provide support not for evolution, but for
de-evolution|--|i.e. evolution-in-reverse. What the evolutionists must
demonstrate is that the development of new and useful organs is
occurring today. They also must prove that a process exists that can
form new structures called nascent organs, instead of trying to
document that once-useful organs now are useless. Evidence for the
development of new organs, or those in the process of evolving, would be
evidence of evolution. As of now, no evidence of any nascent organ exists.
Evolutionary Naturalism or an Intelligent Designer?
Vestigial Orgns and Homology
Embryology and Homology
One major problem is that in many cases organs and structures which
appear identical (or very similar) in different animals do not develop
from the same structure or group of embryo cells.
It is not uncommon to find fundamental structures
(e.g. the alimentary canal) that form from different embryological
tissues in different animals.
For example,
in sharks the alimentary canal is formed from the roof of the embryonic gut cavity;
in frogs it is formed from the gut roof and floor; and
in birds and reptiles it is formed from the lower layer of the embryonic disc or blastoderm.
Even the classic example of vertebrate forelimbs
referred to by Darwin (and cited in hundreds of textbooks as proof for
evolution) has now turned out to be flawed as an example of homology.
The reason is that the forelimbs often develop from
different body segments in different species in a pattern that cannot be
explained by evolution.
The forelimbs in the newt develop from trunk segments 2 through 5;
in the lizard they develop from trunk segments 6 to 9;
in humans they develop from trunk segments 13 through 18.
Denton concluded that this evidence shows the forelimbs usually are not developmentally homologous at all.
As an example, he cited the development of the
vertebrate kidney which provides a challenge to the assumption that
homologous organs are produced from homologous embryonic tissues.
‘In fish and amphibia the kidney is derived directly
from an embryonic organ known as the mesonephros, while in reptiles and
mammals the mesonephros degenerates towards the end of embryonic life
and plays no role in the formation of the adult kidney, which is formed
instead from a discrete spherical mass of mesodermal tissue, the
metanephros, which develops quite independently from the mesonephros.’
This research supports ReMine’ biotic message theory,
the conclusion that the natural world was specifically designed to look
like it did not evolve, but was created. ReMine uses a wide variety of
examples to support his thesis which has been very favorably reviewed by
the creationist community. ReMine notes that homology has been used as
evidence against a designer for decades, but as this review shows, it
strongly supports the biotic message theory.
Evolutionary Naturalism or an Intelligent Designer?
BioChermical Homology
The homology argument from biochemistry parallels the argument in
anatomy. Evolutionists suggest that just as the study of comparative
anatomy has found evidence of anatomical homologies, likewise research
on
“ … the biochemistry of different organisms has
revealed biochemical homologies. In fact, the biochemical similarity of
living organisms is one of the most remarkable features of life … .
Cytochrome enzymes are found in almost every living organism:
plant, animal and protist. The enzymes of the citric acid cycle are also
almost universally distributed.
Chlorophyll a is found in all green plants and almost all photosynthetic protists.
DNA and RNA are found in every living organism and, so far as we can determine, contain the same hereditary coding mechanism.
The
fact that underneath the incredible diversity of living things lies a
great uniformity of biochemical function is difficult to interpret in
any other way but an evolutionary one. Presumably these molecules were
put to their current use very early in the history of life and almost
all modern forms have inherited the ability to manufacture and use
them.”
The fact that animals are ‘so similar in their chemical make-up’ has long been used to support Darwinism.
But extensive biochemical research has revealed that the simplest reason for biochemical homology is that all life requires similar inorganic elements, compounds and biomolecules; consequently, all life is required to use similar metabolic pathways to process these compounds.
Most organisms that use oxygen and rely on the metabolism of carbohydrates, fats and proteins must use a Citric acid Cycle which is remarkably similar in all organisms.
Furthermore,
the metabolism of most proteins into energy produces ammonia, which is
processed for removal in similar ways in a wide variety of organisms.
What evolutionists must explain is why billions of years of evolution
have not produced major differences in the biochemistry of life.
Many biochemical structures/systems in yeasts and
other so-called ‘primitive life’ forms are almost identical to the
biochemical families used in humans. With some minor variations, all
life uses the same sugar and lipid family, the same 20 amino acids,
about 14 vitamins and the same basic genetic code.
Even the complex proteins used in all life are often
identical or very similar. Correspondence even exists between very
different forms of life such as prokaryotes and eukaryotes.
Ribosomes from bacteria, even though translation signals and other
differences exist, have enough similarity that they can be made to
‘translate human messenger RNAs into human proteins—and vice versa’.39
The problem for evolutionists is that the biochemistry of all life, even
that allegedly separated by hundreds of millions of years of geologic
time and evolution, is too similar. Despite the many significant
differences between the two basic cell forms (eukaryotes and
prokaryotes), they are both
“ … remarkably similar on the biochemical level … . Procaryotes and eucaryotes are composed of similar chemical constituents. With a few exceptions, the genetic code is the same in both,
as is the way in which the genetic information in DNA is expressed. The
principles underlying metabolic processes and most of the more
important metabolic pathways are identical. Thus, beneath the profound
structural and functional differences between procaryotes and
eucaryotes, there is an even more fundamental unity: a molecular unity
that is basic to life processes.”
Although many
biochemical similarities exist in life, millions of biochemical
differences exist that are inexplicable via evolution. Many of these
differences do not provide a selective advantage as implied by the claim
that Darwinistic mechanisms have fine tuned life for the past 3.6
billion years.
Creationists suggest that such differences exist due to the need for ecological balance and because the Creator chose to employ variety.
Also, were one compound in an organism to be altered, scores of other
compounds with which it interacts would often also need to be changed so
that the entire biological system could function as a harmonious unit.
Evolutionary Naturalism or an Intelligent Designer?
Genetics and Homology
According to the evolutionary theory, homologous features are
programmed by similar genes. Gene sequence similarity would indicate
common ancestry since such similarities are unlikely to originate
independently through random mutations. If the bones of the human arm
evolved from the same precursors as the wing of a bat and the hoof of a
horse as evolution teaches, then we should be able to trace these
alleged homologies to the DNA that codes for them. Some geneticists
thought this knowledge would allow them to find the chemical formula
needed to produce an arm, leg, or other structure. But once biologists
acquired a greater understanding of genetics, they found that what are
labeled as homologous structures in different species often are produced
by quite different genes.
Homology predicted that features produced by similar
genetic sequences are phylogenetically homologous. There are now so many
exceptions to this prediction that the concept of genetic homology
cannot now be said to be a rule, but the exception. The classic example
is mutations in certain homeotic genes41 which can cause wholesale
changes in morphology such as producing two pairs of wings instead of
the normal single pair, or replacing a fly’ antenna with a leg (or can
even cause eyes to develop on the fly’ leg). Genes that produce results
similar to the homeotic genes for flies’ wings have been found in most
other animal kinds, including mammals and humans.
In another example, the gene that controls mouse eye
colour also happens to control the mouse’ physical size; but the gene
that controls the fruit fly’ eye colour controls not the fruit fly’
size, but female sex organ morphology.43 Although mice and flies share a
similar gene (called eyeless) which functions to control their eye
development, the fly’ multifaceted eye is profoundly different from a
mouse’ mammal eye. In both the fly Antennapedia and mouse eyeless,
similar homeotic genes control development of structures which are not
homologous by either the post-Darwinian phylogenetic or the classical
morphological definition.
The finding that similar genes regulate such radically
different structures strongly argues against the concept of homology.
So many genes used in higher organisms have multiple effects that Ernst
Mayr once suggested that genes which control only a single
characteristic are rare or nonexistent. The finding that a consistent
one-gene/one-characteristic correspondence does not exist has been a
major set back to the Darwinian interpretation of homology. Because
evolutionary biologists have failed to provide a biological basis for
their homology research findings, Roth concluded ‘that the title of de
Beer’ 1971 essay|--|Homology, an unsolved problem|--|remains an accurate
description … . The relationships between processes at genetic,
developmental, gross phenotypic and evolutionary levels remain a black
box’.45 Research at the molecular level has failed to demonstrate the
expected correspondence between gene product changes and the organismal
changes predicted by evolution.
Evolution by DNA mutations ‘is largely uncoupled from morphological
evolution’.46 An example of this is the large morphological
dissimilarity that exists between humans and chimpanzees despite a high
similarity in their DNA. In short we now know:
“ … in general the homology of structures such as
organs or modules cannot be ascribed to inheritance of homologous genes
or sets of genes. Consequently, organ homology cannot be reduced to gene
homology. Van Valen recognizes this too and therefore suggests, as an
alternative, to reduce homology to a continuity of [developmental]
information. Information is not the same as genotypic nucleic acid. But
what it is exactly, and how it is continuous, is still an unsolved
problem.”
Evolutionary Naturalism or an Intelligent Designer?