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?