Before getting into the answer to this question of whether the similarity between human/chimp DNA is, in fact, evidence for naturalistic evolution, it is important to define a few terms. First, what is DNA? It is a molecule that carries genetic instructions for making an organism—like a blueprint or diagram for a biological life form. Both genes and chromosomes are made of DNA, which, again, is a molecule, a chemical compound made up of four other chemical units. The entirety of a life form's DNA, plus its genes, is called the "genome."
Are the similarities in human DNA and chimp DNA evidence of evolution?
Some DNA "codes for genes" and some does not. This is crucial for the layman to understand, because when a scientist tells us "human and chimp DNA is 98% the same" what we imagine, given our limited knowledge of the subject, is likely to be exaggerated. Consequently, the figure 98% is exaggerated (it's closer to 95%). Still, 95% similarity seems like a lot. Let's take a closer look at what this means, exactly.
When looking at a strand of human DNA next to a strand of chimp DNA, scientists noticed that most of the DNA was the same, but certain regions of the DNA in humans was different. They named these differing regions in the human genome "human accelerated regions" or HARs. This seems to suggest a common ancestry: chimps were there, and then an evolutionary occurrence happened in the chimp genome, resulting in an early form of human, and this happened again and again until we had modern man as we see him today.
There are a couple of problems, though. First of all, there are two regions of DNA where HARs exist: some exist in the DNA that "codes for genes" and some exist in the DNA that does not code for genes. Human DNA that does not code for genes AND differs from the rest of the primates would have had to evolve (non-genetically) to alter the organism in just such a way as to separate human beings from primates. Furthermore, the DNA in humans that DOES code for genes and is different from that of primates shows evidence of deleterious mutation. That is to say, "evolution" provided humans with genetic changes which were not advantageous when compared to the same code in primates. This doesn't seem to make much sense from an evolutionary standpoint.
Additional research into the G–C content of human DNA gene-encoding proteins has shown that the behavior of HARs in human DNA is not consistent enough, nor is it advantageous enough, to suggest natural selection as Darwin theorized it. In other words, despite interesting similarities between the species, there is not sufficient evidence to say that humans evolved from chimps. From a design perspective, however, it is very common to use "templates" from which to create different parts or materials. For example, an eye is of the same basic construction in most mammals, with slight differences. Does that mean that one creature evolved from another? The process of naturalistic evolution is exceedingly complex. According to Occam's razor, it is much simpler to believe that a Designer used the same basic part or blueprint and modified in various ways to perform similar functions in different creatures.
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