“As a first principle, we adopt the Darwinian idea that all life is related.”1
Edward O. Wiley
The genetic similarity between organisms represents one of the most cited pieces of evidence for biological evolution. The idea is, if two organisms derive from the same ancestor, then they will have started their evolutionary journey with the same genetic make-up. As the two organisms diverge, they will accumulate different genetic changes, but still retain some of their original genetic profile. This retained genetic material is the basis for their DNA similarity. Accordingly, the more recently the two lineages diverged from the common ancestor the more similar their genetic material.
It’s on this basis that many people conclude humans and chimps evolved from a common ancestor. When scientists performed the first genetic comparisons between these two species, they discovered a 99 percent DNA similarity. According to the evolutionary paradigm, this proves that humans and chimps descended from the same ancestor, making chimps our closest living “relative” in the animal kingdom.
It’s important to recognize, however, that when evolutionary biologists claim genetic similarity among organisms as evidence for common ancestry, they are assuming that conclusion at the outset of the investigation. In other words, many in the scientific community take the evolutionary relatedness of all life as an axiom and then interpret genetic similarities and differences in that light.
As part of RTB’s creation model, we assert that it’s possible to understand the DNA similarity between humans and other animals (including chimps) as reflecting the work of a Creator. (A more detailed presentation of the RTB Human Origins Model can be found in Who Was Adam?) Genesis 2 teaches that Adam and “the beasts of the field and birds of the air” were made from the same stuff, namely “the dust of the Earth.” If this is the case, then the biological similarities between humans and other animals, like chimps, is expected. The DNA similarity can be understood as reflecting the work of a Creator who used the same materials and the same design templates to make humans and chimps. Some of the genetic difference can be understood as intentionally introduced by the Creator to make each creature unique.
Our model further acknowledges that biochemical and physicochemical processes can also introduce differences in animals’ genomes. Moreover, our model takes into account the fact that some of these mechanisms operate at a relatively high frequency and are both nonrandom and reproducible. As such, these frequent, nonrandom, reproducible processes can create similarities that, if the data is being viewed from an evolutionary vantage point, can masquerade as signatures for common ancestry. (Go here and here for articles that describe this phenomenon.)
We do invite serious critique of our model (both theological and scientific). We believe that critical evaluation of our ideas will only improve our case for biblical creation. One such critique appeared recently on The BioLogos Foundation website.2 This critique was offered by Dr. Dennis Venema, Chairman of the Biology Department at Trinity Western University.
Given Venema’s credentials, I expected a thoughtful, insightful critique of our model. However, instead of discussing the scientific weaknesses of our approach, Venema chose to launch an ad hominem attack against me and Hugh Ross, impugning our integrity as scientists and scholars. The crux of his criticism is that:
- We intentionally ignored a key scientific paper about genetic comparisons between humans and chimpanzees that went against our model.3
- We erroneously claim that the genetic similarity between humans and chimpanzees is around 90 percent, not 95 percent (or about 99 percent) as the above-mentioned paper reports.
- We claim that the genetic comparisons between humans and chimpanzees that describe the differences (or similarities) in terms of percentages are meaningless, which according to Venema misrepresents and is contrary to scientific opinion.
The grounds for these complaints, however, are baseless. In 2005, a few weeks after the Chimpanzee Sequencing and Analysis Consortium published the initial whole genome sequence for the chimpanzee, we commented on it on our webcast Creation Update (see the September 20, 2005 edition). In that webcast, we noted that the results of this work fit within the framework of our model and also explained why we feel that the best value for percent similarity is around 90 percent, not 95 percent as reported in the Chimpanzee Sequencing and Analysis Consortium paper. We also explained why this type of genetic comparison lacks meaning and discussed a study that did indeed provide a meaningful genetic comparison between humans and chimps based on gene expression patterns.
It is true, as Venema points out, that the Chimpanzee Sequencing and Analysis Consortium paper was not mentioned in either Creation as Science (2006) or More Than a Theory (2009). The intent of these two works was to summarize the RTB creation model and to present a sampling of scientific studies that support our model. Neither work was meant to be an exhaustive treatment. There was nothing underhanded about the omission (as Venema asserts), particularly since a detailed description of our human origins model was found in Who Was Adam? (2005) and subsequent updates have been provided via webcasts, podcasts, and articles, most of which are free through our website (www.reasons.org).
Next week I will discuss the results of the Chimpanzee Sequencing and Analysis Consortium paper in detail, defending our claims that the similarity between humans and chimpanzees is best reported at around 90 percent. In the following week, I will discuss why this type of comparison is meaningless in a biological sense. Finally, I will round out my response to Venema’s critique by discussing recent work that does indeed highlight the genetic basis of the biological and behavioral differences between humans and chimpanzees
|Part 1 | Part 2 | Part 3 | Part 4 | Part 5|