In the last article I explored contemporary developments in biology that now permit it to proceed in a precise quantitative fashion. This was a very important article that built the foundation for this current article. With this in mind I turn now to one of the most controversial parts of evolutionary science—that having to do with common descent. Since antiquity the Judeo-Christian narrative has held that humans were a specific creation of God on day-6 of creation week—not the product of common descent.  Yet science is finding evidence that would seem to fit a different narrative.

Perhaps the best way to start this discussion is to revisit a memorable exchange that occurred between Thomas Huxley, Chair of Natural History at the Royal College (now known as Imperial College of London) and Samuel Wilberforce, Bishop of the Church of England at Oxford. It occurred during a meeting of the British Association at Oxford in June 1860, where Huxley presented some formal remarks supportive of Darwin's Origin of Species. In response to these remarks, Wilberforce arose to his feet and in a light scoffing tone, attempted to ridicule Huxley by asking whether it was through his grandfather or his grandmother that he claimed his descent from a monkey. Huxley thereafter slowly rose to reply and is reportedly to have muttered, “He has been delivered into my hand,” and then proceeded to say that he would rather have been descended from an ape on both sides of his family than from a bishop who used his talents to obscure the truth. Wilberforce is reported to have retreated in resentment.[1]

The point of my repeating this story is to illustrate the passions this subject can generate; after all it is a very difficult subject and I am not particularly interested in inflaming the passion of readers. So keep in mind that I am looking at scientific findings, and not advocating for one side of this issue or the other. I hope to simply lay out the data in a straightforward, unbiased manner. Intelligent readers can draw their own conclusions.

As a 4^th generation Adventist, reared in a family that most would characterize as very conservative, I held very traditional notions of Genesis 1 & 2 well into adulthood. A couple of decades ago—certainly well before genome mapping—I was confident that an increased understanding of genetics would once and for all settle a major issues of evolution—the issue of common descent. I had a religious tradition, of course, that rejected common descent, but it also just seemed to me intuitive that differing biological classifications were sufficiently distinct that common descent was not possible, genetically speaking. It was my personal working hypothesis that as solid data emerged it would become clear that science was headed down the wrong trail. Because of my interest in the outcome of this issue I have followed the developments in the field of genetics through the years with interest. Unfortunately, most of the research findings have been very disappointing to my Adventist sensitivities. Instead of getting compelling proof that common descent was not feasible, the published data over the past few years tantalizingly renders the possibility more than likely. In what follows, then, are some of the significant findings that, at present, lead knowledgeable scientists to infer common descent. 

First let me refer back to the last article discussing the quantitative progress that has been made. The ability to read the DNA code has reached a level of refinement that permits (to use an example), the degree of relationship to be seen quite transparently and quite definitively—all the way from identification of a blood relative, such as a sibling, to a comparison of humans to primates and on down the genetic tree. All life can literally be catalogued, with the DNA code quantifying the degree of relatedness. Mammals (and all life for that matter) can be placed metaphorically on a genetic tree, with branching based on degrees and closeness of relationship. In DNA terms, Chimpanzees are the closest of the mammals to humans. The latest assessments have concluded their DNA is 98.8% matched to human DNA.[2]

Other than examining DNA code commonalties, there is a strategy for evaluating and validating the relationship of two species in terms of common descent. It is the use of a forensic method looking for mistakes in the genetic code that are shared across closely related species. We are talking here about a specific mutation(s), or mistake that occur out of the billions of base arrangements in a genome. Such mistakes are passed down to posterity and so can be traced back through the linage. Yes, humans and apes share some of the same genetic mistakes. Those who would dismiss such data will have to face the statistical probabilities of such occurrences in a code the size of the biological genome, where the odds increase against the exact same errors showing up independently. An analogy would be to randomly select the correct code to a combination safe—it may be possible—but not very probable. In the real world we must consider probabilities. Let’s consider, then, some of these mutations.

1. One mutation is found in hemoglobin, the oxygen-carrying protein within red blood cells. One of the molecules of human hemoglobin is beta-globin, and is composed of six genes; five are functional, and one right in the middle is broken. It is referred to as a pseudogene. This broken gene contains a series of errors that make it nonfunctional. This error is one that every human carries, and interestingly gorillas and chimpanzees also carry six beta-globin genes, and they are arranged in exactly the same way —five working copies surrounding a pseudogene. [3]

2. Most mammals have a gene that codes for an enzyme called gulonolactone oxidase, or GLO. This enzyme manufactures vitamin C, allowing mammals with this functional gene to not need any dietary intake of vitamin C. Humans, of course, need vitamin C in order to maintain good health, and interestingly human’s have a remnant of the GLO gene that is broken. It has accumulated so many changes in its base sequence as to become nonfunctional. Assuming the viability of the evolutionary model, this very strongly suggests that every human has descended from a common ancestor that also had this broken gene. Yes, some primates—the ones we are most closely related to in terms of DNA patterns such as chimps and gorillas—also have a broken GLO gene. Other more distantly related primates do have a functioning GLO gene. As noted by Kenneth Miller, in the field of forensics, “this notion of unique, matching errors is widely used to determine when one document has been copied from another.”[4] In the case of the GLO gene, the document we can analogize to would be the DNA code. [5]

3. Humans have 46 chromosomes—23 inherited from each parent. Apes, however, have 48, raising the significant question as to how humans and apes could possibly be related (particularly closely related) when humans are missing a couple of chromosomes. Well, this is where it gets interesting, because chromosomes have distinctive structural features with telomeres at the tips, and with a centromere at the center of the chromosome (see the graphic below). Quite unexpectedly humans have a fused chromosome #2. It has fused telomeres and two centromeres right where they would be expected to be if a fusion had occurred. Furthermore, genes on these two chromosomes are arranged in a pattern that is almost an exact match for corresponding genes on the two corresponding chimpanzee chromosomes. The match is so close that scientists have changed chimpanzee genes #12 & 13 to 2a and 2b so as to correspond to the human chromosome #2.  This, of course, suggests an explanation for the “missing” human chromosome. [6]

Well, what should we make of findings such as these? Are they all mere coincidences, or do they lead to the conclusion of common descent? The good news for traditional Adventist thinking is that none of these observations result in conclusions that are definitive on questions of common descent—just tantalizing data that seems to point that direction as determined by subject matter experts. For many this will be enough to casually dismiss this discussion and its implications. But this is not the end of the story, for we can be sure that there are many chapters yet to come. Yet, the data we have just discussed should cause us to pause before offering up knee-jerk responses of ridicule.

Those who have a defining narrative that would deny or ignore the data just discussed can easily find creationists who will be dismissive of the substantive points just made.[7] So the problem for all truth-seeking laypersons is in whom to place trust for a study of very complex issues—the actual subject matter experts[8] or the opinions of those who aren’t?[9] The answer should be obvious.

Another point to consider—most credible experts will openly discuss both strengths and weaknesses of the findings they put forward. Those “experts” who misrepresent the known scientific reality by only presenting one-sided arguments as is done on many radio talk shows, where cherry picked data is presented and problematic data is avoided, are by their very approach untrustworthy. Those who openly discuss vulnerabilities are, by this measure, more credible. In the spirit of this latter point, I have provided readers in footnote form, a website sponsored by an Adventist who dismisses the findings we have just discussed. But should you review that material, please consider the general lack of any discussion of vulnerabilities of the arguments being made.

What I have attempted to provide is a general overview of this challenging subject for the average reader. In actual fact, the details of a discussion like this can very quickly become much more complex and technical. But one thing to keep in mind now that biology has moved into the digital age is that the science community now has the ability to progress rapidly beyond mere speculation by providing mathematical levels of confidence in sorting out some of these issues. Until some more of this can be worked out I would suggest that we are best served by moving away from a dogmatic nineteenth-century worldview, and towards a position of neutrality. If science is on the wrong track, given the recent advances in genetics it should soon become apparent to the science community. In the meantime a position of neutrality can be a way of showing respect for tradition while awaiting further data.

Most of us don’t like to live with ambiguity, and for some nothing short of mental certitude is adequate—never mind the reality. However, those who can adopt a position of neutrality should recognize that scientific knowledge of genetics is still in its infancy. This brings with it the possibility that in time a more mature understanding will emerge that perhaps may salvage aspects of traditional Adventist thinking. But there is also another possibility, and that is that the reality is quite different from what many of us have long assumed.

In the next article I will look at one aspect of evolution that Adventists generally find more encouraging—the question of origins. Then in the last article of this sub-series I will attempt to put some of the varied piece of this discussion together and develop a possible philosophical approach that could lead to helpful theological considerations. Perhaps there is a path forward that is respectful to both Adventist traditions and to the message emanating from science. In the end, the truth of the matter will prevail irrespective of our preferred narrative; the only question that remains is whether we will be open to the evidence—whatever direction the evidence may lead.

Further Reading:

1. Only a Theory: Evolution and the Battle for America’s Soul, Kenneth R. Miller (Viking, 2008)
2. The Language of God, Francis S. Collins (Free Press, 2006)