Passage: God created human beings in his own image. In the image of God he created them; male and female He created them. Then God blessed them and said, “Be fruitful and multiply. Fill the earth and govern it” (Genesis 1:27-28).
Difficulty: Doesn't the science of genetics refute the concept that the entire population of the world came from just one couple?
Explanation: Over the past couple of decades researchers have used “population genetics” to estimate initial population size of the human species. By studying human genetic diversity in the present day, they have tried to extrapolate back to determine the minimum size of the original population of humans necessary to produce the diversity we observe today. Some have argued that it is impossible for civilization to have come from one human couple.
Dr. Francis S. Collins is a physician and geneticist who in 2007 formed the San Diego–based BioLogos Foundation. It is an organization that promotes theistic evolution among evangelicals. Dennis R. Venema, PhD, a BioLogos senior fellow for science and biology chairman at Trinity Western University, is a writer for BioLogos. He too is a theistic evolutionist who is trying to promote harmony of Darwinian science and faith within the evangelical community. Dr. Venema claims that human population “was definitely never as small as two.” He contends that “our species diverged as a population. The data are absolutely clear on that.” 1 He asserts that to reach the level of genetic diversity we see today, the initial population of humans would have had to be several thousand individuals at minimum—not one couple.
Not all biologists, however, agree with Dr. Venema. Dr. Ann Gauger is senior research scientist at the Biologic Institute, a pro–intelligent design research lab based near Seattle, Washington. She earned a PhD in biology from the University of Washington, and later did postdoctoral work at Harvard. In the chapter “The Science of Adam and Eve” in the 2012 book Science and Human Origins, Gauger finds that Venema’s arguments were based upon a now outdated study of genes involved in the human immune system that was published by the geneticist Francisco Ayala in 1995.
According to Gauger, these population genetics studies make many assumptions—including a constant background mutation rate, lack of natural selection, lack of migration, and a constant population size. If any of those assumptions are wrong then the conclusions could be meaningless. Gauger reanalyzed Ayala’s data and found that he failed to control two of the assumptions, and analyzed a portion of the gene known to experience an unusually high mutation rate, causing him to dramatically overestimate the required initial population sizes. When the analysis is done properly, Gauger found that “a first couple could have carried sufficient genetic diversity to account for” the genetic diversity we observe today in humans for this gene. 2 Gauger further found that more recent research reveals this gene shows conflicting phylogenetic patterns, which “cannot be explained by common ancestry” of humans and apes.3
Likewise, Dr. C. John Collins, professor of Old Testament at Covenant Theological Seminary, questions these population genomics figures. He cites 2006 research from Canada, France, and Japan that “indicates ambiguity about the rate of changes in genetic diversity that have been used thus far to calculate primordial population sizes.” 4 Theorizing about how many people it would initially take in the deep past to generate observed human genetic diversity today, according to Collins and Gauger, is far from an exact science.
Another factor that geneticists usually fail to consider is the original genome of the first man and woman, Adam and Eve. From a creationist’s point of view, the optimal DNA and genetic diversity of the first couple formed by the hand of God is impossible to quantify because it has been lost to time, and potentially radically changed since the Fall. But it does seem plausible that Adam and Eve had a physiology and genotype different from our own today. After all, Adam lived to be 930 years old—so clearly his biology was different from ours. So their biological makeup may have been such that their genetic diversity was not comparable to humans today. If that is the case there might be no genetic reason why an initial pair of two humans couldn't have led to present-day human genetic diversity in a short period of time.
