A few weeks ago, I wrote a short post titled, Adam and Eve still a possibility?, in which I drew readers’ attention to the work of geneticist Richard Buggs, Reader in Evolutionary Genomics at Queen Mary University of London, who thinks it’s still theoretically possible that the human race once passed through a short, sharp population bottleneck of just two individuals, followed by exponential population growth. Biologist Dennis Venema, professor of biology at Trinity Western University in Langley, British Columbia, has recently written a two-part reply to Buggs, titled, Adam, Eve and Population Genetics: A Reply to Dr. Richard Buggs (Part 1) and A Reply to Dr. Richard Buggs (Part 2). But in a comment in response to a query of mine, Professor Venema conceded that at the present time, science cannot rule out Dr. Ann Gauger’s hypothesis that there was a severe bottleneck around two million years ago, with the emergence of Homo erectus, whom she identifies as the first true human being. When I pressed Professor Venema, saying, “In plain English, what you’re saying is that science can’t rule out an original couple, if they lived more than 1 million years ago,” he replied:
I guess it depends on how reliable you think PSMC methods are as they approach this time frame. The data looks smooth to me out to around 1.5 MYA or so, plus or minus, but the method loses its power as you go back further and further.
In a recent email message, Dr. Gauger clarified her position on Adam and Eve:
I did not settle on an old age for Adam so that the population genetics would work out or because I was seeking to prove two progenitors. It was because I could not understand why God would create Homo species so close to us and not be part of us, and because of morphology. I find species definitions to be tricky things, and sometimes they are assigned because of an agenda. H ergaster and H habilis are disputed for example. But for me Turkana boy is clearly human.
So I arrived at an early date because paleontology. I am aware of arguments for 200k (first modern skeleton), 70 k (Blombos cave, migration out of Africa), or 20-10k to match Genesis.) We will see if any of these dates, as well as the older one, can accommodate a unique origin based on AFS, LD, and several other pop gen statistics. Feel free to pass this on.
Dr. Gauger has adduced evidence that Homo erectus and Homo ergaster (African Homo erectus) were rational beings, who were capable of foresight: they transported tools over distances of 12-13 kilometers, compared to distances of just tens or hundreds of meters for Australopithecus and early Homo (see here). In addition, there is evidence (see also here) that Homo ergaster was able to tame fire as far back as 1,000,000 years ago, and perhaps use it to cook meat as well, although Wil Roebroeks of Leiden University in the Netherlands and Paola Villa, a curator at the University of Colorado Museum of Natural History in the U.S., cautions that we don’t have evidence of regular fire use going back any further than 400,000 years ago. Finally, excavations at the South African site of Kathu Pan suggest that Homo ergaster had a sense of aesthetics. As Dr. Gauger describes it:
…[T]he site has yielded what is termed, the ‘Master Hand-Axe’ which dates to approximately 750 000 BP rendering it the oldest artifact which is indisputably aesthetic i.e. worked for beauty and symmetry, perfectly oriented, and worked considerably beyond the functional requirements of the hand-axe, which could have been achieved with half or fewer blows (see Figure 4-2). The technology which produced it is known as the Acheulian, and the artifacts are thought to be made by Homo ergaster (Homo erectus in Africa), a diverse grouping of early humans commonly imagined as small-brained, small-jawed and robustly built, with heavy eyebrow ridges.
When I look at that master handaxe, I see aesthetics, painstaking care, and a joy in the materials. I see mind.
In a recent comment on Biologos, I expressed reservations about Dr. Gauger’s ancient Adam and Eve scenario:
However, if I were to identify the chief flaw of the ancient Adam and Eve scenario, it would be this: modern human behavior doesn’t appear until 100,000 years ago. Homo erectus may have had foresight (transporting tools over distances of more than 10 kilometers), the ability to control fire (although this is hotly disputed) and even a sense of aesthetics (judging from the elegance of some Acheulean tools), but it almost certainly lacked the capacity for art, religion and science. This means that in some ways it was less human than we are – which means that if we are to believe in Adam and Eve, we have to give up belief in human equality.
It is instructive to compare Homo erectus with modern-day tribes whose lifestyle has been described by some as “primitive.” Members of these tribes have relatively little trouble in adapting to the cognitive demands of civilization, some making the transition in as little as a generation. I doubt very much whether Homo erectus could have done that. And I also doubt whether anyone could have preached the Gospel to Homo erectus.
Finally, in a recent post on The Skeptical Zone, I marshaled evidence indicating that Homo erectus almost certainly lacked the use of language, and that even the Neandertals probably lacked it. What’s more, the human brain appears to have evolved specific traits in the lineage leading to Homo sapiens, which allowed our species to possess a full-blown theory of mind and imagine what others were thinking about them.
For her part, Dr. Gauger is not troubled by the fact that Homo erectus lacked our level of linguistic ability. And in a post on Biologos, she responded as follows to my concerns about the lack of symbolic culture in Homo erectus: “First of all, our full capacity for art, drama, philosophy, religion and language was not present 300,000 years ago. Nor was it present, it could be argued until the Egyptians, the early Greeks, and the Chinese had their cultural flowering.” I agree with Dr. Gauger that early Homo sapiens, who lived 300,000 years ago, lacked “our full capacity for art, drama, philosophy, religion and language.” I think that these abilities appeared 100,000 years ago, with the emergence of modern human behavior (see also here). Dr. Gauger argues that the long lag between the appearance of Homo sapiens and the emergence of behavioral modernity means that we shouldn’t consider Homo erectus subhuman because it didn’t behave in this way. I would argue, however, that the human brain did not stop evolving with the appearance of Homo sapiens. It may have subsequently acquired the traits which enabled us to use language and to possess a full-blown theory of mind.
So the long and the short of it is: Dr. Gauger’s model of a two-million-year-old Adam and Eve remains scientifically viable, but their minds would have been very different from ours. Personally, I wouldn’t call Homo erectus a true human being. The Neandertals I’m not so sure about, for reasons I’ve discussed previously.
I’ll just finish by mentioning the work of Dr. Joshua Swamidass, who is an assistant professor at Washington University in Saint Louis where he runs a computational biology group. In an article titled, A Genealogical Rapprochement on Adam?, he accepts “the genetic evidence in which it appears (1) our ancestors arise as a population, not a single couple, and that (2) we share ancestry with the great apes,” but also proposes that an individual named Adam “was created out of dust, and Eve out of his rib, less than 10,000 years ago in a divinely created garden where God might dwell with them, the first beings with opportunity to be in a relationship with Him.” After leaving the Garden, Adam and Eve’s offspring blended with that of their neighbors in the surrounding towns. “In this way, they became genealogical ancestors of all those in recorded history. Adam and Eve, here, are the single-couple progenitors of all mankind.” Of course, humans today have many genealogical ancestors, not just Adam and Eve. An article outlining Dr. Swamidass’s hypothesis will appear in the March 1, 2018 issue of PSCF (Perspectives on Science and Christian Faith). The important thing for readers to grasp is that genealogical ancestry is not genetic ancestry: “Though scientific discourse focuses on genetic ancestry, genealogical ancestry is germane to the theological claims about Adam.” Adam and Eve are ancestors of us all, because genealogical ancestry becomes universal in just a few thousand years. Dr. Swamidass contends that “Scripture and theology, at most, make claims about genealogical ancestry, but not genetic ancestry,” because when Scripture was written, people had no notion of what genes were. I’m not sure, however, that it’s that simple. The Bible appears to affirm that Adam and Eve were the only genealogical ancestors of the entire human race. As Acts 17:26 puts it: “From one man he made all the nations, that they should inhabit the whole earth; and he marked out their appointed times in history and the boundaries.” I’m also not sure exactly what new trait Adam and Eve were supposed to have possessed, under the scenario proposed by Dr. Swamidass, since he explicitly declares that even the human beings living outside Adam and Eve’s Graden were made in the image of God. It seems the only thing that was genuinely new about Adam and Eve was that they were spiritually fallen. But because genetic information is transmitted only unreliably, Dr. Swamidass argues that Adam and Eve, if they existed, “probably did not transmit DNA to all their descendants, nor did they transmit any identifiable DNA to any of their descendants.” He continues: “This means that Adam and Eve’s DNA is not how the Fall or original sin, if they exist, is transmitted to all of us.” At any rate, Dr. Swamidass’s article is a very stimulating read, which is sure to take the Adam and Eve debate in a new direction.
I’d now like to throw the discussion open to readers – especially those with a Christian background. If you had your druthers, which Adam and Eve would you pick? A two-million-year-old one, who was perhaps a lot dimmer than us, as proposed by Dr. Gauger? Or a Neolithic one, as proposed by Dr. Swamidass, who interbred with other humans that were made in God’s image and likeness, and left descendants all over the globe? Or neither of the above?
I’ll leave you all with a concluding thought: “We are more different genetically from people living 5,000 years ago than they were different from Neanderthals,” according to John Hawks, a professor of anthropology at the University of Wisconsin-Madison. Many of the genetic mutations that have spread through the human population in the last few thousand years relate to “changes in the human diet brought on by the advent of agriculture, and resistance to epidemic diseases that became major killers after the growth of human civilizations.” Civilization seems to have been what’s changed us most. But how has it changed our brains? That I don’t know. Maybe someone can tell me. Over to you.