The Death of Genealogical Adam: Shipwrecked in the Bass Strait

Computational biologist Joshua Swamidass says a literal Adam & Eve could have lived as recently as 6,000 years ago. Tasmania says otherwise.

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Listen or Read. Your Choice

Today, I’ll hit “pause” on Adam’s Evolutionary Journey to review a new book by computational biologist S. Joshua Swamidass, The Genealogical Adam and Eve.

What does genealogy have to do with Adam and Eve? Simply, it allowed them to become everyone’s “parents” without requiring them to be the first humans. In the “genealogical Adam” scenario, God created Adam from dust and Eve from his rib and placed them in the Garden of Eden in Mesopotamia 6,000 years ago. After being expelled from the garden, Adam and Eve then had children who interbred with the already existing population, and eventually they became related to everyone on Earth by lines on a family tree, rather than by Eve – “the mother of all the living” (Gen. 3:20) – giving birth to the human race.

If that sounds needlessly complicated, it is. “It’s a neat parlour mathematical trick,” population geneticist Graham Coop said on Twitter, but “saying that this reconciles science with the idea of Adam and Eve sweeps a lot of stuff under a very patchy, ugly carpet.” Coop is correct. Genealogical Adam and Eve solves none of the actual problems posed by a literal Adam and Eve.

Since this is a book review, I suppose I should start by mentioning something about the author’s style before we dive into the substance. His prose is serviceable, but reading the book felt more like a chore than a pleasure. Swamidass repeats himself frequently, and he seems determined not to make a claim without qualifying it six ways from Sunday. On page 10, for example, he states his “precise and testable hypothesis, consistent with Scripture,” but immediately we discover that “the details are flexible.” Maybe Adam was directly created by God, maybe not. Maybe he lived in the Middle East, maybe somewhere else. Maybe the garden was a supernatural, perfect environment, maybe it wasn’t. Maybe those “outside the garden” are made in God’s image, maybe they’re not. To this reviewer, the hypothesis seems designed to make a literal Adam and Eve unfalsifiable, not “precise and testable.” In science, I believe that’s called an ad hoc auxiliary hypothesis.

On to the substance. The foundations of Genealogical Adam and Eve rest on a single paper from 2004, “Modelling the Recent Common Ancestry of All Living Humans.”[1] The authors used the genealogical phenomenon of pedigree collapse to estimate the most recent common ancestor for everyone alive today. Since formulas can’t simulate real-world human mating and migration patterns, the authors constructed a simulation program to model the historical world population from 20,000 B.C. to the present. (Think The Sims on steroids.) After running the program countless times and analyzing the “lives” of 1.2 billion sims, the authors concluded that the most recent common ancestor likely lived around 1400 B.C, and by 5400 B.C. everyone alive was either a common ancestor to us all or had no descendants alive today. For religious reasons, Swamidass adds roughly 2,000 years to these dates to arrive at his estimate for Genealogical Adam and Eve, whom he places 6,000 years ago, magically fitting the timetable required by Young-Earth Creationism.

Baptist theologian Kenneth Keathley has said he considers “genealogical Adam” one of just two available options for Old-Earth Creationists. He also specified a scientific challenge to the hypothesis – the relative isolation of Australia and the Americas. The original paper addressed the same problem, and Jotun Hein cautioned in the same issue of Nature:

“Because of the effects of isolation, had we been living in 1700, say, and tried to work out when our universal and identical ancestors lived, the answers would have been further back in time than the answers we obtain now. Tasmania, for instance, was conceivably completely isolated at the time, and probably had been for millennia; this would therefore have pushed back the dates for universal and identical ancestry. So uncertainties about population structure introduce uncertainty into the proposed dates.”[2]

If Tasmania truly was isolated for millennia when Jesus was born, then Adam’s “family tree” had to reach Tasmania before it was cut off from the rest of the world. Otherwise, by the time of Christ the Tasmanians are not “descendants of Adam” and, presumably, not stained by his sin.

Hein’s caveat looms especially large given the specific requirements of Genealogical Adam and Eve. The original simulations ran with a target date of A.D. 2000, since the program was intended to find common ancestors for the present population. Swamidass’ scenario has a different target date. Many Christians believe the apostle Paul’s arguments in Acts 17 and Romans 5 require more than just a literal Adam – they require everyone to be descended from him when Paul was writing. Thus, the target population for “genealogical Adam” must be adjusted to A.D. 1, which explains why Swamidass adds 2,000 years to the original estimates.

Now, we have entered the territory of Hein’s exception. If Tasmania truly was isolated for millennia when Jesus was born, then Adam’s “family tree” had to reach Tasmania before it was cut off from the rest of the world. Otherwise, by the time of Christ the Tasmanians are not “descendants of Adam” and, presumably, not stained by his sin. On top of the 2,000 years that Swamidass already has added, Tasmanian isolation could add another 10-12,000 years to his estimates. In that case, even if Adam and Eve are literal individuals, they no longer fit the preferred 6,000-year timeline.

Swamidass obviously recognized the problem, since he devotes an entire chapter to the “Myth of Isolation.” He downplays Tasmania’s isolation as something “not possible to demonstrate with evidence” (76), and he concludes that it “seems reasonable to wonder if at least one boat managed the crossing every century or so” (73). Is that a reasonable expectation? Everyone who has studied Tasmania and the Bass Strait say, “No.” 

The Devil’s in the Details: Tasmania

During the last glacial maximum 43,000 years ago, sea level dropped about 120 meters, opening a land bridge between Australia and Tasmania. What is now the Bass Strait was then a broad plain with a depression in the center, probably containing a large freshwater marsh or lake. As the earth warmed again and glaciers melted, the rising sea first broached this shallow valley from the west 17,500 years ago, and the land bridge connecting Australia and Tasmania was entirely submerged by 14,000 years ago.[3]

The resulting Bass Strait isn’t your average body of water. The seabed rises abruptly on both ends of the channel, which amplifies the energy of the tidal currents and creates dangerous rips. The Tasman Sea and the Southern Ocean meet in the Bass Strait, and when oceans collide, rough waters are the inevitable result (e.g. the Cape of Good Hope and Cape Horn). On top of everything else, Tasmania sits squarely in the “roaring 40s” – a band of strong winds that circle the globe around the Southern Hemisphere’s 40th latitude. As they whip around Antarctica, these winds meet no resistance from any land masses except Tasmania, New Zealand, and the tip of South America. Everything considered, Bass Strait has a well-earned reputation as one of the most dangerous and unpredictable marine passages in the world.

When water began pouring through the eastern end of the strait, people fled to higher ground on Tasmania. Although the sea would continue to rise for several thousand years, both islands were most likely cut off from the outside world within a few generations, a situation that lasted until the first Europeans arrived in the 17^th century. [4]^–[5]

Despite Tasmania’s isolation, Swamidass points to the seafaring abilities of ancient humans as “evidence that ancient Homo sapiens were capable of crossing large bodies of water” (72). He notes that sapiens most likely arrived in Australia by boat and also colonized more distant islands in the Pacific, and based upon these facts, he concludes that it’s reasonable to think at least one boat every century still crossed the strait to Tasmania.

The experts disagree, and they have for decades. Swamidass seems unaware of the actual archaeological and genetic evidence available. When the Europeans first arrived, they found sophisticated, sail-powered canoes in the north, but elsewhere the watercraft were “poorly constructed and correspondingly fragile, restricted in their use to the quiet waters of sheltered coasts and estuaries.”[6] On both sides of the Bass Strait, boats were made of bundled bark, reeds, and grass, and they were propelled by pole, paddle, or people swimming alongside. In 1978 the archaeologist Rhys Jones made replicas of these watercraft to test their capabilities. Even the best examples fell apart in rough water, and all of them became waterlogged in a day or two.[7]

I asked Univ. of Sydney archaeologist Peter Hiscock whether such boats could reach Tasmania. He replied, “The watercraft Jones described certainly could not cross Bass Strait. The big islands in the center of the Strait were uninhabited because they could not be reached by either Tasmanians or by southern Mainland Aboriginals.”

Swamidass hopefully suggests that an island-hopping strategy would allow ancient mariners to reach Tasmania. For comparison’s sake, a three-man team of professional paddleboarders claimed a “world first” by making that same journey in 2014. They required a week to do it, and the leader of the team remarked, “It was like a constant race every day just to try and beat the tides, so it’s definitely lived up to its name as a gnarly piece of water.”[8] A grass and reed boat that sinks after two days simply wouldn’t make it across the rough waters of the Bass Strait – not even island hopping, not even once a century.

(Swamidass) is not making an evidence-based argument. In terms of scientific process, the better approach is the null hypothesis.

Sandra Bowdler, Emeritus Professor in Archaeology, Univ. of Western Australia

An expert on ancient seafaring, anthropologist James F. O’Connell scoffed when asked about Swamidass’ proposal that one boat per century possibly made the crossing. He said, “An island hop from Melbourne to King Island is about 120 kilometers (75 miles), which is within the scale of crossings made further north in the Pleistocene.  But the risk of crossing Bass Strait is much greater than in the tropics – colder, rougher water. There’s no evidence of Holocene watercraft in South Australia capable of making this transit. So, no, the supposition is not reasonable.”

The myth of progress says that once people acquire a technology, they always retain and improve upon it. Tasmania, because of its isolation, defies that paradigm. Many Neolithic tools the Tasmanians possessed disappeared over the millennia, such as stone thumbnail scrapers and bone points. They stopped eating fish entirely more than 4,000 years ago, abandoning it in favor of protein-rich abalone and shellfish found near to shore, which women harvested by diving into the frigid waters.[9] On top of that, things that were ubiquitous in Australia never appeared in Tasmania. The boomerang was invented more than 11,500 years ago, and the dingo was brought to Australia 4,000 years ago. Neither made it to Tasmania prior to the end of its isolation in the 17th century.[10] Commenting on these facts, Hiscock said, “All the evidence is consistent with Tasmania being isolated. There are new animals and many cultural patterns introduced into Southern Australia after the sea level rise, and none found their way to Tasmania, which is consistent with isolation. Creationists can hardly hold scientists to evidence and expect us to have evidence for every question when they disregard evidence they don’t like.”

Perhaps realizing that his case disregards the evidence, Swamidass focuses on Australia as a whole and claims that “genetic data settles the debate” (72) about isolation. He points to a controversial 2013 study that claimed “substantial gene flow between the Indian populations and Australia” around 4,000 years ago.[11] In making this claim, Swamidass ignores a 2017 study that noted “all studies on mtDNA variation in Aboriginal Australians, including the present one, find no evidence of recent gene flow from the Indian sub-continent during the Holocene. … As all Aboriginal-specific mitochondrial haplogroups are of great antiquity, show considerable substructure, and are (mostly) very widely dispersed across the Australian continent while not being present outside Australia, it can be inferred that after initial colonization some 50,000 years ago there has been a very long period of isolation of humans in Australia.”[12]

I contacted Robert Mitchell, corresponding author on the above study, and asked, “Is there any genetic evidence that would cause you to doubt Tasmania’s isolation?” He replied by email:

“Tasmania’s isolation is a result of geological and geomorphological research. The human genetic studies of all Aboriginal Australians clearly indicate that the Australian gene pool was isolated for at least 40,000 years, and even contact between the gene pools of present day Australia and New Guinea seems to have ceased maybe 30,000 years ago (with a possible exception in Northern Australia). … There have been no Tasmanian Aboriginal Y-chromosomes found to date, but the mitochondrial haplotypes in Tasmania are considerably older than 10,000 years old and they are distantly related to their mainland equivalents.”

It boggles the mind, but the inescapable conclusion is that Tasmania was entirely cut off from the rest of the world for nearly 12,000 years – from 10,000 B.C. until the arrival of Europeans in the 17^th century.

Implications of Isolation

Swamidass brushes aside Tasmania’s isolation as unreasonable and impossible to demonstrate. In his words, “one has to prove that absolutely zero successful immigration has taken place over hundreds or thousands of years” (76).

On the contrary, the burden is upon Swamidass to produce evidence capable of overturning that scientific consensus. O’Connell, a member of the editorial board of the Proceedings of the National Academy of Sciences, points out that “It is on the author to make the case, not on the reader to prove a negative.”

No amount of hand waving or special pleading will make the evidence disappear or the scientists withdraw their opinions.

Sandra Bowdler, Emeritus Professor in Archaeology at the Univ. of Western Australia and one of the foremost authorities on Tasmania, agreed with that assessment. She said, “(Swamidass) is not making an evidence-based argument. In terms of scientific process, the better approach is the null hypothesis. Of course, it’s not possible to prove there was absolutely zero successful immigration. It is possible, however, to disprove that it never happened – one only needs one contrary example. So far, no one has demonstrated one.”

No amount of hand waving or special pleading will make the evidence disappear or the scientists withdraw their opinions. How far does this push “genealogical Adam” back into the past? If we follow Swamidass’ methodology and simply apply the estimates from the simulation to a new target date of 10,000 B.C., then the revised timeline for Genealogical Adam and Eve would fall around 14,000 B.C.

Obviously, the title of this article is an exaggeration. Genealogical Adam and Eve aren’t dead; they’re just 10,000 years older than advertised. Will Young- or Old-Earth Creationists find 14,000 B.C. appealing as a historical location for Adam and Eve? I can’t answer that question, but it does bring up another: Why does Swamidass fight so hard to muddy the waters around Tasmania? Was his primary goal to rescue a 6,000-year-old Adam and Eve from the clutches of science, even at the expense of ignoring evidence? To this reviewer, it appears so.

Next week, we’ll take a look at the problems that Genealogical Adam and Eve create for original sin. Believe it or not, the problems grow even worse.

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[1] D. L. T. Rohde, S. Olson, and J. T. Chang, “Modelling the Recent Common Ancestry of All Living Humans,” Nature 31 (2004): 562–66, https://doi.org/10.1038/nature02842. Rohde also has posted an unreviewed version of the work-in-progress at https://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf.

[2] J. Hein, “Pedigrees for all humanity,” Nature 431, 518-19 (2004).

[3] K. Lambeck and J. Chappell, “Sea Level Change Through the Last Glacial Cycle,” Science 292 (5517): 6798-8 (2001). doi: 10.1126/science.1059549.

[4] R. Sim, “The archaeology of isolation?: prehistoric occupation in the Furneaux Group of Islands, Bass Strait, Tasmania.” (1998). Unpublished Ph.D. Thesis, Department of Archaeology and Natural History, Australian National University, Canberra. http://hdl.handle.net/1885/110266

[5] I. Davidson and D. Roberts, “14,000 BC – On Being Alone: The Isolation of Tasmania,” in Turning Points in Australian History, eds. D.A. Roberts and M. Crotty, Sydney: University of New South Wales Press, (2008): pp. 18-31.

[6] J.F. O’Connell, J. Allen, and K. Hawkes, “Pleistocene Sahul and the origins of seafaring,” in The global origins and development of seafaring, eds. Anderson, A., Barret, J. H., & Boyle, K. V. London: McDonald Institute Monographs (2010): 57-68.

[7] O’Connell et al., “Origins of Seafaring.”

[8] “Australians cross Bass Strait on paddleboards.” (March 5, 2014). Retrieved from https://www.abc.net.au/news/2014-03-05/australian-pair-cross-bass-strait-on-paddleboards/5299038?section=tas. Accessed July 9, 2019.

[9] Davidson and Roberts, “14,000 BC – On Being Alone.”

[10] Davidson and Roberts, “14,000 BC – On Being Alone.” The Tasmanians loved dogs and readily adopted them as soon as they were brought to the island.

[11] Pugach, I., F. Delfin, E. Gunnarsdottir, M. Kayser, and M. Stoneking. “Genome-Wide Data Substantiate Holocene Gene Flow from India to Australia.” Proceedings of the National Academy of Sciences 110 (2013): 1803-8. https://doi.org/10.1073/pnas.1211927110

[12] Nano Nagle, et al., “Aboriginal Australian Mitochondrial Genome Variation – an Increased Understanding of Population Antiquity and Diversity.” Scientific Reports 7, no. 1 (2017). https://doi.org/10.1038/srep4304.

Tagged as: Genealogical Adam & Eve, GAE, Literal Adam & Eve.