Genealogical Adam and Eve: book review

Book cover

The author of this interesting book, S. Joshua Swamidass, posits that the scientific evidence is consistent with the hypothesis that we could all be descended from a single couple who lived in comparatively recent times, say, 10,000 years or so ago. The conventional wisdom is that Mitochondrial Eve, the most recent matrilineal common ancestor of all people alive today, and Y-Chromosomal Adam, our most recent patrilineal common ancestor, lived at very different times 100,000 or more years ago and so could not have been a couple. Dr. Swamidass, an MD, holds a PhD in information science, and is an associate professor at Washington University in St Louis. He is the real McCoy, not someone who has quit to shill for Answers in Genesis, Reasons to Believe, or Aish HaTorah, and must be taken seriously.

The full title of the book is The Genealogical Adam and Eve: The Surprising Science of Universal Ancestry. In it, the author makes a distinction between your genealogical ancestry and your genetic ancestry. He notes that your genes are diluted from one generation to the next, so that eventually people who are in fact your descendants will very probably have none of your genes. I think of it as diluting a solution over and over again: eventually, none of the solute will remain in the solvent, because the solute is not infinitely continuous but rather is made up of atoms or molecules. Once the last solute molecule is gone, the concentration is 0. In the same way, your genes (or your genetic inheritance) are not continuous, and once the last gene is gone, your descendants inherit none of your DNA. (When I read this account, I was reminded of T.H. Huxley’s lament after having read On the Origin of Species: How extremely stupid of me not to have thought of that.)

Your descendants, though they are not genetic descendants, are still your descendants; Dr. Swamidass calls them your genealogical descendants. Unlike your genetic descendants, who dwindle in number, your genealogical descendants are apt to grow in number. Eventually, as they crossbreed with the genealogical descendants of others, one lineage will comprise the entire population of earth (I will not go into detail here, but Dr. Swamidass is at pains to document what you might call sufficient “crosstalk” among nearly all populations on earth, though I think he may have forgotten about New Guinea).

At any rate, one lucky couple eventually becomes the most recent universal genealogical ancestral couple, and Dr. Swamidass dubs them the MRUGA (a designation which, alas, does not have the same ring as LUCA). I did not understand precisely why he chose the date 1 CE, but Dr. Swamidass estimates that the MRUGA may have lived “a few thousand years ago,” and the entire population of the earth became their genealogical descendants in 1 CE. Could they have been Adam and Eve? Did God create them de novo? Sure, I suppose they (or a couple ancestral to them) could have and he could have. I began to think of Russell’s teapot, but Dr. Swamidass presents us with his own version, a unicorn on the far side of the Moon. Dr. Swamidass is somewhat coy, but he remarks on the absence of evidence for or against his hypotheses so frequently, especially in the first half of the book, that I began to think, with Gertrude, the doctor doth protest too much, methinks. Nevertheless, if his purpose is to debunk the conventional wisdom concerning Y-Chromosomal Adam and Mitochondrial Eve, I think he has succeeded admirably. And perhaps he has taught scientists a lesson: Don’t be too sure of yourselves.

Dr. Swamidass’s vision seems to be that of a Garden of Eden in which Adam and Eve are created de novo from dust and a rib, and eventually released into the world of (to borrow a phrase from Gerald Schroeder, 1997 ed.) pre-Adamic hominids; at least, he argues that scientific evidence cannot rule out this possibility, and indeed he considers others as well. Even if Adam and Eve have been created miraculously, the pre-Adamic hominids evolved according to normal evolution. Dr. Swamidass calls Adam and Eve and their descendants, textual humans, because they are mentioned in the Bible. These textual humans and their descendants interbreed with the pre-Adamic hominids, whom Dr. Swamidass calls biological humans, and their descendants. Eventually the textual humans and their genealogical descendants predominate. To put it bluntly, I see no reason to think there is a unicorn on the far side of the Moon, and I similarly see no reason to think that Adam and Eve were created de novo in a sequestered garden just a few thousand years ago, while other humans evolved outside the garden in the normal manner. (Did Adam and Eve have the same genome, incidentally, and if so was their relationship incestuous?)

Dr. Schroeder declared that Adam and Eve were the first hominids to be given souls. As evidence, he points to the sudden flowering of civilization and technology at about the right time. Dr. Swamidass likewise seems to think that there was something (theologically) special about Adam and Eve, but I think he does not really specify what that means. He notes, however, that Adam and Eve and their descendants are otherwise indistinguishable from the hominids living around them and indeed interbreed with them. I am frankly disturbed by this concept, because (protestations to the contrary), it implies that biological humans who did not descend from the Garden of Eden were somehow less than fully textual humans, that is, less than genealogical descendants of the pair in the garden. I do not want to inveigh against a proposition because of its possible consequences, but I know all too well what happens when some people are considered to be intrinsically different (a problem which Dr. Swamidass to his credit also acknowledges).

I hope I am not putting words into his mouth, but Dr. Swamidass must think that something, some essence, call it textuality if you like, somehow propagates to the descendants of Adam and Eve, but exactly how does it do so? Is the textuality encoded genetically? Epigenetically? Is it dominant or recessive? Do all the descendants become textual humans, or do some remain merely biological humans? Is textuality badly diluted generation after generation, until it disappears? If not, does it follow Adam and Eve’s genealogical descendants, and if so, how? None of these questions is posed, let alone answered.

Dr. Swamidass has avowedly written his book in order to attract creationists to evolutionary biology or at least to make them feel less threatened by evolutionary biology, and also to attract atheists and agnostics to religion. I cannot speak for creationists, but I cannot see atheists taking the book very seriously. The last chapter is in part an appeal to anyone who does not take the origin story literally, and Dr. Swamidass rightly corrects those who think that science has definitively ruled out Adam and Eve. He calls for tolerance and suggests that we avoid abusing scientific authority. All very well, and I cannot agree with him more. But does his discovery that Adam and Eve “could have” been an actual couple that existed in the near past influence my belief or nonbelief in God? Not one whit. And the suggestion that they “may have” been created de novo in a walled garden seems to me like sheer fantasy.

I am keenly interested in scientific or textual arguments designed to elucidate the origins of the Bible and the existence or nonexistence of the people and events therein. Perhaps that is one reason that I was interested in the concept of a genealogical descendant. The argument that a single couple could have been the ancestors of everyone alive today was interesting and clever, and people will assume that that couple was Adam and Eve. Indeed, the book would not be particularly interesting if we thought the couple might not have been Adam and Eve. Before the couple’s descendants dominated the entire earth, however, each previous generation would have had a different pair of ancestors, as Dr. Swamidass himself makes clear. Why would we not think that one of those many couples may have been Adam and Eve?

A confession: I could barely get through the theological arguments in the latter part of the book. They read to me like the proverbial angels dancing on the head of a pin, which I have always understood to be a metaphor for answering the question whether angels have volume or mass or something, while implicitly presuming the somewhat problematic existence of angels. Dr. Swamidass expends considerable energy trying to deduce whether people existed outside the Garden. All you have to do is take one look at the text and conclude that, of course, it implies existence of other people (see, for example, Nephilim or the myth surrounding the mark of Cain and Cain’s wife in Genesis 6:4).

But Dr. Swamidass has an ax to grind – he needs to be acceptable to fundamentalist Christians – so he scrutinizes the text in fine detail in order to establish the existence of people outside the Garden Biblically. The Appendix, which is a reprint of a paper by the author, seemed unnecessary and unrelated to the rest of the book; it must similarly be intended to appeal to a fundamentalist Christian audience. I cannot agree with his conclusion concerning the historicity of either Jesus of Nazareth or his supposed Resurrection. I do not doubt that someone like the Jesus described in the so-called New Testament may have existed, but in fact, there is no contemporaneous evidence in support of that contention; even the earliest Gospel was written 40 years after Jesus died. Likewise, I maintain that “prophecies” in the Hebrew Bible are mere cherry-picked anachronisms.

Do not get me wrong. The book is well thought out and mostly clearly written, though frankly it could have used an editor to shorten it by 30 % or so. It has a great many figures, most of which are clear and add to our understanding (I found, among a few others, Figure 1 and one or two of its variants somewhat difficult, however).

The concept of genealogical ancestry is clever, and the estimates as to when they existed are surprisingly recent. Equally surprising, our most recent genealogical ancestors are a couple; this conclusion is contrary to the conventional wisdom, which focuses on genetic ancestry and places Mitochondrial Eve and Y-Chromosomal Adam many thousands of years in the past. Nevertheless, to my mind there is no evidence to suggest that our genealogical ancestors have any Biblical or theological significance whatsoever. Genealogical ancestry is merely an amusing puzzle, and the discovery that our most recent universal genealogical ancestors have been recent seems to me to have no more significance than the discovery that our last universal common (genetic) ancestor was not recent. It does not make me think, “Oh, maybe there is more to this Adam and Eve myth than I had supposed!”

Acknowledgments. Deanna Young, who had little choice, and Glenn Branch, who did, read a draft and provided many provocative comments. You may find Mr. Branch’s review of the same book here, alas, behind a paywall. Joshua Swamidass graciously read a subsequent draft and offered specific criticisms, which I have tried to address.