It is always interesting for a Catholic theologian to observe how important topics in Catholic theology are treated among non-Catholic theologians. The latter can illustrate for the former how different theological tendencies can play out when the guidance of the Church's teaching is not in view. One issue of particular interest in a post-Darwinian world is that of human origins: when did the human race originate and how many human beings were there initially? Catholic theology is normally concerned here with the doctrine of original sin and its relationship to the findings of the natural sciences, including population genetics. Back in 1950, Pius XII's encyclical Humani Generis favoured monogenism (our descent from one couple), saying it was ‘in no way apparent’ how polygenism (descent from a wider population) could be reconciled with Catholic teaching on original sin. Catholic theologians who accept the scientific evidence for polygenism have tried to show that its compatibility with original sin can in fact be made apparent, while others who accept monogenism have tried to show how the latter is compatible with the genetic evidence of a wider breeding population.

Similar positions have been taken up among evangelical Protestants. William Lane Craig is a philosopher of religion, well-known for his work on divine attributes, his Neo-Apollinarian Christology, and his Molinist position on human freedom, who has now made an impressive study of the biblical and scientific issues involved in the ‘quest of the historical Adam’, responding critically to Dennis R. Venema and Scot McKnight's Adam and the Genome: Reading Scripture after Genetic Science (2017). While the latter's starting-point was a now standard polygenist account of genetic evidence for a human population that has never gone below some thousands, from there proceeding to ask how Scripture should be re-read in that perspective, Craig chooses to begin with the interpretation of the Bible. Having familiarized himself with a great deal of Old Testament scholarship on the primaeval narratives of Genesis 1–11, he offers in Chapters 2 to 6 an admirably thorough and detailed treatment of the relationship between myth and history in Scripture and the Ancient Near East, the different uses of genealogies, and so on. He concludes that the Scriptural narratives show a number of the ‘family resemblances’ characteristic of myth, while their genealogical interest indicates that they are not so much pure myth as a ‘sort of mytho-history’. There are few surprises here for an informed Catholic theologian.

However, unlike Catholic theologians and many Protestant ones, the key dogmatic issue for Craig is not original sin. While he recognizes the universality of sin, Craig does not think any transmission of original sin from Adam or the imputation of Adam's sin to his descendants is necessary to maintain an evangelical doctrine of Atonement wrought by the Second Adam. Already in chapter 1 we see that what is at stake for Craig is rather the truthfulness and reliability of Scripture, should it teach that there was an historical First Adam at the origin of the human race. While Craig holds that many New Testament passages need only propose of ‘Adam’ something ‘true in the story’, he concludes in Chapter 7 that some passages do more and hold the truth of Adam's historical existence (Rom. 5:12-21; 1 Cor. 15:21-22). It is for this reason that Craig thinks something crucial is at stake in what the scientific evidence has to say about such things as when the human race originated and how many first human beings there were.

From Chapter 8 onwards he turns from Scripture to science, including evidence from palaeoneurology (Chapter 9) and archaeology (Chapters 10 and 11). He makes a very good cumulative case, especially from Neanderthal material culture and thus their capacity for symbolic behaviour and language, to include Neanderthals and Denisovans within the human family. This leads him to conclude in Chapter 12 that the ‘historical Adam’ is to be located some 500,000 or more years ago within homo heidelbergensis, the hominid population ancestral to Neanderthals, Denisovans, and homo sapiens.

In this way Craig takes a different position from S. Joshua Swamidass, the author of The Genealogical Adam and Eve: The Surprising Science of Universal Ancestry (2019). Like Venema, Swamidass is a biologist. He suggests that Adam and Eve were a fresh creation by God some few thousand years ago who then interbred with an already existing population of homo sapiens, leading eventually to the descent of every individual in the global population from this single couple. While Craig differs from his fellow evangelical in this conclusion, he nevertheless draws on Swamidass's critique of the arguments employed by Venema and others from population genetics against the existence of an original first couple.

In short, Craig follows Swamidass in holding that what can be concluded from genetics about population size not going below some thousands does not apply beyond around 500,000 years ago. This enables Craig to regard his conclusion about the dating of a first couple as possible in light of what we know for certain from population genetics. He notes that Venema has shifted his position in response to Swamidass's critique, Venema now regarding a founding first couple as more highly improbable than absolutely impossible. Craig concedes that if all true human beings are descended from a founding population of a single couple, then Adam and Eve must carry the seeds of current human diversity, and so the genetic differences between them must have been considerable. While allowing the possibility of such monogenism, he recognizes also the possibility of interbreeding of true human beings with the wider homo heidelbergensis population.

One thing that becomes clear by the end of the book is that there is little engagement by professional population geneticists in the question of monogenism. And why would there have been, when they are concerned with the evidence of their own science and not questions arising from Christian Scripture and Tradition? However, just to observe how population geneticists would approach the question would be of interest to theologians, whether Catholic or evangelical.