I have been publishing a series of articles addressing how one might best approach interpreting the early chapters of Genesis, and how science might illuminate Biblical texts and guide our hermeneutics. In the first article, we saw that, even if it be supposed that a young earth interpretation of Genesis 1-11 is the most face-value reading of the relevant texts (a supposition that I am perfectly happy to grant), it does not follow that such an interpretation should necessarily be our preferred one. Given that part of the background information we bring to those texts is that we have good reason to believe that Genesis represents inspired and authoritative Scripture, as well as good reason to believe that the earth is in fact very ancient (on the order of billions, rather than thousands, of years), interpretive approaches that result in harmony between Scripture and science should be preferred over ones that put them in conflict. Non-believing readers, on the other hand, seeing no independent reason to think that the Bible, including Genesis, represents inspired and authoritative Scripture, have no reason to favor interpretive approaches that bring harmony between the statements of Scripture and our independent body of background knowledge. I would, however, like to appeal to my non-believing readers to recognize the in principle legitimacy of the approach I am proposing — that, having independently concluded that Genesis is inspired Scripture, it is perfectly valid to seek to harmonize its text with other data. One might of course reasonably ask what independent reason there is to think that Genesis is indeed Scripture. My appeal here would be to, among other considerations, the testimony of Jesus (whom, I have concluded, through rational inquiry, to have been speaking truly in regard to His self-identification as God incarnate). Since Jesus honored the originalist meaning of Genesis — not to mention the apostles Paul and Peter, who likewise did — that ought to incline the rational Christian to take the text of Genesis very seriously indeed. Of course, one’s confidence in Jesus’ identity will depend very much on how strong one takes, among other things, the evidences for His resurrection to be (which is God’s public vindication of Jesus’ radical Messianic and divine self-claims) and His fulfilment of Biblical prophecy. Thus, these issues are all rather interrelated.
On the other hand, it must be recognized that favoring an interpretation other than the most face-value reading of Scripture (i.e. how it would most likely be interpreted without the influence of scientific data) does somewhat reduce the likelihood of Jesus being God incarnate, since it stands to reason that whatever one who is God incarnate believed (at least on such a matter) is true. The extent to which this evidence bears against Jesus’ deity (and therefore the truth of Christianity) will depend on the plausibility of interpretations of Genesis 1-11 that do not entail a conclusion that is manifestly mistaken (e.g. that the Universe is only six thousand years old).
I must add here, lest I be misunderstood, that as a scholar I believe it is important to give a verdict on whether each individual argument and item of evidence tends towards the truth of Christianity or against it, as well as a verdict on whether the arguments and evidence, taken as a whole, should incline the rational inquirer towards or away from Chsristianity. While I am happy to concede that this or that individual argument may tend against Christianity, I firmly believe that the totality of evidence, considered holistically, is more than sufficient to warrant belief in the gospel’s truth as well as to build one’s life on it.
It is common for lay-people to think of evidence as an ‘all or nothing’ proposition — that is, a piece of evidence either establishes a conclusion or it does not. However, the situation is usually much more complex than that. For example, in a court of law, as in science, it is normal for a conclusion to be established not by a single sufficient piece of evidence but rather by multiple pieces of evidence, none of which individually are of very great weight, which, when taken together, provide sufficient reason to warrant a conclusion. Furthermore, it is not uncommon for theories in science to have anomalous data — that is, data that does not comport with the paradigm — and arriving at a rational conclusion requires an analysis and evaluation of the balance of evidence — that is, which of the explanations makes sense of the data taken as a whole? It is not always bad — contrary to popular perception — to invoke one or more ad hoc auxiliary hypotheses to account for anomalous data, provided that one is candid and upfront about this fact, and that one acknowledges that one’s thesis has taken a probabilistic hit as a consequence. Provided that the reasons for believing the theory in question are, taken together, stronger than the reasons for rejecting it, it remains rational to accept it as true. Therefore, the presence of evidence against one’s thesis does not necessarily render it irrational for one to continue to believe it. Some readers may feel uncomfortable with the fact that there exists any evidence at all against their beliefs. But this arises inevitably from our incomplete knowledge of the world. If we were to possess exhaustive knowledge, then all evidence would be seen to point, with one accord, in the direction of that which is true. Since we lack exhaustive knowledge, we must evaluate the balance of evidence based on the facts and data that are available.
In my second article in this series, I sought to evaluate the Biblical support for there have been no death, of any kind, prior to the fall of man — an issue that is considered by many young earth creationists to be the weightiest of concerns that should compel one to embrace a young earth interpretation. Having carefully assessed the relevant texts, I concluded that, while the Biblical evidence is compelling for there having been no human death prior to the fall, the evidence for there having been no animal death I found to be quite weak, since all of the relevant texts are open to very plausible alternative interpretations. In this case, I am not even convinced that the view of there having been no animal death prior to the fall is most face-value interpretation.
In this article, I will address what I consider to be the single most thorny issue in regards to the early chapters of Genesis — human origins. First, I will argue that the literal historicity of Adam and Eve, being foundational to the gospel itself, is of extreme importance, and that rejection of their literal historicity cannot be assented to without dire theological consequence. Second, I will argue that the Biblical accounts allow for Adam and Eve to have existed hundreds of thousands of years ago, though the most plausible and face-value reading of the relevant texts (in particular the genealogical accounts in Genesis 5 and 11) is that they lived much more recently — perhaps six to ten thousand years ago. Third, I will tackle the question of whether Adam and Eve are compatible with evolutionary theory and will also offer a brief critical appraisal of evolutionary theory. Finally, I shall discuss what we can discern from Scripture about whether Adam and Eve were alone or whether there were other humans on the earth at the time, who themselves were not descendants of Adam and Eve. I shall also briefly address the subject of other ancient hominid species such as the Neanderthals and Denisovans.
How Important Is It to Affirm a Literal Adam and Eve?
The historicity of Adam and Eve is a question which strikes at the heart of the Christian faith. If the primordial pair did not exist, then the historical and biblical doctrine of the fall becomes extremely difficult to maintain. Moreover, the apostle Paul clearly linked God’s redemptive plan and Christ’s atonement for sin with the fall described in Genesis (Rom 5:12-21). We read in Romans 5:12-14,
12 Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned— 13 for sin indeed was in the world before the law was given, but sin is not counted where there is no law. 14 Yet death reigned from Adam to Moses, even over those whose sinning was not like the transgression of Adam, who was a type of the one who was to come.
In 1 Corinthians 15:20-22, we similarly read,
20 But in fact Christ has been raised from the dead, the firstfruits of those who have fallen asleep. 21 For as by a man came death, by a man has come also the resurrection of the dead. 22 For as in Adam all die, so also in Christ shall all be made alive.
Much of Christian theology concerning the gospel is derived from the letters of Paul. While the gospels are our primary sources of information for the ministry of Jesus, the letters of Paul are our primary (though certainly not exclusive) source of information for the theological significance of Jesus’ life and death. As such, we would be significantly impoverished if we did not have those letters. In the passages quoted above, Paul asserts that the fall of Adam brought sin, and therefore human death, into the world, and that this is the reason why Christ had to die physically on the cross in order to bring redemption. The historicity of a literal primordial couple, then, is something that is foundational to what the gospel is. Moreover, the parallel of verse 22, “For as in Adam all die, so in Christ all will be made alive” also suggests that Adam was a literal historical figure in the same sense that Christ was.
Further evidence that Paul took Adam as a literal historical figure can be found in 1 Timothy 2:11-14 where he appeals to this doctrine in order to make an argument concerning the role of women in the church with respect to men. Paul writes,
11 Let a woman learn quietly with all submissiveness. 12 I do not permit a woman to teach or to exercise authority over a man; rather, she is to remain quiet. 13 For Adam was formed first, then Eve; 14 and Adam was not deceived, but the woman was deceived and became a transgressor.
Indeed, Jesus Himself clearly understood Adam and Eve to have been historical figures. In response to questioning from the Pharisees about marriage and divorce, Jesus declared (Mt 19:4-6),
4 He answered, “Have you not read that he who created them from the beginning made them male and female, 5 and said, ‘Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh’? 6 So they are no longer two but one flesh. What therefore God has joined together, let not man separate.”
Thus, not only did Jesus take Genesis to be Holy Scripture; he affirmed the historicity of a literal first couple in particular.
As if that wasn’t enough, the genealogies recorded in Genesis 5, 1 Chronicles 1 and Luke 3 treat Adam as an historical figure. The literature associated with second temple Judaism also recognized Adam as an historical individual.
When Did Adam and Eve Live?
Having established that Adam and Eve are treated unequivocally by Scripture as real historical people, are we able to determine from Scripture when approximately Adam and Eve lived? The common view that is adopted by young earth creationists is that Adam and Eve lived approximately six thousand years ago. This is predicated on the chronology of Archbishop James Usher of Ireland (1581-1656), who placed the creation of the world in 4004 B.C.  Usher’s estimate was based on the Biblical genealogies, in particular those given in Genesis 5 and 11. The scientific data, however, indicates that anatomically modern humans (Homo sapiens) have been on the scene for at least 200,000 years. If we include other hominid species such as Homo neanderthalensis (which date to more than 400,000 years ago) within our race, then that pushes humanity’s origins back even further still. If these dates are to be harmonized with Genesis, there must be a significant level of incompleteness in the Biblical genealogies of Genesis 5 and 11. But does Scripture allow for such incompleteness of the genealogical records?
Reading some modern translations, it is easy to come away with the impression that the genealogies in Genesis 5 and 11 leave no room for gaps. For example, the Revised Standard Version (RSV) renders the pattern of the Genesis genealogies as follows:
When A had lived X years, he became the father of B. A lived after the birth of B Y years, and had other sons and daughters. Thus all the days of A were Z years; and he died.
The rendering in the English Standard Version (ESV) more closely reflects the Hebrew, in translating the text “after he fathered…” rather than “he became the father of…” This difference is subtle but crucially important. This construction allows for genealogical gaps. For example, the gospel of Matthew states that “Joram fathered Uzziah.” But in 2 Kings we learn that Uzziah was in fact Joram’s great-great grandson. Thus, it seems that “A fathered B” can be interpreted to say “A fathered an ancestor of B.” We may identify other instances of compressed genealogies in Scripture. For instance, in Exodus 6:14-27, we learn that Moses was the son of Amram, who was the son of Kohath, who was the son of Levi (who was the son of Jacob). Thus, there would seem to be only four generations between Jacob and Moses. But there is reason to believe that this genealogy of Moses is highly compressed. In Gen 46:11, we learn that Moses’ “grandfather” Kohath was born before Jacob’s family travelled to Egypt, hence before the timespan of approximately 430 years that the Israelites were in Egypt (Exod 12:40-41). If Moses was 80 when the Exodus took place (Exod 7:7), then his presumed grandfather Kohath would have been born a minimum of 350 years prior to Moses’ birth. Another reason to believe the genealogy of Moses to be highly compressed is that, as C. John Collins observes, “Kohath’s descendants numbered 8,600 males over the age of one month (Num. 3:27–28), and 2,750 of them were between the ages of 30 and 50 (Num. 4:34–37)—and this just a month after the Israelites left Egypt (Num. 1:1). That is phenomenal fertility if Kohath was Moses’ grandfather. (We’d expect a number closer to 100.).”  Also, if we look at the genealogy of Joshua in 1 Chronicles 7:23-27, we learn that there were in fact at least twelve generations between Jacob and Joshua. These three observations strongly point to the genealogy of Moses being highly compressed. Thus, we can conclude that Biblical genealogies sometimes included significant gaps, and this opens up the possibility that such gaps exist in the Genesis genealogies as well.
The next question we must address is whether there is a principled upper limit to the amount of gaps that might be contained in a genealogical record. If there is, that would allow us to place an upper cap on when Adam and Eve lived. C. John Collins answers this question: “I know of no way to figure out whether there is even an upper limit to the number of possible gaps.”  Egyptologist Kenneth Kitchen concurs :
Returning to Gen. 1–11, we see the narratives in some cases presupposing immediate fatherhood. See, for example, the wording of Adam-Seth-Enosh in Gen. 4:25–26. But in most cases, one may in principle as easily read the recurrent formulae “A fathered B, and after fathering B lived x years” as “A fathered (the line culminating in) B, and after fathering (the line culminating in) B, lived x years.” Thus we can neither date the flood before Abraham nor the creation before Noah merely by counting the Genesis figures continuously as did the worthy Archbishop Ussher in the carefree days when no evidence from outside the Bible was even imagined, still less thought about or seen. And in the context of that external data, any such literalism fails. If Abraham be set at roughly 2000 B.C., then on those figures the flood would have come in about 2300. But that is about the time of Sargon of Akkad; having been rescued from a river at birth, he would not have been amused by a flood. Worse, his time looked back up to 400 years back to Gilgamesh (ca. 2700), for whom in turn in tradition the flood was even more ancient still! So an Ussherite solution is ruled out; the methods of antiquity apply. The date of the flood remains fluid, one might say! As for the date of the creation, why waste time number-crunching when Gen. 1:1 says it all: “In the beginning …” — which is soon enough.
Given that Genesis 1-11 is very fast-paced in its depiction of world history (the narrative slows down upon introducing Abraham in Genesis 12), it is possible that the genealogies in Genesis 5 and 11 are extremely incomplete, missing perhaps hundreds or even thousands of names. There is simply no way to know for sure. Thus, to attempt to use them to compute the date at which Adam and Eve existed is to use them for a purpose other than that for which these genealogies are intended. Moreover, there is a symmetry between the genealogies of Genesis 5 and 11 — both genealogies list ten names and end with a key figure who is said to have had three sons (Noah and Terah respectively). This sort of symmetric structure resembles the genealogy of Jesus in Matthew’s gospel, which certainly skips generations.
One may object at this point that it is rather ad hoc to presume, on the basis of mere possibility, the existence of thousands of skipped generations between Adam and Abraham when the Biblical text gives us no positive indicators of their existence. Furthermore, we know of no other ancient genealogical record where there are demonstrably thousands of skipped generations. Thus, to invoke their existence in this case in order to evade the falsification of Adam and Eve is to engage in special pleading. There is of course some validity to this objection. However, when one weighs up the alternatives, it appears that the scenario I have proposed is the least epistemically costly option. The competing scenarios include:
- Adam and Eve did not exist.
- The genealogies are complete or nearly complete, and Adam and Eve lived somewhere in the range of six to ten thousand years ago.
- There are many thousands of skipped generations in the Genesis genealogies.
The first option does not come without a cost, since, in my judgment, the historicity of Adam and Eve is essential to the truth of Christianity, arguably at the same level as Jesus’ resurrection. Thus, if we are to entertain the first option then we would have to propose plausible alternative explanations for the numerous lines of evidence that point so powerfully to Christianity’s truth — such as the various evidences for the resurrection of Jesus, and the arguments from predictive prophecy. On the other hand, if we are to opt for the second option, we have to propose plausible alternative explanations for the numerous lines of evidence that point to humanity being much older than six to ten thousand years. The third option requires us to postulate, without independent supporting evidence, the existence of thousands of skipped generations in the Genesis genealogies. Thus, all three options come with an epistemic price tag. The scenario we ought to favor is that which labors under the least implausibility. In my considered opinion, the third option, even though it requires that we propose an ad hoc auxiliary hypothesis, is the least implausible scenario.
A further objection presents itself in regards to placing Adam and Eve hundreds of thousands of years ago rather than more recently. That is, that Genesis 4:17-22 assumes a more recent historical setting, since it describes individuals in Cain’s lineage who pioneered crafts such as city building, ranching, musical instruments, and metal working. Those are generally thought to be crafts belonging to the Neolithic era (10,000 to 3,000 B.C.). Therefore, on the thesis I am suggesting, those allusions, it is argued, would be anachronistic. However, C. John Collins points out that “It is possible to read these verses as describing the trailblazers of the skills that eventually led to the crafts the audience would be familiar with. In fact, Umberto Cassuto argued that the Hebrew terms ‘father’ and ‘forger’ can be read with these nuances.”  One may also alternatively suggest that such crafts did in fact exist earlier than we currently think though the evidence is yet to be discovered. Nonetheless, it must be conceded that these verses are more probable if the author of Genesis intended to communicate that Adam and Eve lived recently (within the last ten thousand years) than otherwise.
One final objection is sometimes raised in relation to the positing of gaps in the genealogy of Genesis 5, and that is that Jude 14 described Enoch as the “seventh from Adam.” This is, in my opinion, the weakest of the three objections. It is typical in ancient genealogies to record only prominent names. The evangelist Matthew, for example, refers to three sets of “fourteen generations” — from Abraham to David, from David to the exile, and from the exile to Christ (Mt 1:17). Perhaps Jude 14 refers to the seventh significant generation, as it is listed in Genesis 5. Moreover, it is probably not by accident that Enoch, who walked with God, is listed as the seventh from Adam, since seven is a sacred number in Scripture that symbolizes completion. Kenton Sparks also notes that “The Mesopotamian king lists often stress the special importance of the seventh king (often Enmeduranki) and his wise advisor (often Utuabzu), who did not die but ‘ascended into heaven.'” 
Thus, while the three lines of evidence that we have considered — the genealogies of Genesis 5 and 11, the historical setting implied by Genesis 4:17-22, and the passing allusion in Jude 14 — do not entail that mankind arose recently (since they can each be harmonized, with the aid of an ad hoc auxiliary hypothesis with a view that places Adam and Eve much further back in time), they do constitute evidence that is confirmatory of a more recent origin. Moreover, the weight of those evidences must be multiplied, not added, to each other. For example, if we suppose that each of two lines of evidence is one hundred times more probable on the hypothesis that Adam and Eve lived recently than on the alternative, this entails that the overall Bayes factor is ten thousand (meaning, both evidences combined are ten thousand times more probable if Adam and Eve lived recently than otherwise).
Therefore, while one can, if compelled to do so by scientific evidence, postulate that Adam and Eve lived hundreds of thousands of years ago rather than just ten thousand years ago, one must, in so doing, candidly acknowledge that the hypothesis that Christianity is true has taken a probabilistic hit. If this was the only evidence bearing on the truth of Christianity then it would incline the rational inquirer towards unbelief. Fortunately, however, there is much other evidence that must be contended with, and it is my considered opinion that the reasons for believing Christianity to be true, taken as a whole, far outweigh the reasons for rejecting it.
Is the Existence of Adam and Eve Compatible with Evolution?
Yet a further question in need of address is that of the compatibility (or otherwise) between evolution and an historical Adam and Eve. This depends, though, on what one means by “evolution.” I would argue that Adam and Eve are not compatible with the standard textbook account of neo-Darwinian evolution, whereby evolution proceeds extremely gradually. According to the standard evolutionary view, there was never any first human couple as such, in the same sense that we might say there is no definable moment as such when a boy becomes an adult — it is a very gradual and slow process that happens over many years. It is important to understand that evolution affects populations, not individuals. As a population shifts the frequencies of different gene variants (called alleles in the technical lingo), the population is said to evolve. To better appreciate this, it is helpful to compare evolution of populations to the change of language over time. While no one individual person can cause significant change to their language (while retaining their intelligibility to others in their community), the language can and does slowly and gradually change over time — but there is never any one distinct moment when a novel language comes into being. The same principle may be applied to evolution. Therefore, theistic evolution, I would argue, is incompatible with an historical Adam and Eve, at least understood in the traditional sense, since there was never any definable moment when mankind came into existence. Some Christians have, however, sought to salvage Adam and Eve while still subscribing to an evolutionary paradigm, and I turn to review those attempts now.
Some have attempted to suggest that God selected two primitive adult humans and endowed them with an immortal soul and the imago dei — a view that we can call the ensoulment view. For example, theologian John Walton of Wheaton College writes, “I believe that the image of God is something that is a direct, spiritually defined gift of God to humans. For those who believe that humans are biologically a product of change over time through common descent, the image of God would be given by God to humans at a particular time in that history. It would not be detectable in the fossil record or in the genome.”  Along similar lines, theologian Tom Wright of the University of St. Andrews contends “that just as God chose Israel from the rest of humankind for a special, strange, demanding vocation, so perhaps what Genesis is telling us is that God chose one pair from the rest of early hominids for a special, strange, demanding vocation. This pair (call them Adam and Eve if you like) were to be the representatives of the whole human race, the ones in whom God’s purpose to make the whole world a place of delight and joy and order, eventually colonizing the whole creation, was to be taken forward.”  This view is also adopted by the British immunologist Denis Alexander of the University of Cambridge, who argues that “God in his grace chose a couple of Neolithic farmers in the Near East, or maybe a community of farmers, to whom he chose to reveal himself in a special way.” 
The sort of scenario envisioned by Walton, Wright and Alexander seems very implausible to me. Every indication in the text of Genesis is that God specially created Adam and Eve de novo. Furthermore, on the ensoulment view, one can deduce that there was a point in human history when there were organisms, biologically and anatomically identical to modern humans, some of which bore the imago dei and some of which did not. But, on such a view, on what basis do we say that unborn embryos possess the imago dei (as opposed to acquiring it at a later point during development)? The imago dei, I would argue, is part of what it is to be human. The ensoulment view also falls short of accounting for the words of Jesus in Matthew 19:4-5:
4 He answered, “Have you not read that he who created them from the beginning made them male and female, 5 and said, ‘Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh’?”
Jesus’ words here imply that the first humans were created male and female. There is no indication here whatever of them having slowly evolved from other primates, or that Adam and Eve in fact had biological parents and were arbitrarily declared the first humans bearing the image of God. To call such an interpretation of Jesus’ words a stretch would be an incredible understatement. Furthermore, Jesus’ words imply that human sexuality has been, from the beginning, God’s special intent for mankind, and that God purposefully designed human beings to be either male or female. If we suppose, though, that blind natural processes produced the bodies of men and women (as maintained by theistic evolutionists), then this seriously undermines the notion that gender and sexuality was God’s purposeful design for humans. One might object that God acts providentially through natural law, and may use secondary causes to bring about His providence. However, in that case, on what basis do we assert that heterosexual relationships and male and female identity is God’s intent and design for mankind, whereas homosexual relationships are not?
The ensoulment view is also challenged by Paul’s words in 1 Timothy 2:12-13, wherein he gives an argument for male and female complementarity that is grounded in the text of Genesis:
12 I do not permit a woman to teach or to exercise authority over a man; rather, she is to remain quiet. 13 For Adam was formed first, then Eve; 14 and Adam was not deceived, but the woman was deceived and became a transgressor.
This text implies strongly that the man was created first, and the woman second, and that out of this arises male and female complementarity. The theistic evolutionist must interpret this text as having nothing to do with the physical creation of mankind by God. This is extremely implausible.
An innovative and provocative attempt to harmonize evolutionary theory with an historical Adam and Eve has recently been proposed by computational biologist Joshua Swamidass of Washington University in St. Louis.  Swamidass proposes that Adam and Eve lived approximately six thousand years ago, in accordance with the traditional creationist understanding. He argues that Adam and Eve did not have parents and were in fact created de novo, as described in Genesis 2. Consistent with a face-value reading of Genesis, Swamidass proposes that Adam was formed from the dust of the earth and Eve from Adam’s side. However, Swamidass argues that Adam and Eve were not the first humans. Rather, their genomes became ‘mixed’ with the rest of the human population outside of the garden through interbreeding (that is, humans who, unlike Adam and Eve, arose naturally through evolutionary processes), such that all extant humans can be said to trace their genealogical ancestry back to Adam and Eve, even though their genetic ancestry includes other lineages, unrelated to Adam, as well. Swamidass points out that universal genealogical ancestors (that is, individuals to whom all modern humans can trace their ancestry) are common, arising often throughout human history. Swamidass proposes that “Adam and Eve are to work as priestly rulers alongside Yahweh Elohim, to expand the Garden across the earth. Civilization is rising, and a new era is coming. Their purpose is to welcome everyone into their family, in a new kingdom of God.”  Swamidass distinguishes between what he calls “biological humans” and “textual humans.”  For Swamidass, “Biological humans are defined taxonomically, from a biological and scientific point of view. From at least AD 1 onward, they are coextensive with textual humans.”  On the other hand, “Textual humans are the group of people to whom Scripture refers. I argue that this group is defined by Scripture to be Adam, Eve, and their genealogical descendants, including everyone alive across the globe by, at latest AD 1. They are a chronological subset of biological humans, meaning that some biological humans in the past are not textual humans, but all textual humans are biological humans.” 
While Swamidass’ model is superficially attractive in that it does not require positing thousands of gaps in the Genesis genealogies, the problems that it raises are too intolerably great for me to commend Swamidass’ solution. For one thing, in what sense, if any, can non-Adamic biological humans be considered to be fully human? Are they affected by original sin, and did Jesus die to save them? Swamidass conjectures that these biological humans bear God’s image but “are not yet affected by Adam’s fall. They have a sense of right and wrong, written on their hearts (Rom. 2:15), but they are not morally perfect. They do wrong at times. They are subject to physical death, which prevents their wrongdoing from growing into true evil (Gen. 6:3).”  The Scriptures, however, make no such distinction between biological humans and textual humans. Swamidass’ view would seem to suggest logically that those individuals who were biological (but not textual) humans are qualitatively indistinct from other animals. But in that case it makes no sense to call their deeds evil, or to postulate that they had a sense of right and wrong. Moreover, if they, as Swamidass suggests, “do wrong at times”, then does this not suggest that Adam’s fall is but one of many falls that have occurred in human history? The theological ramifications that accompany this scenario are too severe for me to entertain Swamidass’ proposal.
If Adam and Eve Are Not Compatible With Evolution, Then What?
If none of the proposed attempts at harmonization between evolutionary theory and the historical Adam and Eve work, what should we conclude from this? My considered opinion is that this should not concern us since the scientific evidence does not support such a gradualist evolutionary account of human origins, and the fossil record does not allow sufficient time to overcome the probabilistic odds of attaining even a single pair of co-dependent mutations necessary to bring about some new feature, or fixing them in the population. Therefore, if the transition from a chimp-like ancestor to a human occurred, it did not take place by a stochastic unguided process of evolution. Let us consider briefly some of the anatomical changes that would be required to transform a chimp-like ancestor into a human being. For one thing, upright walking and running “requires a new spine, a different shape and tilt of the pelvis, and legs that angle in from the hips, so we can keep our feet underneath us and void swaying from side to side as we move. We need knees, feet and toes designed for upright walking, and a skull that sits on top of the spine in a balanced position. (The dome of our skull is shifted rearward in order to accommodate our larger brain and yet remain balanced.) Our jaws and muscle attachments must be shifted, our face flattened, and the sinuses behind the face and the eye sockets located in different places, to permit a forward gaze and still be able to see where to put our feet.”  In fact, Bramble and Lieberman count sixteen anatomical changes that would be required to convert an australopithecine to the genus Homo.  Each of those changes probably required multiple co-dependent mutations to bring about — that is, two or more coincident genetic changes that only together produce an adaptive phenotypic effect that allows for natural selection to operate. The question thus naturally arises as to whether the fossil record affords sufficient time for this transition to have taken place.
All mutations have two time constraints that depend on population size, mutation rate, and generation time. Those are (a) the waiting time for a mutation to arise in a population and (b) the waiting time for fixation of the mutation in the population — that is, the time it takes for the mutation to go from being possessed by a lone individual to becoming the norm that is established in the population. When the population size is large, the waiting time for a mutation to arise decreases (since there are more individuals in which the mutation could potentially occur) but the fixation time increases (since there are more individuals through which the mutation has to spread). Conversely, with small population sizes, the waiting time for a mutation to occur increases (since there are fewer individuals in which the mutation might occur) but the fixation time decreases (since there are fewer individuals through which the mutation has to spread). This gives rise to what might be called the waiting time dilemma. One potential counter-argument here is that neutral mutations (which account for about 75 percent of all mutations) may occur separately, before combining later by sexual recombination. However, it has been shown that “Recombination lowers the waiting time until a new genotypic combination first appears, but the effect is small compared to that of the mutation rate and population size.”  Biochemist Michael Behe of Lehigh University and physicist David Snoke of the University of Pittsburgh have argued that the waiting time for two co-dependent mutations is prohibitive for the neo-Darwinian mechanism of evolution to work.  Behe, in his book The Edge of Evolution, used the example of malarial resistance against chloroquine, which required two co-dependent mutations to arise and therefore took a few years and some 1020 organisms to develop chloroquine resistance.  Applying these data to human evolution (i.e. adjusting for the fact that there are far fewer human individuals) predicted a waiting time of 1015 years. 
Behe’s argument has not gone without challenge. In 2008, two mathematicians from Cornell University, Rick Durrett and Deena Schmidt, published a paper in the journal Genetics in which they put forward a mathematical theoretical model (in contrast to Behe’s analysis, which was based on empirical data), arguing that Behe was in fact mistaken, and that the actual waiting time for a single pair of co-dependent mutations would be only 216 million years.  This was based on an assumed average effective population size of 20,000 individuals per generation (until quite recently the average effective population size of humans — i.e. those that reproduce — was as low as this). However, given that the human-chimp divergence is thought to have taken place only approximately six million years ago, this is highly prohibitive — since many of the anatomical changes that would be necessary to transform a chimp-like ancestor to a human would require at least two co-dependent mutations, and probably more.
As previously stated, however, the waiting time for a mutation to arise is not the only waiting time that must be contended with. There is also the waiting time for a mutation to become fixed in the population — to go from the lone individual out there carrying the mutation to becoming the norm that is established. In 2015, a paper was published in Theoretical Biology and Medical Modelling.  The researchers used a computer simulation to estimate the waiting times, based on reasonable estimates for an ancestral hominin population of 10,000 individuals and a generation turnover time of 20 years. They estimated that the waiting time for the fixation of a specific point mutation was within the range of 1.5-15.9 million years. However, the fixation of a single co-dependent mutation, according to their estimate, blows out to as much as 85 million years. Again, given that the human-chimp divergence is supposed to have happened as recently as six million years ago, this represents a significant problem to the standard evolutionary account of human origins.
That being said, it is also my considered opinion that, while the evidence seems compelling that humans did not arise by blind stochastic processes, the genomic data points in the direction of humans having a shared ancestry in some sense with other primates, and this data too must be taken seriously. It is common for creationists to claim that similarity is equally well explained by common design as by common descent. While there is some truth to this, the reality is that the arguments for evolution, in their most sophisticated form, have more to do with the distribution of similarities and differences than the mere fact of similarity. Space does not permit me to do justice to the various lines of evidence that may be adduced. However, allow me to offer one line of evidence that I find particularly compelling — the argument from the nested hierarchical distribution of endogenous retroviruses. The next four paragraphs get slightly technical scientifically. For readers who are turned off my technical content, I suggest skipping ahead to where I recap the arguments adduced in this section.
Primates are thought to have been on the scene for 50-55 million years. During that history, they have undergone many infections by retroviruses (RNA viruses that can reverse transcribe their RNA into DNA and integrate themselves into the genome of their host). Sometimes, those retroviruses infect the germ cells (those cells that are passed on to an organism’s progeny). When this happens, the retroviruses can be vertically inherited from one generation to the next, becoming permanent relics of past viral infections. These relics are referred to in the technical lingo as endogenous retroviruses (ERVs). There are literally hundreds of thousands of those endogenous retroviruses in the human genome. What evolutionary biologists have noticed is that the distribution of those retroviral sequences across the genomes of different primates forms a nested hierarchy, resembling a family tree — exactly what you would expect to observe on the hypothesis of common descent. 
Furthermore, in addition to the placement of ERV sequences in orthologous loci (and its pertinent nested hierarchical pattern), we must also take into consideration the shared mutations among orthologous ERVs which also fall into very similar nested hierarchies.  Since mutation and ERV placement are independent factors, this is again best explained by the hypothesis of descent. Moreover, the comparative degrees of divergence between the long terminal repeat sequences on both termini of the retroviral sequence (which serve as retroviral promoters) among orthologous ERVs are also implicative of the common descent model. The long-terminal-repeat (LTR) sequences, on either end of the retroviral sequence, must be identical upon insertion. Since LTRs are identical upon reverse transcription and integration, greater mutational divergence (assuming common ancestry to be true) ought to correlate with an older insertion. This is precisely what we observe.  Thus, this three-tiered evidence is quite surprising on the hypothesis of separate creation but not surprising at all given the truth of the scenario of common descent.
Creationists have tended to respond to this evidence in one of two ways. The first is to point to functions that have been identified for these retroviral-like sequences in the context of the human genome, which many creationists take to suggest that these sequences are not of retroviral origin at all, but rather are endemic to the human genome.  For example, the LTR sequences of ERVs in the human genome “have been shown to contribute promoter sequences that can initiate transcription of adjacent human genes.”  Another example is the fusogenic syncytin proteins that fuse placental cells together to form the syncytiotrophoblast and which are known to be essential for placental formation. These proteins are coded for by the envelope (env) gene of an endogenous retroviral insert.  However, these functions appear to have been acquired post-integration, since the evidence indicates quite strongly that these are indeed genuine inserts into the genome. The evidence for this has to do with the integrase enzyme which is responsible for integrating the viral DNA (after it has been reverse transcribed from RNA) into the host chromosome. Integrase breaks two phosphodiester bonds, one on each strand of the host DNA. Integrase does not simply break the bonds between two base pairs. Rather, it separates the breaks by several base pairs, resulting in a jagged cut. When nucleotides are added to fill in the gaps that have been created by integrase, the result is a target site duplication, which is the hallmarks of insertion by integrase. Thus, while there are plenty of examples of functions that may be identified for ERV sequences in the context of the human genome, this is of little value in responding to this argument for common descent, since those functions appear to have been acquired after integration of these retroviral-like sequences into the human genome.
The second creationist attempt to deal with this evidence is to point to target-site preferences.  However, while statistical biases for integration do exist (for example regions of the chromosome that are rich in expressed genes, and near transcription start sites) these biases are not anywhere close to sufficiently locus-specific to make a significant statistical difference.  In fact, these biases require thousands of trials just to detect. Integration of retroviruses into a host genome therefore seem to be rather random.
To recap, we have seen that, while the evidence indicates that a transition from a chimp-like ancestor to humans is unlikely to have occurred by an unguided evolutionary process, there is nonetheless genomic evidence confirmatory of common descent of primates that cannot be ignored. I do not believe evolutionists have adequately responded to the former evidence, and I do not believe creationists have adequately responded to the latter evidence.
How can one make sense of those apparently conflicting sets of evidence? The model I would propose is that God brought new forms of life into being by miraculous divine action, using the genome of a previously-existing species as a template. This suggestion would account for the presence of evolutionary relics in the human genome and yet would also account for the data that shows the strong implausibility of an evolutionary transition having occurred by unguided natural processes. A literal historical Adam and Eve is certainly compatible with the scenario I have proposed.
Some might worry that this solution is ad hoc. However, given the overwhelming scientific evidence that life is the result of design and that unguided processes are demonstrably inadequate to explain the complex features of biology, I think it is legitimate to explore alternative explanations for data that appears on first blush to point to common descent. If there is no natural way to account for the transition from A to B, then how can we be so confident that the transition from A to B in fact occurred at all? Moreover, I do not believe the fossil record at all supports a smooth and gradual transition from the australopithecines to our genus Homo. In fact, one paper put it, “We, like many others, interpret the anatomical evidence to show that early H. sapiens was significantly and dramatically different from…australopithecines in virtually every element of its skeleton and every remnant of its behavior.”  The famed late evolutionary biologist Ernst Mayr likewise stated that “The earliest fossils of Homo, Homo rudolfensis and Homo erectus, are separated from Australopithecus by a large, unbridged gap. How can we explain this seeming saltation? Not having any fossils that can serve as missing links, we have to fall back on the time-honored method of historical science, the construction of a historical narrative.” 
Another question of interest is whether Adam and Eve were, at the time of their creation, the only humans on the earth, and therefore our sole progenitors, or whether there were other humans on the earth as well. It is sometimes alleged that the population genetics evidence precludes our being a descendent from a single primordial pair.  Based on the level of genetic diversity that exists in the human population, it is argued, the human population never fell below several thousand individuals. According to this argument, human genetic diversity is too great to be accounted for by a single founding couple. However, it must be recognized that this argument assumes an evolutionary model of human origins. One can reject this and propose instead that the first founding couple was created with initial diversity. Both individuals would carry 22 pairs of autosomal chromosomes (i.e. non-sex chromosomes) in addition to either a pair of X chromosomes (for the female) or an X and a Y chromosome (for the male). If each of the four copies of the autosomal chromosomes (Adam and Eve each possessed two copies) was created unique, this would result in a large number of single nucleotide polymorphisms (SNPs) — that is, nucleotide differences that result in gene variants — which would all have been present within the first generation. There could also have been created diversity associated with the three X-chromosomes (two possessed by the female and one by the male). Since an initial founding couple would have only one Y chromosome between them, created diversity cannot be invoked for the Y chromosome. However, the diversity of the Y chromosome appears to be much less than for other chromosomes. 
Biologist Ann Gauger and mathematician Ola Hossjer have recently put forward a theoretical model that reveals that an initial founding pair is possible.  Summarizing their research, Gauger and Hossjer state, “We show that a single-couple origin of humanity as recent as 500kya is consistent with data. With only minor modifications of our parsimonious model assumptions, we suggest that a single-couple origin 100kya, or more recently, is possible.” 
However, if it were the case that a single primordial couple were excluded on the basis of population genetics, would this fact falsify the historicity of the Genesis account? Not necessarily. In fact, there is evidence in Scripture that is at least suggestive that there may have been additional people on the earth alongside Adam and Eve. For example, when God pronounces judgment on Cain following his murder of his brother Abel, Cain expresses concern to God that “whoever finds me will kill me” (Gen 4:14). This implies that there were other people walking the earth at this time, even though Cain was only the second generation from Adam. Though Cain had other siblings, such as Seth, it is noteworthy that Cain’s expressed concern is not that “if one of my brothers finds me, he will kill me.” Rather, it is “whoever finds me will kill me.” While this text is not inconsistent with the subject being Cain’s brothers, it is slightly suggestive that it refers to someone outside of his immediate family. Another text that suggests the presence of other individuals alive at the time is the allusion to Cain building a city (Gen 4:17), though this is probably an anachronistic use of language that refers to some kind of settlement. Who is Cain expecting to dwell in such a settlement, if indeed there is no other human, outside of his immediate family, alive at this time? If there were other humans alive at the time, this would also answer quite naturally the age-old question of how Cain got his wife (Gen 4:17). While young earth creationists typically answer this question by asserting that Cain married his sister (which, they argue, would have been safe given the genetic purity of the early human race), this is not anywhere stated by the text. Rather, it is casually stated that “Cain knew his wife,” (Gen 4:17). However, it should also be noted that the traditional creationist view that Cain married his sister is also scientifically possible and in-breeding depression need not be a problem if we assume that the first human couple possessed only neutral variants (i.e. those that are not harmful to their fitness).
While those textual clues are surely suggestive, they are not decisive enough to arrive at a firm conclusion, and there are texts that also seem more consistent with Adam and Eve being alone. For example, we read, “The man called his wife’s name Eve, because she was the mother of all living,” (Gen 3:20). This is probably the most difficult text to harmonize with the notion that there were other humans alive at the time who were not descended from Adam and Eve. However, it is possible to take this as a figurative, rather than literal, motherhood — indeed, the term “father” is used in a figurative sense in Genesis 4:20-21. Furthermore, if Adam and Eve are understood to be the ‘king’ and ‘queen’ of their people, then they may legitimately be described as the father and mother of their people, even if not in a biological sense. Thus, Genesis 3:20 is not devastating to the proposal that Adam and Eve were not alone. The other significant text that on this question is Acts 17:26, which says that “he made from one man every nation of mankind to live on all the face of the earth, having determined allotted periods and the boundaries of their dwelling place.” Depending on one’s view of the flood, however, this may alternatively refer to Noah. My own view is that this text most likely refers to Adam.
Some have argued that Genesis 2 represents a sequel to Genesis 1, rather than an elaboration on the sixth day. This view would allow one to take the creation of humans in Genesis 1:26-27 as being a separate event from the creation of Adam and Eve in Genesis 2. John Walton, for example, argues in support of this that the introductory formula “These are the generations” (Gen 2:4) is a literary device indicating that the next account is a sequel to the previous one. He argues, “The formula introduces either a narrative of that person’s sons or a genealogy of that person’s descendants. In other words, it tells about what came after that person (though it sometimes overlaps with the life of the person) and what developed from that person. In Genesis 2:4, it is not a person’s name. Using the same logic, we would conclude that the section being introduced is going to talk about what came after the creation of the heavens and the earth reported in the seven-day account and what developed from that. In other words, the nature of the introduction leads us to think of Genesis 2 as a sequel.” 
I think John Walton’s interpretation of Genesis 2 as a sequel to Genesis 1 is unlikely. For one thing, even John Walton has to concede that of the ten introductory formulae of this sort that occur in Genesis, a few (Gen 11:10; 25:19; 37:2) are not sequels but rather are recursive, and one additional case contains both a parallel to a previous account as well as a sequel (Gen 5:1).  Walton’s argument here is thus really quite weak. Furthermore, Genesis 2:1-3 indicates that God rested on the seventh day, which suggests that he did not create anything more afterwards. The creation of man in Genesis 2 is therefore best understood, in my opinion, as an elaboration on the sixth day of creation.
Personally, I think that the balance of textual evidence tends to support the traditional view that all people are descended from one single human couple — Adam and Eve. However, it should be recognized that while a demonstration of the impossibility of mankind having descended from a single primordial couple would constitute evidence against Adam and Eve, it would not constitute a decisive refutation of Adam and Eve. As things stand right now, I do not think that the scientific evidence (either the paleontological or genetic data) at all rules out an initial founding couple, and thus I embrace the traditional view.
If there were more people alive at the time who were not themselves descendants of Adam and Eve, what would the theological ramifications of this be? I agree with C. John Collins that “If someone should decide that there were, in fact, more human beings than just Adam and Eve at the beginning of mankind, then, in order to maintain good sense, he should envision these humans as a single tribe. Adam would then be the chieftain of this tribe (preferably produced before the others), and Eve would be his wife. This tribe ‘fell’ under the leadership of Adam and Eve. This follows from the notion of solidarity in a representative. Some may call this a form of ‘polygenesis,’ but this is quite distinct from the more conventional, and unacceptable, kind.”  We can call this the ‘tribal representative’ view. I think this view allows one to retain a robust view of original sin. On such a view, Adam and Eve, as the first priest and priestess of mankind, would be the representatives of their fellow humans, both present and future. I would argue that it is theologically acceptable to suggest that Adam and Eve were among the first human beings that were created, but not acceptable to suggest that Adam and Eve were preceded in time by other humans who lived before them.
What About Other Hominid Species?
One thing I am often asked about is the other hominid species, such as the Neanderthals or the Denisovans, and what their relationship to modern humans might be. Space does not permit me to offer a detailed discussion of this subject. However, I would be remiss not to include at least a short discussion. The most obvious view would be to define Biblical humans as equivalent to the taxonomic categorization of our genus Homo, with Adam and Eve being the first members of our genus. However, this scenario is problematic because the earliest member of our genus Homo is dated to some two million years ago. It also leaves a very significant period of time without there being any evidence of culture in the paleontological record. I do not think it is necessary to equate humans in the Biblical sense with the genus Homo. Indeed, to interpret Scripture in view of modern taxonomic classification is anachronistic, in the same way that it is anachronistic to criticize the Biblical authors for identifying bats as birds rather than mammals (Lev 11:19). There are other organisms alive today (e.g. the chimpanzee) who exhibit anatomical features that resemble those of modern humans, and this causes us no concern.
That being said, I tend to believe that at least some other hominid species are in fact descended from Adam and therefore are in truth a subset of our species. It is generally thought that some interbreeding took place between Homo sapiens and the Neanderthals and Denisovans, since fragments of Neanderthal and Denisovan DNA have been identified among modern humans.  This admixture is thought to have taken place at least 50,000 years ago and perhaps later also. Given that the evolutionary model predicts that Homo sapiens diverged from those archaic hominins more than 500,000 years ago , it would be quite astonishing if these two populations, having split so long ago, were still able to interbreed to produce fertile offspring. Thus, I tend to think that Neanderthals and Denisovans are descendants of Adam and Eve. This fits well with independent evidence of archaic human art and culture. 
In summary, we have seen that the Scriptures affirm Adam and Eve as real historical individuals. While a face-value interpretation of Genesis, especially chapter 5, would lead one to believe that Adam and Eve lived quite recently (perhaps as recently as six thousand years ago), this is contradicted by compelling scientific evidence that places humans much further back than that. Of the available explanations of this apparent discrepancy, the least epistemically costly approach is to posit the existence of thousands of gaps in the Genesis genealogies. The literal existence of Adam and Eve, I have argued, is incompatible with evolutionary theory, though this need not be of concern since the scientific evidence for evolutionary theory is, in my judgment, unconvincing (and there are plenty of compelling reasons to question its validity altogether). The balance of Scriptural evidence suggests that Adam and Eve were alone on the earth as the first human couple, though it is possible to interpret the Scriptures in view of there having been a population of humans, of which Adam and Eve were tribal representatives. Finally, we have seen that there is no need to define Biblical humans as coextensive with the genus Homo, since this is anachronistic. However, there is scientific reason for believing that some archaic humans, notably the Neanderthals and Denisovans, in fact do belong to our species, being descendants of Adam and Eve.
 Charles Richard, Elrington, ed. The Whole Works of the Most Rev. James Usher, D.D. (Dublin: Hodges and Smith, 1847).
 C. John Collins, Science & Faith: Friends or Foes? (Illinois: Crossway), 109.
 Kenneth A. Kitchen, On the Reliability of the Old Testament (Michigan; Cambridge, U.K.: William B. Eerdmans Publishing Company, 2006), 441.
 C. John Collins, Reading Genesis Well: Navigating History, Poetry, Science, and Truth in Genesis 1-11 (Michigan: Zondervan, 2018), 146.
 Kenton L. Sparks, “Genesis 1–11 as Ancient Historiography,” in Genesis: History, Fiction, or Neither? Three Views on the Bible’s Earliest Chapters, ed. Charles Halton and Stanley N. Gundry, Zondervan Counterpoints Series (MIchigan: Zondervan, 2015), 120.
 John H. Walton, The Lost World of Adam and Eve: Genesis 2-3 and the Human Origins Debate (Illinois: IVP Academic, 2015), 194.
 Tom Wright, Surprised by Scripture: Engaging Contemporary Issues (California: HarperOne, 2014), 37.
 Denis Alexander, Creation or Evolution: Do We Have to Choose? (Oxford, UK: Monarch Books, 2008), 236.
 S. Joshua Swamidass, The Genealogical Adam and Eve: The Surprising Science of Universal Ancestry (Illinois: IVP Academic, 2019).
 Ibid., 176.
 Ibid., 134.
 Ibid., 175.
 Ann Gauger, “Science and Human Origins,” in Science and Human Origins, ed. Ann Gauger, Douglas Axe & Casey Luskin (Washington: Discovery Institute Press), kindle.
 Dennis M. Bramble & Daniel E. Lieberman, “Endurance running and the evolution of Homo,” Nature 432 (November, 2004), 345-352.
 Freddy B. Christiansen et al., “Waiting with and without Recombination: The Time to Production of a Double Mutant.” Theoretical Population Biology 53, no. 3 (June 1996), 199-215.
 Michael J. Behe and David W. Snoke, “Simulating Evolution by Gene Duplication of Protein Features That Require Multiple Amino Acid Residues,” Protein Science 13, no. 10 (October, 2004), 2651-2664.
 Michael J. Behe, The Edge of Evolution (New York: Free Press, 2008), kindle.
 Rick Durrett and Deena Schmidt, “Waiting for Two Mutations: With Applications to Regulatory Sequence Evolution and the Limits of Darwinian Evolution,” Genetics 180, no. 3 (November, 2008), 1501-1509.
 John Sanford et al., “The waiting time problem in a model hominin population,” Theoretical Biology and Medical Modelling 12, no. 18 (2015).
 Welkin E. Johnson and John M. Coffin, “Constructing primate phylogenies from ancient retrovirus sequences.” Proceedings of the National Academy of Science 96, no. 18 (August, 1999), 10254-10260.
 Laurence Bénit, Philippe Dessen & Thierry Heidmann, “Identification, Phylogeny, and Evolution of Retroviral Elements Based on Their Envelope Genes,” Journal of Virology 75, no. 23 (December, 2001), 11709-11719.
 Hugo Martins & Palle Villesen, “Improved Integration Time Estimation of Endogenous Retroviruses with Phylogenetic Data,” PLoS One 6, no. 3 (March, 2011).
 Shaun Doyle, “Large scale function for ‘endogenous retroviruses’,” Journal of Creation 22, no. 3 (December, 2008).
 Andrew B. Conley, Jittima Piriyapongsa and I. King Jordan, “Retroviral promoters in the human genome,” Bioinformatics 24, no. 14 (May, 2008), 1563-1567.
 Christian Lavialle et al., “Paleovirology of ‘syncytins’, retroviral env genes exapted for a role in plancentation,” Philosophical Transactions of the Royal Society B 368 (2013).
 Hingguang Liu & Charles Soper, “The Natural History of Retroviruses: Exogenization vs Endogenization,” Answers Research Journal 2 (2009), 97-106.
 Rick S. Mitchell et al., “Retroviral DNA Integration: ASLV, HIV, and MLV Show Distinct Target Site Preferences,” PLoS Biology 2, no. 8 (August 2004), 1127-1137.
 John Hawks, Keith Hunley, Sang-Hee Lee, & Milford Wolpoff, “Population Bottlenecks and Pleistocene Human Evolution,” Molecular Biology and Evolution 17 (January, 2000), 2-22.
 Ernst Mayr, What Makes Biology Unique?: Considerations on the Autonomy of a Scientific Discipline (Cambridge, England: Cambridge University Press, 2004), 198.
 Dennis R. Venema & Scot McKnight, Adam and the Genome: Reading Scripture after Genetic Science (Michigan: Brazos Press, 2017), 43-65.
 M.A. Wilson Sayres, K.E. Lohmuller & R. Nielsen, “Natural Selection Reduced Diversity on Human Y Chromosomes,” PLoS Genetics 10 (2014).
 Ola Hossjer & Ann Gauger, “A Single-Couple Human Origin is Possible”, Bio-Complexity 2019, no. 1 (October, 2019).
 John Walton, The Lost World of Adam and Eve: Genesis 2-3 and the Human Origins Debate (Illinois: IVP Academic, 2015), 65.
 C. John Collins, Did Adam and Eve Really Exist? Who They Were and Why You Should Care (Illinois: Crossway, 2011), 121.
 Benjamin Vernot & Joshua M. Akey, “Resurrecting surviving Neandertal lineages from modern human genomes,” Science 343, no. 6174 (February, 2014), 1017-1021.
 Marc Haber, Massimo Mezzavilla, Yali Xue & Chris Tyler-Smith, “Ancient DNA and the rewriting of human history: be sparing with Occam’s razor,” Genome Biology 17, no. 1 (2016).
 D.L. Hoffmann, “U-Th dating of carbonate crusts reveals Neandertal origin of Iberian cave art,” Science 359, no. 6378 (February, 2018), 912-915.