Really, really old models of Adamic origins

Young Earth Creationist (YEC) thinkers believe most if not all species in the Homo genus comprise the species of Adam (e.g. here, here, but see a contrasting view here), and at least some Intelligent Design proponents seem to agree (see the chapter on human fossils here). These are the arguments for and against for such a position:

For:

Adam and his descendants need to be completely different from anything that came before them, not just in terms of cognitive capacities but also anatomy. Even the earliest members of the Homo genus have a suite of anatomical features that look completely different from the ape-like creatures that existed before them. Furthermore, different species with the Homo genus differ only slightly. As such, the genus seems to comprise a tightly similar unit of human-like creatures that are unlike anything that came before, which respects the traditional intuition about human uniqueness. The YEC Marvin Lubenow in his Bones of Contention argued as such, so did ID theorist Casey Luskin in his chapter in the Science and Human Origins. Perhaps the most sophisticated defense of the view comes from the YEC Todd Wood, who claims to demonstrate evidence of "biological discontinuity" between Homo and non-Homo species based on a trait-based clustering method (see some of his latest stuff here, and responses to criticisms here). Wood claims his analysis is compelling and robust, since they reveal the same pattern of clustering regardless of which fossil trait datasets or statistical tools are used.

Against:

Humanness necessitates two things - human-like cognitive abilities, and anatomical similarities. The further back we place Adam, the more difficult it gets to defend the idea that his earliest descendants demonstrated cognitive capacities found in modern humans. Not unsuccessful, to be sure, but difficult. Similarly, the more different Adam and his earlier descendants look from us, the harder it becomes to say that they were humans.

Personally, I'm more sensitive to the arguments against this model than the ones in favor of it. For example, Ian Tattersall claims the definition of Homo is a vestige of old-time taxonomy, where systematists felt the need to place everything in either the Australopithecus basket or the Homo one. If that is true, it becomes more contentious to claim that the earliest members of the Homo genus would have anything to do with modern humans.

Maybe a more direct disproof of this view would come from the anthropological research conducted by Gregory Forth who, based on his analysis of testimonies given by indigenous people of Flores, comes to the remarkable conclusion that Homo floriensis are either still alive, or were alive until recently (book, interview). For our purposes, the relevant bit of his research is that the people of Flores almost unequivocally classify these creatures as being non-human. I think that testimony is really powerful, since probably the most compelling criteria of humanness is I know it when I see it.

I'm curious why, despite such potential problems with this model, it continues to be popular. I suspect the most recent book on YEC paleontology also argues for this view.

Maybe it's because the argument for the view - the necessity for biological discontinuity - is seen to be a far more powerful consideration than those against. After all, it's probably difficult to show that earliest hominins did not have modern-type cognition. One of these days I want to do a thorough investigation of the model.

Andrew Loke: How to affirm radical human uniqueness yet not risk scientific falsifiability

Continuing our series on investigating the "limit scenarios" of human evolution, today we have Andrew Loke's book The Origin of Humanity and Evolution: Science and Scripture in Conversation. For those looking to buy the book, let me just say that virtually all of the material relevant to human origin model-building is found in chapters 5 and 6, and even there a lot of the discussion is relevant only to Christian-specific concerns like interpreting Genesis, original sin and the Fall, etc. Make of that what you will.

Recap

Going back to our "traditional intuitions" about human origins outlined in the last post:

1. Unique properties. Adam and his descendants - the "humans" if you will - have properties that were never had by any other biological creature. Usual candidates of such properties include language or symbolic thought, particular spiritual propensities, perhaps a different physical constitution as well.

2. Unique ancestry. All descendants of Adam trace their lineage uniquely to Adam and Eve, with no interbreeding with non-Adamic creatures. None of us are 95% Adam and 5% something else.

3. Ancient humans are modern humans. All of us - all of Adam's offspring - had and have abilities that made Adam unique - language, advanced cognitive skills, religion, culture, and the human "look". There might be differences between them, but all of his children would be immediately recognizable as human.

4. Recentness. Adam and Eve were ancient, but probably not very ancient - they had some connection with the rest of humanity's history that followed them.

While Swamidass' contributions were useful for points 3 and 4, Loke's contributions are most useful for point 1. To recap, by replacing the "unique ancestry" requirement with "genealogical ancestry", Swamidass was able to demonstrate that the common ancestor of all currently living humans could be located pretty recently in history, as recently as perhaps six to fifteen thousand years ago. I think even a 50,000 year old Adam would respect our intuitions #3 and #4. The question then becomes, by pushing back the date for the universal common ancestor, can we also reduce the amount of Adamic-non-Adamic interbreeding that happened, and still respect population genetics considerations? One suspects that if the extent of such interbreeding is low enough - say just the occasional contacts between two groups not unlike human-Jinn cohabitations - it might become theologically palatable. That's really the big question Swamidass' analysis leaves us with.

Loke's contributions

Loke's big coup, on the other hand, has been to argue that we can get away with quite a bit of uniqueness in Adam and his descendants, and yet not run into scientific difficulties. What are such scientific difficulties? Well, if Adam and his descendants suddenly "leapt into the scene" with unique capacities, it's plausible to believe such an event would leave some kind of a mark on history and/or archaeology. Indeed, the Reasons to Believe ministry posits such abruptness as a prediction of an Adamic origins model (at least in their older model). If that is the case, then this is certainty scientifically falsifiable. Vincent Torley, for example, goes through ten plausible candidates of what sets Adam apart from non-Adamic creatures, and argues that none of those features show any evidence of abrupt emergence in history. Rather, they all seem to have appeared gradually, with no particular privileged point in history that could be identified as signifying de novo emergence. Secondly, if Adam did indeed have unique biological properties, faithfully passing on those properties to his descendants via biological reproduction might cause difficulties, especially if we also want to maintain that his descendants occasionally interbred with non-Adamic hominins. I don't know if there's any mileage to this argument, but it's one more possible point of contact with scientific evidence.

How does one get around these problems? Following Loke, we can posit Adam-specific capacities that are (i) thin enough that they would not necessarily leave a mark on history, (ii) significant enough that it nonetheless respects intuition #1, and (iii) posited to be a feature of the soul, not the body, so not biologically tractable.

For Loke, the special feature of Adam and his descendants (the imago dei, to use equivalent Christian terminology) consists of a vocation bestowed by God, and a set of capacities that make such a vocation possible. Such capacities could include: (i) the capacity to implement "a unique kind of dominion that could extend to the whole world and over all kinds of creatures", (ii) "a sense of responsibility towards

the Creator God and other creatures for this kind of dominion", and (iii) "becoming conformed to Christ", the non-Christian equivalent might be some other elevated spiritual property. Furthermore, he posits such difference doesn't even have to be qualitative:

"[D]ifference in degree is an ontological difference, and one can suggest a possible scenario in which the uniqueness of human beings lies in the fact that only they have the degree of capacity to demonstrate the kind of unique dominion and responsibility to God explained earlier and are elected by God for the role of royal representatives."

Finally, such capacities can be said to be a feature of the soul, so we wouldn't need to rely on genetics or biological reproduction to faithfully equip each child of Adam with them. Loke outlines mechanisms of how souls are passed on to offspring, but I don't think that question is particularly contentious. As Muslims, we believe each individual child is bestowed with a new soul at a point in their embryological development; and that's how each child of Adam would have received these properties.

Evaluation

1. What were Adam's capacities, really? While Loke's proposal is certainly interesting, I'm left somewhat unsatisfied by the fact that he doesn't really flesh out his account of human specialness. For example, what does the ability to "exercise a unique kind of dominion" mean? On the face of it, and at the risk of being reductive, it sounds like Adam and his descendants would have greater problem-solving skills - they'd be able to extend their reaches to the furthest corners of the planet and beyond, in a way no other biological creature could. If that's the case, then it's not clear why such a property couldn't be biologically tractable.

In his defense, his project is to put forward a model that could, for all we know, be true. So the mere possibility of falsifiability doesn't threaten his case. That might actually be a good point - in defending human uniqueness, maybe we should not aim for complete scientific intractability, just for it to be "thin enough" that it lies outside the streetlight of scientific investigation. So even though Loke's description of human capacities leave a lot unstated, as long as it is thin enough to not have a significant biological footprint, we should concede the success of his project. This also means his model can fend off any objection Vincent Torley can throw at him.

2. Can we add in more ways in which Adam was unique? Perhaps the most popular suggestion for Adam's uniqueness is the capacity of language or symbolic thought, with spiritual responsibility being a close second. I think this is the next natural step for Loke's project: can we expand his conception of Adam's uniqueness by adding in these properties, while retaining scientific plausibility?

This leads to two important questions worth pursuing in the longer run:

(i) Can we attribute capacities of language use/symbolic thought to the soul?

(ii) If Adam and his descendants were uniquely gifted with language, should we expect an archaeological footprint corresponding to their emergence?

In his essay in The Soul Hypothesis, linguist Mark Baker suggests human linguistic capacity is irreducible to the physical, and to my non-expert ears, it seems like Chomsky and Berwick's view is at least reminiscent of this position. However, it seems like the latter's answer to the second question is a strong "yes", which brings us to the problem of scientific falsifiability. Interestingly, the "lack of archaeological remains" is a problem faced by scientists who ascribe human-like cognitive capacities to Neandertals and other hominins as well. They take refuge in the incompleteness of the archaeological record, and perhaps a similar strategy can be available for proponents of thicker forms of human uniqueness as well. This is a strategy Loke himself adopts in defending a more ancient date of Adam's origin. Again, as long as we're trying to tell a story that's not unfalsifiable in principle, but only in actuality, such a move might succeed.

Religious sensibilities is an interesting question in its own right, and I suspect similar issues would be relevant there as well.

3. Problems of interbreeding. If someone opts for Adamic-non-Adamic interbreeding to deal with problems of population genetics, but at the same time wants to preserve thick forms of human uniqueness, we would run into the problem of Adam's children cohabiting with creatures that were unlike us in significant ways. Loke speculates on the possibility of Cain marrying into a non-Adamic hominin family:

[I]t is plausible to think that Cain’s wife could, indeed, enter into a primitive marriage relation, play a primitive role of a mother and wife, speak and communicate in primitive languages like Cain; the only thing she would lack would be one/some or all of the ‘image of God’ properties mentioned previously. . . On the other hand, Cain’s role in marriage and family life and his communicative abilities might have been quite primitive as well; after all, the earlier mentioned capacities had only just begun to be realized. Thus the differences in behaviour between Cain and his wife might not have been very great, though the differences might still have caused difficulties and thus such a relationship would not have been ideal (unlike the case of an ideal helper for Adam, see previous discussion).

I suspect this is an important motivation for maintaining a sufficiently thin concept of human uniqueness, which doesn't encompass "big" properties like use of language. This is yet another reason why it's important to investigate the extent of interbreeding required to hold off the population genetics objections. If the children of Adam cohabited with non-Adamic humans who were nonetheless quite different from them, it doesn't seem like this could've been a very regular occurrence. It seems to maintain the joint occurrence of thick human uniqueness and interbreeding, the extent of the latter would need to be significantly constrained; which, in turn, raises the question of whether that amount of interbreeding can make sense of the population genetics data.

It is important to note, however, that interbreeding and human uniqueness don't come in the same package. Even if interbreeding places constraints on certain forms of human uniqueness, Loke's contributions still remain important in their own right. We can try to develop a model without interbreeding (if we can solve the population genetics-based objections in other ways), while affirming strong views of human uniqueness along similar lines.