(EDIT) The current RTB model for humanity has been challenged by the work of our host. (/EDIT)
This is not a death blow against OEC by any means, or even the overall RTB model, which they call the “testable creation model”. For example the astronomical aspects of their model still do quite well. The question of whether humanity evolved from a common ancestor with chimpanzees via known evolutionary processes is a separate question from whether there were humans outside the garden before Adam and Eve, how long ago all this happened, and also separate from the question of whether the flood of Noah eliminated the balance of humanity or just the balance of the line of Adam.
This new data just means that they may need to adapt their model in a way which accommodates what we have learned, much like evolutionary theory itself changes to accommodate new data. They can continue to represent the OEC position (which I also think is the “most correct” overall view).
If so, what should this model now look like with respect to humanity? I have a few suggestions and you may have some of your own. I realize the TE members of this board may not appreciate this exercise. I ask that they not switch forks on their putative evolutionary tree (go ape) over this, but I’d like to bring RTB closer to Peaceful Science by first getting us all to agree on what happened before we get to questions about how it happened.
Obviously the OEC position in particular with respect to humanity is that both the race adam and the man Adam were specially created by God, though these can now be seen as separate events and therefore not necessarily done by the same means. The good thing about this for RTB is that they no longer have to stretch the genealogies to the breaking point with vast “gaps”. The genealogies are for the line of the man Adam, not the race adam which was already present (though not as agriculturalists).
The new RTB model could reject the claim that humanity arose 310,000 years ago and propose a more recent though still ancient date. The molecular clock evidence suggesting a date for humanity of 260 K ago could be explained by the initial human population (in the new model God would have created a “host” of humans prior to Adam and Eve) containing some genetic diversity. That is, the initial human population was somewhat different from the start, thus not all of the differences were due to acquired mutations. This would show an older clock time than actual time. Some evidence suggests that molecular clocks run fast anyway. This would be easy to do because the evidence for a 300K plus date for humanity is very much over-blown IMHO.
The issue of limited in-breeding between humans and other hominids should be addressed by the model. I propose that it be turned into a plus not a minus. It allows us to test for anomalies in the standard evolutionary model. While there is evidence that such in-breeding occurred, the same evidence indicates that there were barriers to hybrid fertility. Lions and tigers can sometimes produce offspring, but they are not known to breed in the wild and those offspring likewise have fertility problems. So we can see that in nature things can happen which nature itself does not “prefer” in terms of Darwinian outcomes.
There is evidence to suggest that most of the genes we may have acquired from hominids such as Neanderthals are slowly being weeded out of the human genome over time, as if nature was correcting a mistake. There are also signs that many other genes which were thought to be a result of such hybridization are now considered to be the ancestral state of our own species. That is, they represent a re-introduction of genes originally possessed but lost by chance in our own human ancestors and thus do not represent a genuine influx of new genetic material to our species. Perhaps it is best to consider Neanderthals and Denisovans to be like the satyrs of myth- like us, interested in us, but not really “of” us.
That brings me to another point which could be a part of the new OEC model. Instead of humans originating in Africa, perhaps they originated in the mid-east or in many places at once but the vast majority of those who survived were from Africa. Thus the OOA movement 55-60K ago was humanity re-populating the rest of the old world, absorbing or wiping out small and scattered human groups- who may have been highly admixed with other hominids and the true source for much of the few non-human genes we still see in our own genomes. As our power to analyze genomes increases we see tantalizing hints of this previous larger human population in some isolated human groups, particularly those in SE Asia, and the islands near to Australia. I think they admixed with other human groups as well, but the work of Dr. Swamidass has shown how quickly genetic minorities can become genetic ghosts. This applies to more than just Adam. It could apply to this proposed non-African human population as well.
This brings me to another point. Much of what we think of as “human evolution” in the old world may simply be an artifact of the genetic impact of hybridization events with other hominids being weeded out over time. That is, the original group of human beings may have looked much like the San do now and not like “archaic” Homo Sapiens at all. The OEC position can postulate that the “archaic” appearance was a result of hybridization with these other hominids, and the loss of such “primitive” features would simply be “evolution” via reversion to the mean for humanity- a still ongoing process.
Under this scenario I would expect to find in Africa an inconsistent pattern of human remains- features far too “modern” looking for their time in some finds and typically “archaic” in others. Perhaps even in the same digs. Thus Africa would represent a place where some populations of humanity resisted being “dragged down” by hybridization events which spelled doom both for the human populations whose participation in such events became the norm and the other hominid groups as well. Unfortunately I don’t think we have enough finds in Africa at present to establish much of a pattern either way.
This brings me to Adam. While it may very well be that Adam and Eve have become “genetic ghosts”, if they left a detectible signature one of the traits of this signature would be an absence of other-hominid genes relative to surrounding populations. That is, they would not have Neanderthal or Denisovan genes, and thus modern populations which contained more of their genes would have fewer of these genes than populations which had lost most or all of their genes. A sudden appearance of a population with a reduced load of non-human genes in the same time and place as Adam would represent an anomaly explainable by a de-novo creation of Adam as a “re-do” of the original human condition.
So while the new findings may be considered a setback for some aspects of that specific model, the new data presents new opportunities to explore and improve OEC models.