Which of Noah's ancestors mated with a Neanderthal?

This is my first post in a year and a half. A reader recently suggested I write more. In all honesty, I doubt I will be able to do much. My inspiration and motivation left me. I am also out of the habit of thinking of topics so I am not sure what to write about that is fresh. I did read something recently that gave me an idea for a post, so I'll try one more and see how it goes.

About a month ago, it was reported that there is evidence for interbreeding between Neanderthals and Homo sapiens, based on analysis of the Neanderthal genome. The evidence supports 1-4% gene flow about 50,000-80,000 years ago. It's fascinating research, as we continue to learn more about our ancestry. I recommend Carl Zimmer's summary here if you are not familiar with the work.

What I would like to talk about is the creationist response. Old earth and young earth creationists have different responses. The leading OEC group believes Neanderthals are a separate species from modern humans, so they have to reconcile this evidence of similarity. The problems with their approach are summarized here. YEC groups such as Answers in Genesis on the other hand have always claimed that Neanderthals are simply degenerate humans and not a separate species. They pounce on these results as supporting their view that Neanderthals are just a different kind of human, since they can mate with humans. That is the response I would like to address.

First, this result isn't suprising from an evolutionary perspective. Until fairly recently, Neanderthals were often classified as a sub species of Homo sapiens, rather than a different species. We know they are fairly similar. The question of whether there was interbreeding has been hotly debated by biologists for decades (based on evidence, and not dogmatically assumed one way or the other). Preliminary molecular evidence suggested little or no interbreeding, so the new results are only surprising in light of that recent data. Even with this evidence, and assuming the interpretation is correct, having one period of 4% gene flow 60,000 years ago is not a lot of mating, considering that the two species coexisted in Europe for 60,000 years.

However, I would like to focus on another aspect of AIG's approach, a problem that is very common in creationist arguments. The problem is they take conclusions which rely on an application of evolutionary theory and apply the conclusions to their model, not the method of getting the conclusion. They take the conclusions, not the data. The entire analysis of the data is based on evolution and would not be valid if not for evolution, so they are completely unjustified in using the conclusions. This happens all the time with creationists--they read the conclusions of a study and twist it to fit their agenda, without bothering to analyze the data from within their model.

Let me illustrate the problem with the Neanderthal data. One of the lines of evidence for interbreeding is that there are Neanderthal genes present in modern humans, but these genes are only found in a subset of humans. Specifically, they are found in those of European or Asian descent, but not those in Africa. The most parsimonious interpretation of this data is that there was mating between Neanderthals and the early immigrants of Homo sapiens out of Africa, which then populated the rest of the world.

AIG simply takes the conclusion, that there was mating, without looking at how it was derived. However, the conclusion relies on assumptions about human migration patters, the molecular clock, and models of gene flow, all assuming evolution. What AIG must do is to start with the raw data and analyze it using their models to determine if there was gene flow. And therein lies the problem.

According to YECs, Neanderthals were a degenerate descendant of Adam and Eve that were destroyed in the Noachian flood. Therefore, if there was mating between Neanderthals and humans, it must have occurred in the ancestors of Noah or his wife. The Neanderthal genes would then be present in all of Noah's children, and therefore all modern humans (since there were many dozens of gense involved, it is impossible that any of their children would have no Neanderthal genes just by independent assortment). According to YECs, we are all descended from Noah and his wife. Therefore, if there was mating between humans and Neanderthals prior to the flood, all modern humans would have those genes. YEC cannot account for the genes being present in only Europeans and Asians.

It would get even messier if they were to try to quantify the gene flow. There were fewer than 100 generations (2000 years) between Adam and Noah, during which time the Neanderthals would have had to have first diverged, and then mated back with humans. YECs cannot even account for modern human diversity. According to them, all of the differences between any two humans today has arisen in the past 5000 years from Mr. and Mrs. Noah. There is no reasonable model that can account for the generation of that much genetic diversity in that little time. But the problem is much worse when we look at Neanderthals prior to the flood.

Neanderthals were about four times more divergent from humans than any modern is from any other human. The young earth model cannot even account for the diversity of all modern humans in 5000 years, but they also have to explain how Neanderthals became four times more different in less than 2000 years (remember, they believe Neanderthals are humans, descendants of Adam). Have YECs calculated the rate of change, and shown how it could occur? Of course not. They have made no attempt to account for the genetic difference between humans and Neanderthals from within their model.

That is the first step. Then they have to estimate when in that 2000 years the mating with humans had to occur to account for 1-4% gene flow. In order for it to be that dilute, it would have had to have been many generations prior to Noah, so that gives even less time for Neanderthals to form in the first place. Who knows, maybe they could make it work, but of course, they haven't even tried. (Actually, I am sure it would not work unless they invoke miraculous mutation rates or intervention. I never understand the YEC's penchant for mixing the natural and miraculous. They try so hard to explain things with their strange natural theories of flood geology, but whenever things become too difficult, they invoke a miracle. Why not just forget the painfully twisted natural explanations and go straight for the miracle?).

What AIG needs to do, is to take the data from the Neanderthal genome, and model it using their assumptions, not the assumptions of evolution. They need to figure out if their was gene flow, when it happened, how much without the use of evolution. They need to do the math, and determine which generation mating occurred in. They have to use their models to explain the geographic distribution of the genes. That would be what we call doing science. But they don't do science. They take the results of science, and twist them to fit their view. They gladly accept conclusions that agree with them, even if the conclusions depend from top to bottom on evolutionary assumptions and even if the conclusions could not possibly be produced using their assumptions.

Scientists constantly accuse creationists of not doing science. This is an example of why. If there are any creationists out there that would like to try to actually do creation science, I have a project for you. Access the raw data of the Neanderthal genome. Use your models of human history, migration, population size and bottlenecks, and time frames. Determine if there was mating between humans and Neanderthals, when it happened, and how it lead to the present distribution of genes in humans. You are not allowed to slip in any conclusions from other researchers based on an old earth or on ancient populations in the tens of thousands. If your model doesn't give you the answer you want, you are not allowed to insert "and then a miracle happens" to make it work out. Since we have the complete ancestry of Noah in the Bible, perhaps you can tell us exactly which of his ancestors begat with a Neanderthal. But please, do not claim that science based on evolutionary assumptions can be transferred whole into your model. Do your own science