Neandertal genome like ours
(There may be Neandertals at your next family reunion!)
Published: 1 June 2010 (GMT+10)
Although the conclusions are controversial, scientists are triumphantly claiming an amazing feat within modern genetics. They have completed a draft sequence for approximately 60% of the Neandertal genome.1
After testing several Neandertal bones found in the sediments of a cave in Croatia, they decided upon three that showed the most promise. Even though it took them longer than expected and there was general concern that they would not be able to pull off the task,2 they managed to retrieve DNA and then used it to reconstruct the Neandertal genome. Since there were two different and distinct mitochondrial genomes present, and since the bones came from different layers, at least two individuals, and probably three, were represented. Thus, the resulting genome is a composite of two or three individuals, much like the original human genome, which was generated from the DNA of several individuals.
In several recent articles on the Neandertal mitochondrial genome,3,4,5 I was hesitant to make many predictions about the full Neandertal nuclear genome because I had questions about the quality of ancient DNA (aDNA) and because I was not sure if I could trust the data, since it would have been thoroughly filtered by the evolutionary gatekeepers. Even if I had made predictions, I would not have dared to make any as bold as the conclusions of these evolutionary scientists. Needless to say, I am quite pleased with what they said. This is certainly not the last word, though, as there is always controversy within such forensic science.
Why is the Neandertal genome controversial? First, there are always questions about aDNA. Neandertal bones are thousands of years old and the DNA within them is always highly degraded. In this case, most of the Neandertal DNA has broken down into pieces no more than 50 nucleotides long and more than 95% of the DNA found within these bones was from contaminating bacteria. The fact that they were able to get useable DNA out of their samples is simply amazing. Also, aDNA techniques are extremely sensitive to contamination. DNA from modern humans is of exceptionally high quality compared to the highly degraded DNA within old samples. However, the scientists went to extreme lengths to prevent and test for contamination and they concluded that no significant contamination occurred after performing several critical tests. But the question of contamination will always be present in studies of this nature.
Second, the origin of Neandertals and whether or not they are part of the human family line has always been a hot button of contention among both scientists and the public. There is considerable debate among evolutionists about the nature of Neandertals. A summary article in the New York Times hinted at some of this controversy, citing other geneticists and one paleontologist who disagreed strongly with the conclusions made by the Neandertal DNA team.6
Third, the authors tested for evolutionary relationships (in which they assumed any similarities are due to common ancestry) among apes, Neandertals and various groups of modern humans. This is where the real controversy lies, for the answers they came up with are not what most expected. They discovered that (1) Neandertals are well within the range of diversity of modern man, that (2) the Neandertal genome is incredibly similar to the genome of modern man, and that (3) there are only a few fixed differences between modern man and Neandertals. But even those few fixed differences could vanish as we learn more about modern human and ancient Neandertal genetic diversity (the more we study, the more variation we find and so the “fixed” differences tend to be reduced over time).
Even more controversial, the few variations that Neandertals share with modern humans are only shared with people living outside of Africa. So, not only are Neandertals fully human, but the evidence is that they interbred with the ancestors of modern Europeans, Asians, Australians, and Native Americans, but not Africans. Thus, Neandertals are either the cousins or the ancestors to people outside Africa. The lead author attests to this unexpected result, “ … we were baffled that this affinity with Neandertals was not only in Europe and West Asia [where it was most expected], but also in Papua New Guinea … ”7
But when would this mixing have occurred? Evolutionists assert that Neandertal remains have not been found outside Europe and western Asia (not all creationists agree, however8). How could they be related to people across the world but not the Africans? In the Out of Africa scenario,9 it must have happened after modern humans left Africa but prior to their dispersal across the globe. This must have occurred in the Middle East.
In the creation model, it could very well be that the Neandertals are the ancestors to the people currently living in the areas where the Neanderthals once lived (this, of course depends on the accuracy of the Neandertal genome reconstruction!). Why, then, do people outside the Neandertal areas also carry the Neandertal genes? The Table of Nations in Genesis 9–10 describes the initial peopling of the world after Babel. With the exception of Northern Africa, the areas described match very well with the locations in which Neandertal remains have been found. Places outside these regions would have been settled later, and so there may not have been any “Neandertals” left. If the classic Neandertal shape is due to longevity,10 for instance, their shorter-lived descendents would have carried their genes, but not their form, as they spread to the remotest parts of the earth.
Note that the Neandertal bones studied belonged to individuals who lived outside Africa. This may be the source of the discrepancy. If Neandertals or Neandertal-like peoples lived in Africa,8 examination of their DNA might tell us that they left descendants in Africa as well. However, well-preserved remains of ancient humans are rare and we might not ever learn the answer to this riddle.
In a related paper, scientists focused on specific areas of the Neandertal genome known to be different between humans and chimpanzee. In all, they studied 14,000 protein-altering locations (places where humans and chimps have different amino acids within otherwise similar proteins) and got results for nearly 11,000 of those.11 They discovered that Neandertals carried the same amino acid as modern humans in at least 91.5% of these positions. The remaining 8.5% were called “ancestral”, but this is assuming a common ancestor with chimps, that Neandertals were not themselves mutated in these positions (because of mutational hotspots, for example), and that modern chimps have not themselves changed over time. In all, they found 88 amino acid locations that all modern humans share. They called these non-ancestral, “recently fixed” mutations, but again, there are evolutionary assumptions behind the conclusions.
What are the possible creationist interpretations of the two new sets of Neandertal genome data?
Here is where things get complicated. CMI has long maintained that Neandertals are fully human, that they lived in Europe after the Flood, and that they were descendants of Noah and his family.12 This new data strengthens our arguments considerably, but exactly who and what the Neandertals were is still a bit of a mystery. I will outline three (out of many) possibilities.
They may have been our ancestors (the Patriarchs and the early post-Flood generations), living among some of our more recent ancestors for hundreds of years after the Flood. In this case, their strange features could have been a result of long life spans and delayed maturity,10 although this is controversial among creationists,8 and their genetic differences could be due to the small sample size. We know from studies of small populations (e.g., Iceland) that a minority of people living at any point in time will be the ancestors of a majority of the future population.13 Should we therefore be surprised that not all of the Neandertal genes made it into the current population?
Since they appear to be genetically distinct, it is also possible that they are descended from a child that one of the Patriarchs fathered in his old age. Based on a paper by the evolutionary geneticist James Crow, it appears that mutational load in children increases with the age of the father.14 Thus, any child born to an ancient person could theoretically carry many genetic differences from other people. Extrapolating from the data of Crow, a man 400 years of age would donate approximately 10,000 mutations to a child (the current average is expected to be around 200, according to Crow). If that child went on to form a dynasty or clan, those people could be very distinct from their contemporaries.
Or, they could have been just one tribe of people, dispersed from Babylon with the rest, highly inbred, and pushed out, conquered, or killed as the European ancestors migrated into Europe. There are many other possible scenarios, but realistic modeling has yet to be performed.
How does this affect the arguments of long-age Christians?
The discoveries, although tentative, strongly contradict the arguments put forth by Reasons to Believe (RTB) and other old-earth organizations. Here is evidence that suggests modern humans have Neandertal ancestors and it stands against their major claim that Neandertals were soulless animals that just happen to look very much like us.
How do they respond? Based on a podcast featuring their two most prominent scientists,15 they conclude that this is clear evidence of interbreeding, but then they reject the biological species concept (one of the fundamental theorems of biology) and claim that evidence of interbreeding does not mean two organisms belong to the same species! Strangely, they then cite examples of the mule and wholphin, animals which we have written about previously and which we claim are evidence for the biblical idea that God created distinct “kinds” from which today’s interrelated species have descended.16 If interbreeding occurred, and fertile offspring were produced, and these offspring became the ancestors to people living today, would that not conclusively demonstrate that Neandertals and humans belong to the same created kind? RTB plays the game of equivocation here (changing of definitions in the middle of an argument). We have written extensively about changes within created kinds, the development of new “species” over time, etc., and there is no basis to claim Neandertals are a completely different creation from humans (see Speciation questions and answers).
They also claim that the data indicate Neandertals and humans are distinct species and that the young-earth position has been falsified because the differences are too extreme to call them the same species “by a wide margin”. Personally, I have no idea where they get these ideas, since there is nothing in this study that gives any basis for their claim. As a person who studies, speaks and writes about genetics extensively, I do not yet have a way to gauge species differences based on genetic data alone. However, these differences are trivial and are what we would expect to find within a single species. In fact, humans are less diverse than many other species17 and Neandertal still fits in. To add perspective, two living chimpanzees can be farther from one another than Neandertal is from modern human.18 Everyone accepts that chimpanzees belong to the same species, so why not include Neandertals with modern humans? They do not accept this because they cannot without contradicting one of their pet theories, and there is an extensive inventory of references to this theory on their website and in their books.19
The Neandertal genome is not in its final version and there is considerable controversy swirling around it, but the papers that have been published strongly challenge the RTB model.
How does this impact the Out of Africa Theory?
The Neandertal genome data is having an interesting effect on the evolutionary establishment. First, because Neandertals are so similar to modern man and yet so distant in our past, the gap between man and apes has suddenly widened. Add to this the recent publication of the chimpanzee Y chromosome,20 where only 70% similarity was found (approximately what is expected between man and chicken) in the 50% of the chromosome that is sequenceable, and the gap becomes wider still.
Second, the Out of Africa theory is in trouble and the classic view that we have been hearing echoed by nearly all media outlets for the past 20 years is suddenly in question. As reported in Science, “The finding of interbreeding refutes the narrowest form of a long-standing model that predicts that all living humans can trace their ancestry back to a small African population that expanded and completely replaced archaic human species without any interbreeding.”21 What is to replace the old, outdated view? “Modified multiregionalism”, where the people coming out of Africa did not completely replace the archaic populations, but interbred with them as they eliminated and replaced them. A very popular evolutionary weblog concluded that not only are Neandertals unequivocally human, but that we are now all multi-regionalists!22 The winds of change are both fickle and forgetful!
But modified multiregionalism will create additional problems. For example, now that many believe Neandertals interbred with modern humans on our way out of Africa, the question of Neandertal origins is suddenly glaring at us, as well as the question of how Neandertals could have remained able to interbreed with our ancestors after a supposed half a million or so years of separation.
Why this matters
The existence of Neandertals has been used as a club to beat creationists since the first Neandertal skeleton was discovered in the 1800s. Generations have been raised to believe in the half-ape, half-man, primitive cave man called Neandertal. This is no longer believed by the evolutionary establishment, but the indoctrination has been effective and the effects will be long-lived. Europeans especially are being challenged, as they have tended to have visceral reactions against any idea of interbreeding with Neandertals, which I find humorous considering that evolutionary theory says we came from apes, so who cares if we also came from Neandertals? It also illuminates a war among evolutionists, as the various parties snipe at one another regarding their personal views of human origins. And, finally, it provides strong support for the biblical model that all people descended from a small population of people living in the Middle East in the recent past.
- Green, R.E., et al., A draft sequence of the Neandertal genome. Science 328:710–722, 2010. Return to text.
- Pennisi, E., Computer kid makes good. Science 328:683, 2010. Return to text.
- Carter, R., The Neandertal mitochondrial genome does not support evolution, Journal of Creation 23(1):40–43, 2009. Return to text.
- Carter, R., Taking a crack at the mitochondrial genome, 2009. Return to text.
- Carter, R., A reply to ‘Taking a crack at the Neandertal mitochondrial genome’, Journal of Creation 23(1):47–49, 2009. Return to text.
- Wade, N., Signs of Neandertals mating with humans, New York Times. May 6, 2010. Return to text.
- Gibbons, A., Close encounters of the prehistoric kind. Science 328:680-684, 2010. Return to text.
- Habermehl, A., Those enigmatic Neanderthals: What are they saying? Are we listening? Answers Research Journal 3:1-21 2010; (note: I do not agree that H. erectus is non-human, as the author suggests in this article.) Return to text.
- Carter, R., The Neutral Model of evolution and recent African origins. Journal of Creation 23(1):70–77, 2009. Return to text.
- Cuozzo, J.W., Neandertal children’s fossils: Reconstruction and interpretation distorted by assumptions, Journal of Creation [formerly TJ] 8(2):166–178, 1994. Return to text.
- Burbano, H.A., et al., Targeted investigation of the Neandertal genome by array-based sequence capture. Science 328:723–725, 2010. Return to text.
- See the Neandertal section at Anthropology and Apemen Questions and Answers. Return to text.
- This is the essence of “coalescence theory”. See my short discussions in references 3–5 above. Return to text.
- Crow, J.F., The origins, patterns and implications of human spontaneous mutation. Nature Reviews Genetics 1:40–47, 2000. Return to text.
- As of the time of writing, only a few days have passed since the publication of the original articles so not much has been written. The scientists are Hugh Ross and Fuzz Rana. See http://reasons.edgeboss.net/download/reasons/newsflash/20100510-HRFRKS.mp3. Return to text.
- Batten, D., Ligers and wholphins? What next? Creation 22(3):28–33, 2000. Return to text.
- This fact can be found in many sources. See for example, Lynch, M., Rate, molecular spectrum, and consequences of human mutation. Proceedings of the National Academy of Sciences (USA) 107(3):961–968, 2010. Return to text.
- See reference #8 in Taking a crack at the Neandertal mitochondrial genome. Return to text.
- See, for example, Neanderthal-to-Human Link Severed, where they state quite clearly, “The conclusion is undeniable: Neanderthals did not give rise to modern humans.” Return to text.
- Hughes, J.F., et al., Chimpanzee and human Y chromosomes are remarkably divergent in structure and gene content. Nature 463:536–539, 2010. Return to text.
- Gibbons, A., Close encounters of the prehistoric kind. Science 328:680–684, 2010. Return to text.
- See the Thursday, May 6, 2010 entry in John Hawks’ weblog. Return to text.