Latest Genetic Evidence Indicates No Interbreeding between Neanderthals and Humans
I don’t want my teenage daughters to date Neanderthals. Apparently, the first human fathers didn’t like the idea much either.
New findings reported at a recent Biology of Genomes meeting (Science, May 18, 2007, p. 967) douse the flames of romance between humans and Neanderthals, seemingly once and for all.
In the last decade, paleoanthropologists have isolated and analyzed DNA fragments from the fossil remains of at least thirteen distinct Neanderthals. These specimens typically date between 30,000 to 40,000 years in age (though one specimen is about 100,000 years old) and encompass most of the Neanderthal’s range (Europe, western Asia, and the Middle East).
The DNA sequences from all the Neanderthal specimens indicate that humans and Neanderthals must be distinct species. These species are so different that, if viewed from an evolutionary standpoint, it appears as if the last shared ancestor for Neanderthals and humans lived nearly 800,000 years ago. More importantly, the data also indicates that Neanderthals did not evolve into humans.
These results invalidate traditional evolutionary models, like multiregionalism, and at the same time powerfully support RTB’s views on human origins. The RTB model regards the hominids recovered from the fossil record as separate species, distinct from anatomically and behaviorally modern humans. Accordingly, these animals were created by God, and since that time they have gone extinct. Genesis 1 makes no specific allusion to the hominids. Their creation along with other animals on either Day 5 or Day 6 can only be inferred.
In response to this data, some anthropologists have advanced more sophisticated human evolutionary models. One version, for example, maintains that when modern humans migrated around the world they interbred with Neanderthals and Homo erectus whenever they encountered them. Even though Neanderthals didnâ€™t evolve into modern humans, some evolutionary biologists think that they still may have contributed to human origins through interbreeding, infusing their genes into the human gene pool.
This idea has not received much support. Analysis of mitochondrial DNA by researchers from the Max Planck Institute seemingly indicated that Neanderthals and modern humans did not interbreed. This work compared DNA recovered from four Neanderthals with corresponding DNA isolated from the remains of five modern human fossils. The Neanderthal and modern human specimens all date within the same time period (between 30,000 and 40,000 years ago) and were recovered from corresponding geographical locations. Even though the Max Planck Institute investigators readily recovered Neanderthal-type DNA from the Neanderthal specimens, they did not detect any in the modern human remains. This suggests that Neanderthals likely did not make any genetic contribution to the earliest modern humans.
Preliminary results from studies of Neanderthal nuclear DNA were much less certain, however (Science, November 17, 2006, p. 1068-1071). Analysis of nuclear DNA is potentially much more informative than mitochondrial DNA. One analysis of Neanderthal nuclear DNA sequences found no evidence for interbreeding. Another analysis, however, noted some genetic signatures in the Neanderthal genome that could be taken as evidence that humans contributed to the Neanderthal gene pool.
The latest work compared the Neanderthal DNA signatures with the DNA signatures from African and European DNA and found no evidence for gene flow between humans and Neanderthals. Analysis of human and Neanderthal Y-chromosome sequences support this conclusion as well. Humans and Neanderthals did not interbreed.
Now, if only I could get one of my daughters to fall for a rich doctor!
For a more detailed discussion of how Neanderthals fit into RTB’s human origins model, see Who Was Adam?