Archive for May, 2010

Neanderthal interbreeding

Tuesday, May 11th, 2010

So the first draft of the Neanderthal genome has now been published (http://www.sciencemag.org/cgi/content/full/328/5979/710). The authors  found that Neanderthals contributed 1-4% to the genomes of non-Africans. They use SNPs and five full genomes from different ethnic groups to arrive at this conclusion. Aspie-quiz has also found that all non-Africans have similar levels of Aspie-traits, while people of African descent have much lower levels of Aspie-traits (1/6th for African-Americans), and might even totally lack these traits when unmixed with non-Africans.

 The study claims that admixture most likely occured in Middle  East, but this is not supported by Aspie-quiz. Aspie-quiz instead seems to indicate that East Asians mixed with Neanderthal before Europeans. Aspie-quiz also give native American Indians the highest scores of any population, and thus it seems like they have the largest Aspie rate in the world. South Asians are lower than Europeans and East Asians. There is a cline in Eurasia where the north has much higher Aspie-rates than the south. This could be compatible with interbreeding in the Middle East, and later African migration into south Asia, but it matches the “southern migration route” of modern humans far better. Under this scenario, Africans and south Asians are largely devoid of primary interbreeding with Neanderthal. Interbreeding started in Central Asia, and this population then split into a western part that ended up in Europe and formed Caucasians, and an eastern part that ended up in East Asia and formed Mongoloids and Native Americans. Native Americans then got isolated from further gene-flow from South Asia, and thus today has the world’s highest level of Neanderthal ancestry.

 The 1-4% of Neanderthal ancestry probably refers to neurotypicals only. Typical Aspie scores for neurotypical people are around 40-50. Typical Aspie scores for Aspies are three times larger. We would therefore assume that Aspies perhaps has 5-15% of Neanderthal ancestry using this as an indication. OTOH, if we assume that 1-4% is the average Neanderthal ancestry in Eurasia, and that all of this is attributable to Aspie traits, and the proportion of  Aspie traits is around 10%, it would mean that Aspie traits have 10-40% of Neanderthal ancestry.

Another recently published article on the same theme came to similar conclusions (http://www.nature.com/news/2010/100420/full/news.2010.194.html). Although, here  the authors see two different hybridization events. This scenario in fact is supported in Aspie-quiz. Not only is there a signature of Neanderthal interbreeding leading to the introduction of the Aspie-traits, but there is also a signature of the introduction of “neurotypical compulsion” traits that essentially describes modern humans.

To resolve these issues there is a need to sequence full genomes of Aspies.