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On May 6, 2010, the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany presented the world with a draft of the genome sequence of the Neanderthal (press release here (pdf) and full article here (free), NYT article here). As part of the announcement, the team presented their conclusion that 1% to 4% of the genome of non-Africans is derived from Neanderthals:
“An initial comparison of the two sequences has brought some exciting discoveries to light. Contrary to the assumption of many researchers, it would appear that some Neandertals and early modern humans interbred. According to the researchers’ calculations, between one and four percent of the DNA of many humans living today originate from the Neandertal. ‘Those of us who live outside Africa carry a little Neandertal DNA in us,’ says Svante Pääbo. Previous tests carried out on the DNA of Neandertal mitochondria, which represents just a tiny part of the whole genome, had not found any evidence of such interbreeding or ‘admixture.’”
Once this study came out, I knew it was only a matter of time before companies began offering tests that examined the percent of Neanderthal contribution to a test-taker’s genome.
The Neanderthal Index
In May 2010, DNA Consultants began offering a test called the Neanderthal Index. Priced at USD $90.00, the test purports to “estimate how much Neanderthal is in your ancestry.” From the test description:
“Created in response to the phenomenal interest generated by the revelation in scientific journals on May 8, 2010 that most humans are part Neanderthal (Green et al), our autosomal DNA Neanderthal Index can be added to your DNA Fingerprint Test or DNA Fingerprint Plus. It reports any strong matches you have with populations identified as Archaic, those preserving the earliest earmarks of interbreeding between Neanderthals and humans (Homo sapiens sapiens). The stronger the match the higher the likelihood that your ancestors gave you Neanderthal genes.”
It is vital to understand that this test does NOT test SNPs. Instead, it uses CODIS markers to estimate whether a test-taker’s results are likely to be found in “archaic populations,” which themselves are hypothesized to be more likely to possess Neanderthal DNA (i.e., “relatively little genetic inflow.”). The list of archaic populations is found in the FAQ, and includes many Middle Eastern and worldwide indigenous populations. From the test description:
“Note that this test does not directly examine your genetic material. Only a large-scale genomic sequencing procedure like the Human Genome Project or Draft Neanderthal Genome can do that. The Neanderthal Index is based on probabilistic predictions of the occurrence of your unique DNA Fingerprint in Archaic Populations retaining Neanderthal genomics and traits.”
While the website does a good job of explaining that it does not identify any specific “Neanderthal SNPs” but rather makes a incredibly rough probabilistic estimate based on the Science paper, it is important to fully understand the many limitations of this test.
Meanwhile, over at 23andMe, several test-takers refuse to wait for commercial companies to offer Neanderthal-specific testing. In addition to asking in the 23andMe forums when the Ancestry Painting will include the percentage of Neanderthal DNA, others have proposed several so-called “Neanderthal SNPs” based on research published in other recent papers. These SNPs include rs1864325 (forum discussion here) and rs930557 (forum discussion here). This collaborative effort by 23andMe’s test-takers is just one of the many reasons that personal genomics and affordable sequencing are so exciting.
Although the science behind these Neanderthal SNPs is only in its infancy and should only be taken with an enormous grain of salt at this stage, there will be more of these types of studies in the future to provide companies and pioneers with new data to explore. And we, the personal genome pioneers, will get to learn and explore as these developments unfold.
While there aren’t yet any commercially-available tests that examine your genome for evidence of Neanderthal contribution, there will undoubtedly be such tests in the next few years, especially as further drafts of the Neanderthal genome are released.