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Stanford Medicine

Autoimmune Disease, Evolution, Genetics, Infectious Disease

Humans share history – and a fair amount of genetic material – with Neanderthals

If you have found yourself inexplicably offended by Geico’s “caveman” commercials, new research may have an explanation: that most humans share up to 4 percent of their genes with Neanderthals.

In 2010, scientists published the incomplete-but-functional Neanderthal genome. The finding has been an understandably hot topic for geneticists. As new discoveries about this genome arise, it becomes increasingly clear that the Neanderthals, a species that died out about 30,000 years ago, played a critical role in human history – and the contemporary human genome. It seems that Neanderthals interbred with humans, probably during their migration out of Africa (which may explain why Africans don’t share nearly as many genes with Neanderthals as, say, Europeans), permanently altering our genome for the better.

Gene-by-gene comparisons between the Neanderthal and human genomes suggest that interbreeding occurred around 65,000 – 90,000 years ago. This is consistent with archeological finds pinpointing early human migration out of Africa to around 50,000 – 100,000 years ago. As researchers mine the Neanderthal genome, the effects of this interbreeding surface. Stanford graduate student Cory McLean, for example, found that Neanderthals share some of the genetic deletions that differentiate humans from other primates.

Interbreeding is also partially responsible for some of our important disease-fighting genes. According to Stanford immunogeneticist Peter Parham, PhD, interbreeding endowed humans with the genetic diversity that makes our immune systems so very functional.

Even the differences between Neanderthal and human genomes are historically revealing. Neanderthals lived in small communities of hunter-gatherers, whereas human populations tend to form larger groups, which would explain why Neanderthals lack certain forms of genes that protect humans from epidemic diseases like measles. The fact that very little autoimmune disease existed in Neanderthals (they lacked, for example, the gene variants linked to celiac disease) suggests that these human-specific defensive genes may also be linked to autoimmune diseases. This information could help scientists identify when autoimmune disease arose in humans.

Future research on the Neanderthal genome promises to provide further fascinating insights into human genetic history and, surely, some touching tales of the inter-species love that made us who we are today.

Previously: Roots of disease may vary with ancestry, according to Stanford geneticist and Open-source encyclopedia of human genome’s functional elements in the works
Via Nature News

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