Most people are part-Neanderthal. That may be a protection against viruses

MOST modern human beings have Neanderthal genes lurking in their DNA. That is well known. Only Africans, or those of recent African ancestry, are exempt. Genetic analysis makes it clear that there were at least two periods when Homo sapiens and Homo neanderthalensis (a species found only in Europe and Asia) interbred with one another: one 100,000 years ago, the other 50,000 years ago. The amount of Neanderthal genetic material in the descendants of these unions ranges between 2% and 3%, and the presumption is that this DNA enhances survival, or has done so in the past.Precisely how, has been mysterious. But research just published in by Dmitri Petrov of Stanford University and David Enard of the University of Arizona shows that the interloping Neanderthal DNA is most often found in genes whose products interact with viruses. Perhaps, therefore, it is protective against disease.