First modern humans protected themselves against disease after leaving Africa by 'interbreeding with Neanderthals'

First modern humans protected themselves against disease after leaving Africa by 'interbreeding with Neanderthals' - It might seem like a novel way to keep disease at bay.

Researchers claim that the first modern humans protected themselves against unfamiliar illnesses by interbreeding with Neanderthals.

Although it was known that homo sapiens had bred with Neanderthals after leaving Africa, a study has concluded that in doing so they picked up genes which protected them and eventually helped them to populate the planet.

Your place or mine? Research suggests that intimate relations with Neanderthals and humans strengthened man's immune system

The publication of the Neanderthal genome last year provided proof that modern man also enjoyed intimate relations with other races including the Denisovans, a species identified from a Siberian fossil.

However it had been unclear until now whether or not their sexual shenanigans had influenced their evolution.

According to New Scientist, the research was carried out by Peter Parham, from California's prestigious Stanford University, who carried out research into human leukocyte antigens (HLAs) - which are vital to the human immune system.

HLAs contain some of the most variable genes in the population - known as alleles - which allow the body to react to both established and new diseases.

Gene pool: Neanderthals probably passed vital genes on to homo sapiens as they populated the rest of the world

And while the humans that left Africa probably only carried a small number of the HLA alleles, the research indicates they picked up new ones from the Neanderthals they interbred with as they established themselves in other parts of the world.

One such allele, known as HLA-C*0702, for example, is common among modern Europeans and Asians but is never seen in African nations - suggesting that it found its way into humans through breeding with other races.

Another, the HLA-A*11 - seen among Asians but not those of African descent was discovered by Parham in the Denisovan genome, indicating that its source was interbreeding outside of Africa.

Although the majority of the modern human genome originated in Africa, Parham found the share of HLAs acquired as a result of interbreeding to be much higher.

He told New Scientists that half of European HLA-A alleles come from other ancient races, while those figures rise to 72 per cent of the population in China and over 90 per cent for those in Papua New Guinea.

Parham added that because Neanderthal and Denisovan races had lived outside Africa for over 200,000 years before encountering homo sapiens, their immune systems would have been well suited to local diseases - thus helping to protect modern humans also.

He presented his findings at a recent Royal Society discussion meeting on human evolution which took place in London. ( dailymail.co.uk )