Hay fever sufferers set to cope with itchy eyes and runny noses next summer can thank their ancestors, who indulged in passionate affairs with their ancient cousins The Neanderthals, according to researchers.
Two scientific studies have suggested that key genes in the immune system are inherited from our ancient ‘cousins’ the Neanderthals and Denisovans which predispose some to allergies including hay fever.
Neanderthals and Denisovans are extinct species of human.
The genes which cause hay fever were passed onto modern humans because our distinct relatives mated with Neanderthals and Denisovans more than 40,000 years ago.
The research found that all non-Africans carry 1pc-6pc of Neanderthal DNA. Those who did not leave the continent would not have crossed paths with the Denisovans or the Neanderthals who lived around Serbia at the time.
The three genes responsible for hay fever, asthma and other allergies are amongst the most common strands of Denisovan and Neanderthal-like DNA pin-pointed in modern humans. The genes can also be attributed to a boosted immune system as those who have them have better defences against pathogens like bacteria and fungi.
The genes are thought to have been passed onto modern humans when small groups of explorers left Africa and discovered Neanderthals.
“A small group of modern humans leaving Africa would not carry much genetic variation,” said Janet Kelso, lead researcher at the Max Planck Institute for evolutionary Anthropology in Leipzig.
“You can adapt through mutations, but if you interbreed with the local population who are already there, you can get some of these adaptations for free.”
The scientists analysed the genes of modern humans as well as those of the Neanderthals and Denisovans to study the changes in our immune system throughout tens of thousands of years.
The researchers admitted that the interbreeding might make those with the genes more likely to have allergies, but it has benefited modern humans greatly in terms of fighting pathogens.
"The evidence suggests that this genetic region contributes to the immune system of modern day humans," Dr Michael Dannemann of the Max Planck Institute for Evolutionary Anthropology in Germany.
"At some point in history it might have been an advantage to have these Neanderthal genes in terms of fighting off infections or lethal pathogens from 10,000 years ago.
"It could also still be an advantage today but this is difficult to pinpoint."
A second group of researchers in the United States and France came to similar conclusions when they independently analysed the genetic data of modern humans and pitted them against those of ancient humans.
Dr Lluis Quintana-Murci of the Unit of Human Evolutionary Genetics, Institut Pasteur, Paris said the findings were interesting.
"Our big surprise was to find that this gene region has such a high Neanderthal ancestry because this region has been shown to have a major biological relevance in host survival against pathogens," he said.
"Maybe we should thank Neanderthals for having given us diversity in innate immunity to survive better against pathogens."
Are you one of the squillions of people who are suffering from hay fever, allergic rhinitis, conjunctivitis, sinusitis or head colds at the minute? If so, don't go anywhere because this week's column is all about you.