Neanderthals responsible for allergies

Neanderthal genes don't just result in heavy brows. Now, scientists have identified genes involved in your immune system and allergies. Ginny Smith explained to Kat Arney how these genes were passed to us and whether they actually serve a purpose...

Ginny - Well I have a story that you may be able to to blame the neanderthals for your hayfever and other allergies.  Scientists have known for a while that when our ancient ancestors moved into Europe, they mated with the neanderthals and their close relatives, the denisovans.  This means that those of us who don't have purely African heritage, we all have some neanderthal DNA in us and it's estimated to be around 1-6%.  But this week, really interestingly, two separate papers have come out and they've shown that some of the most common neanderthal and denisovan genes that we have are actually involved in boosting our innate immune systems, and that's the first response our body mounts when it encounters a pathogen.  So one of these studies looked at whole genome sequences and they analysed variability basically, and they found that there were these two sets of genes that were involved in innate immunity that were more similar to neanderthal genes than the rest of our genome was.  And they also found evidence that these sets of genes had been positively selected for...

Kat - So there must be an advantage to having them?

Ginny - Exactly.  And the second paper found something very similar looking at one particular set of these genes.  So, this is really strong evidence that we got these sets of genes from these ancient ancestors and that they were then selected for.  So, the most likely scenario was as our ancestors left Africa, travelled across the world, they came across these other ancient humans and they were already well adapted to their environments.  So, when our ancestors bred with them, they kind of stole bits of their immune... well they shared their immune systems and the ones that got these genes from the ancestors who'd been there for longer, the neanderthals, they survived better because their immune systems were more reactive to these kind of local pathogens.  But it isn't all good news because these genes also seem to encourage overly sensitive immune systems so, those that carry them are more at risk of things like asthma, hay fever because, of course, these are also linked to your immune system.  So, you might have the neanderthal to blame when you get the sneezes.

Kat - It's something we're hearing a lot about in the media at the moment.  Sort of boosting your immune system with detoxing after Christmas and you have to remember that boosting your immune system does give you allergies.

Ginny - Not always good news.