Why do people have allergies? Because your ancestors had sex with Neanderthals

Those of us with peanut allergies know how difficult it is to avoid peanut products.

Chocolate bars, cereal, fried foods, and even kissing people who have eaten something that contains peanuts can cause allergic reactions.

But why do people have allergies?

We know there is a reason for these types of allergies. We know why your throat closes and why it is difficult to breathe when you eat or breathe something you are allergic to, and why you swell when stung or bitten by certain insects.

And it all began tens of thousands of years ago when our ancestors made contact with Neanderthals.

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There is a very likely reason why people develop allergies overall. And what matters is that our ancestors had sex with Neanderthals more than 40,000 years ago.

A 2014 study by genetics company 23andMe suggested that all non-African individuals carry between one and six percent of Neanderthal DNA, and that three genes, particularly in that DNA, may be responsible for hypersensitive immune systems that make us susceptible to allergies.

But a 2016 from the American Journal of Human Genetics It’s more likely that 2 percent of most people’s DNA comes from sexual relationships between humans and Neanderthals.

The 2014 study found that carriers of these three genes were more likely to suffer from hay fever, asthma, and other allergies.