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

Those of us with a peanut allergy know how hard it is not to be around products containing peanuts.

Chocolate bars, cereals, fried foods, and even kissing someone who has eaten something that contains peanuts can cause an allergic reaction.

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 in something you are allergic to, and why you swell when you are stung or bitten by certain insects.

And it all started 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 at all. And the bottom line is that our ancestors had sex with Neanderthals more than 40,000 years ago.

A 2014 study conducted by the genetics company 23andMe believed that all non-African individuals carry between one and six percent of Neanderthal DNA, and three genes in this DNA in particular may be responsible for hypersensitive immune systems that affect our predispose to allergies.

But a 2016 study conducted by the American Journal of Human Genetics found that it is more likely that 2 percent of most people’s DNA came from sexual relationships between humans and Neanderthals.

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