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.
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.
Researchers think the genes spread when pioneers leaving Africa had sex with Neanderthals living in Eurasia. As the Neanderthals lived in this area for over 200,000 years, their immune systems adapted to any new infections.
Janet Kelso, principal investigator at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said, “A small group of modern humans leaving Africa would not bring much genetic variation. You can adapt through mutations, but if you crosses with the locals who are already there, you can get some of these customizations for free. ”
The researchers looked at the genomes of modern humans to see if Neanderthal DNA was present; they then looked at the commonality between people from all over the world.
They found that two of the immune system’s three genes closely matched this DNA.
The 2016 study found that the Neanderthal part of your DNA not only gives you allergies, but can also help fight disease.
The geneticists believe that there is a group of genes in our DNA that we inherited from Neanderthals that is the first line of defense against dangerous pathogens entering our bodies, provided these genes also affect people’s allergies.
Janet Kelso, a researcher at the Max Planck Institute for Evolutionary Anthropology, said, “Increased resistance to bacterial infection was beneficial, but may have resulted in some increased sensitivity to non-pathogenic allergens.”
These genes provide an innate immune response to pathogens that enter our body.
The innate immune response is the body’s first line of defense against disease. Usually it can destroy pathogens before we realize we are even sick.
Since the Neanderthals introduced this reaction into human DNA, it has survived for so long because of natural selection and the idea of survival of the fittest.
So those who are not killed by the disease, those with an innate immune response, can reproduce and pass on the genes. Therefore, we are still seeing the return of Neanderthal genes in modern humans.
If you developed allergies in your lifetime, you owe it to your ancestors.
Editor’s Note: This article was originally posted in January 2016 and has been updated with the latest information
Samantha Maffucci is an editor for YourTango who has written hundreds of articles on relationships, trending news and entertainment, and astrology. Visit her author profile for more content.