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.
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.
Researchers suspect that when pioneers who left Africa had sex with Neanderthals living in Eurasia, the genes spread. Since the Neanderthals lived in this area for over 200,000 years, their immune system adapted to any new infections.
Janet Kelso, senior researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, said: “A small group of modern people who left Africa would not have large genetic variations. They can adapt through mutations, but if you can cross local people Those who are already there can get some of these adjustments for free. “
The researchers examined the genomes of modern humans to see if Neanderthal DNA was present. Then they examined the similarities between people from all over the world.
They found that two out of three immune system genes are closely related to this DNA.
The 2016 study found that the Neanderthal portion of your DNA not only causes allergies, but can also help you fight disease.
Geneticists believe that our DNA contains a group of genes that we inherited from Neanderthals. This is the first line of defense against dangerous pathogens entering our body, 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 infections was beneficial, but may have increased sensitivity to non-pathogenic allergens.”
These genes create an innate immune response to pathogens that invade our body.
The innate immune response is our body’s first line of defense against disease. Usually, it can destroy pathogens before we even realize we are sick.
Since the Neanderthals introduced this reaction into human DNA, it has survived for so long due to natural selection and the idea of survival of the fittest.
Those who are not killed by the disease who have an innate immune response can reproduce and pass on the genes. This is why we still see the reappearance of Neanderthal genes in modern humans.
If you have developed allergies in your life, you must thank your ancestors for them.
Editor’s Note: This article was originally published January 2016 and has been updated with the latest information
Samantha Maffucci is an editor at YourTango and has written hundreds of articles on relationships, breaking news and entertainment, and astrology. Visit her author profile for more content.