According to James Fowler, professor of medical genetics and political science at the University of California and co-author of the study, looking at the entire human genome, he found that, by and large, it is quite similar among friends.
“We have more DNA in common with the people we choose as friends than with strangers in the same population,” he says. That's awesome, isn't it?
The study that reveals genetic similarity between true friends is based on a genome-wide analysis of nearly 1.5 million markers of genetic variation, and is based on data from the Framingham Heart Study.
The Framingham dataset is the largest available to date, and the authors are aware that it contains a level of genetic detail and who is friendly with whom.
To conduct the research, scientists focused on unique themes and no less than 1,932 peer comparison pairs of unrelated friends versus peers of unrelated strangers.
The same people, who were neither relatives nor spouses, were used in both types of samples. The only thing that differs between the participants is their social relationship.
The results are not, according to the researchers, an artifact of people's tendency to make friends with people of similar ethnicities. Framingham data is dominated by people of European origin. Although this is a problem for some researchers, it may be advantageous for this study because all the subjects, friends or not, were genetically drawn from the same population.
The researchers also controlled the data by ancestry, using the most conservative techniques currently available.
The observation proposed by this study goes beyond what you would expect to find among people with shared genetic inheritance. According to Fowler, the study's co-author, the results are a "network of ancestry."
How genetically similar are real friends?
Researchers have found that real friends, those friends of the heart, the brothers we choose, have genetic similarities that equate to a degree of kinship similar to that of fourth cousins, or people who have the same great-great-grandfather. In other words, this translates to about 1% of our genes.
Did you find little?
1% may indeed seem small, but for geneticists this is a really VERY significant number. Even more so if you think most people don't even know who their fourth cousins are.
In a way, it gives you something to think about. Think: I don't know who my fourth cousins myself are, but, by chance, I chose to relate to people who might well be related to me. These people could be from my real family without me knowing that.
In the study, the researchers also developed a scale they called the “friendship level,” which they can use to predict the likelihood that people will be friends at about the same level of confidence that scientists currently use to predict a person's chances. be obese or have schizophrenia. Clap for them!
Friends with benefits
Attributes shared between friends or “functional kinship” can confer a variety of evolutionary advantages. Something like if your friend is cold when you make a fire, you both benefit from the fire. This is also the case for some traits that only work if your friend has them too.
Fowler exemplifies: “The first mutant to speak needed someone to talk to him. This ability would be useless if there was no one to share it with. ” These kinds of traits in people are a kind of effect of living in society.
Why don't you and your friends get sick at the same time?
In addition to the "macro" similarities, the researchers also looked at a set of focused genes. So they found something unusual: They think friends are more similar in genes that affect the sense of smell.
The opposite is true for genes that control immunity. That is, friends are relatively more unequal in their genetic protection against various diseases.
The finding supports what people have recently found in relation to their peers. And there is a fairly simple evolutionary advantage to this: Having connections with people who are able to resist different pathogens reduces their interpersonal spread. But how do we select people for this benefit of immunity? The mechanism still remains unclear.
The issue of similarity between olfactory genes is also open to debate and needs further research to draw conclusions. But so far, scientists assume that the explanation may lie in the fact that our sense of smell, when similar, can draw us into similar environments.
So it is not difficult to imagine that people who like coffee, for example, go to coffee-smelling places and find people who have the same taste there - even though this selection is not on the level of consciousness.
Scientists also note that there are probably several mechanisms that operate in parallel, guiding us to choose genetically similar friends.
“With a Little Help From Our Friends”
Perhaps the most intriguing result of the study is that genes that were more similar among friends seem to be evolving faster than other genes. Fowler and his team say this may help explain why human evolution seems to have accelerated over the past 30,000 years, and suggest that the social environment itself is an evolutionary force.
So here's the best tip of all time: keep friends around.