Is Hamilton’s rule correct? Yes, we are ready to lay down our lives for two brothers or eight cousins

Sacrificing your life for an uncle, brother or cousin so that your family has a better chance of procreating. This evolutionary strategy has been proven in animals for some time, but now an experiment shows that it also works in humans.

Scientists, among others from MIT (Massachusetts Institute of Technology) wanted to demonstrate that Hamilton’s Rule applies not only to animals but also to humans. This evolutionary rule assumes that relatives help each other, even at the cost of their own survival. Professor Andrew Lo of MIT and Professor Moshe Levy of Hebrew University found strong evidence for this rule in an experiment in which people exchanged money with other people who were related to them in varying degrees, such as write the scientists in a scientific journal Proceedings of the National Academy of Sciences. “Our discoveries are not only important because they Hamilton’s Rule directly in financial situations, but also because they show that the principles of evolutionary biology and economics are more closely linked than we thought,” says Lo.

to give life
Hamilton’s Rule is summed up in a famous quote by evolutionary biologist JBS Haldane: “I would lay down my life for two brothers or eight cousins. William Hamilton converted this theory of evolution into a simple mathematical formula in 1964, which assumes that an individual’s willingness to help another is directly related to the amount of genetic material they have in common.

“Evidence for this rule has been found in a wide range of species, including bees, wasps, birds, shrimp, monkeys, and even plants. It is widely regarded as the most important explanation for altruistic behavior in animals and considered “one of the greatest theoretical breakthroughs in evolution since Darwin”, write Lo and Levy.

Previous studies have already shown that human behavior is consistent with Hamilton’s Rule, but there has never been a maximum amount a person is willing to pay for a particular benefit to another person, based on their degree of genetic kinship. This is known as the cutting cost in Hamilton’s rule.

Photo: Rattanakun

$50
In their study, Lo and Levy test the size of this amount by asking people to give money to other people who are genetically related to varying degrees. They asked the subjects how much they were willing to pay for someone else to receive $50. The recipients were siblings, half-siblings, cousins, identical and non-identical twins, and random individuals. Subjects could earn a maximum of $50, but if they made a deal with someone, they also had to pay the agreed amount to the other person. When they made a deal, the researchers actually gave them $50, so it was more of a hypothetical situation. Scientists have discovered that the cutting costs corresponded to the genetic kinship of the subjects. It even corresponded exactly to Hamilton’s mathematical formula.

Lo and Levy point out that their findings not only confirm Hamilton’s rule, but also shed light on people’s motivations in financial decision-making. “It is surprising how powerful evolutionary forces are in such complex human behavior. It is possible that these primordial forces influence human behavior, social network formation and moral values ​​indirectly and below the surface.