“Don’t cheat on your friend’s wife” and “husband and wife look alike” have physiological basis

The latest research shows that the saying "Don't cheat on your friend's wife" has a physiological basis. A study from the University of Missouri showed that testosterone levels in adult men dropped when they interacted with the wives of close friends.

Mark Flynn, a professor of anthropology at the University of Missouri who participated in the study, said: "Although men have many opportunities to pursue their friends' partners, very few actually do so. However, men's testosterone levels usually increase when they interact with potential sexual partners or the partners of their enemies. Our research shows that men generally believe in respecting stable relationships between friends and their lovers." This shows that men do not compete with each other for partners, which is also constrained by biological mechanisms. Understanding this is very helpful in clarifying how people cooperate with each other to form a group.

Professor Flynn said that from an evolutionary perspective, men who consistently betrayed the trust of their friends and jeopardized the stability of their families would put their entire group at a disadvantage. If the male members of the group do not trust each other, they will be vulnerable when facing external attacks. The cost of being disgraced is too great to be compensated by the benefits of having children with your friend's lover.

Professor Flynn said that this research conclusion may be beneficial to achieving world peace and cooperation. "Ultimately, our study of testosterone levels in men explains how humans evolved to form alliances. Understanding human nature from an evolutionary perspective can help us find solutions to global problems.

If we think more about the Earth as a single community of humans, we’ll be better able to address the common threats we face, such as climate change.

Spouses often have similar DNA

Multiple studies have found that people tend to marry those who are similar to themselves in age, race, religious beliefs, economic income, educational background, social class, and upbringing. Recently, a new study involving 825 Americans from the University of Colorado published in the Proceedings of the National Academy of Sciences found that when choosing a mate, people are more inclined to choose someone with similar genes to themselves. Dr. Benjamin Domingo, who led the new study, said that the results of the DNA similarity comparison study showed that married participants had a higher DNA similarity with their spouses than randomly paired single participants.

Couples who look alike exist all over the world, and the American media selects the "Best Couples Who Look Alike" every year. They found that couples tend to look more and more alike over time. There is a special couples dating website in the UK that helps unmarried men and women find partners who look similar to themselves. A Russian survey shows that couples who look like husband and wife tend to have happier marriages.

Why do couples look alike? Scientists have given many explanations. Recently, British scientists analyzed these studies and summarized several of the most convincing reasons.

First, both parties live together for many years, have the same diet structure and schedule, so their body shapes tend to be similar.

Second, couples often have the same emotions, so their facial wrinkles tend to be the same. In addition, as people age, many of their distinctive physical features disappear, such as subcutaneous muscles and hair, and their appearance shows more skeletal features.

Third, when people first choose a spouse, they tend to choose the opposite sex with similar physical characteristics to themselves.

Fourth, in psychology, there is an effect called the "chameleon effect", which means that it is easy for us to imitate others. The closer the person is, the easier it is for us to imitate them. When couples imitate each other, their movements, expressions, and temperament will become more and more similar.