Testosterone Makes Gerbils Hug, Not Just Fight

A new animal study finds that testosterone can promote friendly and prosocial behavior in men.

Studies on Mongolian gerbils Proceedings of the Royal Society B.

Aubrey Kelly, assistant professor of psychology at Emory University and lead author of the paper, said: the study. “This is amazing testosterone As increased sexual behavior and aggression. However, we showed that it can have more subtle effects depending on the social context. “

The study also revealed how testosterone affects the neural activity of oxytocin cells, the so-called “love hormone” associated with social bonding.

Kelly’s lab recently used an model in rodents to look at the neurological effects of oxytocin. Thompson’s lab is investigating the neurological effects of fish steroids.How are both scientists trying to solve the problem? hormone It works in the brain to allow animals to rapidly change their behavior in response to social situations.

A large body of human research shows that testosterone enhances aggressive behavior. Together, they thought it might dampen prosocial behavior in general. But they also hypothesized that it might do something more fundamental. In fact, it enhances positive social responses in situations where it is appropriate to act prosocially.

To test this question, Kelly’s lab tested Mongolian gerbils, rodents that form permanent pairs, and raise a puppy together. Males can be aggressive during mating and to protect their territory, but after females become pregnant they display cuddly behavior and display protective behavior towards puppies.

In one experiment, male gerbils were introduced to female gerbils. After mating was formed and the female became pregnant, the male exhibited normal cuddling behavior towards his partner. Researchers then injected male subjects with testosterone. They expected that if testosterone generally acts as an antisocial molecule, the resulting sharp rise in testosterone levels in men and a decrease in snuggling behavior.

“Instead, we were surprised that the male gerbils became more cuddly and social with their partners,” Kelly says. “He’s become like a ‘super partner’.”

In a follow-up experiment after one week, researchers conducted resident and intruder tests. Females were removed from their cages so that each male gerbil that had previously received testosterone injections was alone in his home cage. An unknown male was then introduced into the cage.

“Usually, males will chase or try to avoid another male when they enter the cage,” Kelly says. “Instead, resident males who had previously been injected with testosterone were more friendly towards intruders.”

However, when the original male subjects received another injection of testosterone, their friendly behavior suddenly changed. “They suddenly woke up and seemed to realize that they shouldn’t be friendly in those situations,” Kelly says.

The researchers found that male subjects experienced a surge in testosterone while they were with their partners, which not only caused a rapid increase in positive social responses to them, but also showed that the male subjects would not only experience a rapid increase in positive social responses to them in the future, but would also find that the situation changed and that another male was in front of However, the second testosterone injection rapidly prompted the male intruder to switch behavior to become more aggressive in response to the situation.

“Testosterone seems to enhance situational behavior,” says Kelly. “It seems to play a role in amplifying cuddling, protective or aggressive tendencies.

Experiments in the lab have, in a way, slowed down what males might experience in the wild at about the same time. In their natural habitat, mating with a partner raises testosterone, and even if their testosterone levels drop, they will behave in a cuddly manner in the moment and in the near future while living with their partner.

If a rival enters the burrow, the gerbil will likely experience another surge of testosterone, quickly adjusting its behavior to fend off the rival and help protect the pups. As it changes, it appears to help animals switch rapidly between prosocial and antisocial responses.

The current study also examined how testosterone and oxytocin interact biologically. showed more oxytocin activity in the brain during the interaction of

“We know that the oxytocin and testosterone systems overlap in the brain, but we don’t really understand why,” says Kelly. “Taken together, our results suggest that one reason for this overlap may be to allow them to work together to promote prosocial behavior.”

Rather than just pressing an ‘on’ or ‘off’ button to regulate behavior, hormones seem to play a more nuanced role, says Kelly. One dial may need to move up a bit and another down.”

Human behavior is much more complex than that of gerbils, but the researchers hope the findings will lay the groundwork for complementary studies in other species, including humans.

“Our hormones are the same, and they work in the same parts of the brain,” says Thompson. Knowing how hormones like testosterone help other animals adapt to rapidly changing social situations can only help us understand the biological basis that influences animal behavior. but also help us predict and ultimately understand how the same molecules in the human brain help shape our own behavior. reaction. “

This work was supported by the National Science Foundation.

sauce: Emory University