A recent study in rodents has found that testosterone – although often associated with aggression – can also promote friendly behaviors in males.
For the study, published in The Proceedings of the Royal Society B, neuroscientists from Emory University in Atlanta, Ga., looked at how hormones affect Mongolian gerbils, with results Results show that testosterone has the ability to promote aggression, as well as “cuddle” behavior.
“For what we believe is the first time, we have demonstrated that testosterone can directly promote non-sexual, pro-social behavior, in addition to aggressive behavior, in the same individual.” Aubrey Kelly, assistant professor of psychology at Emory University and first author of the study, said in a press release.
“It’s surprising because normally we think testosterone increases sexual behaviors and aggression. But we’ve shown that it can have more nuanced effects, depending on the social context. “
The scientists chose to study Mongolian gerbils because they tend to form long-lasting pair bonds and raise their pups together.
Although males can be aggressive during mating, the researchers say they will become increasingly cuddly after the female becomes pregnant, along with being protective of their offspring.
For the study, the scientists waited for male and female gerbils to form a pair bond and get the female pregnant, after which the males exhibited their usual cuddling behavior. The researchers then injected the males with testosterone.
While they expected testosterone to reduce cuddling behavior in males, the researchers say male gerbils became even more cuddly and friendly with their mates – becoming a “super partner” in the this scene, Kelly said.
The researchers then removed the females and introduced an unidentified male.
Similarly, males that have been injected with testosterone are more friendly to intruders.
However, this changed when the male subjects were injected with another dose of testosterone. When this happens, they exhibit the typical chase and avoidance behaviors you would see if an intruder were present.
“It seems that testosterone enhances contextual behavior,” says Kelly. “It seems to play a role in amplifying the tendency to cuddle and be protective or aggressive.”
The researchers say testosterone may prompt male gerbils to become more sociable in the future, even with other males, and potentially allow them to switch rapidly between pro- and anti-behavior. society depends on the social context.
The study also looked at the effect of testosterone on oxytocin cells, which the researchers describe as the so-called “love hormone” involved in social bonding.
Their study found that male subjects who received testosterone injections produced more oxytocin activity in their brains while with their partners, compared with men who did not receive the injection.
“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 of the reasons for this overlap could be that they may work together to promote pro-social behaviour.”
While the researchers say human behavior is much more complex than that of the Mongolian gerbil, their hope is that the study will complement research in other species, including humans.
Richmond Thompson, a neuroscientist at Oxford University Emory University, co-author of the study and Kelly’s husband, said: “Our hormones are the same and the parts of the brain they work on are similar, too. together.
“So understanding how hormones like testosterone help other animals adjust to rapidly changing social contexts will not only help us understand the biological factors that influence their behaviour, but also to predict and ultimately understand how similar molecules in the human brain that help shape us respond to the social world around us.”
