An intriguing study suggests that a chemical excreted by babies could influence the degree of aggression in humans, exacerbating this behavior in women while mitigating it in men. This work is published in the journal Science Advances.
We know that hexadechannel (HEX) plays a role in mouse behavior. A study published in 2015 reported that this molecule could reduce stress responses in these animals through a process known as "social buffering." More recent research has also revealed that this chemical may play a role in modulating human behavior by reducing our startle responses.
This new study builds on these earlier findings by focusing on the influence of HEX on aggressive behavior humans.
As part of this work, researchers from the Weizmann Institute of science, Israel, recruited two hundred participants to explore the effect of HEX on aggression through two behavioral experiments aimed at measuring a person's aggressive responses. This work has indeed revealed that exposure to this chemical substance does indeed influence the degree of aggressiveness.
"We found that HEX has no noticeable odor, but when you sniff it, it affects how you behave towards people. others, especially your aggressive responses to others “, explains Eva Mishor, lead author of the study.
Interestingly, these results were also gender discordant. Overall, women exposed to these molecules displayed increased aggressiveness while men developed reduced aggression .
Functional magnetic resonance imaging (fMRI) brain activity measurements then revealed that exposure to HEX increased activity in the left angular gyrus of all the participants. In contrast, the connectivity of this brain region to others differed by sex. These different brain processes therefore seem to induce more "social regulation" in men, while they raise a red flag in women.
At this time, it is unknown why men and women react differently to this product, but researchers have come up with a hypothesis. These sex-specific responses could be a tool developed by babies to enhance their chances of survival .
As part of this work, the researchers discovered that the secretion of this product was greater on the scalp of newborns. The authors therefore speculate that HEX could be an important chemical signaling tool for babies towards their parents.
“Babies cannot communicate through language, so chemical communication is very important to them “, explains Noam Sobel, co-author of the study. "And as a baby, it's in your best interest to make your mother more aggressive and reduce your father's aggression “.
The researcher here refers to the phenomenon of infanticide , commonly observed in the animal kingdom. In mammals, we know that the greater the paternal aggression, the greater the risk of infanticide. On the other hand, a more aggressive mother will be better able to defend her offspring.
So, "if babies had a mechanism that could increase aggression in females while regulating it in males, it would likely increase their chances of survival “, can we read in the study.
Remember that this is only a hypothesis based on a study involving only two hundred people. Further work will therefore be necessary to truly understand the possible associations between exposure to HEX and alterations in brain activity in humans.
