The Weizmann Institute of Science in Rehovot has discovered that the odor coming from the scalps of newborn mammals, both humans and mammals, serves a purpose: species survival.
Prof. Noam Sobel of the Department of Brain Sciences and Dr. Eva Mishor have published their study in the peer-reviewed journal Science Advances in collaboration with the Azrieli National Institute for Human Brain Imaging and Research.
They discovered that volatile substances emitted from the body can effectively activate or prevent aggression in terrestrial mammals.
They examined the effects of hexadecanal (HEX), a volatile molecule found in the human body that has been identified as a mammalian-wide social chemosignal, on human aggression. They discovered that sniffing HEX, whose scent cannot be detected by the human nose, reduced aggression in men but increased in women.
They then discovered a pattern of brain activity mimicking behavior using functional brain imaging. HEX enhanced activity in the left angular gyrus, a brain region that is linked in the perception of social cues, in both men and women, according to the findings.
In the study, they made a computer game that had two parts: a “provocative” stage meant to make the 130 people who took part angry, and a “reaction” stage where they could vent their anger. The HEX molecule was administered to half of the individuals, while the other half served as a control group.
To test their skills against the computer, each participant had to face off against a computer disguised as an actual human being. During the first half of the game, they were asked to share an amount of money with each other, but the game kept most for itself. In order to “punish” the automated opponent, each participant was given the ability to make a loud explosion sound. The volume of the sound signified the level of aggression displayed by the participant.
The participants reacted differently than the control group, according to Mishor, who led the experiment. However, the results did not appear to be consistent at first. The picture became evident only after the researchers recorded the gender of each subject. The perfume of the HEX molecule made men less violent, while the scent of the “baby scent” made women more aggressive.
They next put 50 people who had been exposed to the chemical into a functional MRI (fMRI) scanner, which detects changes in blood flow to quantify brain activity. The subjects had no way of knowing if they had been exposed to HEX or not.
The chemical triggered the left angular gyrus in both men and women, which is important in social signal processing. Men and women, however, have clearly different connection between this brain region and others. HEX decreased the neural connections between the social, emotional, and decision-making areas of the brain in women while increasing them in men.
According to Mishor, the reason for this development was that male hostility in mammals often manifests itself in violence toward their offspring, but female aggression manifests itself in protecting their children. According to researchers, one-quarter of male mammals, such as rodents and monkeys, kill some of their offspring, especially when living in big groups.
“Because infants can’t communicate verbally with their mothers, they have the possibility of communicating with chemicals,” Sobel added.
The team reached out to a Japanese expert who is researching baby odor molecules. They decided to pool their data and discovered that HEX is one of the most commonly produced compounds by newborns’ scalps.
Animals send chemical signals from their smelling organs that influence social behaviors, but before the Weizmann study, no one knew they also influenced people.
“Humans smell each other all the time,” the author concluded. “Now we apparently understand what happens when we smell babies, how our brain processes this information and what could be the evolutionary role of this effect.”
Image Credit: Getty
You were reading: Newborn babies’ super strong smell has opposite effects on parents