Sniffing a chemical in human body odor – commonly known as BO – triggers aggression in women but blocks aggression in men, a new study shows.
Researchers in Israel looked at the effects the chemical compound, called hexadecanal (HEX), has on the human brain.
Unlike many of the compounds in body odor, HEX has no discernible smell to humans but it can likely be sensed by all mammals.
The researchers found HEX decreases connectivity in parts of the brain that regulate social decision-making in women – including the decision to become aggressive – while in men it increases this connectivity.
HEX is also found in abundance on the heads of newborn babies.
As an evolutionary tool thousands of years ago, HEX on a baby’s head likely suppressed aggression in men to make them less likely to harm the infant, the researchers suggest.
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As to why this molecule affect the sexes differently, [researcher] Dr. [Eva] Mishor suggests an evolutionary explanation.
‘Male aggression translates many times into aggression toward newborns – infanticide is a very real phenomenon in the animal kingdom,’ she said.
‘Meanwhile, female aggression usually translates into defending offspring.’
