Olfactory Modification

(WSJ graphic)

In a double-blind study men and women displayed opposite behaviors when they were exposed to hexadecanal (HEX), a chemical found on babies' scalps: [bold added[

breathing in HEX influences our social behavior, dialing up aggression in women but attenuating it in men. This sex difference stunned the researchers. Based on mouse studies, they expected HEX to have a calming effect across the board...“Women exposed to HEX reacted 19% more aggressively, while men were 18.5% less aggressive.”

...The authors speculate that HEX is an ancient survival mechanism. Mothers exposed to the chemical signal would be more likely to defend their babies against threats, while fathers who inhale it would likely be less aggressive.

Brain scans confirmed that exposure to HEX caused sections of men's brains to react very differently than women's.

Because the dimensions of aggressiveness and agreeableness are not as value-laden as, say, intelligence ("more aggressive" is not necessarily a compliment while "more intelligent" is), the apparent findings of an inherent sex difference in reacting to a chemical has escaped controversy.

Let's hope that researchers will design, conduct, and report on future experiments in this area with neither fear nor favor.