Study Finds “Baby Smell” Affects Men and Women Differently

Ask most people what a baby smells like and you might get a few different answers. Some might say it’s powdery, or musky, or sweet, or milky. But, the baby scalp smell -regardless of how it is described- has an intoxicating effect on most adults. This is down to the chemicals found in a baby’s smell which are largely concentrated on the head. Now, a recent study shows that how men and women process this pleasant smell differs quite a bit- and leads to different behaviors across the sexes.

The study was led by researchers Dr. Eva Mishor and Prof. Noam Sobel and was produced through the Azrieli Institute for Human Brain Imaging and Research at the Weizmann Institute of Science in Israel. In studying how the baby smell affects people they used a molecule isolated from the scent, hexadecanal (known as HEX), which makes up a large part of that familiar baby scent. It is said to have no distinguishable odor all on its own.

However, the effects of HEX on the brain can change the behavior of those who smell it.

Most of the participants were studied using a provoking computer game and then were given either HEX or a placebo to smell. Players of the game were then given the option to “punish” other players of the game with a loud noise. While this punishment wasn’t real- players were playing against a computer the whole time- the act of choosing to send a loud noise to someone was viewed by researchers as a measure of aggression. Another group was tested after smelling both a placebo and HEX.

Men who smelled the HEX molecule were shown to have a reduction in aggressive behavior. On the other hand women who were exposed to HEX showed increased signs of aggression within the context of the game.

Scans of players’ brains using fMRI imaging showed that HEX affected the left angular gyrus region of the brain in men and women, and that this was linked to social thinking. But, the behavior exhibited by each group was different despite the same region of activation in the brain.

Researchers speculate that the reduction in aggression and a more open social attitude that the male participants exhibited is the type of behavior that might result in lower rates of infanticide, which is a troubling (yet regular) part of life for many mammals in the wild.

The increased aggression of women under the effect of HEX is speculated to stem from a desire to protect young offspring.

Professor Sobel explained that non-verbal babies need a way to communicate with their caregivers and that, “As a baby, it is in your interest to make your mom more aggressive and reduce aggressiveness in your dad.” The chemosignal of HEX does just that, inducing a variety of behaviors with just one molecule.