The smell of babies calms men and increases aggression in women

A new study by scientists at the Wiseman Institute has found that the smell of newborn babies has a direct impact on human behavior. The response differs by gender, increasing aggression in women and decreasing it in men. Hexadecanal (HEX), a chemical that the infant body exudes, also plays a role in reducing stress in mice. That said, exposure to HEX in humans is known to reduce a person’s response to fright. A recent study examined the effects of HEX on aggression levels, specifically its difference by gender.

The study was conducted using functional magnetic resonance imaging. In both sexes, HEX increased activity in the left angular gyrus of the brain, but the relationship of this area to others was different. Women exhibited increased aggression when exposed to the substance, while men calmed down. Researchers speculate that such gender-specific reactions may be an evolutionary tool by which toddlers have an increased chance of survival.

The highest concentration of HEX is secreted by a newborn’s scalp, so the substance is most likely a signal element from the baby to the parents. While the infant is not able to talk, chemical communication plays a key role for the baby. In the animal world, the phenomenon of infanticide in male mammals has been observed, while increased maternal aggression helps the female protect her offspring. At this age, it is highly beneficial to make the mother ready to defend herself, while calming the ardent father.

The study does not yet claim definitive conclusions. The link between HEX exposure and fluctuations in brain activity is clear, but it is still not known whether just the olfactory impulses and the volume of the substance secreted by infants is enough to cause a noticeable change in behavior. However, the results do not suggest that odors play an important and complex role in the behavior of young parents beyond the simple release of serotonin and dopamine.