The smell of babies

“Babies smell good.”  I’ve heard more than one person say that over the years, usually a woman, and I’ve always thought that person was, perhaps, just a little strange.  The babies I’ve known–always from a distance–didn’t smell like much of anything, and when they did, it was a signal to change their diapers.

But since my wife and I will have a baby of our own in just a few weeks, I’ll soon be able to test the statement “babies smell good” myself.  Perhaps I can even repeat the research recently carried out at Lund University in Sweden that showed that, surprisingly, men are more sensitive to the smell of babies than women.

Bill Hansson and his researchers had been studying how moths and rabbits use the sense of smell to communicate with each other (moths with moths and rabbits with rabbits, presumably, not moths with rabbits) when Hansson suddenly became interested in the question of baby smells.  (He became a father.  And it was his project.  Who was going to argue?)

Hansson wanted to know if babies really have a special scent, and if so, if the scent affects adults’ behavior.  He wondered if only parents could pick up on the baby scent, and how long babies smell like babies. 

It seemed reasonable to suppose human infants would have a scent that attracted adults.  We’re hard-wired in other ways to be attracted to infants, so we’ll look after them; that’s why we find things with big wide eyes, chubby cheeks, big heads and snub noses “cute.” 

To test their hypothesis, Hansson and his colleagues turned to Robyn Hudson and Hans Distel at the Munich Institute of Medical Psychology.  They’d been experimenting with smells for years, by giving test subjects T-shirts to wear for a given length of time while respecting strict procedures.  Afterwards, the T-shirts were locked up in airtight containers, and eventually used for aroma samples in various studies.

Twenty-four newborn Swedish infants between the ages of one and four weeks and the same number of older children aged two to four were given a bath in unscented soap, then put to bed wearing the special research T-shirts.  The T-shirts were recovered the next day and put into airtight containers.

Next, the researchers gave the shirts–24 sets of three containers with one T-shirt per container–to each of the children’s parents and the same number of childless men and women.  Each set contained one T-shirt worn by the newborn, one worn by the older child, and one clean T-shirt. The adults were asked to smell the T-shirts in each set and guess which one had been worn by the newborn.

To the researchers’ surprise, only men were any good at all at telling the difference.  Fathers were better at it than the single men. None of the women could distinguish between the T-shirts worn by the older children and those worn by the newborns; and, in fact, they much preferred the smell of the clean, unworn shirts.

This was surprising because women have a superior sense of smell to men, and previous research had shown that mothers can successfully distinguish their own child from other children by smell alone a short time after birth.

The explanation given by the researchers, after some thought, was that throughout evolutionary history, men often had to be away hunting for food.  The most successful hunters were the aggressive men, and that aggressiveness could prove dangerous for small, helpless children back at the campfire.  It would be important, then, that newborns have a smell that is both obvious to men and calms them.

With the use of a gas chromatograph, which identified the individual components in air blown through the fibers of the T-shirts, the researchers showed that T-shirts worn by newborns contained components not present in the T-shirts worn by the older children or in the clean, unworn T-shirts.

These components on their own have no noticeable smell–which probably means that the special scent of a newborn operates at a subconscious level, activating the vomeronasal organ, a tiny bundle of nerves that may also pick up pheromones, instead of the main olfactory nerve.

Hansson thinks it might one day be possible to develop an artificial baby aroma that could be used to pacify aggressive men.  In the meantime, though, he has at least proved one thing:  babies smell like babies.

Whether that’s a good smell or not…well, I’ll keep you posted.

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