Women's sense of smell evolved to sniff out bad mates

A new paper in the journal Flavour and Fragrance points to an evolutionary explanation for women's superior sense of smell relative to men: they use it to sniff out genetic deficiencies in potential mates.

"Women have a larger interest in reproductive events because they have fewer opportunities for passing on their genes than men," said George Preti, a Monell Chemical Senses Center organic chemist...

"Men produce thousands of gametes every day, women just one every month," Preti said. "Their investment in a reproductive event is higher than men's, so they're more biologically attuned to who they're mating with."

Preti and other pheromone researchers suspect that mammalian olfactory systems actually evolved to detect chemical traces of genetic incompatibility in the odors of potential mates.

An Evolutionary Explanation for Sexual Smell Differences

(Image: Someone Sniffs, a Creative Commons Attribution licensed photo from Orin Optiglot's photostream)

• [Noctis]

  Meh, so much of this is cultural. Studies using American college students show that women can distinguish more colors than men, but the results *don’t hold when testing subjects from nonwestern cultures*. Turns out that distinguishing colors is a trait one can learn, and female-reared people in the U.S. are expected to be able to tell the difference between turquoise and teal, while male-reared people are not.

  That said, progesterone heightens the sense of smell, which makes sense, since it is high in pregnant women, who should avoid eating tainted foods. But other than that, a sex difference does not make sense unless you assume that human men really don’t have much involvement in mate-partnering, which is empirically false. Men are involved in childrearing, and like women have a genetic interest in doing so with a good partner.

• [Jim Terr]

  This reminds me of a theory I heard once (not sure how widespread it is – maybe very) that the basis for body smell being sexually attractive or not, is that it’s an indicator of whether the other’s IMMUNE SYSTEM is complementary to yours. i.e., the other’s immune system covers a range of stuff which yours does not, so that your offspring would have a wider range of immunity, and therefore better survival of course. I love neat little theories like this, but wonder whether it’s been out there widely, and confirmed or debunked.

• [The Unusual Suspect]

  “Biologically attuned”?

  “Genetic incompatibility”?

  What the hell does that mean in the context of a scientific study?

• [The Unusual Suspect]

  “Biologically attuned”?

  “Genetic incompatibility”?

  What the hell does that mean in the context of scientific research?

• [Anonymous]

  OK, guys, I know you like to pooh-pooh research, but let’s face it: the research is out there that shows that:

  A) women use sense of smell to detect genetical compatibility
  B) genetic compatibility can actually be quantified in this sense (e.g. ‘different enough’)
  C) these papers are not just theory, e.g. “girls like pink because berries are pink and women gather berries,” but actual studies with actual tests, not just extrapolating from “evidence” but also testing the theories the other way as well
  D) artificial birth control actually lowers this sniff-ability to judge mates, so it’s unlikely to be related to any “pregnant, bad food sniffing improved” systems

  Google it. Use lexis nexis. Then instead of bleeting randomly on the internet, you could be informed.

  Oh, person who said that men and women have the same number of offspring — “in a balanced population” — you are denying fundamental evolutionary facts about our nearest animal cousins, and us.

• [ZDepthCharge]

  A BIG problem with these kinds of studies is not the study itself or results, but how people interpret the results. There appears to be a human need (is it cultural?) to discover THE cause or reason, when there may be MANY causes or reasons.

• [jancola]

  What Noctis said. If women truly have a more sensitive sense of smell, isn’t it more likely related to progesterone, which serves an immediate purpose during pregnancy? This sniffing out of potential mates seems a lot less evolutionarily likely than the ability to avoid foods that would hurt a fetus.

• [Lauren O]

  I tend to be pretty skeptical of such studies, although this one seems less questionable than most (e.g., the “study” I read that literally claimed that women like pink more than men do because they evolved to search for berries). It’s pretty difficult thing to say we evolved a trait for a certain specific reason, given all the unknown factors that have been going on for hundreds of thousands of years.

• [Anonymous]

  The paper
  “Cross-adaptation of a model human stress-related odour with fragrance chemicals and ethyl esters of axillary odorants: gender-specific effects”
  at Flavour and Fragrance Journal

  only shows that women are less easily confused in their ability to detect body odor
  and not
  that they can select better compatible mates for a long term relationship with commitment.

  Regards,

  Fernando Ardenghi.
  Buenos Aires.
  Argentina.
  

• [Anonymous]

  “Women have a larger interest in reproductive events because they have fewer opportunities for passing on their genes than men”
  This is nonsense. In a balanced population, males and females have the same average number of children, unless some of the children have more fathers than mothers.

• [Anonymous]

  I would believe from personal knowledge that a woman’s sense of smell during pregnancy is to eliminate possible toxins to her body. I was a big sniffer of my babies, particularly the back of the neck. I do know there was one experiment of women choosing their own babies by smell alone. All mammals smell their young,I know i did and 50 years later can recall the smell.

• [Anonymous]

  Not to mention that blue-pink boys-girls is an extremely recent and exclusively western cultural practice.

• [Spikeles]

  I remember watching one of those science shows on the sci-fi channel a couple of years ago where they did some research about this. They got these women to spend a week wearing their shirts and doing lots of exercise. Then they got some men to rate the smell of the sweat based on how much they liked it, then they compared each persons genetics in the test with other.

  Turned out the men very accurately rated the sweat by how genetically close they were to each other, where the nicer the smell was, the more distant genetically the person was.

  Dammit wish i could remember the name of it.

• [Noctis]

  Meh, so much of this is cultural. Studies using American college students show that women can distinguish more colors than men, but the results *don’t hold when testing subjects from nonwestern cultures*. Turns out that distinguishing colors is a trait one can learn, and female-reared people in the U.S. are expected to be able to tell the difference between turquoise and teal, while male-reared people are not.

  That said, progesterone heightens the sense of smell, which makes sense, since it is high in pregnant women, who should avoid eating tainted foods. But other than that, a sex difference does not make sense unless you assume that human men really don’t have much involvement in mate-partnering, which is empirically false. Men are involved in childrearing, and like women have a genetic interest in doing so with a good partner.

• [Noctis]

  Meh, so much of this is cultural. Studies using American college students show that women can distinguish more colors than men, but the results *don’t hold when testing subjects from nonwestern cultures*. Turns out that distinguishing colors is a trait one can learn, and female-reared people in the U.S. are expected to be able to tell the difference between turquoise and teal, while male-reared people are not.

  That said, progesterone heightens the sense of smell, which makes sense, since it is high in pregnant women, who should avoid eating tainted foods. But other than that, a sex difference does not make sense unless you assume that human men really don’t have much involvement in mate-partnering, which is empirically false. Men are involved in childrearing, and like women have a genetic interest in doing so with a good partner.

• [Noctis]

  Meh, so much of this is cultural. Studies using American college students show that women can distinguish more colors than men, but the results *don’t hold when testing subjects from nonwestern cultures*. Turns out that distinguishing colors is a trait one can learn, and female-reared people in the U.S. are expected to be able to tell the difference between turquoise and teal, while male-reared people are not.

  That said, progesterone heightens the sense of smell, which makes sense, since it is high in pregnant women, who should avoid eating tainted foods. But other than that, a sex difference does not make sense unless you assume that human men really don’t have much involvement in mate-partnering, which is empirically false. Men are involved in childrearing, and like women have a genetic interest in doing so with a good partner.

• [WalterBillington]

  @3 I saw a similar show, with Professor Robert Winston (of the televisual moustache).

  His intriguing test was similar, only he was meant to rate the shirts on how attracted he was to the smell. Some he hated, some he loved.

  The nicer the smell, the more he was attracted – i.e. inbuilt genetic mechanism to prevent us shagging our sisters.

  Good, eh? Ol’ Mother Nature knew what she was doing. If only God wouldn’t get in the way.