Mosquitos are super annoying, and I hate being attacked by them. Researchers have determined that blood type isn't the lure some had thought, but rather the scent profiles of certain carboxylic acids our skins release.
I hate being bitten in my sleep, to wake up with some awful itchy bite.
The researchers analyzed the subjects' scent profiles to see what might account for this vast difference. They found a pattern: the most attractive subjects tended to produce greater levels of carboxylic acids from their skin while the least attractive subjects produced much less.
Carboxylic acids are commonplace organic compounds. Humans produce them in our sebum, which is the oily layer that coats our skin; there, the acids help to keep our skin moisturized and protected, Vosshall says. Humans release carboxylic acids at much higher levels than most animals, De Obaldia adds, though the amount varies from person to person. The new study had too few participants to say what personal characteristics make someone more likely to produce high levels of carboxylic acids—and there's no easy way to test your own skin's carboxylic acid levels outside of the laboratory, Vosshall says. (She muses, however, that sending people skin swabs in the mail could make for an interesting citizen science project in the future.)
But we do know that skin maintains a relatively constant level of carboxylic acids over time. This, in turn, leads to a consistent odor profile. (Mosquitoes could also be attracted to skin bacteria digesting the carboxylic acids we produce, Vosshall suggests.) When Vosshall and De Obaldia ran their tournament multiple times several months apart, they found that people's attractiveness rankings remained largely the same. Any personal factors that may have changed over those months—from what each subject ate to the kind of soap they used—didn't seem to make a difference.
"This property of being a mosquito magnet sticks with you for your whole life—which is either good news or bad news, depending on who you are," Vosshall says.