“This study offers some of the most recent evidence that people perceive all sorts of interesting things about one another through olfaction. Airborne molecules that elicit a reaction in a member of the same species are called pheromones, and the most famous ones are potent aphrodisiacs, like androstenone and androstenol in the saliva of male boars. If a fertile female gets a whiff of these molecules, she’ll present her rear to the male, a universal gesture in wild pig patois that means, “Let’s start a family.” […]
In one 2005 study, gay men given anonymous samples of sweat preferred the scent of gay men, and heterosexual men fancied the scent of women. One’s nose can also help identify a genetically compatible mate. Researchers asked women to rate the odors of T-shirts worn by different men. Women preferred men whose DNA was different enough from their own that it would increase the likelihood of producing a child with a robust immune system.
Newborns preferentially scoot toward the scent of breasts. And adults can often tell by smell whether the person who produced perspiration was anxious or not.”