Two putative human sex pheromones turn out not to be

FOR several decades biologists have pondered the question of whether men and women produce pheromones. A pheromone is a chemical signal from one animal to another. Often, though not always, such chemicals indicate sexual availability—and when it comes to human mating signals in particular, those looking into the matter have a couple of specific molecules in mind.

Androstadienone (AND) and estratetraenol (EST) are derived, respectively, from male and female hormones and are exuded in sweat. The idea that they are pheromonal is thus worth investigating. The results of such investigations as have been made so far, though, are contradictory. Some experiments have found that these molecules make opposite-sex faces, or photographs thereof, appear more attractive to heterosexual volunteers. Others discern no such effect.