Can you find a mate by just following your sense of smell? That's what some researchers believe, although the jury is out on whether or not humans secrete and respond to pheromones. These chemicals are excreted from animals to elicit a social (alarm, food, etc.) or mating response. In other words, they can be used to attract mates in nature. Insects such as wasps, moths and flies use them for such purposes, as do birds, amphibians and non-primate mammals. But when it comes to apes, monkeys and humans, secreting and detecting pheromones doesn't seem to have a lot of effect on potential mates. That's because many researchers believe primates evolved and lost the organ used to detect pheromones. And even if it does exist, pheromone studies on humans are difficult because of our tendency to bathe frequently and wash pheromones away or mask them with perfumes and colognes.