Narrator: Unlike today, our cave-dwelling ancestors probably didn't waste a lot of time with romance—early Man was too busy trying to survive to plan a white wedding.
But some intriguing studies done over the past few decades suggest that we, like our more primitive counterparts,
may be following our noses rather than our hearts or brains when it comes to making a 'love connection'.
Celia Dominguez, MD: The response of the ovaries and the testies is to making hormones starts out in the nose.
Narrator: That's because our hormones emit airborne chemicals called "pheromones' that are detected by other members of the same species. In the animal kingdom, pheromones play a vital role:
Lisa Smith: They have to be able to smell predators even if they can't see them. They've got to be able to find females that are receptive.
They do that by smelling urine and dung piles that are left by the animals before them.
Narrator: In one study, women who were exposed to the 'sweat samples' of different men seemed to prefer those who were genetically different from themselves—for a species, that means less chance of inbreeding.
In other experiments, females were more attracted to the odors of men with immune systems similar to their own—another way our species may have learned to survive.
What's true for Man may also be true for certain primates, like gorillas.
Charles Horton: Quite often females will, when they reach adolescents or young adulthood, will migrate out of the group they were born in and go join up with the new guy because they're so impressed by him.
Narrator: Pheromones are also thought to be responsible for the synchronized menstrual cycles women tend to share when they live in close quarters, like a dormitories.
One possible explanation: early human females, like these gorillas, needed to attract males in order to survive.
Human females were most likely to have that opportunity when the men returned from a long hunt.
Celia Dominguez, MD: If another female took that man or the man was attracted to another female that would be very detrimental to our survival with respect to food.
Narrator: Of course humans today can better control what input they choose to pay attention to, and, in some cases, even alter the way they perceive the pheromones of others.
Some women who take birth control pills, for example, have been shown to respond favorably to male pheromones that are NOT genetically different from their own.
Celia Dominguez, MD: Does that eventually end up that we're actually choosing different partners? That's extremely unclear
Narrator: Marketers are hoping to clear up which scents best attract the opposite sex and clean up by harnessing and bottling the stuff.
Celia Dominguez, MD: There's a lot of money going into 'can we find this kind of love potion number nine?' and make it that we can make ourselves attractive to everyone.
Narrator: But don't hold your breath waiting for it. For WebMD, I'm Damon Meharg.