Odorless pheromones are secreted by many animals to attract mates. But they're also synthesized and marketed to consumers as potions to increase sexual attractiveness.
They've been sold for years, but new studies and claims are making these items hotter than ever. Paris Hilton knows. She added them to her latest perfume. But the debate remains: Do pheromones really work or is this just all hype?
"I think our product is the only product that has any proof behind its claims," said biologist Winifred Cutler, a leading pheromone champion and owner of the Athena Institute, which manufactures and sells pheromone products.
Cutler said she had proof they worked for 75 percent of customers who had tried her products, which sell for about $100 for 1/6 of an ounce.
"Our pheromones are sexual attractants. They do make the wearers more sexually attractive," she said.
Some scientists remain skeptical about the existence of human pheromones. "Maybe just the idea of knowing that you're wearing the stuff will help," said Dr. Stuart Firestein, a biologist at Columbia University who studies the science of smell. "There's certainly always going to be a very strong placebo effect in these sorts of things."
Firestein said even if synthesized pheromones worked, they were not likely to be the only source of an attraction.
"We use all sorts of cues. A pheromone alone is unlikely to do it. It's part of a whole package," Firestein said.
To test whether these potions helped people find romance, "20/20" sent sets of 20-something male and female twins to a speed-dating event and gave them each a scent -- one twin in each set received a scent containing Cutler's pheromones. No one knew who had what.
The female twins, Bridget and Sarah, were introduced to us through twinsworld.com. They said they would be convinced the pheromones worked if one of them was approached by more men at the speed-dating event.
They went on 10 dates each lasting five minutes. The daters then filled out forms stating which of the people they would like to see again.
At the end of the night we tallied the results: Nine men wanted to see Sarah again and five men wanted to see Bridget again. As for the guys, 10 women were interested in Dave and only six women were interested in Paul.
Sarah and Dave were wearing the pheromones.
It might seem that singles in their 20s wouldn't even need the pheromones, so "20/20" wondered how these perfume additives would help an older woman.
"Women in their 40s are not excreting the same level of pheromones they might have been when they were in their 20s or their 30s," Cutler said. "Adding the pheromone to their perfume can be just the kick that restores some of what they thought they had lost."
To see whether it would work for them, "20/20" asked Kathleen and Lisa Ann, both in their 40s and single, to wear pheromones every day for three months and to keep a video diary of their experience.
Lisa Ann said that while she did "get attention," she was not in a committed relationship. Kathleen said she never had trouble meeting men but was starting to long for a partner.
"I'm one of eight kids and when I go home to my family for Christmas, everyone's married with kids except me," she said. "I just would love to have a boyfriend for Christmas this year."