The mucus inside the male elephant's trunk helps deliver a concentrated whiff of the seductive scent. He double-checks the urine test, and if he senses a green light, mating begins.
Elephants and Moths
The researchers also discovered that the "odorant binding protein" in the mucus of the trunk puts the brakes on love. When mating is completed, the protein mops up leftover pheromones so the male is no longer stimulated
Heretofore scientists thought that the protein only helped deliver the message that the female was ready, "but it's not FedEx, it's the janitor," Prestwich says.
"Although the elephant has the largest nose and most incredible olfactory system of any animal, its chemical senses had never been studied before," Rasmussen says.
Rasmussen and Prestwich teamed up six years ago after meeting at a conference in Chile and, remarkably enough, realizing they were studying the same pheromone in two altogether different creatures: the elephant and the moth.
"The substance responsible for mating behavior and attraction was essentially the same (in both creatures) ... which strains the credibility of evolutionary biology," Prestwich says.
Collecting the Evidence
Prestwich worked only in the lab, but Rasmussen went into the field. For a month at a time she observed elephants from a jeep in Nagarhole National Park in southern India, running out to collect urine samples, and testing them on male elephants in Burmese logging camps.
She also reached inside the gaping mouths of captive elements to collect mucusand help read the secrets there.
Knowledge of the elephant's love letters aids conservation. "Increasing birth rates in captive elephants while we still have them as ambassadors to help their wild counterparts is important," says Dennis Schmitt, a reproductive specialist at Dickerson Park Zoo, in Springfield, Missouri.
Mike Keele, assistant director of the Oregon Zoo, in Portland, Oregon, who wrote the master plan for the elephant "Species Survival Program" for all zoos, points out another application of the research. Wild elephant populations are declining worldwide, from about 1.4 million in 1971 to approximately 350,000 todaypartly from human-elephant conflict.
Since bulls are drawn to females in heat, the pheromone could possibly be used to steer rogue elephants away from crops and villagesand destruction.
"The more we know about elephant reproduction, the better chance we have to save them," Riddle says.
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