Elephant Sex

UPDATE: Lois Elizabeth “Bets” Little-Rasmussen, died in a Seattle hospital on September 17,2006 aged 67, of a bone marrow disorder. Little-Rasmussen collected elephant urine and found the sex pheromone that females secrete to let bulls know they’re ready to mate. She determined that other secretions were associated with the animals’ sexual activity and conflict resolution. She pioneered a technique for collecting and analyzing the breath of aquatic animals, so that it could be used to monitor their health. SOURCE: Stanford.

Elephant sex is quite surprising, not because of the sheer bulk of the beasts involved and the forces they employ, but because of the rather circuitous route taken by the sex pheromones exuded by the female.

Josef Lazar of Columbia University, New York, and chemist Elizabeth “Bets” Rasmussen of Oregon Health and Sciences University in Beaverton working with David Greenwood of the Horticulture and Food Research Institute of New Zealand Ltd and In-Seok Bang and Glenn Prestwich of the University of Utah in Salt Lake City have made a rather unexpected discovery about pheromone transport in the Asian elephant, Elephas maximus, an endangered species of which only a few thousand individuals remain. Female elephants communicate their readiness to mate by excreting a sex pheromone – (Z)-7-dodecenyl acetate (Z7-12:Ac) – in their urine, explains Lazar. The male elephants, for their part, respond by sniffing out the pheromone in a “check and place” response in which they touch the tip of the trunk to the pheromone-loaded urine. Next, the male places the pheromone urine in his mouth, behavior known as “flehmen”. Mating behavior quickly ensues.

Lazar points out that the sex pheromone therefore has to travel through and survive a number of different environments, from serum to urine to mucus, if successful mating is to occur. His team has now revealed that serum albumin, an abundant protein present in the serum and used by vertebrates to transport chemicals such as hormones, lipids, or drugs through the bloodstream, plays an unexpected and multifaceted role. It acts as a shuttle material protecting and transporting the pheromone outside the elephant’s body.

The chemical structure of the Asian elephant pheromone is well known and can be easily prepared synthetically, explains Lazar. This, coupled with the strong behavioral response of the elephant to it, means that despite the difficulties associated with working with such large and intelligent animals, it is possible to learn about the effects of the pheromone on them. Wider studies of elephant sexual behaviour might also give us a general understanding of the reproduction of mammals, including humans.

According to the team’s latest work, elephant serum albumin (ESA) transports the sex pheromone from serum to urine and extends the period of time that the pheromone remains available for detection in the environment. It does this without masking the pheromone and hampering detection.

The complex between the pheromone and ESA falls apart in the low pH environment of the male elephant’s trunk, which produces a pulse of the volatile pheromone during flehmen behavior. The exploitation of albumin in this way complements the lifestyle of Asian elephants, Lazar adds, by reflecting the uniqueness of elephant anatomy, physiology, and behavior.

“The Asian elephant is an endangered species, so better understanding of elephant reproduction will contribute to preservation of this species, and perhaps of other endangered species as well,” Lazar told Reactive Reports. “It is likely that the African elephant uses a similar pheromone system,” adds Lazar, “The pheromone itself, however, is most likely a different chemical than Z7-12:Ac.”

Research Blogging IconLazar, J., Rasmussen, L., Greenwood, D., Bang, I., & Prestwich, G. (2004). Elephant AlbuminA Multipurpose Pheromone Shuttle Chemistry & Biology, 11 (8), 1093-1100 DOI: 10.1016/j.chembiol.2004.05.018