At dusk, Amazonian river dolphins, or botos, transform themselves into handsome Caucasian men and come ashore to seduce young women. Locals often invoke this legend to explain unexpected teenage pregnancies. It also explains why some of them buy and sell the creature's body parts in area markets: Hold the dried eye of a boto while chatting up a member of the opposite sex, the story goes, and one becomes irresistibly attractive. (The boto's gaze conquers even the stoniest hearts.) Likewise, the dried genitalia of the dolphin, when ground up and mixed with talcum powder, can turn a lackluster lover into a superstud. Luckily for the river dolphin, these items may be mostly fakes, researchers say.
Tomas Hrbek, a biologist at the University of Puerto Rico in San Juan, and colleagues at the Universidade Federal do Amazonas and the Instituto Nacional de Pesquisas da Amazônia, both in Manaus, Brazil, purchased 43 salted eyeballs from markets in three cities: Belém, near the coast; Manaus, more than 1000 kilometers upstream; and Porto Velho, deep in the interior. The researchers extracted DNA samples from their market-bought fetishes and compared the sequences with those of known samples from botos and other species. None of the fetishes turned out to be from botos, the team reports in the current issue of Marine Mammal Science. All of the fetishes from Belém and Manaus were from dolphins of the genus Sotalia, which live in estuaries closer to the coast. Farther upstream in Porto Velho, one fetish was a match for Sotalia, but the rest were pig or sheep.
The trade in dolphin parts may be a relatively recent development, says Hrbek. The original inhabitants, indigenous people living in the country's interior, fear the boto in addition to respecting its supernatural romantic powers, Hrbek says; they have taboos against killing the boto and appear not to use boto love fetishes. But people of West African heritage, who migrated to Amazonia during the rubber boom of the late 19th century, may have melded local legends about the boto with their own religious practices, which include the ritualistic use of fetishes. Hrbek believes their descendants are the ones generating both the demand for boto fetishes and the supply. Concentrated along the coast, this population apparently has no taboos against killing botos, Hrbek says, but they never actually come in contact with them because the botos live in fresh water farther upriver.
The study is "an intriguing mix of the latest genetic science with ancient mythology," says ecologist Anthony Martin of the University of Kent in the U.K. Although the official position of the International Union for Conservation of Nature is that there's too little data to assess the vulnerability of boto populations (ditto for Sotalia), Martin says he's relieved that none of the love fetishes turned out to be genuine boto parts. The boto is already under "severe threat" from hunters who use the carcasses for fish bait, he says. "Less than 2 years ago, its Chinese equivalent, the baiji, was declared extinct, demonstrating the unique pressures faced by landlocked dolphins unable to get away from humans."