Different studies show animal prostitution exists among species such as Adélie Penguins, chimpanzees, and crab-eating macaque. Penguins use stones for building their nests. A shortage of stones led female Adélie Penguins to trade sex for stones. The female penguins, even when in a committed relationship, will exchange sexual favors with strange males for the pebbles they need to build their nests. Prostitution is also observed among chimpanzees, who trade food for sex.
The first documented case of prostitution in animals was reported in 1998 by Fiona Hunter and Lloyd Davis, who had spent five years observing the mating behavior of penguins. The study was conducted as part of an Antarctica New Zealand program on the Ross Island, approximately 800 miles from the South Pole. The female penguins observed under the study were coupled with males. The females will go outside alone to collect pebbles, but the males did not suspect their female partners. According to the observations and analysis made by Hunter, the prostitute penguins targeted single males, because if instead they picked a male penguin with a partner, the male penguin’s current partner will come in conflict with the prostitute female.
The female penguins would sometimes perform courtship ritual as a trick to lure the males leading to sexual intercourse. However, after taking the pebbles, the females would run off. Hunter was reported by the BBC as saying that the female penguins probably didn’t engage in prostitution only for stones. Hunter believed ‘what they are doing is having copulation for another reason and just taking the stones as well. We don’t know exactly why, but they are using the males.’ This behavior was also suggested as a mate choice process by which the females might find a possible future mate. This would provide a female penguin with another male penguin should their current mate die. The male penguins, the study speculates, were engaged in sex with the prostitute females only for sexual satisfaction. According to Hunter’s observation, the number of prostitute penguins was very low, and she approximated this as ‘only a few percent.’
A study conducted by the Max Planck Institute for Evolutionary Anthropology in Leipzig found support for the meat-for-sex behavior hypothesis, according to which, in early human societies the best male hunters had the maximum number of sexual partners. Researchers observed chimpanzees in the Taï National Park and concluded that a form of prostitution exists among the chimpanzees in which females offer sex to males in exchange for meat. According to Cristina Gomes of the Institute, the study ‘strongly suggests that wild chimpanzees exchange meat for sex, and do so on a long-term basis.’ According to research paper published in the journal ‘Animal Behaviour,’ long-tailed macaque males use grooming to pay for sex. In a study at Yale – New Haven Hospital, capuchin monkeys were taught to use silver discs as money. Researchers observed that some of the monkeys who learned the monetary value of the discs would trade them for sexual favors.