London, September 3 (ANI): A new study has shown that female gorillas use sex as a tactic to thwart their rivals.
Diane Doran-Sheehy, a primatologist at Stony Brook University in New York, has found that pregnant apes court their silverback male to stop other females conceiving.
"It seems to us that mating is another tactic that females use to compete with each other - in this case to gain favour with another male," New Scientist magazine quoted her as saying.
She and her colleagues studied the sex lives of five female western lowland gorillas and one silverback, almost every day for over three years.
"We wondered if, basically, (pregnant) females can mimic (ovulating) females and dupe the male into mating with them and distract him from what those other girls are doing," Doran-Sheehy said.
She believes that such a competitive behaviour in gorillas may help understand how humans evolved into a mostly monogamous species.
Her team recorded most copulations and all births among a human-habituated group of gorillas at the Mondika research centre in the Republic of Congo for 1147 days between September 2003 and January 2007.
According to the researchers, all five females gave birth to one infant during the study, and all engaged in sex after pregnancy.
However, females seemed to time such post-conceptive romps with the fleeting fertility of another female, the researchers said.
Tara Stoinski, a primatologist at Zoo Atlanta in Georgia, said that delaying the pregnancy of others could give females a reproductive advantage over competitors.
"I agree with Diane's assertion that females are competing with each other," said Stoinski, who found that pregnant female gorillas in captivity also time their sexual advances to coincide with those of other females.
A research article on the study has been published in the American Journal of Primatology. (ANI)