LONDON (AFP) - - Female chimpanzees are hungry for sex with as
many males as possible, and keep their mouths shut about it to
boost their chances of luring the top chimps, a British university
said.
Scientists at the University of St Andrews studied the
copulation calls -- sounds they sometimes make during mating -- of
female chimpanzees in Uganda to find out more about what they
mean.
The Scottish institution's team concluded that female chimps
sometimes keep quiet during sex so their female rivals do not find
out what they have been up to.
Evolutionary psychologists Simon Townsend and Klaus Zuberbuhler
studied chimp behaviour in Uganda's Budongo Forest over 16
months.
The team established that female chimpanzees hid their sexual
activity when high-ranking females were nearby, perhaps in a bid to
reduce competition for good quality males.
This could prevent higher-ranking female chimpanzees from
turning on them.
They also found the females produced more copulation calls when
high-ranking males were around to attract them to have sex.
The scientists believe that having sex with several males causes
confusion among the male chimpanzees as to which one sired the
offspring.
The males are therefore less likely to kill any babies that
might be theirs.
The study found no evidence that males were competing to have
sex with females after they produced copulation calls, and no link
between a female's fertility and her use of the calls.
"Chimpanzee females adjusted their calling behaviour in flexible
ways, potentially to avoid aggression from other females and
possibly to secure future benefits from the socially important
males," the study said.
The research indicated that the social pressures deriving from
resource competition acted as an important selective force, shaping
the copulation calling behaviour in wild chimps.
"Competition between females can be dangerously high in wild
chimpanzees," said Townsend, part of the team.
"Our findings highlight the fact that these females use their
copulation calls in highly tactical ways to minimise the risks
associated with such competition.
"The female chimps we observed in the wild seemed to be much
more concerned with having sex with as many different males as
possible, without other females finding out about it, than causing
male chimps to fight over them.
"We also found that the calling behaviour of copulating females
was unrelated to their fertile period and therefore not linked to
the likelihood of conception."
Zuberbuehler added: "Copulation calling may be one potential
strategy employed by female chimpanzees to advertise receptivity to
high-ranked males, confuse paternity and secure future support from
these socially important individuals."
