...Evolutionary psychologists Simon Townsend and Klaus Zuberbuhler studied chimp behavior 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, presumably to attract them.
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.
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(Discovery Channel)