" From an evolutionary perspective, nothing could be worse for a male than to eliminate his own progeny. It’s assumed, therefore, that nature has provided males with a rule of thumb to attack only infants of mothers with whom they have had no recent sex. This may seem foolproof for the males, but it opens the door for a brilliant female counterstrategy. By accepting the advances of many males, a female can buffer herself against infanticide because none of her mates can discard the possibility that her infant is his. In other words, it pays to sleep around. "

― Frans de Waal , Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are