Hinny is easier to obtain when the lower chromosome count, the donkey, is in the male. Therefore breeding for hinnies is more hit-and-miss than breeding for mules." The male hinny or mule can and will mate, but the emission is not fertile. Male hinnies and mules are usually castrated to help control their behavior by eliminating their interest in females. Female hinnies and mules are not customarily spayed, and may or may not go through estrus. Female mules have been known, on rare occasions, to produce offspring when mated to a horse or donkey, although this is extremely uncommon. Since 1527,
Extended female sexuality males. According to Hrdy's hypothesis, extended female sexuality is an adaptive process with an aim of creating paternity confusion in their male counterparts. Paternity confusion refers to the male being unsure as to whether offspring are genetically his own. If the female mates with different males (at all points of her ovarian cycle) whilst concealing fertility, then the males will inevitably have paternity confusion. Paternity confusion is proposed to be an adaptive function for preventing infanticide. Thus, if the female can successfully create paternity confusion, males will be less likely to kill her offspring, as the lack of paternity certainty