Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Multi-male group more than one adult male, more than one adult female, and offspring. Within Order Primates, it is the most common social group type, with group sizes ranging from 10 to 100 individuals composed of several males, and numerous females and offspring. Large groups of primates are called "troops”, which are characterized by complex intratroop politics and competition. Multi-male groups are most common among semi-terrestrial primates such as savanna baboons and macaques, but is also seen in some colobus and New World monkeys. Social lemurs sometimes often live in multi-male groups, and other primate species like chimpanzees live in fission-fusion multi-male