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,
Female cosmetic coalitions will be whether Male B gains sufficient fitness via a roving strategy of picking up cycling, non-cosmetic females. If Male A is not able to compete with Male B in terms of dominance, he is better off choosing the cosmetic females. Because Female B and her non-cosmetic female neighbors get the attentions, but no reliable investment, from Male B, they discourage any investment from the likes of Male A. Once costs of encephalization begin to bite and cooperative strategies are needed to support offspring, how many females will be choosing philanderers in preference to investors? Those females are not likely