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,
Leo Africanus suggested that William Shakespeare may have been inspired by Leo Africanus' book to create the character of Othello. Leo Africanus Joannes Leo Africanus (; born al-Hasan ibn Muhammad al-Wazzan al-Fasi, ; c. 1494 – c. 1554) was a Berber Andalusi diplomat and author who is best known for his book "Descrittione dell’Africa" ("Description of Africa") centered on the geography of the Maghreb and Nile Valley. The book was regarded among his scholarly peers in Europe as the most authoritative treatise on the subject until the modern exploration of Africa. For this work, Leo became a household name among European geographers.