Humanzee

The humanzee (sometimes chuman, manpanzee or chumanzee) is a hypothetical hybrid of chimpanzee and human, thus a form of human–animal hybrid. Serious attempts to create such a hybrid were made by Soviet biologist Ilya Ivanovich Ivanov in the 1920s, and possibly by researchers in China in the 1960s; however, neither succeeded.

The portmanteau humanzee for a human–chimpanzee hybrid appears to have entered usage in the 1980s.

The possibility of hybrids between humans and other apes has been entertained since at least the medieval period; Saint Peter Damian (11th century) claimed to have been told of the offspring of a human woman who had mated with a non-human ape, and so did Antonio Zucchelli, an Italian Franciscan capuchin friar who was a missionary in Africa from 1698 to 1702, and Sir Edward Coke in "The Institutes of the Lawes of England".

Chimpanzees and humans are closely related. Genetic animal hybrids with different chromosome numbers decrease the probability of viable offspring and rarely occur in the first cross. Evolutionary biologists have found evidence that hybridization between humans and Pan troglodytes resulted in some varieties of archaic humans. Chimpanzees and bonobos are separate species, but hybridization has been documented. Genetic similarity, and thus the chances of successful hybridization, is not always correlated with visual appearances. Domestication and backcrossing has been found to increase fertility in subsequent generations.

All great apes have similar genetic chromosome structure. Humans have one pair fewer chromosomes than other apes; humans have 23 chromosome pairs, while all other apes have 24, with ape chromosomes 12 and 13 fused in the human genome into a large chromosome (which contains remnants of the centromere and telomeres of the ancestral 12 and 13). Chromosomes 6, 13, 19, 21, 22, and X are structurally the same in all great apes. Chromosomes 3, 11, 14, 15, 18, and 20 match among gorillas, chimpanzees, and humans. Chimpanzees and humans match on 1, 2p, 2q, 5, 7–10, 12, 16, and Y as well. Some older references include Y as a match among gorillas, chimpanzees, and humans, but chimpanzees, bonobos, and humans have recently been found to share a large transposition from chromosome 1 to Y not found in other apes.

The degree of chromosomal similarity among apes is roughly equivalent to that found in equines. Interfertility of horses and donkeys is common, although sterility of the offspring (mules) is more common. Complexities and partial sterility pertain to horse–zebra hybrids, or zorses, whose chromosomal disparity is very wide, with horses typically having 32 chromosome pairs and zebras between 16 and 23 depending on species. The Przewalski's horse (Equus ferus przewalskii) with 33 chromosome pairs, and the domestic horse (E. f. caballus) with 32 pairs, have been found to be interfertile, and produce semi-fertile offspring: male hybrids can breed with female domestic horses.

In 1977, researcher J. Michael Bedford discovered that human sperm could penetrate the protective outer membranes of a gibbon egg. Bedford's paper also stated that human spermatozoa would not even attach to the zona surface of non-hominoid primates (baboon, rhesus monkey, and squirrel monkey), concluding that although the specificity of human spermatozoa is not confined to Homo sapiens sapiens alone, it is probably restricted to the Hominoidea. However, in the opposite direction of closely related species, it has been found that human sperm binds to gorilla oocytes with almost the same ease as to human ones.

Hybridization between members of different, but related genera is sometimes possible, as in the case of cama (camel and llama), wholphin (common bottlenose dolphin and false killer whale), and some felid hybrids. Even hybridization between different families, as in the case of the sturddlefish, is possible (albeit exceedingly rare) provided the parent species are genetically similar enough to one another.