The word “humanzee” is used to describe the hypothetical offspring that would result if a human were to mate with a chimpanzee. The ability for two separate (but closely related species) to produce offspring is well documented in nature, although typically the offspring are not fertile. Well known examples include mules (a cross between a horse and a donkey) and ligers (a cross between a lion and a tiger).
It has long been acknowldeged by scientists that chimpanzees are our closest living relatives and it is therefore perhaps not surprising that this has generated interest in whether a human / chimpanzee hybrid species would be viable. To date, no compelling evidence has been supplied to suggest that such a pairing would prove viable, and for understandable ethical reasons such experimentation is deemed out of the bounds.
That’s not to say, however, that scientific experiments haven’t been attempted. Most notably, and controversially, the Russian biologist Ilya Ivanov attempted to create a human / ape hybrid during the 1920s. Ivanov initially attempted to use artificial insemination of human sperm with chimpanzee females but none of these attempts led to a pregnancy. Then, in 1929, he changed tack and organised for ape sperm to be used with human female “volunteers”. This attempt was hindered, though, by the death of his last orangutan and, shortly afterwards, he lost the support of the Soviet government and was sent into exile.
Whilst such direct attempts to create a human / ape hybrid would not be tolerated today, mankind has a history of being unable to resist the temptation to explore and push the boundaries of what is possible. More recent lab research has shown that human sperm can penetrate the outer membranes of gibbon eggs (gibbons being another ape species), and we cannot rule out the possibility that more comprehensive attempts will be made to prove or disprove conclusively the question of whether a humanzee (or other human / ape hybrids) are possible.
Genetic evidence has also emerged which suggests that some inter species cross breeding continued in the initial period after the human and chimpanzee species diverged from their common ancestor. A New York Times article, in 2006, quoted from analysis undertaken by David Reich and Nick Patterson at the Broad Institute in Cambridge, Massuchussets, which stated that “there were in fact two splits between the human and chimp lineages, with the first being followed by interbreeding between the two populations and then a second split.” This, of course, is a highly contentious view but nevertheless is interesting. And one thing is for certain, the research that’s been done in recent years has conclusively shown how close we are to our ape relatives in terms of our DNA – we share 95% of their DNA. Indeed, we are more closely related to chimpanzees than horses are to donkeys.
One reason that is often given in opposition to the potential for a humanzee is the fact that humans have one fewer chromosome than the other ape species. However, this is not a total block on cross breed success. For example, the Przewalski horse (33 chromosomes) and domestic horses (32 chromosomes) can produce semi-fertile offspring.
There have been several reported instances of humanzees, of which the most well known is the case of Oliver in the 1970s. However, Oliver (despite his fondness for walking upright) was found to be a normal chimpanzee and there have yet to be any verified instances of a proper human / ape hybrid. It’s possible that the evolution of modern humans was influenced by a certain amount of cross breeding with early chimpanzees but that this ability has been lost as the species have diverged further from their common ancestor.
Sources:
http://en.wikipedia.org/wiki/Humanzee
http://en.wikipedia.org/wiki/Hybrid_species#Examples_of_hybrid_animals
