The idea that a chimpanzee and human can interbreed, forming a hypothetical hybrid species known as a
humanzee, is not uncommon. Since chimpanzees and humans are closely related species (sharing 95% of their DNA sequence, and 98% of coding DNA sequences), it has lead to contested speculation that a hybrid is possible, though no specimen has ever been confirmed.
While there is a commonality in gene sequence between us and chimpanzees, humans still have one fewer pair of chromosomes (46 chromosomes) than other apes (48 chromosomes). This makes conception between the two species naturally impossible. However, a different numbers of chromosomes is not an absolute barrier to hybridization. Similar mismatches are relatively common in existing species, a phenomenon known as
chromosomal polymorphism.
The first documented, scientific test to see whether humans and apes could interbreed started in the 20th century. In the 1920s, the Soviet biologist Ilya Ivanovich Ivanov carried out a series of experiments to create a human / non-human ape hybrid by artificially inseminating female chimps with human sperm. None of his attempts created a pregnancy.
As far back as 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 (such as baboon, rhesus monkey, and squirrel monkey), concluding that although the specificity of human spermatozoa is not confined to man alone, it probably is restricted to the
Hominoidea.
A performing chimp named Oliver (left block in the picture above) was popularized during the 1970s as a possible
humanzee. Genetic tests, however, concluded that, despite Oliver's somewhat unusual appearance and behavior, he was a normal chimpanzee. As a result of being humanized (habituated to humans rather than to chimps), Oliver was said to be attracted to female humans, and did not mate with chimpanzees.
