Biology Question #72

Michel, a 14 year old female from the Internet asks on September 28, 1999,

If Humans and Apes are related, why aren't we able to reproduce together?

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The answer

Barry Shell answered on September 28, 1999

They are related, but they are not the same species. The definition of a species is that animals within a species must be able to mate to produce breeding fertile offspring so the species can continue. Within the definition given above, there are 5 species of great ape currently on the planet: Gorillas, Orangutans, Chimps, Pygmy Chimps, and Humans. Each species is genetically isolated from all others (that is, they cannot cross breed to create fertile offspring.) On a molecular level, this separation is maintained through a number of interesting mechanisms. For example humans have 23 pairs of chromosomes, while chimps have 24 pairs. Ignoring behavioral issues such as how to get a chimp and a human in the mood for each other, and making the huge assumption, given that they have mismatched chromosomes, that the offspring could grow to adulthood, the offspring would have huge problems with meiosis due to their odd chromosomes and would therefore be infertile. If your question is not whether a human could have fertile offspring with another great ape, but instead whether that offspring would be viable (as with mules, who are the offspring of a horse and a donkey), I can't say for certain whether this is possible. However, there is no reference to such an occurance in biology texts anywhere, so therefore I doubt it. [With thanks to Chris Carlson, of the Mad Scientist Network (]

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