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Name: Samantha
Status: Student
Age: 17
Location: N/A
Country: N/A
Date: 2002


I am doing research for a project. The following question is a bit unusual but I was wondering if you could offer some insight and advice. Is it possible that millions of years ago, before history records, early human genetics could have been so different as to afford the possibility to interbreed with other species and produce fertile offspring, therefore creating the possibility that today's humans could be the descendents of primitive human and non-human life forms?

By definition a species is a species because it breeds successfully only with members of its own species. If some cross breeding did occur, by such a definition the "other breeding members would have been the same species.

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy


Most geneticists _define_ individuals of the same species as those which are able to reproduce and produce fertile offspring. So if our early ancestors bred and their offspring were fertile, they would be what we consider the same species.

There are present-day examples of interbreeding between species: Mating a female horse with a male donkey will produce a hybrid animal, the mule. But, the mule is sterile because while the horse and donkey chromosomes are similar enough to form a hybrid animal, the chromosomes differ sufficiently between species that additional rounds of reproduction are not possible. Presumably this would be the case in the scenario you suggest. Hope this helps.

Paul Mahoney, Ph.D.

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