Monogenism - Interfertility and Biological Unity

Interfertility and Biological Unity

The interfertility of human races was debated, applying to human speciation arguments advanced already by Georges-Louis Leclerc, Comte de Buffon. The criterion of interfertility for a single human species was not universally accepted, being rejected, for example, by Samuel George Morton.

Charles Darwin regarded the evidence of interfertility as conclusive, and substantiating the biological unity of humankind. He rejected claims of Paul Broca concerning the lack of fertility of unions of European settlers and Aboriginal Australians; and relied on data of John Bachman of the fertility of mulatto (mixed race) persons. On the other hand Darwin's theory admitted the idea of "varieties of man": it was neither purely monogenist (in the sense of the term previously used), nor polygenist.