Ed Heist wrote:
> ... intergeneric hybrids among
> vertebrates are rare, and that I am aware of studies in which attempts
> to produce intergeneric hybrids in vertebrates resulted in successful
> fertilization but abnormal development and death of the embryos, just
> the phenomenon described in the original post of this thread.
Humans and chimpanzees are probably about 6 million years apart. How
chronologically separate are horses and donkeys, or lions and tigers, both
of which can produce viable hybrid offspring?