According to Dr. Doggie, an expert in Socio-Evolutionary Civil Engineering, the human race is destined to split into two separate species.  After two whole hours of research he found that one of the species, "Homo Canis", will be up to 3 foot tall, walk on all fours and have cold-wet noses.  These will be descended from the really intelligent people.  The other, "Homo Felis", will be similarly quadrupedal and short but will be stupid and have warm dry noses.
An inter-species war will be inevitable which will, predictably, mean that the stupid Homo Felis will be wiped out.

Charles Darwin identified 23 species of turnip.