We don't know which species should be classed as 'human'

Re:We don't know which species should be classed as 'human' by Scarblac on Monday January 11, 2016 @01:53PM (#10882305)

I don't think there's been any point in your ancestry where one of your ancestors wasn't the same species as his parents, using that definition.

So all your ancestors count as the same species. And all their descendents count as the same species. So there is a single species.