An Impertinent Question

This is what we look like after how many generations of using each other’s heads for pinatas?

[See previous post, if you haven’t seen it already.]

So cultural practices–like, for instance, clubbing each other on the head–can shape our physical evolution? Really?

Given, then, the enormous cultural differences that we find all over the world, some of them going way back in time, how come the human race is still one species? Shouldn’t we have evolved in dozens of species, based on our widely varying cultural practices?

No easy way out of this one!