When you are sorting things, you can divide them up into as many categories as are useful. Typically, you start with two categories—either/or. Then you might have three categories when you find either/or doesn’t work. The maximum number of useful categories seems to be around seven or eight. After that, it’s too much to remember. So people may create seven categories, and then go to subcategories.
So I will go out on a limb and say there are no more than eight races.
In reality, functionally speaking, people tend to use between three and five races.
Of course, no one can define race in such a way as to categorize people as they see themselves, nor is there anything that genetics offers to make a sensible division between races.
Race is a social/political concept where number of races makes no sense. It would be better to ask how many us vs them situations do we have in the world? How many ways do we use looks or speech as a way to establish status?
There are no races and there are an infinite number of races… well, not quite infinite; perhaps as many as there are people on the planet. In the end, it’s all about status. What else is new?
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