The concepts of race and ethnicity are so intertwined that it's sometimes hard to tell one from the other. Even unwound, the ideas are not as well-defined as many would present them to be.
The reason for that is simple: Yes, humans are a diverse lot. We can look distinctively different. We're seen sometimes completely differently. We come from different places (though we all, as a species, come from modern-day Ethiopia), and the groups from which we have grown — our families, our clans, our cultures, our nations — all have traveled different paths. A wide world of factors have influenced our appearance and our ways of life during thousands of years of evolution and migration.
Yet all those amazingly diverse peoples don't exist in a vacuum. Over all those millennia and all those miles, we've become mixed. And we continue to mix.
Putting us in distinct boxes with fixed labels is near-impossible. Even the labels get jumbled.
"I think there's a ton of overlap [between the terms ethnicity and race]," says Douglas Hartmann, a professor of sociology at the University of Minnesota and co-author of "Ethnicity and Race: Making Identities in a Changing World" (with sociologist Stephen Cornell). "I really think it's difficult to disentangle them. And maybe even inappropriate. Because all of these categories have elements of identity, self-assertion, culture and heritage. But they also have elements of labeling, of stigma, of differential treatment, of power inequality, etc."
Still, maybe because of some innate need for order — or something more sinister — we continue to define. We identify people as this race or that ethnicity. We self-identify, too.
And so it is that these labels become blurry and, at times, inseparable.