Only yesterday, all animals were wild. Zoological archaeologists assert that about 15,000 years ago, our hunter-gatherer forebears achieved the first domestication — the dog. Over the course of ensuing millennia, they proceeded to domesticate sheep, cattle, and other livestock. By the advent...

Commentators rightly decry the excessive segregation of American neighborhoods by race and social class. If all demographic groups were randomly distributed throughout a metropolitan area, however, there would be great diversity within each neighborhood, but no diversity among them. There is...