The Human as a Walking Zoo

Following up on last week’s post (Nice Lice Give Advice!), the New York Times informs us that the Epic of Human Migration Is Carved in Parasites’ DNA:

A human body is not the individual organism its proud owner may suppose but rather a walking zoo of microbes and parasites, each exploiting a special ecological niche in its comfortable, temperature-controlled conveyance. Some of these fellow travelers live so intimately with their hosts, biologists are finding, that they accompany them not just in space but also in time, passing from generation to generation for thousands of years.

The latest organism to be identified as a longtime member of the human biota club is Streptococcus mutans, the bacterium that causes tooth decay…