Ask someone to think of an animal, and chances are they’ll come up with one of our relatives among the mammals. A few people might go further afield and mention other vertebrates, like birds and fish.

We have a natural fascination with time—how landscapes have been carved over millennia, how our bodies grow and sag with age, how the stars traverse the sky each night. Scientists probe the layers ...

The group with the world's simplest animals—tiny blob-like life forms with no organs and just a few cell types—finally has a fleshed-out family tree built by a research group led by the American ...