Population ecology is the study of how populations — of plants, animals, and other organisms — change over time and space and interact with their environment. Populations are groups of organisms of ...

The global human population has been climbing for the past two centuries. But what is normal for all of us alive today — growing up while the world is growing rapidly — may be a blip in human history.

It wasn’t expected to happen so soon, but it has been a long time coming. Earlier this week, for the first time in six decades, official statistics revealed a dip in China’s population. At the bottom ...