A January executive order by President Donald Trump designates people as female if they make the “large” reproductive cell (the egg) and male if they make the ...

Editor in Chief Nancy Shute discusses the centennial of quantum mechanics’ framework, Hubble’s 35th anniversary and the legacy of Kanzi the bonobo.

You lay a plastic sheet on the mud. Then you lay your body upon the sheet. Without any direct contact between mud and body, you spend several minutes enjoying the soft and saunalike heat, sweating all ...

A new fossil and DNA analysis traces how dozens of sloth species responded to climate shifts and humans. Just two small tree-dwelling sloths remain today.