Using thousands of genes from 90 animal species, investigators established models suggesting placental mammals diversified across the Cretaceous-to-Paleogene boundary.
Sequencing could help resolve Homo naledi's spot on the hominid family tree, but Jennifer Raff writes at the Guardian that its DNA has been hard to find.
The New York Times reports that experts say President Joe Biden's goal of vaccinating 1 million people a day in the US in the next 100 days is too low a bar.
