When Kevin Hatala asks his students on the first day of class, “What are the characteristics that make us human?” the first response they tend to give is opposable thumbs. “But if you look ...

Elizabeth Hlavinka is a staff writer at Salon covering health and drugs. She specializes in exploring taboo topics and complex questions that help humans understand their place in the world.

As polar bear habitats shrink due to rising temperatures, they are crossing paths with grizzlies more often. Their offspring inherit the polar bear’s ability to handle extreme cold and the ...

Two ancient hominid species with slightly different gaits crossed paths in East Africa ... a flatter arch than those of present-day humans, showing that their foot motions and perhaps their ...

literally crossing paths. The discovery raises intriguing questions about the relationship between the two species and any competition for resources. Some of the footprints of two human species ...