Why do humans keep pets? A new international study suggests that some of the behavioral foundations of human-animal companionship may have much deeper evolutionary roots than previously thought.

The fact that monkeys can keep "pets" or even raise other species could hint at the evolutionary origins of empathy.

If you've ever gone hiking and reached a fork in the trail, you may be confronted with two triangles: one pointing right, one pointing left. You know the direction they're pointing has meaning, but at ...