Why the Latest Science Leads Us to a New Theory of Human Nature, by Jonathan Leaf (Bombardier, 320 pp., $21) Ever since Darwin, biologists have believed that much could be learned about human nature ...

Humans appear to be the only species clearly proven to shed tears specifically because of emotions. Elephants, primates, and dogs show behaviors and biological responses that come closest to human ...

Stories centered around true love's kiss might be tales as old as time. And, according to a new study, kisses might even have been around before humans walked the earth. Humans kiss each other ...

A new study suggests that primates like bonobos are capable of understanding the difference between imagination and reality.