You share everything with your bestie. Even brain waves

Researchers have also been intrigued by evidence of friendship among nonhuman animals, and not just in obvious candidates like primates, dolphins and elephants

A friend will help you move, goes an old saying, while a good friend will help you move a body. And why not? Moral qualms aside, that good friend would likely agree the victim was an intolerable jerk who had it coming and, jeez, you shouldn’t have done this but where do you keep the shovel?

Researchers have long known that people choose friends who are much like themselves in a wide array of characteristics: of a similar age, race, religion, socioeconomic status, educational level, political leaning, pulchritude rating, even handgrip strength. The impulse toward homophily, toward bonding with others