
Lydia Denworth: Friendship
A child reports having a best friend and a worst friend (no friend at all). Adults typically need 40-60 hours of being together to form a casual friendship and 200+ hours to rate someone as a best friend. Maintaining close relationships boosts quality of life and benefits our health, Lydia Denworth writes in Friendship: The Evolution, Biology, and Extraordinary Power of Life’s Fundamental Bond.