The reward system is central to everything an animal does, says Osvath. It’s why we eat and why we have sex. It’s why some of us watch birds and why some of us study them. “A lot of us do things for no particular purpose,” says Osvath, “science, culture, writing books—we do these things mainly because we like to do them. It’s very much associated with our exploratory or play behavior. It’s completely useless to study birds or go to the moon or investigate
