Patricia Greenfield has tracked families in Chiapas, Mexico, over four decades. Many were very poor when she started her study. Slowly, over time, they grew wealthier.
Along the way, Greenfield noticed something: As the people she followed grew richer, they became more individualistic. Community ties frayed and weakened.
Greenfield expanded her findings to form a more general theory about the effects that wealth has on people: "We become more individualistic, less family and community oriented."