When: The Scientific Secrets of Perfect Timing

by Daniel H. Pink

However, another explanation is also plausible. In 2012, five scientists asked zookeepers and animal researchers in three countries to help them better understand the more than 500 great apes under their collective care. These primates—chimpanzees and orangutans—ranged from infants to older adults. The researchers wanted to know how they were doing. So they asked the human personnel to rate the apes’ mood and well-being. (Don’t laugh. The researchers explain that the questionnaire they used “is a well-established method for assessing positive affect in captive primates.”) Then they matched those happiness ratings to the ages of the great apes. The resulting chart is shown here.9