In brief: Traumatized elephants
A report in the British journal Nature provides vivid evidence that other animal species suffer from the psychological symptoms of traumatic stress that we like to think of as human disorders.
Elephants, like humans, are a highly intelligent, long-lived mammalian species with strong family ties, a complex social life, and long memories. They grow up in extended families headed mainly by grandmothers (older females). Human violence and habitat destruction have been breaking up those families for a century or more. It's estimated that in 1900, there were more than 10 million elephants in Africa; in 2005, after a century of ivory poaching, habitat loss, and legal culling, about a half million are left.
It's well known that early traumatic experiences can have long-lasting effects, raising the risk of post-traumatic stress disorder, depression, and violence. Today, in increasing numbers, elephants are showing signs of abnormal startle responses, unpredictable aggression, and antisocial behavior. The loss of older family members is especially devastating for adolescent males. Often they have only young unexperienced mothers, or no mothers, to raise them, and there are few older males to mentor them during adolescence.