About 15 years ago a woman in my advanced animal behavior course asked me if wild nonhuman animals suffer from PTSD or other psychological disorders. And just yesterday a therapist who works on human animals asked me if it's possible that wild animals don't naturally suffer from PTSD but only when they're mistreated by humans or experience family and friends tortured by humans. These are great questions to which there seem to be no good answers. Here's what I wrote in 2007 in my book The Emotional Lives of Animals about the possibility of wild animals suffering from various psychological disorders.
"Because it's usually ignored, I want to pose a final question in this chapter: if animals feel many, if not most, of the emotions humans feel, can they also become mentally ill? While we see emotions being freely and openly expressed in a wide variety of species, often there are individuals who seem be 'out of it.' For example, on occasion I've seen a young animal who just doesn't seem to get it, an individual who just doesn't know how to play. I remember a coyote pup named Harry who didn't respond to play signals by playing, as did most of his littermates. Harry also didn't use play bows very often and just didn't seem to have a clue about how to initiate play, or even how to play if he got to do it at all. For a long time I simply chalked it up to individual variation, figuring that since behavior among members of the same species can vary, Harry wasn't all that surprising.
"But I was recently asked if there were autistic animals, and I thought about Harry and realized I wasn't sure. Because there are autistic humans, there likely are nonhuman animals who suffer from what might be called autism. Perhaps Harry suffered from coyote autism. Simon Baron-Cohen has made great strides in learning about human autism using ethological studies, and ethologist Niko Tinbergen eventually turned his attention to the study of autism, so there may indeed be a useful connection.
"I remember other animals. There was another coyote, a large male named Joe, who seemed to go all over the place. He'd often seem to be sulking and moping around for no obvious reason and then instantaneously run around as if he were happy, seemingly without a care in the world. Then there was Lucy, a young wolf who behaved similarly to Joe. Some days Lucy behaved 'normally,' like a typical wolf, whereas on others she was either really wired or really down. Other colleagues have also remarked that on occasion one of the animals they're watching seems to be very unusual. But we never thought to call the out-of-the-ordinary individuals autistic or bipolar.
"Perhaps, to be consistent with arguments about evolutionary continuity and emotions, this would not be out of order. As I've noted above, experienced ethologists and psychologists now believe that elephants likely suffer from post-traumatic stress disorder, so how far do we need to stretch to include autistic and bipolar animals? Many different psychological disorders have been diagnosed in dogs, so there's no reason why this couldn't be true for their wild relatives and other creatures."
We didn't have enough data to study in any detail how other pack members interacted with these individuals but nothing stuck out as being unusual.
Currently, we're really not much closer to knowing much about wild animals but it's clear captive animals do indeed suffer a wide range of psychological disorders including PTSD. Research by Dr. Hope Ferdowsian and her colleagues has clearly shown that captive chimpanzees display behavior patterns similar to post-traumatic stress disorder (PTSD) and depression. The same goes for elephants abused in circuses where they are treated incredibly harshly (egregiously and inhumanely "broken") so they will perform unnatural tricks and for those kept in tiny cages in zoos absent social companions and a physical environment where they can do the things their wild relatives routinely do (see note 1 below). It's also been suggested that captivity drives killer whales crazy. I'm sure when similar research is conducted on other animals we'll discover the same trends. It's not all that surprising that captive animals show severe signs of stress and depression given how their lives are reprehensibly and severely compromised.
Scanty but compelling observations show exploited wild elephants also display signs of trauma and depression. The photo here is of a highly traumatized orphaned young elephant I met at the David Sheldrick Wildlife Trust outside of Nairobi, Kenya, who was being treated after seeing, hearing, and smelling her family and friends being killed by humans. The teaser photo is also from this wonderful rehabilitation center. At the David Sheldrick Wildlife Trust incredibly dedicated caregivers remain with these individuals, sometimes for years on end, to help them get through their severe trauma. Some do and very sadly some don't. When I put my hand in this youngster's mouth her entire body went limp with relaxation. As we locked eyes tears came to mine.
Perhaps wild animals who deeply grieve the loss of family and friends from natural conditions also suffer severe and prolonged psychological problems. I once saw individuals in a pack of wild coyotes deeply grieve the loss of their mother. We (and most likely they) never knew if she went off and died or simply disappeared but their demeanor showed clearly they missed her and were depressed. But after a few weeks life went on as usual because it had to. There was no one who could or would take care of them. Traumatized wild animals seem to recuperate rapidly because they have to. In his book Waking the Tiger renowned psychologist Peter Levine considers the ways in which wild animals overcome trauma and applies this to his work on humans.
I don't know of any data that show that wild animals torment one another to the extent of causing severe psychological trauma that even marginally resembles how humans routinely harm other humans or members of other species. I've seen a very few scapegoats in wild packs of coyotes who were unrelentingly threatened and occasionally dominated by other pack members. After a while the scapegoats just avoided the more dominant individuals and were left alone. Did these scapegoats suffer long and enduring depression? It didn't seem so and on two occasions a male and female subsequently became fully functioning members of their pack.
Because wild animals don't get the medical care to which our companion animals are privy, those who suffer from extreme and debilitating psychological disorders simply die, as do those who suffer serious physical injuries and illness.
So, my guess is yes, wild animals do indeed suffer from PTSD and other psychological disorders under natural conditions and that as time goes on we will learn more about the extent of these maladies. I encourage field workers to look for this and to report instances of psychological trauma. Even in the absence of a sufficient database, I can't imagine that the extent of psychopathologies among wild animals comes close to how rampant PTSD and other disorders are among captive animals whose lives have been highly compromised by humans by being forced to live in highly unnatural conditions in unnatural social groups.There's no evidence wild animals torment and torture one another to the extent that humans torment and torture one another and members of other species.
What allows us to continue to abuse and torment other animals as well as other humans needs more study because this is another example of human exceptionalism of which we should not be proud. We suffer the indignities to which we subject others and we need to change our ways. We can learn a lot from other animals.
(1) For those who need some good news, Field Entertainment, the parent company of Ringling Bros. Circus, was just slapped with the largest penalty in circus history for alleged violations of the federal Animal Welfare Act.