Many of us have tended to think that mental illness is a purely human trait, but mounting evidence shows that our fellow creatures very likely suffer from mental health disorders that are quite similar to those we humans suffer, according to Shreya Dasgupta in BBC Earth. While it’s sad to think of our fellow creatures suffering so, the fact that they do may help us understand why humans become mentally ill, and why these disorders ever evolved at all.
Most of us have either seen or heard of pets who became sad after a companion died. In some cases, there have been animals who were so devastated by the loss that they died as well.
This is what happened to Flo and Flint, two chimps made famous by primatologist Jane Goodall at Gombe Stream National Park, MinnPost reports.
Chimpanzee mothers and their offspring form tight bonds, perhaps for the same reason that we do.
“Orphans are, as you might imagine, deeply affected by the loss of their mother, responding much as we would expect grieving children to respond, ” said Professor Michael Wilson of the University of Minnesota. “Jane Goodall vividly described how when old Flo died, her orphaned son Flint was listless and despondent and died soon after.”
Over the course of her long life, Flo gave birth to five children: Faben, Figan, Fifi, Flint, and Flame, according to The Jane Goodall Institute of Canada. Flo was kind, affectionate, supportive and playful with the first three, but she was beginning to look elderly when the time came to wean Flint. When little Flame was born, she hadn’t succeeded in weaning him.
“When Flame died at the age of six months, Flo stopped even trying to push Flint to independence. Flint became abnormally dependent on his old mother and when she died in 1972, he was unable to cope without her. He stopped eating and interacting with others and showed signs of clinical depression.”
His immune system began to crash and was too feeble to keep him alive.
“He died at the age of eight and a half, within one month of losing his mother,” the Institute reports.
Wilson noted that a “normal” adult’s reaction to the death of another adult is a rather elusive research subject, due to the fact that older chimps usually die alone.
He cautions us to not anthropomorphize other species and says we shouldn’t project our own natures on them. Wilson and several other scientists from the university have studied chimps extensively in the park where Goodall began documenting chimpanzee behavior in the 1960s.
A 2010 study conducted by Dora Biro of England’s Oxford University showed that chimp mothers seemed to be similarly distraught when their young ones died, MinnPost reports.
Jire, a chimpanzee who lived in the forests surrounding Bossou, Guinea, carried the body of her dead infant for 27 days. She continued to groom the little body, cuddled it in her nests and became upset if she was separated from it.
The research team documented two other chimp mothers who carried the corpses of their offspring for as much as 68 days — even as the bodies were rank with decay and mummified.
Wilson was not part of the study, but he’s not surprised by this.
“I’ve spent much more of my time than I would like watching dead and dying chimpanzees, and the responses of mothers and others to them,” Wilson told MinnPost. “It’s fairly common for chimpanzees, as well as various other primates, including baboons and rhesus monkeys, to carry their infants long after they’ve died.”
The behavior is well established, but the question is: Are these caring moms expressing grief as we understand it?
There may be other explanations for this, he said. Reproduction is a powerful evolutionary force that drives the survival of a species. It’s a force that can extend to caring for the offspring until they are able to reproduce on their own.
Which means that the chimp mothers’ behavior could be seen as “adaptive,” Wilson noted.
“It’s likely a more costly mistake not to carry an ailing infant long enough (because) a sick baby might, after all, get better, than to carry it for too long … after it’s dead or even mummified,” he told MinnPost.
Do animals suffer other forms of mental illness that mirror our own?
Mental illness in our fellow creatures can take many forms, BBC Earth notes. Parrots are known to obsessively pluck their feathers, and dogs have been known to repeatedly lick their paws or tails, much like some humans who wash their hands obsessively. Other animals inflict self-harm by doing things like pulling out their own fur.
Evidence seems to say that mental illness in animals can be triggered by many of the same events that cause mental illness in people. This includes the loss of family or friends, loss of freedom, stress, trauma, and abuse. This is most easily observed in captive animals.
That’s where the lioness I mentioned at the top comes in. The video below shows her pacing endlessly, then shows several other captive animals and all of them are doing this.
Animals have evolved over millennia and they developed physical, physiological, and behavioral traits that optimized their chances of surviving in the wild, BornFree reports.
Since animals didn’t evolve to be held in zoos, circuses, or other forms of captivity, they face numerous challenges that evolution hasn’t prepared them for. Climate, diet, and the size and characteristics of their cages is likely completely alien to a species as it exists in the wild.
Captive creatures may not be able to have control over their environment. They might not be able to carry out evolved behaviors that enhance their welfare or survival prospects. Instead, they have to rely on us to provide for their physical, social, biological and other needs.
If an animal is held in a captive environment that doesn’t meet its specific needs, there can be significant deterioration in the creature’s physical and mental health. As a result, it may develop abnormal behavior and disease, and may die at an early age, BornFree reports.
Mental stress can also be exacerbated if the animal’s movements are restricted, or if training by using negative reinforcement is used. Training them to perform unnatural behaviors (like, say, forcing an elephant to stand on its head), or making modifications to the normal physiology of an animal to reduce risks when handling can cause severe and lasting mental illness. This is torment for animals that are meant to be wild, and it can result in certain stereotypic behaviors. These are behaviors which don’t have an obvious goal or function.
When you go to the zoo and you see a lioness in a tiny cage pacing back and forth, that’s a stereotypic behavior. Other such examples can include swaying, head-bobbing or circling, and biting the bars of the cage–behaviours that are “demonstrably caused by the frustration of natural behavior patterns, impaired brain function, or repeated attempts to deal with some problem,” BornFree reports. Things like over-grooming, excessive licking and vocalization are known as displacement behaviors, “arising out of conflict when an animal is driven to perform two behaviors at the same time.” For instance, the animal can be conflicted between the fear of its keeper and the desire to eat.
What this really means is that wild animals really aren’t meant to be kept in zoos or circuses. They aren’t supposed to be entertainment for us.
Humans don’t do well in solitary confinement either.
There are an estimated 75,000 state and federal prisoners in the U.S. being held in solitary confinement, The New York Times reports. At the very least, these prisoners spend 23 or more hours a day in their cells. They are allowed out only for showers, doctor visits, or a bit of exercise.
Prisoners kept in solitary confinement make up three to eight percent of the nation’s prison population, the Times notes, but they account for about 50 percent of prison suicides. Cutting and other forms of self-harm are also more common in isolation units than in settings that are less restrictive.
Our fellow creatures can become so stressed out that it can even affect them genetically, Dasgupta notes.
In parrots, for instance, stress can leave marks on their genes.
In 2014, researchers working with African grey parrots that were housed alone found that these birds suffered more genetic damage than parrots who were housed in pairs. Examining the parrot’s telomeres–little caps on the ends of their chromosomes that slowly deteriorate with age or stress, the researchers found that 9-year-old parrots that were raised by themselves had telomeres as short as pair-housed birds that were 23 years older.
“It seems that social deprivation is stressful for parrots, just as it is for humans,” she wrote.
She illustrates many more points in the article, but what became especially clear is that we do share at least some genes associated with disorders like autism and schizophrenia with other animals, something I hadn’t been aware of before.
In a 2014 study, Eric Vallender, an associate professor at the University of Mississippi Medical center and his colleague, Lisa Ogawa, a doctoral student at Yale University studied genes that are thought to be associated with schizophrenia and autism in 45 mammalian species, Dasgupta writes.
Had these genes changed more in humans than in other species, this would imply that the disorders were exclusively human.
However, that wasn’t the case. Sure, the genes had changed in humans, but they also changed in Old World monkeys, apes, and even mammals that are distantly related, like dolphins.
At this point it’s not clear what this really means for these animals’ mental health, Vallender says. “All we know at this point is that the proteins seem to be changing.”
Dasgupta writes that there’s a long way to go, but these genetic studies suggest that all animals with brains have the capacity to lose some aspects of their minds.
It is amazing to think that just like more physical disorders such as cancer, mental illness can also be traced back to the genes and proteins within our cells, not just in ourselves, but in so many other animals as well. We are great apes, and we share this bond with so many of our fellow creatures.
