Captivity Causes Brain Damage in Large Mammals, Research Shows

Keeping large animals captive can be detrimental to their physical health in many ways. Being constantly watched and confined to a small areal can cause undue stress for many animals and even keep some of them from breeding, which is particularly catastrophic for endangered species.

In elephants, captivity can cause arthritis, obesity, and skin problems. Orcas may develop pneumonia, kidney disease, infections, or gastrointestinal problems. For both elephants and orcas, captivity can lead to severe dental problems.

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Many animals develop strange behaviors to help them cope with the stress of being held in captivity, such as bobbing their heads, swaying back and forth, or chewing on the bars of their cages or other items as available. Big cats and other large animals will often pace from side to side within their enclosures. Elephants tend to rub their tusks on things, sometimes even breaking them. These are all signs of an animal going through stress on a much more regular basis than it needs to.

But this is just the tip of the iceberg. New research suggests that captivity can cause more than just stress and physical ailments. It can also cause brain damage in large mammals.

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Brain changes have been documented in rodents, rabbits, cats, humans, and other species that have been held in captivity, but they may be the most noticeable in large mammals. Aside from looking directly at the brains of their subjects, researchers have used behavioral changes, blood stress hormone levels, and other biomarkers to help them “see” changes in large animals’ brains.

Captivity can cause animals’ capillaries and neurons to shrink and their dendrites to become less complex, which impairs communication between different parts of the brain. The cortical neurons of captive animals also process information less efficiently. Prolonged stress increases stress hormones in the brain and can damage neurons and the brain’s complex circuitry.

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Researchers believe that the lack of socialization and intellectual stimulation in most captive mammals’ lives play a huge role in their compromised brain function. These animals’ inability to exercise their minds and bodies on a regular basis causes thinning in the cerebral cortex—an area of the brain associated with voluntary movement, memory, planning, decision-making, and other higher-level functions.

Elephants, for example, typically travel anywhere from 15 to 200 miles per day in the wild, but they’ll only travel about three miles a day in captivity. The same goes for orcas, which may swim as many as 156 miles per day in the wild; their tanks are roughly 10,000 times smaller than their natural home range, restricting their activity level.

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Exercise increases blood flow to the brain, promotes the creation of new connections, and enhances cognitive abilities, so the decreased activity in captivity also impacts animals’ brains. The chronic frustration and boredom caused by captivity have a huge impact on the mental and physical health of the animals.

Living in captivity also fosters a level of learned helplessness in the animals, affecting the hippocampus and amygdala, which are responsible for memory functions and emotions.


Stressful situations in humans can provoke depression, anxiety, mood disorders, and PTSD. Researchers have shown that many large animals have similar reactions to the stress of captivity. All wild creatures should remain free, or at least in wide-open spaces at the sanctuaries that protect them, where they’re able to exercise their minds and bodies as they’re meant to.

Elizabeth Nelson

Elizabeth Nelson is a wordsmith, an alumna of Aquinas College in Grand Rapids, a four-leaf-clover finder, and a grammar connoisseur. She has lived in west Michigan since age four but loves to travel to new (and old) places. In her free time, she. . . wait, what’s free time?

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