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What are apes afraid of?

Apes, including chimpanzees, gorillas, orangutans, gibbons, and humans, experience fear just like many other animals. Fear is an adaptive response to potential threats or danger in an ape’s environment. While each ape species has evolved different instincts and reasons to be fearful, there are some common fears seen across all apes. Understanding what fears apes experience can provide insight into their environments, psychology, and evolution.

Common ape fears

Fear of snakes

One of the most common fears seen in apes is a fear of snakes. Studies have shown that both wild and captive chimpanzees, gorillas, and bonobos all exhibit fear responses when seeing snake models or real snakes. Even apes that have never seen a snake before still seem innately afraid of them. This suggests primates evolved an adaptive fear of snakes over their evolutionary history due to the threat venomous snakes posed. Snakes can still be a major threat to apes living in the wild across Africa and Asia today.

Fear of large carnivores

Apes also commonly fear large carnivores like big cats, wild dogs, hyenas, crocodiles, and eagles. These predators will hunt, kill, and eat apes when given the opportunity. Just the scent or call of a large predator nearby is enough to strike fear in apes. Young apes are especially vulnerable to being killed by predators. Apes have evolved instincts to immediately flee, hide, or band together to intimidate predators when detected.

Fear of unfamiliar humans

While apes have learned to associate certain individual humans with safety and care thanks to ecotourism, research, and captivity, most apes still fear unfamiliar humans. Humans remain one of the biggest threats to apes due to poaching, habitat destruction, and diseases. Strange humans create fear and uncertainty in wild apes, causing them to flee or hide. Even apes habituated to humans will show fear responses to unfamiliar looking humans or sudden human actions.

Fear of isolation/separation

Apes are highly social animals. Being isolated or separated from their social group creates stress and fear in many ape species. Baby apes cling closely to their mothers for safety and care. Juveniles fear being left behind by the moving group. Adults can become anxious when unable to see or hear other group members. Prolonged isolation has detrimental psychological effects on captive apes. Apes have evolved to be afraid of isolation because of their strong social bonds and interdependence.

Fears specific to certain ape species


In addition to the common ape fears, chimpanzees also exhibit unique responses to other potential dangers in their forest environments. Chimps fear falling trees, nesting in trees themselves every night. The sound of a cracking branch triggers chimps to hastily climb down or leap to another tree. Chimps are also cautious around steep cliffs and ravines which pose a falling hazard. And male chimps can react fearfully and aggressively towards other strange male chimps entering their territory.


Gorillas have an extra fear of water and wet ground. They avoid wading through streams or marshes and dislike rain. This is likely because their heavy body weight makes it difficult for them to pull themselves out of muck. Silverbacks may fear being challenged by younger males trying to take over their troop. And mother gorillas are very protective of their vulnerable infants, fearful of any potential harm.


Orangutans have less common predators in the rainforest canopy compared to ground-dwelling apes. But they do fear large pythons which can prey on juvenile orangutans. Their arboreal lifestyle also makes orangutans cautious of overlapping or unstable branches when moving through the treetops. And orangutans fear human-caused deforestation destroying their habitat. The loss of nesting trees and food sources causes stress.


Gibbons share a fear of predatory birds while living in forest canopies across Southeast Asia, especially large raptors like hawk-eagles. Gibbons use loud songs to mark territorial boundaries and warn others of dangers. Strange gibbons entering another family’s territory triggers fear and aggressive responses to protect resources. Gibbons also react fearfully to humans logging and burning down their forest habitats.


Modern humans share many innate fears with our ape cousins, like snakes, spiders, heights, and strangers. But thanks to culture and technology, humans also developed unique fear responses. These include fears of public speaking, flying, financial ruin, or terrorist attacks. Some human fears relate to dangers faced by our primate ancestors, while others represent new threats in our complex societies. Fear continues to be an essential mechanism for human survival and adaptation.

Causes and effects of fear in apes


The main cause of fears in apes is evolution. Natural selection favored apes that reacted fearfully to dangerous stimuli like predators, venomous species, or environmental hazards. Fear motivated apes to flee from or avoid peril. This enhanced their chances of survival and passing along those fear instincts to offspring. So while ape fears can seem irrational today in some contexts, they were vital protective responses in the past.


Fear responses are also driven by innate instincts imprinted in apes. Even apes hand-raised by humans with minimal exposure to threats will still exhibit fear when confronted with potential dangers like real snakes. The instincts to fear snakes, cats, or strangers served apes well over eons and do not require any learning. Apes instinctively know what to fear.


While some ape fears are inborn, others are acquired through experience and learning. If a young ape survives an encounter with a leopard, it will learn to fear that predator. If an ape falls from a tree and gets hurt, it may develop a fear of heights. Traumatic events teach apes associative fear responses for protection in the future. Social learning about dangers also occurs in ape groups.

Effects on health

Fear has many effects on apes. Acute fear triggers the sympathetic nervous system, causing a release of stress hormones like cortisol and adrenaline. This prepares the ape’s body to respond to the threat by fighting or fleeing. Chronic fear and anxiety can weaken the immune system and cause long-term health impacts. However, appropriate fear responses to genuine threats have protective effects for ape survival.

Effects on society

Fear affects ape social dynamics. Alarm calls warning of danger promote group cohesion. But unnecessary fear can be disruptive, like male chimps overreacting aggressively to each other. Leadership by dominant apes likely evolved to coordinate fearful groups against threats more effectively. Too much fear makes apes unwilling to explore and adapt. But healthy fear bonding helps social groups survive in harsh environments.

How apes cope with fear

Apes have evolved a variety of behavioral strategies to help them regulate fear and maintain wellbeing:

Social support

Being embedded in a social group buffers apes against fear. Baby apes find security clinging to mothers. Juveniles play together to learn appropriate fear responses. Adults huddle for protection and intimate social grooming to reduce stress. Simply being near protective group members provides fearful apes a sense of safety in numbers.

Information seeking

Apes often seek more information to assess the level of threat when afraid. Peering towards an unknown sound, sniffing the air, or searching for a lost group member helps apes determine risk and decide how to respond. More information can reassure apes that immediate danger isn’t imminent.

Escape and avoidance

When faced with acute fear, apes instinctively flee from the threat or avoid the fearful situation altogether. Fight-or-flight and risk avoidance behaviors likely evolved as the go-to strategies for fearful ancestral primates. Escaping or avoiding peril remains the first line of defense for modern apes when afraid.

Alarm communication

Apes vocalize loud alarm calls like screams, barks, hoots, or whimpers to communicate danger to others. Alarm calling alerts relatives and group members to the present threat, allowing them to also flee or take defensive action. Sharing information on threats helps all apes cope together.


On occasions when escape is impossible, apes may aggressively confront a threat rather than freezing in fear. Flailing, charging, throwing objects, or mobbing serves to intimidate predators or dangerous rivals. Aggression channels fearful energy into protective attack rather than paralysis.

Security behaviors

When resting after facing fear, apes often exhibit substitute behaviors that provide comfort and security, like embracing, nest-building, grooming, or playing. These behaviors seem to relieve residual stress and anxiety until the fearful stimulus has passed and homeostasis is restored.

Helping captive apes cope with fear

Zoos, sanctuaries, and research institutions that house captive apes have a responsibility to provide environments and care that minimizes unnecessary fear and anxiety. Some best practices include:

Naturalistic habitats

Enclosures should resemble the wild as much as possible, with adequate space, natural vegetation, climbing structures, and visual barriers. Familiar environments are less likely to trigger fearful responses in captive apes.

Social groups

Apes should be housed with compatible social partners, ideally consisting of related individuals spanning different age-sex classes like in wild groups. Social bonds provide security. Solitary housing causes fear.

Enrichment and choice

Enrichment like puzzles, toys, and hidden foods allows apes to exhibit species-typical foraging behaviors which reduce anxiety. Giving apes choices and control over their environment also lessens fearful uncertainty.

Positive reinforcement training

Reward-based training strengthens the bond between apes and caretakers. It also empowers apes to willingly cooperate with veterinary procedures that might otherwise cause fear due to a lack of control.

Secure attachments

Caregivers should work to build secure emotional attachments with young apes through responsive feeding, comforting, play, and protection. Secure attachments early in life provide the best foundation for confident adult apes who can cope with fears.

The future of ape fear research

There are still many open questions when it comes to understanding the nature and origins of ape fears. Further research directions include:

– Comparing fear responses and threat sensitivity across ape species and populations. Are some species or groups more innately fearful than others?

– Investigating how early life experiences and rearing conditions influence fear and anxiety later in development. Does variable parenting style affect fearfulness?

– Exploring the role of fear in the evolution of ape social complexity, relationships, communication, and intelligence. Did fear drive cognitive advancement?

– Studying how wild apes teach fear responses to each other and offspring. Is fear culturally learned?

– Using neuroimaging to map fear circuits in ape brains for comparison with human anxiety disorders. Do apes suffer clinical anxiety?

– Testing interventions like cognitive behavioral therapy to reduce trauma and unnecessary fear in captive apes. Can apes unlearn fears through therapy?

– Surveying humans living alongside wild apes to better understand the origins of mutual fear and human-ape conflict. Could cross-species fear be reduced?

– Investigating how fear and chronic stress in wild apes are affected by human encroachment, habitat destruction, and climate change. Are apes becoming more fearful of humans?

Overall, a better understanding of ape fear can benefit both human and nonhuman primate welfare, improve captive care, and inform conservation in the wild. More research on this evolutionarily important and psychologically complex topic is still needed. Overcoming fears, whether ape or human, may help advance the species.