Watch what happens when a chimpanzee snaps – even lions back off

There are some people in this world that are completely enamored with chimps. People who want to own them, dress them up, and love them like children. But chimps are not children, and pretending like they are can be the worst mistake you ever make. What draws many people to chimps, and what makes certain people see them as children, is exactly what makes me wary. That they're our closest living relatives, and we share 98.8% of our DNA with them. I think I've avoided making this video for that exact reason. Learning about chimps, in many ways, is like looking into a mirror. And I've feared that it's a mirror that would reflect the worst parts of us. Just like humans, they can be violent, vengeful, veering into the sadistic. They wage full-on wars with one another, and even cannibalize their enemies. And this fact has made me avoid wanting to learn too much about them. But if you take a bigger perspective, chimps are probably the single most fascinating animal to study on this planet. Because chimps are extremely intelligent. So intelligent that sometimes, chimp intelligence seems to even exceed our own. Evidence shows that chimps have photographic memory. Something that almost no adult human has. And this incredible intelligence allows them to lead extremely complex lives, with strong social cohesion, empathy, and friendship. And yet, violence is a pillar of their highly sophisticated society. Why is violence so important in the lives of chimps? Why do they have photographic memory? And do they have the capacity to understand the atrocities they commit? Chimpanzees are great apes that inhabit the dense ancient forests and grasslands of Africa, from Senegal to Tanzania, where the echoes of their calls resonate through the canopy. And although chimps are our closest living relatives, we have dramatically different ways of moving about the world. We are obligate terrestrial bipeds, meaning we are built to walk on two feet all the time. Our feet have a longitudinal arch and an enlarged, robust calcaneus. These help stiffen the foot, and store elastic energy that can be released during the contact of each foot to the ground. Additionally, our big toe is aligned in parallel with our other toes, giving our foot a lever shape that makes walking long distances easy and efficient. We don't have any prehensile ability with our feet, maybe beyond picking up dirty laundry and flinging it into the basket. And when humans walk, our hips and ribs swing in opposite directions. This saves energy. Chimps, on the other hand, can walk on two hind legs, and will occasionally do it, but it's not how they usually get around. In fact, they have an opposable big toe, or hallux, making their whole foot resemble a hand. And it can grasp much like a hand can. And they don't have as much of a stiffening arch. Anteaters also swing their hips more than humans when they walk on their two feet, and their ribs move in the same direction as their hips, which is less efficient. So instead, they usually walk quadrupedally, using a style of locomotion called knuckle-walking. This is where they curl their fingers into a fist and put their body weight on their knuckles. Only the African great apes, and oddly some anteaters, pangolins, and platypuses do this. But why? What does this odd group of animals have in common? These animals all have highly specialized front feet, needed for things other than locomotion. Anteaters and pangolins have extremely long claws that they use for digging up insects that can get in the way of walking. Platypus fingers have webbing that extends past the fingers to aid in swimming, so knuckle walking helps them not trip. And chimps, bonobos, and gorillas have long fingers that would become overextended and get in the way of regular walking. Knuckle walking also allows the African apes to carry stuff like fruit or tools while still walking on four legs. And those long fingers are a crucial adaptation needed to securely grip branches during brachiation, a form of arboreal movement where chimps swing from branch to branch. And their fingers aren't just long, but curved. When we grasp a horizontal pole, our straight fingers sort of make a square shape and pressure is unevenly spread. But when the curved fingers of a chimp grasp a pole, their fist is more circular and pressure is more evenly spread across the pole. And even though the distance between the pole and the bones of the fingers are the same in both, the chimp can grasp a much bigger pole. And this grip is strong. Grip strength is the amount of force a person or chimp exerts when holding onto an object, or how tightly they can grasp something. The average healthy grip strength for men is a squeeze of about 73 pounds or 33 kilograms, while women typically measure around 44 pounds or about 20 kilograms. The sources vary on this, but some report that the grip strength of an adult chimpanzee is around 440 pounds or 200 kilograms, while other sources claim figures of up to 730 pounds or 330 kilograms. The source here isn't great, and it's in Russian, so I'm not really sure if this is correct, but it's not so hard to imagine. Chimpanzees find most of their preferred foods in tree canopies, and thus have to have incredible grip and upper body strength. Chimps are known to hang by one arm for 35 minutes a day. I could probably do this for about 5 seconds. Chimps have long been known to have what many call super strength. For a long time, it was said that chimps have the strength of 5 men. And this, too, is probably an exaggeration. But a study in 2017 worked to quantify the differences in strength and muscle between chimps and humans. And the reality is still striking. Fast twitch muscle fibers are skeletal muscles that contract quickly and create a lot of explosive bursts of energy, like throwing a punch or launching a jump. Human muscle is composed of 40% fast-twitch fibers, and chimpanzee muscle is composed of 67%. And the same study found that pound for pound, chimps' muscles are 1.5 times stronger than ours. Chimps also have denser bones and stronger tendons, which contribute to their ability to handle and apply greater force without injury. So in one swift motion, a chimp could easily rip your face off. But it doesn't stop there. Chimps also have enormous canines, especially the males. These formidable teeth are weapons of war. They're used as threat displays, and when necessary, will tear an enemy apart. Chimps are arguably the most violent of any of the great apes, besides humans. They wage wars, engage in murder, and even cannibalism. And they notably attack and brutally maim human caregivers, or captors depending on how you want to look at it, more than any other ape. During attacks, chimps will target a person's hands, face, feet, and genitals. Why are they seemingly so much more brutal than the other great apes? Violence in the great apes is not completely uncommon. males sometimes fight one another for territory or mates. And while gorillas are definitely formidable, severe aggression is rare in stable gorilla groups. With bonobos, the closest relative to chimps, the males do sometimes fight, but overall they're considered a peaceful ape. And humans, well, you know. But violence in chimp societies feels different. And it started to come to light in the early 1970s, When primatologist Jane Goodall and her colleagues started studying chimps in Gombe Stream National Park in Tanzania. And during the course of their observations, they watched a group of chimps descend into a horrific and bloody civil war. A once-unified group was spread over the lower Kokombe Valley, consisting of 14 adult males and 25 females. But soon, seven males started hanging out in the community's southern edge, forming a southern subgroup. At first, contacts between these groups remained peaceful, but slowly a fracture began to form. The southern subgroup was now akin to a group of separatists trying to claim some territory for themselves. This would prove to be a fatal mistake. The first blood was spilled on January 7th, 1974, when six male chimps from the northern main group ambushed a single southern subgroup male and beat him to death. Later the northern males, and intriguingly one female, isolated another separatist male and killed him too. And the targeted attacks continued. Next was the most tragic. An elderly male from the separatist group named Goliath was located by the northerners. And Goliath greeted his old friends amicably. But this didn't stop them from brutally attacking him and even as they tore away at him, Goliath could not bring himself to fight back against the chimps that were once his friends. Soon after, another male vanished, never to be seen again, assumedly also attacked and killed. At this point, there were only three males of the separatist group left. The next male's death wasn't observed by the researchers, but fishermen heard sounds of a fierce and ugly fight, and days later, a corpse was found. Next, another male disappeared without a trace. The last remaining male held on for over a year. The scientists hoped he might escape or be welcomed back into the main group. But no, they killed him eventually too. And it wasn't just the males that were killed. Several females were also brutally attacked, killed, or kidnapped. The northern males succeeded in quelling this separatist movement. But peace was short-lived. Soon after, another war broke out between the winning group and another neighboring group. The separatists had acted as a buffer, and that buffer was gone. Violence was a part of life for years for chimps in this area, with territories constantly shrinking and dividing, alliances being broken and built. These observations sent shockwaves through the scientific community. And it wasn't just the fact that these chimps killed each other, it was how gut-wrenchingly brutal the killings were. Witnessing this violent reality of chimps for the first time haunted Jane Goodall. That was very shocking when I realized chimps are capable of extreme brutality and violence just like us. It was really horrifying. In her 1990 memoir, she wrote about how she would lay awake at night remembering the images of chimps drinking blood from their victim's body. Of hurling enormous rocks at an already incapacitated enemy. At ripping each other apart by the skin. At chimps beating another to death. A chimp that the assailant once looked up to. And worst of all, she remembered one chimp eating another's baby, her mouth smeared with its blood. It's hard to unlearn certain facts about chimps. It's so hard that for a long time, people didn't want this violence to be true. They wanted to blame it on humans. In fact, they blamed Jane Goodall for it, saying without her interference, none of it would have happened. The crux of this argument was that Goodall and her colleagues would leave bananas in a clearing, to draw the chimps in to better observe them. And soon, fighting began over the bananas, and then all-out war erupted. No one had ever witnessed this level of chimp brutality before, so it makes sense that some people were trying to blame an outside influence. But a new analysis looked at hundreds of combined years of observations, a comprehensive overview of chimpanzee killings. And they found that human impact, like habitat disturbance or feeding by researchers, had no bearing on how many killings occurred at a given research site. And for the chimps at Gombe, they concluded that the war likely began due to an existing power struggle between three high-ranking males, exacerbated by a competition for females with low reproductive availability. Chimps are just naturally territorial, and naturally pretty brutal. Males need to fight to expand territory, to be able to obtain more food for themselves, for their mates, and their offspring. The same study found that the best predictor of violence among chimps is the number of males in a community and the population density. The more males, and more chimps in general, the higher the likelihood that there will be bloodshed. Today, we know that intergroup aggression is a widespread characteristic of chimpanzee societies. Attacks by other chimps are the second most frequent cause of death. As for why chimps are so much more violent than, say, gorillas, it's hard to say for sure. It could be down to chimps fighting over more precious resources. Or it could be that chimps are smarter. They can strategize things like ambush hunting, and have more complex mating hierarchies within their communities. And even though in the wild, chimp violence is not caused by people, in other situations, it very much is. Travis was born on Connie Casey's compound in Festus, Missouri, the subject of the new HBO docuseries. He was taken from his mom at three days old and sold for $50,000 to Sandra and Jerome Herold in Stamford, Connecticut. Sandra and Jerome treated Travis like their child, and he went everywhere with them. He was socialized to people since birth and even appeared on TV for things like Pepsi ads. He could open doors using keys, dress himself, and often sat at the dinner table and drank wine with the rest of the family. By adulthood, Travis weighed 200 pounds or 90 kilograms. And in 2009, their happy family life was no more. He's killing my girlfriend! What is the problem? He's killing my friend! Who's killing your friend? Jim, my chimpanzee! Listen to me! They gotta shoot him, please! Please, hurry, hurry!" Travis attacked and mauled Sandra's friend, Carla Nash, for 12 minutes. She did survive, but Travis had torn away her eyelids, nose, jaw, lips, and most of her scalp. He'd broken nearly all of the bones in her facial structure and bitten her hands almost completely off. Travis had to be shot and killed by the police. This is not fun to talk about, but is the devastating reality of keeping chimps as companions. And it's easy to want to paint Travis as a horrific monster in this scenario. But chimps are wild animals. They are not babies, they are not people, and they are not monsters. Travis's violent nature was simply ignored. But I don't doubt that the people who have lived with chimps sincerely love them. And I don't doubt that there can be a very real connection between humans and chimps, however misguided. Because chimps have the capacity for meaningful friendships and complex social bonds. Social bonds made possible by their profound intelligence. Chimps are known to live in groups that range in size from 15 to 150 individuals in what is known as a fission-fusion society. The total hierarchical group is known as a fusion of chimps, but within each large group, smaller sub-communities form. These are called fissions, sort of like cliques in a high school cafeteria. But unlike band or soccer or Yu-Gi-Oh!, the glue that holds these groups together and the basis of nearly all chimp friendship and alliance is grooming. Picking little bugs, parasites, dirt, plants, dead skin, whatever, out of each other's fur. And the amount of grooming between primates is considered to be an indicator of their relationship quality. And sometimes it's, uh, quite intimate. For chimps, there is no such thing as a private part. From our human perspective, this is kind of scandalous and funny, but all chimps, and even male chimps, touch each other unselfconsciously. Male chimp friendship sort of stands out as being kind of unusual among animals. For most animals, males compete for access to females and for rank. They're not friends. But male chimps groom each other and spend much of their time together. For a long time, it was assumed that these relationships were fleeting, with the animals only interacting over short periods to fulfill an immediate need. But a 2009 study found that male chimp dyads, meaning pairs of two, would be close friends for years, sometimes up to 10 years, with half of all the subjects being homies for at least 5 years. Bonds were particularly strong if the chimps had the same rank, or if they shared a mom — meaning that they were actually half-brothers. So what is the purpose of such tight male friendship in chimps? One reason is resource sharing. Meat, for example, is a precious and valuable resource, and when it's obtained, it's shared with a chimp's closest friends. Male chimp dyads also back each other up when it comes to dominance. They give each other coalitionary support. These coalitions are vital for challenging higher-ranking males or defending against potential rivals. In the competitive environment of a chimpanzee group, having allies increases an individual's chances of rising in rank, which in turn provides better access to resources, mates, and protection. Males similarly make close friendships, for protection and resource sharing, and tend to make friends with similarly ranked females, and sometimes with males too. Some bonds are stronger than others, and this creates an entire complex network of relationships, just like in human societies. And this can get complicated. But chimps have a strong memory, and this enables them to remember past interactions with others, including who has been helpful or hostile. And recently scientists discovered that chimps and bonobos have the longest long-term memory ever found in any non-human animal. In 2023, researchers showed bonobos and chimpanzees side-by-side pictures of other members of their species. One picture was a stranger, the other picture was a former groupmate that they hadn't seen in a very long time. The scientists tracked the ape's gaze to see if they would preferentially look at the ape that they once knew. And sure enough, they did. One bonobo recognized a picture of her sister that she hadn't seen in 26 years. And it's not just their long-term memory that's incredible. Their short-term memory is so good that they sometimes remember things better than humans. In one study, numbers 1 through 9 appear on a screen. The test subject needs to remember the spatial location of these numbers. After a short time, the numbers are replaced by boxes, and the subject needs to repeat the pattern that the numbers were in. Here's another example for you to try. Here is a series of numbers on screen. Count them, try to remember where they are. Now let's replace these numbers with boxes. Can you remember exactly what the order was? Making it even more difficult is the increasing speed of the test. In the first trial, the numbers are on screen for 650 milliseconds. The next, 430. The next, just 210 milliseconds. Here's my attempt at this game. Even when I study the numbers, I'm not that good at this. And when the numbers are just a flash, it's hopeless. This is impossible. In the experiment, the scientists tested humans, adult chimps, and 5-year-old chimps. The chimps had been previously taught the order of the numbers and how to use a touchscreen, which is impressive on its own. In the trial, the humans did about as bad as I did, and so did the adult chimps. But now watch as the younger chimps complete this task with amazing speed and precision. Even at the shortest duration of the numbers being on screen, a small fraction of a second, essentially just a flash, the young chimps nailed it. But 210 milliseconds isn't even enough time for the eyes to scan the numbers. For this reason, scientists think that young chimps have a type of photographic memory, called eidetic memory. This is the phenomenon where a subject can memorize an accurate, detailed image of a complex scene or pattern. And it seems that all young chimps can do this. Some young human children can do this too, but only about 2-10% of them. And it usually fades. For chimps, it fades too, but their memory still seems to trump ours. This becomes particularly clear in a competitive video game setting. In a 2014 study, researchers set up an experiment involving a two-player game. In front of each player is a left or right square on a touchscreen panel. The goal for one player is to try to get their selection to match the other player. The goal for the other player is to try to make their selections not match. The two players can't see each other's selections, and their opponent's choice is displayed only after both have selected. In games like this, the players are guessing what their opponent is going to do based on their previous choices, and they adjust their own choices accordingly. In a perfectly optimum world, both players make the most strategic choices, and an equilibrium state emerges. Scientists can predict what this equilibrium state is using game theory. But the world is not perfectly optimum, and players don't always make the best choices. In the study, scientists had pairs of humans play this game, and pairs of chimps. When humans played, their guesses were far from optimum, and their games drifted far away from equilibrium. But chimps, on the other hand, played a nearly perfect game. Their games were much closer to equilibrium. Since the game is a test of how much the players can recall their opponent's choice history, along with a test of how well they can employ strategy based on this history, these results suggest that chimps have both a better memory than us, and better use of strategy than us. But why? What would be the evolutionary purpose of this incredible working memory? In the wild, scientists think that this memory skill might be useful for memorizing fruit locations at a glance or making a quick map of all the branches and routes in a tree. It might also be useful for quickly identifying threats, something humans don't need to worry about as much. Instead of a strong working memory, our brains have evolved for things like language. Human brains and chimp brains are simply prioritizing different things. So with all of this memory, intelligence, social intricacy, and brain capacity, do chimps really know what they're doing when they commit heinous acts of violence? Are they capable of cruelty in a human sense? Inflicting physical and mental pain deliberately, knowing that suffering will result. Jane Goodall believed that only humans are capable of evil, because she believed chimps cannot consider the pain and suffering they inflict. I know she was probably trying to make herself feel better about witnessing chimps eat each other's babies, But I don't necessarily agree with this. Some light gets shed on this debate by looking at the concept called theory of mind. The ability to understand that other individuals have mental states, like beliefs, intentions, and knowledge. For a long time, scientists believed that no other creature besides humans had this ability. That even our closest living relatives, the chimps, could only understand surface-level behavior, and never grasp the psychological states of others. But bit by bit, studies have been refuting this. And certain studies that specifically involve competition for food are the most compelling. The basic idea is that when competing with others for food, chimps take into account what their competitor can and cannot see, what he can and cannot hear, and even what he does and does not know. In one study, for example, two chimps compete to grab food. One chimp was dominant, and one chimp was subordinate. In this series of experiments, these chimps competed for two pieces of food. One of which could be seen by both of them, and one that could only be seen by the subordinate individual because a barrier was blocking the dominant's view of it. Would the subordinate chimp know to go for the food that the dominant one couldn't see? Results showed that subordinates did prefer to pursue the hidden food, suggesting that they do understand what information another individual has. And other experiments have had very similar results, with chimps even recently being found to have a basic understanding of false beliefs. These studies basically go like this. The chimps are shown a video of person A placing an object in box A. Person A leaves the room, and person B moves the object to box B, without person A seeing. The scientists then measured where the chimps looked when person A returned to the room to gauge if they would expect Person A to look in Box A or Box B. And it turns out the chimps looked in the original location, suggesting that they understood Person A would not know the object had been moved. That is, they understood Person A had their own set of beliefs and view of the world, separate to Person B, and separate to themselves. False belief tests are considered to be the litmus test for theory of mind, Because they assess an individual's ability to understand that others can hold beliefs that are different from reality and from their own beliefs. So chimps do seem to grasp that others have their own unique and personal experiences. So back to the question of whether or not chimps can commit evil. Or at least whether or not they know how much damage and suffering they cause. I think we have to collectively admit that they totally know what they're doing. That they know ripping someone's face off is going to cause profound suffering. That eating someone's baby is going to cause distress. But whether or not this is evil is hard to say. I think it's incredibly difficult to not imagine human emotions and human intent within the actions of chimps. But maybe we shouldn't. They are so similar to us, but they are not us. They are wild animals, who do what they have to do to survive in a complex, competitive, and sometimes brutal environment. So at this point in the video, you might be having some complex thoughts about chimps. I know my feelings straddle between horror, awe, and total empathy. Empathy for the chimps who are kept in human homes. Empathy for the ones kept in cages. Empathy for the ones who did harm a human and got shot by police. Like with so many wild animal encounters that go badly, it's really the humans that are to blame. And my empathy for chimps doesn't stop at the ones in weird people's basements in Missouri. The ones in the wild are also facing dire threats from humans, mostly in the form of poaching and habitat destruction. It's estimated that there are only 170,000 to 300,000 chimpanzees left in the wild, with some populations on the brink of extinction. My opinion has always been that if we want to talk about conservation, let's have some solutions in mind. Rather than dwell on how terrible humanity is, let's figure out how we can make things better.