How Strong Is a Chimpanzee? What Studies Actually Show

How much stronger than a human is a chimpanzee?

For decades, books and websites repeated that a chimpanzee is several times stronger than a grown man. In 2017, a team led by Matthew O’Neill published a study in the Proceedings of the National Academy of Sciences that tested the idea directly.

The researchers first reviewed the available strength data and concluded that, per kilogram of body mass, chimpanzees perform on average about 1.5 times better than humans in pulling and jumping tasks. They then measured the properties of individual chimpanzee muscle fibers and built computer models of whole muscles. Their result: a chimpanzee muscle produces about 1.35 times the maximum force and power of a human muscle of the same size.

That is a real advantage, but a modest one. Because wild male chimpanzees usually weigh 34–70 kg (75–154 lb) and females 26–50 kg (57–110 lb), a typical chimpanzee is lighter than a typical adult man, so its total strength is impressive rather than superhuman.

Where did the “five to eight times” myth come from?

The legend of chimpanzee “super strength” goes back to the 1920s. Early tests at a zoo used spring scales and pulling devices and reported that some chimpanzees pulled several times as much as strong men. These tests were not well controlled: the number of trials was small, the apes and people were not tested in the same way, and the human volunteers were not necessarily trying their hardest.

Later experiments in the 1940s, in which chimpanzees pulled on ropes attached to a measuring device, gave far lower results, with adult chimpanzees performing no better than adult men. A basic problem runs through all such tests: no one can tell an ape to try its best. A chimpanzee may give up, get bored or pull in bursts of excitement, so its true maximum is very hard to measure. Large round numbers such as “five times” or “eight times” were repeated long after the studies themselves had been forgotten.

Why are chimpanzees so powerful?

The 2017 study found that, fiber by fiber, chimpanzee and human muscle work in much the same way. The differences lie in the mix of fibers and how they are arranged:

• More fast-twitch fibers. About two thirds of the fibers in the chimpanzee muscles tested were fast-twitch fibers, which contract quickly and powerfully. Human muscles generally contain a higher share of slow-twitch fibers, which are better for endurance.
• Longer muscle fibers. Longer fibers can contract over a greater distance and at higher speed, which increases power.
• Body proportions. Chimpanzees have long arms, broad shoulders and short, strong legs. Their body is built for climbing, hanging and swinging, which demands bursts of strength in the arms and shoulders.

Everyday life keeps them fit, too. Chimpanzees climb tall trees many times a day to feed and to build sleeping nests, and males perform vigorous charging displays in which they drag branches and throw objects.

Why did humans lose strength?

The study’s authors suggested that the human lineage gradually lost some maximum power over the past several million years. Muscles rich in slow-twitch fibers are less explosive but use energy more efficiently and resist fatigue. That suits a species that walks and runs long distances on two legs, carries food and children, and makes fine, repeated movements with the hands.

So the difference is a trade-off rather than a simple win for chimpanzees. A chimpanzee is better at short bursts of power; a human is better at endurance.

How does a chimpanzee compare with other apes?

For the largest ape, see How strong is a gorilla?, and for other record holders, our list of the strongest animals.

Are chimpanzees dangerous?

Even without “super strength,” an adult chimpanzee is a powerful and quick animal with long canine teeth, and males can be aggressive, especially toward strangers. Attacks on people are rare in the wild and mostly happen near villages and farms. Former pet and entertainment chimpanzees have also caused serious injuries, which is one reason chimpanzees should never be kept as pets. Anyone visiting chimpanzees in the wild should go only with trained guides and keep the distance required by the park.