The chimpanzee, one of the four species of great apes in the animal kingdom, is an extremely powerful animal. An adult male is approximately five times stronger than a male human being. Despite their use in motion pictures and circuses and their humanlike appearance, they can be extremely dangerous whether they intend it or not, simply because of their great strength.
In an interview with Discover Magazine, world-renowned primatologist Dr. Jane Goodall referred to an incident with a chimpanzee that led her to estimate his strength at eight times her own. Although Dr. Goodall is a slender woman, not a bodybuilder, most sources agree that a chimpanzee's strength, while often exaggerated, can be reasonably estimated at about three to five times that of an average man. Whether or not a chimpanzee could win a tug-of-war with a champion bodybuilder is another question. Even if one could persuade a chimpanzee to participate in such a contest, their human competitors have far greater-than-average strength themselves. Either way, it is safe to conclude that given the wide disparity in these estimates, an adult chimpanzee may be as little as twice as strong as some people, or as much as eight times as strong as others.
Chimpanzee strength can be traced to a number of factors, including their body and muscle structure, the demands of their semiarboreal lifestyle, the interaction between their musculature and nervous systems and the influence of genetics.
Dr. John Hawks, Associate Professor of Anthropology at the University of Wisconsin, points to a combination of skeletal muscle structure and genetics as part of the reason for the chimpanzee's strength. The muscle fibers of the chimpanzee are longer than those of a human, enabling them to generate twice the work output over a wider range of motion. He also points out that certain genes that limit muscle development have been deactivated in the human, but are still present in the chimpanzee.
In addition, primatologist Dr. Ann MacLamon's research indicated that the motor neurons in the spinal cord that control muscle function in the human are less prevalent in the chimpanzee, giving the animals immediate access to far greater muscle power than humans have. This enables the chimpanzee to use far more of its potential strength than is possible for a human being, due to the constraints our nervous systems place upon us
Chimpanzees stop being cute and cuddly upon reaching adolescence, which begins after the animal passes the age of 5. At that point, they begin to assert dominance in order to secure their place in the troupe. When their "troupe" is a human family, this can have disastrous results. This innate and inescapable biological tendency, coupled with their great strength, makes the primates entirely unsuitable as pets.
A recent and tragic example of what can happen is the case in which a chimpanzee named Travis attacked and severely wounded his owner's friend and neighbor. Travis had been a pet for 14 years. He had been taught by his owner to wear clothing, drink wine and eat steak and lobster. He had figured in television commercials and was almost a mascot in the neighborhood, but one day in February of 2009 he lashed out, and although his victim survived the attack, she was badly disfigured. Travis, however, did not survive. Attempts by his owner to stop him failed, and he was shot and killed by a police officer.
According to Dr. Franz de Waal, a primate specialist and lead biologist at the Yerkes National Primate Research Center in Atlanta, this is not surprising behavior in an adult chimpanzee. He describes Travis as a "time bomb" whose behavior, while it might serve him well in the wild, makes him a hazard in a human household.
Despite the incidence of attacks on humans, experts such as Dr. Jane Goodall and Dr. de Waal agree that chimpanzee attacks are not motivated by malice, meanness, evil or hatred. They are usually the tragic results of a chimp being a chimp. In the wild, they are in competition with other chimpanzees who are at least as strong or stronger than they are. In captivity, these dominance displays are directed against human beings. Chimpanzees may not know exactly how strong they are, but they are quick to learn that they're stronger than we are.
For a chimpanzee to survive in the wild, physical strength is absolutely essential. It must be able to climb rapidly in order to escape predators and find food, it must be able to manipulate and bend large tree branches to make its nest each night, and it must be able to defend itself against dominance attacks from other chimpanzees.
In her book "In the Shadow Of Man," Dr. Jane Goodall documented the day-to-day lives of the chimpanzees at the Gombe Reserve. She saw first-hand the dominance displays, hunting behaviors previously unknown in chimpanzees, and conflicts between neighboring troupes that she described as war. None of these behaviors are possible without the physical strength to carry them out. Her pioneering research, and that of many others, all show that pound for pound, the chimpanzee is an extremely powerful animal with strength that far exceeds its size.