The subspecies that spend more time in the trees, have less specialized anatomy. Gorilla subspecies that rely on knuckle-walking to different degrees have notably different levels of adaptation. The degree of specialization in certain hand and feet bones is related to degree of arboreality even within gorilla subspecies. For more on gorilla metacarpal morphology and knuckle-walking, read here. These bone features only exist in knuckle-walking apes. The bone shape is slightly different and it has a ridge that prevents joint hyperextension during knuckle-walking. In their hands, the third metacarpal bone is uniquely evolved for knuckle-walking. Therefore, gorillas have unique forearm and wrist bones that interlock to create a stable structure. Repetitive stress loads on bones and ligaments can cause deterioration and stress fractures. Gorillas have specialized adaptations to support knuckle-walking that are evident in their hand structure.īone structure in the hands and forearms of gorillas reflect adaptations to support their immense weight during knuckle-walking. Arboreal monkey and ape species rely on brachiation, swinging from branch to branch, more so than quadrupedalism. Some other apes, like orangutans, are arboreal, meaning they spend more of their time in the trees than on the ground like terrestrial species. Gorillas are the most terrestrial of the non-human great ape species. During knuckle-walking, the ape bends its fingers on its front hands (not quite in a fist) and their middle knuckles strike the ground. Knuckle-walking is a form of quadrupedal locomotion which is movement on four feet. Gorillas locomote, or walk around, via knuckle-walking. How do gorillas walk? Mountain Gorilla ( Gorilla beringei beringei) knuckle-walking. She could understand over 2,000 spoken words and could respond with sign language. Interestingly, in California, a female gorilla by the name of Koko was taught over 1000 different signs for American sign language and could effectively communicate with her handlers. They also use a large array of tools such as rocks and sticks for processing food. Gorillas are also documented using various gestures for communication, including social grooming. Having an opposable thumb allows for greater dexterity, tool use, and social interactions. Gorilla hands share this trait with humans. Old world monkeys including the great apes, baboons, macaques, and others have opposable thumbs like humans. New world monkeys including capuchins and lemurs have a pseudo-opposable thumb that is not truly opposable but does have some functionality. The only primates with non-opposable thumbs are marmosets and tarsiers. Only a few mammals other than primates have opposable thumbs, such as opossums, koalas, and panda bears. Primates are unique in the animal kingdom because of their opposable thumbs. What is unique about primate hands? This infant gorilla is using its opposable thumb to grasp and chew on a stick. Considering the timeline of mammal evolution (with the first mammal arising 65 million years ago), this is quite recent! The close evolutionary histories of gorillas and humans explain many of the similarities that appear between the species. The lineage that includes chimpanzees and humans diverged from a common ancestor with gorillas about 12-17 million years ago. As such, they are closely related to orangutans, chimpanzees, bonobos, and humans. They are the largest primate on Earth and are a member of the great apes. There are two species of gorilla and four subspecies: western gorillas (including western lowland gorillas and Cross River gorillas) and eastern gorillas (including eastern lowland gorillas and mountain gorillas). Gorillas are large terrestrial mammals that live in Africa primarily in Rwanda, the Congo, Uganda, Angola, Cameroon, Central Africa, Equatorial Guinea, Gabon, and Nigeria depending on the subspecies. What are Gorillas? A male eastern lowland gorilla sits in the brush.
If they are so similar, what makes human and gorilla hands different? This article explores some of the interesting similarities and differences between human and gorilla hands. Although most people could probably tell a gorilla hand and a human hand apart, humans and gorillas are close relatives that share many similarities under their fur and skin.
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