Lemurs: Lemurs exist only in the very limited, isolated territories of the Comoro Islands and Madagascar. They live in densely forested, jungle environments, and it isn’t hard to see how they have adapted to make the most of the space they occupy. Most lemurs’ time is spent in trees, although there are some families that spend a relatively large amount of time on the ground. Lemurs locomotor patterns include clinging and quadrupedal locomotion, and it is a testament to their isolation that lemurs possess such diverse locomotor traits. Because they face little to no competition with, and predation from, other species, they are able to occupy multiple areas within the forest, both low to the ground and high in trees. Of note are the sifakas, which have extremely large legs that allow them to easily jump between tree environments but restrict ground locomotion to hopping instead of walking; unlike other lemurs, they also have only vestigial tails. The highly specialized locomotor patterns of the lemur are well adapted to their very unique environment.
Lemur
Spider monkeys: Spider monkeys are also primarily arboreal primates. They prefer to remain in the high trees of rainforests and mangrove forests in Central and South America and spend little time on the ground. When they do, they exhibit quadrupedal locomotion; usually, they can be found climbing or using suspensory locomotive traits, like brachiating, to move among trees. The spider monkey’s development of suspensory locomotion is clearly a very useful adaptation to the densely forested habitats in which they live. Generally speaking, it seems less useful to have highly developed quadrupedal locomotion in an environment where much of an animal’s time is spent moving in and among trees (although spider monkeys still exhibit this type of locomotion during the limited times they are on the ground, and when they are eating).
Spider Monkey
Baboons: Baboons are Old World primates that can be found in various terrestrial environments within Africa. They are generally found on savannahs and hills. Baboons primarily exhibit quadrupedal locomotion, and some subspecies have even developed quite efficient bipedal locomotion, especially during feeding. They have powerful hindquarters and legs, and can move quickly across the ground. These abilities can be viewed as adaptations to their generally treeless and open environment: baboons live in relatively arid climates devoid of sheltering trees and forestation, and at the same time face predation from large cats and humans. The ability to use locomotor traits effectively on the ground in such environments is invaluable to the species.
Baboon
Gibbons: Gibbons are rainforest dwelling lesser apes that can be found in south and East Asian locations. They exhibit traits uniquely suited to brachiation, which is the type of locomotion they use most commonly. One such trait is a specialized ball-and-socket joint in the wrist that is able to allow the hand and arm a greater range of motion and agility during swinging. Brachiation is a highly efficient type of locomotion given the rainforests gibbons are native to. With little need for ground locomotion and thick groves of trees to move among, swinging is a useful adaptation for gibbons’ navigation of their environment.
Gibbon
Chimpanzees: Chimpanzees can be found throughout Africa, especially along the Congo River basin. Their primary habitat is rainforest, but they can adapt to living situations in woodlands and savannahs as well. They are highly intelligent and highly adaptable to changes in environmental structure. This is reflected in their unique locomotor patterns. Chimpanzees “knuckle walk” by dragging their knuckles along the ground and using them for support during bipedal locomotion. They can also walk fully upright in certain instances, such as when using a tool or performing a task that requires the use of both hands. Chimpanzees also brachiate when swinging and exhibit climbing and other suspensory behaviors as needed. The variation in environments the chimpanzee inhabits is reflected in the adaptation of its locomotor traits to accommodate various circumstances. The locomotion of the chimpanzee has also adapted to reflect the chimp’s use of its environment, such as upright bipedal locomotion during hand use.
Chimpanzee
Summary: The most pronounced differences in primate locomotive adaptation seemed to occur between the primarily arboreal and the primarily terrestrial primates. It also seemed that the more intelligent, and the more adaptive, primates have locomotor patterns that have adapted in response to their interaction with the environment. Clearly, the huge difference in locomotion between tree and ground primates is directly related to the habitat of each primate, and it is therefore relatively easy to see why the adaptations took place and why locomotor patterns differ so widely between primate species.
