Evolutionary Background, Close Relatives, and Taxonomy
Gorillas are fascinating creatures because they are so like humans, yet still obviously have many very different qualities. Both humans and gorillas share a common ancestor which was some sort of primate millions of years ago, however somewhere down the line the species diverged into two separate lineages. One of these ultimately evolved into gorillas and chimpanzees, while the other evolved into humans. Researchers believe that Gorillas began to differentiate from other apes and monkeys because they began to evolve into a larger and stronger species, which in turn caused a loss of agility and the gradual loss of a tail because their bodies eventually became too heavy to swing from trees. Instead, they began to swing with their powerful arms, which is why their arms are longer and stronger than their legs. These strong arms also help for balance, and although they are able to stand and walk in an upright position, they are more comfortable on all fours with their knuckles being the point of balance.
The taxonomy of the Gorilla is as follows:
Species: Gorilla and Beringei
Gorilla scientific classification has been divided into three subspecies based on where each is geographically located in Africa. The Western Lowland Gorilla (Gorilla gorilla gorilla) is the smallest of all three subspecies. These gorillas typically live in the tropical forests of West Africa, and are the most common in zoos. The Eastern Lowland Gorilla (Gorilla gorilla graueri) is slightly larger in size and typically resides in the rain forests of central Africa. Finally, the Mountain Gorilla (Gorilla gorilla beringei) is the largest and rarest of all the subspecies. These are naturally found in the Virunga Volcano range of Africa, and have darker coloring than the other subspecies because of the high altitudes in which they live.
It is very common to confuse apes with monkeys because the two words are often (wrongly) used interchangeably. However, I would like to try and clarify a distinction between the two. Gorillas are classified as apes, while others, like baboons for example, are classified as monkeys. The main detail that differentiates apes from monkeys is that apes do not have tails while monkeys do. Also, apes typically having larger body sizes and weights, as well as more of an upright body position. Great apes also tend to be more ground-dwelling than monkeys who are typically more tree-dwelling. This distinction has led to many evolutionary changes in the muscle and skeletal structure of the arms of apes because they are not as adapted to things like swinging from trees as monkeys are. So, while gorillas indeed appear to be very similar to their other primate relatives, it is important to keep in mind the details and characteristics that separate them as apes from monkeys.
Fun Fact: Humans are more closely related to chimpanzees and gorillas than either of them are to orangutans!