Current nomenclature divides the apes into two distinct families: the greater apes and the lesser apes. Historically, apes were classified together in the family Pongidae, which excluded humans. Now there are two families, Hominidae and Hylobatidae. The greater apes comprise the family Hominidae, consisting of gorillas, chimpanzees and bonobos, orangutans, and humans. There has been much discussion on the nomenclature of the great ape. Current DNA evidence implies that humans share a common ancestor with the chimpanzee/bonobo line and that this ancestor is extinct. On the primate family tree, humans separated much more recently than the gorilla did. When looking at the family tree, the four African great apes shared a common ancestor between 8 and 10 million years ago, the orangutan and gorilla separating from the ancestral line prior to chimpanzees, bonobos, and humans.
With the advent of DNA analysis, a new understanding of primate genetic diversity has come about. Chimpanzees, gorillas, humans, and orangutans are all more closely related to one another than any of these four genera are to the gibbons. Humans, chimpanzees, and bonobos share 98.4% of the same DNA sequence. Gorillas share 97.7% of their DNA with humans, chimpanzees, and bonobos. Orangutans share 96.4% of their DNA with humans, chimpanzees and bonobos, and gorillas. One important difference between humans and great apes is humans’ comparative low level of genetic variation. Just like cheetahs, which have little variation in their genes, humans went through a population bottleneck of approximately 10,000 people, which greatly diminished genetic variability. Signs of past bottlenecks are also evident in the populations of western chimpanzees.
All living members of the family Hominidae have no tails and differ from the lesser apes by being larger in size, spending more time upright, having fewer young, and having a higher level of parental investment. Apes have five molars in the Y-5 pattern as compared to the Old World monkeys, which have four molars in a bilophodont pattern. Apes have a more mobile spine compared to Old World monkeys. These are all anatomical adaptations to the apes’ vertical hanging and brachiation locomotion. Except for gorillas and humans, all true apes are agile climbers of trees. Their diets are best described as omnivorous, consisting of fruit, grass seeds, and in most cases small quantities of meat either hunted or scavenged, along with anything else available and easily digested. Gorillas, chimpanzees. and bonobos live in Africa, in complex social groups. Orangutans live as solitary individuals in the forests of Indonesia.
Apes’ forward-pointing eyes were used to spot potential predators, prey, and social signals. An evolutionary adaptation to a life in socially complex groups gave way to a large, complex brain. Chimpanzees and orangutans are known to make simple tools to extract insects from holes and extract nuts from hard shells. Tool making involves a preconceived image of what the tool will look like. The capacity to visualize the scenario is possible only with an advanced brain. Orangutans have even been observed untying knots, unscrewing large bolts, working out for themselves the steps necessary to achieve a complex task. The hominids were able to master tool use and shape their environment. Great apes also have the capacity to understand and communicate using abstract symbols and gestures, such as American Sign Language.
All ape species, except humans, are rare or endangered. All great ape loss, whether it be caused by habitat destruction, the pet trade, or the bushmeat trade, is a consequence of humans overpopulating the globe at an alarming rate, resulting in social and environmental changes.
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