Ape is a common, yet rather imprecise, name for some animals of the order Primates. Its earliest meaning was a tailless (and therefore exceptionally human-like) non-human primate, but as zoological knowledge developed it became clear that taillessness occurred in a number of different and otherwise unrelated species.

Modern scientific usage includes as apes:

  • the families Hylobatidae (6 species of gibbons and the siamang), known as lesser apes
  • the family Hominidae or great apes, consisting of Gorillas (Gorilla gorilla), Chimpanzees (common chimpanzees, Pan troglodytes and bonobos, Pan paniscus), humans (Homo sapiens), and Orangutans (Pongo pygmaeus).

The great ape family was previously referred to as Pongidae, and humans (and fossil hominids) were omitted from it, but on grounds of relatedness there is no argument for doing this. Chimpanzees, gorillas, humans and orangutans are all more closely related to one another than any of these four genera are to the gibbons and siamangs. Awkwardly, however, the term "hominid" is still used with the specific meaning of extinct animals more closely related to humans than the other great apes (for example, australopithecines. It is now usual to use a subfamily to separate the hominids, in this narrow sense, from the extant non-human members of the family Hominidae.

Current evidence implies that humans share a common, extinct, ancestor with the chimpanzee/bonobo line, from which we separated more recently than the gorilla line. All living members of the Hylobatidae and Hominidae are tailless, and humans can therefore accurately be referred to as bipedal apes. However there are also primates in other families that lack tails.

Both great apes and lesser apes fall within the infra-order Catarrhini, which also includes the Old World monkeys of Africa and Eurasia. Within this group, both families of apes can be distinguished from monkeys by the number of cusps on their molars (apes have five - the "Y-5" molar pattern, monkeys have only four in a "bilophodont" pattern). Apes have more mobile shoulder joints and arms, ribcages that are flatter front-to-back, and a shorter, less mobile spine compared to monkeys. These are all anatomical adaptations to vertical hanging and swinging locomotion (brachiation) in the apes.

The original usage of "ape" in English may have referred to the baboon, an African monkey. Two tailless species of macaque are commonly named as apes, the Barbary Ape of North Africa (introduced into Gibraltar), Macaca sylvanus, and the Sulawesi black ape or Sulawesi Crested Macaque, M. niger.

Except for gorillas and humans, all true apes are agile climbers of trees. They are best described as omnivorous, their diet 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. They are native to Africa and Asia.

Most ape species are rare or endangered. The chief threat to most ape species is loss of tropical rainforest habitat, though some populations are further imperiled by hunting for bushmeat.

Cultural aspects

The intelligence and humanoid appearance of apes are responsible for legends which attribute human qualities; for example, apes are sometimes said to be able to speak but refuse to do so in order to avoid work. They are also said to be the result of a curse -- a Jewish folktale claims that one of the races who built the Tower of Babel became apes as punishment, while Muslim lore says that the Jews of Elath became apes as punishment for fishing on the Sabbath. Christian folklore claims that apes are a symbol of lust and were created by Satan in response to God's creation of humans. It is uncertain whether any of these references is specifically to apes, since all date from a period when the distinction between apes and monkeys was not widely understood, or not understood at all.