We are Hominids, or Hominidae, also known as great apes.

Our taxonomic family of primates includes four extant genera: the chimpanzees (Pan) with two species; gorillas (Gorilla) with two species; humans (Homo) with one species; and orangutans (Pongo) with two species.

Homininae, a subfamily of Hominidae that includes members of hominini—humans, as well as gorillas, chimpanzees, bonobos and some extinct relatives—comprises all hominids that arose after the split from orangutans (Ponginae).

A number of known extinct genera are grouped with humans in the Homininae subfamily, others with orangutans in the Ponginae subfamily.

The most recent common ancestor of the Hominidae lived roughly fourteen million years ago, when the ancestors of the orangutans speciated from the ancestors of the other three genera.

The subtribe Hominina is the "human" branch, including the genus Homo, which has its beginnings in this eon, which spans a quarter of a million years.

The fossil record suggests that individuals of the species Gigantopithecus blacki are the largest apes that ever lived, standing up to three meters (nine point eight feet feet) and weighing up to five hundred and forty kilograms (one thousand one hundred and ninety pounds).

Gigantopithecus, having come into existence perhaps nine million years ago, exists to as recently one hundred thousand years ago in what is now Nepal, China, India, and Vietnam.

This places Gigantopithecus in the same time frame and geographical location as several hominin species.

In addition to the Homo genus to which we belong, other members of the family include Orrorin, Ardipithecus, Kenyanthropus, and the australopithecines Australopithecus and Paranthropus.

The name of the genus Orrorin means "original man" in Tugen, and the name of the only classified species, O. tugenensis, derives from Tugen Hills in Kenya, where the first fossil was found in 2000, followed by another score or so more in the ensuing years.

Apparently a climber of trees, Orrorin lives in dry evergreen forest environment estimated at six point one million to five point seven million years ago (Mya).

If Orrorin proves to be a direct human ancestor, then australopithecines such as Australopithecus afarensis ("Lucy") may be considered a side branch of the hominid family tree: Orrorin is both earlier, by almost three million years, and more similar to modern humans than is A. afarensis.

The relationship of the Ardipithecus genus to human ancestors, and whether it is a hominin, or not, is unknown.

The literature describes two species: A. kadabba, dated to approximately five point sixmillion years ago (late Miocene), and A. ramidus, which lived about four point four million years ago during the early Pliocene.

Like most hominids, but unlike all previously recognized hominins, it had a grasping hallux or big toe adapted for locomotion in the trees.

It is not confirmed how much other features of its skeleton reflect adaptation to bipedalism on the ground as well.

Like later hominins, Ardipithecus had reduced canine teeth.

The brain of Ardipithecus ramidus, measuring between three hundred and three hundred and fifty square centimeters, is slightly smaller than a modern bonobo or female common chimpanzee brain, but much smaller than the brain of australopithecines like Lucy (around four hundred to five hundred and fifty square kilometers) and roughly twenty percent the size of the modern Homo sapiens brain.

Kenyanthropus platyop, a three point five million to three point two million year-old (Pliocene) hominin fossil discovered in Lake Turkana, Kenya, is believed to have lived in a “mosaic” environment of grassland and some forested areas.

In contrast, their close relative, A. afarensis, found in sites such as Laetoli, Tanzania, and Hadar, Ethiopia, are believed to have spent a lot of time among trees.

Maeve Leakey proposed in 2001 that the fossil represents an entirely new hominine genus, while others classify it as a separate species of Australopithecus, Australopithecus platyops, and yet others interpret it as an individual of Australopithecus afarensis.