It is believed that Hominids diverged from other Hominoids around 6 m.y.a. - it was recently announced that paleoanthropologists in Kenya had discovered fossil fragments which could date back this far. However, until a formal description of Orrorin tugenensis is presented, the oldest recognized Hominid fossil remains Ardipithecus ramidus.

Australopithecus (southern apes) and Paranthropus
This is a genus of Hominids that lived in Africa from the late Miocene (around 5.3 m.y.a.) to the beginning of the Pleistocene (about 1.6 m.y.a.). Believed by most paleoanthropologists to by an ancestor of modern humans, but there is disagreement as to whether the various forms of Australopithecus represent a single lineage or a number of parallel species. The australopithecines were bipedal and had a brain capacity roughly the same as that of modern apes. There are two distinct categories: gracile and robust. Gracile skulls have finer facial features, the robusts have large jaws and strong teeth. The robust form is considered to be a separate genus by many and given the name Paranthropus (near man).

Australopithecus anamensis (southern ape of the lake)
Discovered by Meave Leakey and the Kenya National Museum hominid team in 1994 at Kanapoi on the shore of Lake Turkana, northern Kenya. Australopithecus anamensis lived between 4.2 and 3.9 m.y.a. in riverine woodland or bushland. A single tibia (knee bone) is the earliest proof of bipedalism.

Australopithecus afarensis (southern ape of Afar)
The famous example, Lucy, was discovered in 1976 at Hadar, Ethiopia, by Don Johanson and was named after a Beetles song. Fossil footprints attributed to afarensis were discovered at Laetoli, Tanzania, in 1978 by geochemist Paul I. Abell. Australopithecus afarensis lived between 3.8 and 2.8 m.y.a. in broken woodland (a mixture of terrestrial and arboreal habitat). Post-cranial bones show it was adept at walking upright and capable of running.

Kenyanthropus platyops
The discovery, from the western shore of Lake Turkana in northern Kenya, was announced by Meave Leakey in March 2001. Kenyanthropus platyops is dated to between 3.5 and 3.2 m.y.a. It is claimed to represent a completely new branch of the hominid family tree.

Australopithecus barelgazeli
In 1995 French paleontologist Michel Brunet discovered part of a fossilized jaw at Koro Toro, Chad (2,400 km west of the Eastern rift Valley), which closely resembled that of afarensis. This species is dated to 3.3 to 3 m.y.a.

Australopithecus garhi
Discovered by Tim White in 1997 near the village of Bouri, in the Afar region of Ethiopia -- garhi means surprise in the Afar dialect. Australopithecus garhi is dated to between 2.5 and 2.3 m.y.a., exhibits a mixture of gracile and robust features, and was found in association with stone tools.

Australopithecus africanus (southern ape of Africa)
The Taung skull, described by Raymond Dart in 1925, is the most famous example. The skull is more developed than that of afarensis whilst the body is more primitive. Australopithecus africanus is dated to between 3 and 2.3 m.y.a. and lived in broken woodland -- although the light bone structure suggests it was primarily a tree dweller.

Paranthropus aethiopicus
The earliest of the robust hominids, aethiopicus has been found at Lake Turkana and in Ethiopia. The most famous specimen is The Black Skull which was stained black during the fossilization process. Paranthropus aethiopicus is dated to between 2.5 to 2.3 m.y.a. and used its massive teeth and jaws used to process low-nutritional plant material found on the savanna.

Paranthropus boisei
Specimens recovered from Lake Turkana, Kenya and the Olduvai George, Tanzania, were originally classified as Zinjanthropus by Louis Leakey in 1959 -- it was also the first hominid found outside of South Africa. Paranthropus boisei is dated to between 2 and 1.2 m.y.a. and probably evolved from aethiopicus. Massive jaws and molars, largest of any hominid, led to the common name of Nutcracker Man.

Paranthropus robustus
The South African form of robust hominid first discovered by Robert Broom in the 1940s at Kromdraai near Sterkfontein. Paranthropus robustus is dated to between 1.9 and 1.3 m.y.a. There is a controversy over the origins of robustus which is a contemporary of the East African boisei -- if it evolved from africanus rather than aethiopicus, as is claimed by many South African paleoanthropologists, it should have a separate genus to the East African robusts, i.e. it is not a Paranthropus.

Homo rudolfensis
Originally classified as the male form of Homo habilis, it was later re-classified as a separate species Homo rudolfensis. Specimen KNM-ER-1470 was discovered at Koobi Fora near lake Turkana in 1972 (when it still retained its colonial name of Lake Rudolf) by Richard Leakey. Homo rudolfensis is dated to between 2.4 and 1.9 m.y.a. It has recently been suggested by Meave Leakey et al. that it belongs to the newly identified genus of Kenyanthropus.

Homo habilis
Discovered by Louis Leakey, Phillip Tobias and John Napier at Olduvai George in Kenya in 1961. It has since been found in a wide variety of locations along the Rift Valley, as well as the Omo River valley in Ethiopia, and potential finds at Swartkrans, South Africa. Homo habilis is dated to between 2.3 and 1.6 m.y.a. It is considered by many to be an advanced form of gracile australopithecine rather than Homo.

Homo ergaster
Turkana Boy, the best example of ergaster, was discovered by Richard Leakey and Alan Walker at Nariokatome on the banks of L. Turkana in 1984. (This specimen is also known as Narikotome Boy.) Homo ergaster is dated to between 1.75 and 1.4 m.y.a.

Homo erectus
Although specimens of erectus were found in Morocco as early as 1933, a positive identification was not made until Louis Leakey found fossil 'OH 9' at Olduvai George, Tanzania in 1960. Homo erectus is dated to between 1.6 and 0.3 m.y.a. and is believed to have evolved from Homo habilis or Homo ergaster.

There is a lack of fossil remains in Africa for the period 1.5 to 0.5 m.y.a., though there are many signs of erectus in terms of tools and camp sites. The diamond digging areas of N. Cape, for example, have a large number of rich Achuelian tool sites. In addition, the study of the Swartkrans deposits, South Africa, suggest that erectus had mastered fire by 1.1 m.y.a.

Homo erectus was first hominid to migrate out of Africa -- starting around 1.5 m.y.a. and reaching Java and China by 1.2 m.y.a. -- bringing to an end the period for which Africa was the lone home for humankind's ancestors.

A future article will look at the evolution of hominoids before 6.m.y.a.

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