Homo ergaster

Homo ergaster Fossil range: Pleistocene
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Subfamily: Homininae Tribe: Hominini Subtribe: Hominina Genus: Homo Species: H. ergaster
Binomial name
Homo ergaster Colin Groves & Vratja Mazak, 1975

Homo ergaster (Greek derivation: working man), an early hominid (refer also to hominim), may either have been a predecessor of Homo erectus or an early group of Homo erectus. H. ergaster’s presence has been dated variously and may have ranged over a period of 1.9 to 1.5 million years ago. Remains of H. ergaster have been discovered in Kenya and Dmanisi in the Republic of Georgia.

Description

H. ergaster had a rounded cranium and a prominent browridge. Compared to Australopithecus, its teeth were significantly smaller. Features that distinguish H. ergaster from H. erectus were thinner bones of the skull and the lack of an obvious sulcus, or depression, immediately posterior of the browridge.

Associated artifacts

Tool making and use

H. ergaster evidently used large cutting tools of stone, primarily hand axes and cleavers. These tools represent an advanced stage of stone tool technology known as the Achulean stone tool industry now believed to have developed after hominid migration out of the region of eastern Africa.

Important fossils

KNM ER 3733 cranium

Discovered by Bernard Ngeneo in Koobi Fora, Kenya in 1975, ER 3733 is a mature female that may have lived about 1.75 million years ago.

KNM ER 3883 cranium

Discovered in 1976 by Richard Leakey, the ER 3883 is a skull cap which retains an intact right orbit. ER 3883 has no sulcus or depression behind its large browridges.

Found in Koobi Fora, Kenya, ER 3883 was originally thought to be species Homo erectus but has been reclassified as Homo ergaster. ER 3883 may have belonged to a male that lived about 1.5 million years ago.

KNM ER 992 mandible

ER 992 was discovered in 1971 by Richard Leakey in Koobi Fora, Kenya. It is dated to about 1.5 million years ago. The ER 992 mandible shows a lighter build and smaller teeth than Homo erectus.

KNM WT 15000 (Turkana Boy)

Turkana Boy is a nearly complete skeleton discovered in West Turkana, Kenya, August 22, 1984 by Kamoya Kimeu. It is one of the most significant finds in paleoanthropology. TW15000 is the skeleton of an immature boy, about 9-12 years of age, already more than 5 feet in height at the time of death Its height is a significant increase in size over earlier hominids which were about the size of modern chimpanzees. At maturity it might have attained a height of about 6 feet and approximately 150 lbs. WT 15000 lived about 1.6 million years ago. Cause of death is unknown.

WT 15000 cranial capacity is measured at 880cc and might have attained an adult cranial capacity of 909cc.

WT 15000 had slender hips that were better adapted to walking and running over long distances than other hominids. Arm and leg bones were proportioned more like those of modern humans, rather than the shorter legs and longer arms (or more ape-like proportions) of Homo habilis and Africanus afarensis. The long and slender, body was likely more adapted to a tropical environment, an inference drawn from the fact that most modern humans that live in the tropical areas are similarly built.