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This hominid is one of the gracile australopithecines. Its known fossil range is approximately 2.7-4.0 mya, which makes it the precursor of Australopithecus africanus (2.0-3.0 mya, and the successor of Australopithecus anamensis (3.9-4.2 mya) (see Human Evolution Timeline >>).
Discoveries of Australopithecus afarensis remains have occurred only in eastern Africa (at Koobi Fora and Lothagam in Kenya; at Belohdelie, Fejej, Hadar, Maka, and Omo in Ethiopia; and at Laetoli in Tanzania). Most of the material has been collected in the vicinity of Hadar, in the Afar region of northeastern Ethiopia (see map) — So this is a hominid best known from Afar.
The Hadar site yielded the famous "Lucy," a set of skeletal remains (see picture, below right) from a single Australopithecus afarensis individual dating to 3.2 mya (Johanson and Maitland 1981). The sex of this specimen was inferred from pelvis morphology (i.e., width of the pelvic opening).
In life, Lucy had a height of approximately 1.1 meters (~3' 7") and weighed about 30 kilograms (~66 lbs). She was bipedal and yet had tne cranial capacity of an ape (Johanson and Maitland 1981), which shows that bipedalism preceded increase in brain size during the course of human evolution (this is under the assumption that it can be taken for granted that Lucy actually was ancestral to modern humans, a disputed point in scientific circles).
Certainly, the earliest indisputable proof of bipedalism in a hominid dates to the time of Australopithecus afarensis — Mary Leakey discovered actual footprints at Laetoli, similar to those of a small modern human being, preserved in hardened volcanic ash that, given their age (3.5 mya), were probably made by A. afarensis individuals (although the recently discovered Kenyanthropus platyops also dates to this period).
No shaped stone tools are associated with A. afarensis remains. However, a recent paper (Harmand et al. 2015) reports the discovery of such tools in Kenya that are contemporary with A. afarensis. They date to between 3.11 and 3.33 mya. Previously, the earliest stone tools known dated to approximately 2.5 mya (Semaw et al. 1997, Semaw 2000), A. afarensis which was consequently put out of the running as a stone tool maker.
There is no evidence that hominids of this type used fire. The habitat in which they lived, apparently, was a mixed savanna-woodland environment.
Lucy was discovered by Donald Johanson in 1974. Her skeleton is in the collection of the National Museum of Ethiopia in Addis Ababa, Ethiopia. Numerous additional A. afarensis fossils have been collected since the discovery of Lucy, but the remains of no other individual have been as complete.
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