Page 113 - Encyclopedia Of World History Vol III

932 berkshire encyclopedia of world history

Observe constantly that all things take place by change, and accustom thyself to consider
that the nature of the Universe loves nothing so much as to change the things that
are, and to make new things like them. • Marcus Aurelius (121–180 ce)

evolution as the development of walking, speaking, and nized the cooling effects of upright posture, the advan-
the hunting-gathering adaptation remain subjects of sig- tages of a panoramic view, especially when striding
nificant debate. through tall grass, and the convenience of carrying food,
artifacts, or children with free hands. The occasional
Earliest Hominids bipedalism that natural selection steadily reinforced as
Despite unresolved disagreements and uncertainties, and australopithecines adapted to their special niche set the
evidence for the development of a discernibly upright stage for the subsequent evolution of every other funda-
posture in primate evolution, paleoanthropologists have mental feature that separates us from our hominoid
focused on bipedal locomotion, the peculiar human cousins. It probably contributed to such physical modi-
capacity to walk efficiently on two legs with a fully erect fications as progressive hair loss, improved sweat glands,
posture, as the key to understanding what separated our and the refinement of the human hand. By indirectly
oldest forebears from other hominoids. Indisputably,Aus- encouraging tool use and heightened levels of social
tralopithecines living in eastern and southern Africa had interaction, it may even have served as a fountainhead for
ape bodies adapted to permit upright balance and a the development of cultural behavior.
striding gait. Bipedalism represented a beneficial adap- For several decades after the discovery of Australop-
tive response to Africa’s expanding open woodlands and ithecus afarensis in 1974, paleoanthropologists devoted
savanna environments. Compelled to traverse the con- considerable attention to the fossil evidence for this rel-
siderable distances between shrinking wooded areas as atively small, gracile species known as Australopithecus
they foraged for sustenance or sought a refuge as night- afarensis, which lived in East Africa between 4 and 3 mil-
fall approached, our distant forebears must have recog- lion years ago. Still viewed by most investigators as the
common ancestor of all subsequent hominid forms,
afarensis possessed an almost humanlike skeleton below
the neck, but a braincase only about one-third that of the
IMPORTANT SITES
modern average. In the mid-1990s, archaeologists dis-
in AFRICA
ASSOCIATED with covered the remains of two other previously unknown
Fayyum
HUMAN EVOLUTION Depression hominids, Australopithecus amanensis, an apelike crea-
ture that apparently lived in the dense forests of East
N Africa at least 4 million years ago, and what researchers
originally called Australopithecus ramidus, another East
Koto Toro
Gona
Middle Aramis African species remarkably similar to chimpanzees.
Awash Bouri
Hadar Ramidus inhabited flat, forested regions as many as
Omo Koobi Fora
Lothagam 5.8 million years ago, and apparently did walk upright,
Kanapoi Allia Bay
Serengeti at least on occasion, although doubts about its capacity
Olduvai Gorge Plain
Laetoli for bipedialism have led some investigators to conclude
0 1,200 mi Valley that it should be treated as a distinct genus, Ardipithecus
Rift
0 1,200 km ramidus. If that judgment is sustained, then only ama-
nensis will be viewed as a direct precursor of Australop-
Transvaal
Makapansgat ithecus africanus, which itself completely died out 2.5
Sterkfontein
Taung million years ago, but not before giving rise to other vari-
eties of australopithecines as well as to the most ancient
members of our genus almost 3 million years ago. One of
these species, Australopithecus africanus, lived in south-