Geography Reference
In-Depth Information
Geography is history. From the geographic factors that determined the course of evolution to the fact that
people built their cities near rivers to all the wars that men have fought to get what was on the other side
of the hill, geographic factors have shaped the events that have shaped our world.
Until now, this topic has looked at what the world looks like without too much interference from people.
Now the emphasis shifts. This chapter sets out to condense about five million years of human history into
an overview of the geographic factors that have brought our maps to their present state.
Are We All “Out of Africa”?
Library shelves are groaning with rival paleontologists doing an evolutionary version of Abbott and Cos-
tello's famous “Who's on First?” routine that might be called “Who Came First?” The crux of the debate
is where on the human family tree certain fossils discovered during the past two decades fit. The bickering
between rival camps has not been pretty.
But there are many basic points of agreement. Rounding things out a bit, it is safe to say that human
precursors were on the scene four to five million years ago. That seems like a long time. But that time
period represents about one thousandth of the earth's life span. Pretty humbling stuff.
And none of the rival bone-hunting camps dispute the notion that those precursors came from Africa.
To simplify matters, the primate and human fossil record goes something like this. Human precursors
called
australopithecines
(“southern apes”) seem to have emerged in Africa four to five million years ago.
By 2.5 million years ago, these upright walkers were at home in both trees and on the ground and were
probably using crude tools made of bone and stone. Perhaps the most famous of them is paleontology's su-
perstar, “Lucy,” a remarkably complete skeleton found in 1974 by a team led by Donald Johanson. Dated
to more than three million years ago, Lucy was also known as
Australopithecus afarensis
, because the skel-
eton was found in the Afar region of Ethiopia. In 1984, another team working in Kenya found the jawbone
of an
afarensis
that was dated to five million years ago, the oldest known representative of the hominid
line.
Why Africa? Geography has everything to do with this. To paraphrase bank robber Willie Sutton, who
said he hit banks because that's “where the money is,” Africa is where the primates were. And the evol-
ution of the primate behavior and physiology that finally produced humankind was fostered by the geo-
graphic factors of climate and topography. During this much cooler time in the earth's history, the Sahara
was a fertile region teeming with large-animal life, and much of the African rain forest was replaced by
grasslands, where the ability to walk upright was advantageous for seeing across the open savanna. The
