Page 90 - The Restless Earth Fossils

Fossils in the human Family

or destroying them. Humans again left Africa 85,000 to 90,000
years ago when the climate was right. They spread throughout the
world as H. erectus had done so long before. Nature provided one
more surprise for early humans 71,000 years ago. The volcano of
Toba on the island of Sumatra erupted with a violence 700 times
greater than Mount St. Helens in 1980. Data from ice cores and
measurements of ash layers in India and elsewhere indicate that
6 years of global winter were followed by a thousand years of
harsh climate. Worldwide, human populations may have crashed
to just a few thousand individuals. But perhaps—although there
is no way to know for sure—this, and other similar crises, may
have helped forge another change in the people who survived to
become us.

the iMagination renaissance
Humans may have walked for 6 million years, made tools for
more than 2 million years, and possessed essentially the same
body and brain size for nearly 200,000 years, but many scientists
see something unique in human behavior that appeared between
70,000 and 50,000 years ago. These examples of modern behav-
iors include

F he making of finely crafted projectile points and other tools
t
that are not only made with care and attention to detail, but
vary from region to region;
F long-distance trading for raw materials;
t
F he making of harpoons, sewing needles, awls, and other
tools with very specific purposes from bone, bamboo, and
other materials;
t
F he creation of art in the form of jewelry and, later, in the
form of cave paintings and rock art.

These behaviors imply the abilities of abstract thinking, plan-
ning for future events, innovation, and the use of symbols to
represent concepts that together create human culture. In short,

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