Paul Ehrlich talks about Earth's dominant animal

To track how humans became Earth's dominant animal, Ehrlich began
with a photo of a tarsier in a tree. The little primate had a
predator's binocular vision and an insect-grabber's fingers. When
(possibly) climate change drove some primates out of the trees, they
developed a two-legged stance to get around on the savannah. Then
the brain swoll up, and the first major dominance tool
emerged---language with syntax.

About 2.5 million years ago, the beginnings of human culture became
evident with stone tools. "We don't have a Darwin of cultural
evolution yet," said Ehrlich. He defined cultural evolution as
everything we pass on in a non-genetic way. Human culture developed
slowly-the stone tools little changed from millennium to millennium,
but it accelerated. There was a big leap about 50,000 years ago,
after which culture took over human evolution---our brain hasn't
changed in size since then.

With agriculture's food surplus, specialization took off. Inuits
that Ehrlich once studied had a culture that was totally shared;
everyone knew how everything was done. In high civilization, no one
grasps a millionth of current cultural knowledge. Physicists can't
build a TV set.

Writing freed culture from the limitations of memory, and burning old
solar energy (coal and oil) empowered vast global population growth.
Our dominance was complete. Ehrlich regretted that we followed the
competitive practices of chimps instead of bonobos, who resolve all
their disputes with genital rubbing.

"The human economy is a wholly-owned subsidiary of the Earth's
natural systems," said Ehrlich, and when our dominance threatens the
ecosystem services we depend on, we have to understand the workings
of the cultural evolution that gave us that dominance. The current
two greatest threats that Ehrlich sees are climate change (10 percent
chance of civilization ending, and rising) and chemical toxification
of the biosphere. "Every cubic centimeter of the biosphere has been
modified by human activity."

The main climate threat he sees is not rising sea levels ("You can
outwalk that one") but the melting of the snowpack that drives the
world's hydraulic civilizations--- California agriculture totally
dependent on the Sierra snowpack, the Andes running much of Latin
America, the Himalayan snows in charge of southeast Asia. With
climate in flux, Ehrlich said, we may be facing a millennium of
constant change. Already we see the outbreak of resource wars over
water and oil.

He noted with satisfaction that human population appears to be
leveling off at 9 to 10 billion in this century, though the remaining
increase puts enormous pressure on ecosystem services. He's not
worried about depopulation problems, because "population can always
be increased by unskilled laborers who love their work."

The major hopeful element he sees is that cultural evolution can move
very quickly at times. The Soviet Union disappeared overnight. The
liberation of women is a profound cultural shift that occurs in
decades. Facing dire times, we need to understand how cultural
evolution works in order to shift our dominance away from malignant
and toward the benign.

In the Q & A, Ehrlich described work he's been doing on cultural
evolution. He and a graduate student in her fifties at Stanford have
been studying the progress of Polynesian canoe practices as their
population fanned out across the Pacific. What was more conserved,
they wondered, practical matters or decoration? Did the shape of a
canoe paddle change constantly, driven by the survival pressure of
greater efficiency, or did the carving and paint on the paddles
change more, driven by the cultural need of each group to distinguish
itself from the others.

Practical won. Once a paddle shape proved really effective, it
became a cultural constant.

--Stewart Brand
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