How Humans Became Masters of the Earth

NEW-YORK — Why is it that humans emerged from the natural world, yet we portray ourselves as modifiers of it, even its adversaries?

Paleoanthropologist Rick Potts thinks that fluctuations in the environment in which our ancestors lived were responsible. Our ancestors responded by becoming more versatile through a suite of changes that included an ability to modify our environment. Potts' theory is known as the variability selection hypothesis.

Human ancestors adapted "to novelty and to change itself," he told an audience here at a conference on climate change and human evolution at Lamont-Doherty Earth Observatory yesterday (April 19).

Our species, Homo sapiens, has existed for a mere 200,000 years, but since our line split from that of our closest living relatives, chimpanzees, more than 6 million years ago, global climate has grown increasingly variable, fluctuating between warm and ice-age extremes, but becoming cooler overall.
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