Darwin's Interlude

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by Richard Crews
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A few years ago I read about three stages in the development of life on our planet. The first, called "abiogenesis" or "chemical evolution," was the fortuitous gathering together (perhaps with lightening sparking interactions) of more and more complex molecules, especially carbon molecules. This occupied the first couple of billion years of the Earth's existence.

By the end of that period the developing carbon chemistry had become complex enough to be called "organic" and, with the curious advent of self-replicating carbon compounds, "biologic."

The following few billion years (until about 10,000 years ago) can be called the "Darwinian Interlude." During that period biological systems (that's us) developed--or we can legitimately say "evolved"--according to Darwin's profound insight: through natural variation and natural selection. (Darwin's breakthrough concept has been called "the most important idea anyone ever had.") Spencer provided the term "survival of the fittest"; Mendel, the necessary statistical mechanisms of "genetics"; Gould, the broken flow refinement of "punctuated equilibrium." All in all, the theory of "evolution" seems to explain neatly how the complex living world we see around us arose from that primordial organic soup.

That is, until about 10,000 years ago. At that time a new force began to sweep across the planet, increasingly diverting and overwhelming natural evolutionary processes: modern humans appeared on the scene with their hunting, agriculture, animal husbandry, and general determination to bend the environment (including the biological environment) to their wishes. (I pause here for a round of applause.)

Granted, shifting the patterns of the Earth is like turning a battleship--it occurs slowly. For many centuries the Grand Old Lady, Earth, continued to "Darwin" along on its way. But there was a rising tide (or perhaps I should say, "a gathering storm"). The use of land (and sea and air) were increasingly determined by totally unnatural variations and unnatural selections made by human beings.

These days our species rules the Earth. We decide which other species live (and which few flourish) and which ones die. We decide what land is to grow certain plants for our pleasure, and what land is to lie fallow or die from subversion of its water and exhaustion of its nutrients.

This is a heavy responsibility. Are we up to it? Are we mature enough to manage our sweet mother planet wisely? The jury is still out on this question, but leaks from the jury room suggest that the verdict will be "no."