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Rereading Darwin

Science now takes for granted the importance of forces and time spans we can’t perceive directly

Robert L. Dorit

A Subtle Blow

By the 18th century, scientists in various disciplines had used diverse approaches to calculate the planet’s age and reached different conclusions. As they did, the Earth got older. Still, by the mid-19th century, when Darwin was writing the Origin, the age of the planet was a contentious issue. Although the 4004 B.C. date had fallen from favor, estimates still varied wildly and tended to err on the side of youth.

What Darwin realized was that a youthful Earth was appealing not only because it adhered to the biblical time line, but also because it was simply easier to imagine. He knew that his own argument for natural selection depended on vast conceptions of time, and he also understood that the time spans required would be nearly impossible to comprehend. In a section of the Origin entitled “On the Lapse of Time,” he wrote:

It is hardly possible for me even to recall to the reader, who may not be a practical geologist, the facts leading the mind feebly to comprehend the lapse of time. He who can read Sir Charles Lyell’s grand work on the Principles of Geology … yet does not admit how incomprehensibly vast have been the past periods of time, may at once close this volume.

Darwin feared that his readers would be unable to understand the deep time over which natural selection acts, and that their failure would be problematic for his argument. Those with limited imaginations might as well put away his book at once.

From the time he began writing in his notebooks after returning from his voyage on the HMS Beagle, Darwin knew that his was a radical theory, time spans aside. In 1837, 22 years before the publication of the Origin, he wrote “cuidado” (caution) in his journal as he thought about the implications of his ideas. As many have noted before, in the new Darwinian reality, human beings were still a unique species—but no more so than any other species, living or extinct. Gone forever was the notion that we were special, that our origins were unlike those of any other organism on Earth. Darwin carefully avoided mentioning human beings in the Origin, writing, in a masterpiece of understatement buried on page 488 of the first edition: “Much light will be thrown on the origin of man and his history.” Indeed.

Still, when I recently reread the Origin, I was struck by a subtler blow the book delivers to human hubris. The Origin remains, even in the 21st century, a radical work, which argues that the fundamental forces driving life on this planet occur on timescales that render the span of a human life insignificant. Furthermore, although the effects of natural selection are there for all to see, its daily operation is almost completely hidden from view. Both our life spans and our five senses are inadequate to the task of comprehension: The most powerful mechanism of organic change lies well beyond our everyday experience.

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