Field Work

A Story of Evolution in Our Time
By Jonathan Weiner
Knopf, 332 pp.

If nature abhors a vacuum, journalism despises common knowledge. On that basis alone, this book should be a disaster.

It is a work of popular science that recounts not the birth of a revolutionary theory, but the confirmation of an old and established one. Journalism generally prefers rupture and surprise.

Journalism also requires above all a narrative trajectory – which means deeds and personalities, usually in some sort of conflict. But The Beak of the Finch is an account of the most grindingly pedestrian aspect of scientific research: the rote accumulation of data. There are no deeds beyond measurement and number-crunching. There are no personalities to speak of. There is only the description of how the data were gathered, and the pellucid explanation of what they reveal.

Still, what the field work confirms are ideas as crucial to modernity as those of Marx, Freud and Einstein. The book is about how Darwin was not only right, but more right than he knew. The result is enlightening, intelligent and engaging – which is a testament to Darwin’s genius and the ingenuity of the researchers putting his theory to the test, as well as the skill of Jonathan Weiner, a former writer and editor for The Sciences and the author of two previous popular science books. As a dividend, The Beak of the Finch exposes the standard rules of science journalism as formulas made to be broken.

Weiner’s starting point is an irksome and persistent blind spot in evolutionary science. Darwin held that life evolved via the action of natural selection: Individual animals better adapted to their surroundings would have more offspring than their less hardy kin, simply because they stayed alive longer or were more desirable mates. Therefore, the conditions of the wild worked to propagate certain attributes rather than others. As environmental circumstances shifted – as climactic change killed off an animal’s customary food supply, for example – the shape and behaviour of subsequent generations changed in response, as selection pressures favoured different characteristics.

When it was published in 1859, On the Origin of Species was more than revolutionary – it was heretical. It argued that the breathtaking variety of life on Earth had neither been created nor ordained by an omniscient architect. Instead, every plant and animal on the planet was a mechanistic reaction to an infinitely complex set of competitive pressures. Life had indeed evolved, and continued to do so right before our eyes – although in such slow motion as to be invisible.

At the time, the theory struck the progressive-minded intelligentsia as a bolt of insight. They could taste the truth of it. But if natural selection worked on variations within populations, even Darwin couldn’t explain where these variations came from in the first place. That gap was filled in later with an understanding of genetics, from chromosome shuffling to DNA mutation. The problem that remained, however, even after the theory became orthodox, was its gradualism.

Logic said the theory was correct. So did a mass of circumstantial evidence, from the fossil record to animal husbandry. But the fact remained that no one had actually seen natural selection measurably change the contours of a species. And because everyone assumed it happened so gradually that it couldn’t be detected in a human lifetime, no one actually looked carefully.

Enter Peter and Rosemary Grant, whose work forms the spine of The Beak of the Finch.

For the past 20 years, the Grants have run the world’s most painstaking bird-watching program under the world’s most arduous conditions. Every year they head south from Princeton University to a deserted volcanic rock in the Galapagos (“the biggest ashtray in the world,” according to their graduate students) where they spend every working hour monitoring, capturing, banding and measuring every one of all 13 species of finch on the island. What they’ve shown is exactly what Darwin predicted, happening faster than he ever imagined.

The Galapagos islands are especially suited to this sort of study, since they’re natural laboratories: isolated and self-contained ecosystems, simple enough for the researchers to be able to see the forces of natural selection at play. These are also the islands that inspired the young Charles Darwin, naturalist aboard HMS Beagle, to first think along the lines of evolution.

It turns out that the pressures of natural selection exert themselves on the most minute variations with profound effect – a fraction of a millimeter in the length of a bird’s beak can make all the difference. The fifth season of the Grants’ finch watch, for example, saw an exceptionally harsh drought that dwindled the birds’ food supply of plant seeds and killed six out of every seven finches.

The team’s meticulous measurements demonstrated that the birds that survived had larger-than-normal beaks: In the scramble for food, nature had favoured those able to crack the toughest seeds. As well, more males had survived than females, providing the females with their choice of mates once the rains returned and breeding season began. Systematically, the females chose the most powerful males, again pushing the population toward larger beak size. In the space of a year, the Grants’ team had documented what Darwin thought it might take centuries to notice.

Besides the Grants’ study of the Galapagos finches, The Beak of the Finch deals with comparable studies of Hawaiian fruit flies, Venezuelan guppies and B.C. sticklebacks – all of which show the same thing. (Gratifyingly, Canadian universities loom large in this story. Researchers at Queen’s and the University of British Columbia are in the forefront, and the Grants began their field work while at McGill.) In sum, the book is a compelling overview of the power of Darwin’s ideas. This is science writing at its most accomplished: both an account of how science is done and an eloquent illustration of why we do

  • Globe and Mail July 2, 1994