On a desert island in the heart of the Galapagos archipelago, where Darwin received his first inklings of the theory of evolution, two scientists, Peter and Rosemary Grant, have spent twenty years proving that Darwin did not know the strength of his own theory. For among the finches of Daphne Major, natural selection is neither rare nor slow: it is taking place by the hour, and we can watch. In this dramatic story of groundbreaking scientific research, Jonathan Weiner follows these scientists as they watch Darwin's finches and come up with a new understanding of life itself. The Beak of the Finch is an elegantly written and compelling masterpiece of theory and explication.
One of the details I hadn't appreciated is that evolution isn't just slow because changes are tiny, but because most of the time there are a variety of selective pressures pushing in different directions. The Grants observed a measurable and statistically significant change in the average beak size of the finches in response to a single catastrophic drought; however, a few years later, a massive El Nino produced another measurable effect in the opposite direction. So evolution dithers around the current average conditions, but several drought years in a row -- perhaps the result of climate change, for instance -- could produce a measurable effect much more quickly than I imagined.
This is engagingly written and well-aimed at the intelligent layperson who doesn't know the details of biology; it perhaps errs a bit on the side of caution (explaining the evolution of antibiotic resistance in bacteria, for instance, which is pretty well-known and could probably have been assumed), but overall I recommend it highly.
In a famous passage in his seminal book, Darwin wrote:
It may metaphorically be said that natural selection is daily and hourly scrutinising, throughout the world, the slightest variations; rejecting those that are that bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers…. We see nothing of these slow changes in progress, until the hand of time has marked the lapse of ages, and then so imperfect is our view into long-past geological ages, that we see only that the forms of life are now different from what they formerly were.
[The Beak of the Finch], published in 1994, tells of a long-term (and still ongoing) research project that reveals evolution in action. Written by Jonathan Weiner, a teacher of science writing at Columbia University's Graduate School of Journalism, the book was awarded the Pulitzer Prize for general nonfiction in 1995. It's entirely readable. And it's an important report on what scientists now have observed about how natural selection works.
The project was launched in 1973, when Dr. Peter Grant and his wife and research partner Dr. Rosemary Grant, accompanied by several post-doctoral assistants, traveled to the Galápagos archipelago, and settled for a couple of months on a small, deserted, volcanic cone jutting from the ocean. Daphne Major, the Grants' island laboratory, has little vegetation but it's inhabited by frigatebirds, boobies, mockingbirds, hawks, and--most important--several species of finches, collectively known as Darwin's Finches. What the team did was capture, measure, and band every finch. The species of each finch was determined, and measurements of the birds were meticulously recorded in special waterproof notebooks. Meteorological data likewise was recorded daily. Close observation provided information about what the different finches ate, breeding preferences, longevity, and so on.
At the end of the season, the Grants returned home and keyed their data into a computer. They wrote scientific, academic papers describing their findings, gave lectures, taught in colleges. Most important, they repeated the enterprise year after year for two decades. They lived with and recorded the finches through the worst drought, a year in which many of the birds died of starvation. They collected data through the wettest year. And each fall, back at college, the Grants would transfer their handwritten records into the computer. A computer, of course, allows a massive database to be searched and sorted, and facts pertinent to questions, propositions, ideas, and theories are put at researchers' fingertips.
Alterations and variations in the beaks is telling. Weiner writes:
There are about nine thousand species of birds alive in the world today….Flamingos' beaks have deep troughs and fine filters, through which the birds pump water and mud with their tongues. Kingfishers' beaks have such stout inner braces and struts that a few species can dig tunnels in riverbanks by sailing headlong into the earth, over and over again, like flying jackhammers. Some finch beaks are like carpentry shops. They come equipped with ridges inside the upper mandible, which serve as a sort of built-in vise and help the finch hold a seed in place while sawing it open with the lower mandible.
According to his [Darwin's] theory, even the slightest idiosyncrasies in the shape of an individual beak can sometimes make a difference in what that particular bird can eat. In this way the variation will matter to the bird its whole life…"
Evolution by natural selection works. The Grants and their cadre of assistants have seen it. They have documented it. Their work has, of course, inspired additional such research around the world, focusing on other species of birds, of fishes, of insects. Research using DNA is ongoing, and it is demonstrating the evolution is in the world's DNA.
This is an in depth look at the evolution of these finches and the continuing selective pressure they are under as they continue to evolve, season by season, as each year brings a bit different conditions to these islands.
Most of this is seen through the lens of Peter and Rosemary Grant, two dedicated scientists who have devoted their careers to the teasing out the secrets of evolution as shown by these birds.
It's not just about finches, though, as later chapters deal with topics such as climate change, pesticide and antibiotic resistance.
This classic book was first published in 1995 and won a Pulitzer. Nevertheless, while older, the information is still solid. I feel this book is accessible and downright fascinating.