The Beak of the Finch: A Story of Evolution in Our Time

Weiner casts humankind as a central actor in the unfolding drama of global warming. At the time of Weiner’s writing, the national dialogue around climate change was tense and speculative. He does not fixate on the science but asserts that if warming proceeds as expected it will alter evolutionary processes across the planet. Exceptional weather patterns have already influenced the evolution of Darwin’s finches; the dramatic years of the drought and the flood produced the most radical selection events in the Grants’ two-decade study. Any significant changes in the climate of the archipelago would likely demand adaptive radiations, driving some species to extinction or perhaps producing something new. Trevor Price calculated that this could happen in as few as 20 generations, within the span of a century, swiftly altering the bodies or beaks that have taken millions of years to evolve. Weiner’s emphasis on speed persists in both content and style of prose as the story’s momentum builds to its conclusion.

Humans are both subject to and agents of ecological and evolutionary change: “as the dominant species on the planet, we are both an effect and a cause of evolution—masters and slaves of Darwin’s process” (276). Human activities such as agriculture and industrial production affect evolution in the species with which we share space. For example, during the Industrial Revolution in England, the soot produced from factories in Manchester blackened the trees in the surrounding landscape; a local species of white moth turned black, surviving by blending in with the now-sooty bark on the trees where they lived. When emissions were later regulated, the moth population swung back in the direction of white bodies and wings in a relatively short time.

The study of evolution is now “excruciatingly timely.” Carbon dioxide produced by humans contributes steadily to global temperature rise, which will accelerate evolution globally. With technology we can manipulate genetic material, creating rudimentary organisms, agricultural products, and animal species. This growing field may, in time, have its own drastic effects on the natural world. Weiner notes darkly that a species has risen to planetary dominance only five times in Earth’s history, according to the fossil record, each followed by mass extinction. No species has ever had such awareness of its dominance and its effect: “Never before was the leading actor aware of the action, concerned about the consequences, conscious of guilt” (277).

Many thinkers identify humans’ remarkable self-awareness as the trait that makes us unique among all other living things. Some take this as evidence of a miraculous creation; current science indicates that the trait emerged gradually, alongside the other animals. Humans first diverged from other primates when we came down from the trees and began walking on two legs. Our skulls and brains evolved quickly afterward, at some point gaining heightened consciousness, the origin of which is “one of the greatest remaining mysteries in biology” (281). Comparing consciousness to the crossbills’ unique beaks, Weiner explains that because humans arrived in the niche of consciousness first, we have dominated the niche and continue to reap its benefits, much like the crossbills and their pinecones.

Darwin theorized that with unusual traits, such as that of the human mind, variability would be exceptionally high. Diversity of mental faculty is readily apparent in the extensive specialization of human culture. Similar behavior has been observed in finches: On the island of Cocos, north of the Galápagos, members of the same finch species vary widely in hunting and nesting habits, and they pass knowledge of their “trades” on to their children. They don’t diverge and speciate because their island is too small. For humans, the planet has quickly become a small island, where we specialize but may not further diverge (284).

Humans’ speedy development is not necessarily a boon for the planet: “The rapid accumulation of change is not always progress, and forward motion is not always an advance” (289). Weiner mentions certain cactus finches on Genovesa that, when snipping the nectar of cactus flowers, snip their stigma to avoid being poked in the eye. The plants are thus sterilized, unable to reproduce. While this provides an individual benefit, it reduces the food supply of the flock, effectively “trampling on the commons” (291). This speaks to the human situation, in which a divided population habitually pursues individual benefit that ultimately threatens the species.

Weiner closes by noting Darwin’s optimistic belief that Man is “the wonder and the glory of the universe” (292). Weiner speculates that perhaps human ingenuity will outpace the challenges of a changing planet. Striking a reverent tone, Weiner draws another vivid comparison between conscious, questioning human beings and a flock of birds, implying both similarity and difference between the species. In closing, Weiner imagines an individual human watching flying birds in awe: “high above the plains of our first hours, winged only with questions” (293).

The Grants wander Daphne in the spring of 1993, during an unprecedented string of wet seasons. One of the finches the Grants trapped in the book’s opening passage has died, but the other is alive and still breeding; the scene suggests that the Grants’ work is ongoing and vital as ever. They and their students continue their research, though it is slow work, demanding years or decades of observation. Weiner contrasts this slowness with the fact that, when viewed on the scale of millennia, the Grants’ long study and all human history have been relatively brief. No one has been watching long enough to fully predict what’s next. Weiner connects the mystery of our future to popular questions of life on other planets. Humans may eventually make a “big move,” exploring and inhabiting another “island,” or planet, to visit or to stay.

At the time of Weiner’s writing, half of Americans did not believe in evolution, according to the author. The Grants and their associates tend to avoid creationists and fundamentalist Christians as a rule. On the other hand, Darwin’s formative intellectual experiences grew from a creationist tradition. At the end of his life, he was sure of evolution, but “beyond this, Darwin admitted ignorance” (298).

Weiner describes the discovery of volcanic mounds deep underwater near the Galápagos. These appear to be former islands that rose, perhaps played host to life, and then sank into the sea. The final sentences ruminate on the point that new islands continue to rise, and the islands we know now will sink. The final image depicts Daphne Major at a distance across the water; its inhabitants will “keep their covenant” with their home, continuing to live and to change (303).