Humankind Advancing, Vol.9, No.1 January 1998

THE GENIUS OF DARWIN

Review

The Beak of the Finch

by Jonathan Weiner


The inner struggle of Charles Darwin, who wrestled himself free from his original belief that the efficiency of all living organisms proves the existence of a purposeful designer, constitute the heart and the core of the book. -- Based on thorough observation and reasoning alone, Darwin had taken the unique step of trusting factual evidence, even though it conflicted with his belief system and that of his time. What he concluded was that competition among living entities was sufficient to explain the generation of ever more effective and more complex variations, and that those superior in the struggle for existence would leave more offspring than those who were not. The book confirms his genius.

"The more alike the varieties," Weiner says, "the more frequently they will find themselves going for the same seed, the same nook, the same niche, at the same time. An exceptional individual will benefit under these conditions. Any escape, however partial, from that oppressive competition will be an enormous release -- almost like finding a fresh island. The lucky individual that finds a different seed, or nook, or niche, will fly up and out from beneath the Sisyphean rock of competition. It will tend to flourish and so will its descendants -- that is those that inherit the lucky character that had set it a little apart." (p.142).

Darwin and his theory have been vilified by faithful religious believers and other goodhearted persons, to whom the endorsement of heartless and ruthless competition as a source of evolutionary progress appeared abhorrent -- and in spite of its verification in following decades through countless independent discoveries in many other fields (from microbiology to geology and astronomy), the belief is still widespread that the creation of a better world demands the rejection of Darwin's conclusions.

That is not the case. Among the devices that brought enormous release from competition were symbiosis and cooperation, which occurred without awareness before the human brain developed, and consciously thereafter. Widespread collaboration in non-human nature has been documented by many recent biologists (the entire flourishing of multicellular organisms, for instance, would be impossible otherwise) without therefore invalidating Darwin's principles. What is invalidated, however, is the conviction that competition and conflict are the only avenues for further advance.

The concern of the book with this question is only implicit. Its explicit theme are painstakingly exact observations of conscientious biologists on several lonely lava outcrops in the Pacific with sparse vegetation and a restricted number of birds, esp. finches, whose physical and behavioral characteristics can be measured and described in relation to environmental fluctuations. In the harshness of this climate, and while suffering severe personal hardships, dedicated men and women were able to show, over years and decades in succession, how evolution proceeded directly in front of their eyes.

In normal years, interbreeding took place between finches that had become nearly separate species; differences tended to converge. But when prolonged drought parched the islands and nearly all vegetation wilted or was devoured, only distinctive individual attributes led to survival. The last vegetation to grow on the drought-stricken islands were thistle-like Tribulus plants, which had developed long, sharp spikes to protect their seeds. Only a few of the birds, whose beaks were strong enough to twist the spikes off and long enough to reach the seeds, could stay alive and produce some sparse offspring. 1/2 millimeter of beak length could decide their fate. The struggle was terrible. Dead birds and their bleached skulls and bones were found everywhere on the islands. Would the drought have lasted longer, the capacity of near-species to interbreed would have been lost; they would have turned into different species.

That's what happened when the vampire finches evolved (found chiefly on two rough, remote, cliff-walled islands). These birds, driven by the insanity of thirst, invented the habit of perching on the backs of boobies (web-footed seabirds) to peck on their wings and tails, draw their blood, and drink it. They smash boobies' eggs and drink their yolk -- they even drink the blood of their own dead.

The lessons for our own species from this research on evolution in action are undeniable. If increasing population pressure and unreasonable demands denude our earth of resources, the death of all surplus population is the least we have to fear. Far more dreadful will be the selective advantage of ruthlessness and cruelty.

But Weiner's book also describes examples of that harmony of nature, which is lauded as its only aspect by those who refuse to see the other side. -- Cocos, an island at the outskirts of the Galápagos, is drenched with rain almost every day. Here, vegetation flourishes year after year. Because the place is too small and isolated for speciation to occur, all finches have similar physical characteristics, the same all-purpose beak, and yet their behavior (learned rather than inherited) varies widely. These birds have discovered that individual pursuit of different specialties permits a far more efficient use of resources than would be possible if everyone would compete for the same nutrient. Unbound by inherited restrictions to a certain seed or season, they were nevertheless observed, while foraging close together in a small patch of hibiscus, "each going after food in his or her own way at the same time in the same bush, like blacksmiths, bakers, printers, and tailors in the shops around a village green. Some gleaned bugs from branches, some probed the branches, some gleaned from living leaves, some from dead, curled leaf clusters, and some sipped nectar from flowers. Whatever their mêtier, they kept at it hour after hour, day after day." (p.284) The place is a paradise.

But even a paradise can be destroyed. Some of the finches, for instance, who drink the nectar of cactus flowers, invented a way to get their sweet drink earlier in the morning, before the blossoms had fully opened, by simply clipping the interfering stigma off, which at this time of the day is lying over the delicacy. (Later, when the flower opens fully, the stigma straightens, and can be bent aside.) Discarding the stigma, of course, prevents the flower from setting fruit, and a new cactus from growing. If too many birds develop this greedy behavior, the island will be denuded. Researchers counting the clipped flowers found just a few on some islands, up to 50% on others, and one of the islands completely bare of cactus plants and nectar sipping birds. The deplorable aspect is that the "reasonable" birds are punished together with the perpetrators. The finches, of course, are unable to understand the consequences of their conduct, but the correlation with human behavior is dramatic.

How can we fan the timid glimmer of understanding within our own species? At the end of his book, Weiner points again to adaptive radiation -- the encouragement of divergence -- as one of the most successful devices of evolution. "Our minds and talents are variable for the same evolutionary reason as finches beaks are variable...And what drives this radiation within our species is a process of character divergence. Though we may not think of it as Darwinian, we all feel its pressure, wanting and needing to do what we are made for -- seeking the task for which we are most fit." (P.288) -- If we are fortunate, one of these variants will lead to a new ethic that selectively encourages whatever is best for our earth and our descendants.

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Jonathan Weiner, formerly a writer and editor for The Sciences, is author of Planet Earth and The Next One Hundred Years.