Galápagos: Lessons from Finches, Marine Iguanas, and Islands

Now, as we careen into the Anthropocene era, the human species has seemingly become the prime mover of ever-accelerating change; but we are nonetheless subject to it. Subject to inexorable processes of evolution. “In this changing world everything is subject to change,” says the Isha Upanishad.

The Galápagos Islands, famous as Darwin’s “laboratory” of evolution, offer us lessons in natural forces and the ever-changing world: lessons from Darwin’s finches, still diverging and evolving, still surviving—precariously; lessons of the islands themselves, born of fire extruded from deep in the earth, sliding slowly (two inches a year) eastward toward extinction; lessons of marine iguanas, the world’s only seafaring lizard, the island of their origins 10 million years ago now drifted halfway to South America and 2,000 feet under the sea, still sinking.

The Galápagos are like no other islands on Earth. The endemic finches, giant tortoises, and marine iguanas are like no other species on Earth. To see them for ourselves, to wonder at them, to learn from them—such was the purpose of a recent New Year pilgrimage for me and my wife Ruth.

They evolved powerful long tails for swimming, special glands to filter salt, snub mouths to feed efficiently on green algae, special endobacteria for digesting marine vegetation, and dark colors for absorbing enough sunlight to warm their cold blood after seafloor foraging. They learned to cooperate with finches and Sally lightfoot crabs who pick ticks, mites, and algae off their hides. They evolved to fill their own special niche and thus minimize competition. In doing so they face other risks, including powerful surf and playful sea lions. When a strong El Niño strikes and the algae die off in warming waters, marine iguanas also die, in catastrophic numbers. Such are the risks of adaptation and evolution.

The finches arrived much later than iguanas, two or three million years ago when there were only five islands. Molded by harsh terrain and shortage of food and water, they evolved into 13 distinct species, unlike finches anywhere else on earth. Each species has evolved for a particular role in an island ecosystem, a role often filled elsewhere by some other species. The insectivorous warbler finch becomes possible on islands without true warblers to compete. The woodpecker finch, adept at peeling bark and picking out grubs, becomes possible where there are no woodpeckers. Lacking a woodpecker’s coiled tongue, it fashions probes from cactus spines to reach its prey. Nectaring finches evolve where there are no bees and hummingbirds and so replace them as pollinators. Sharp-beaked finches peck at the wings of Nazca boobies, drawing blood for liquid and food. Ground finches pick ticks from underbellies of giant tortoises, who raise themselves up to aid this welcome service.