Over the next five weeks, while helping to charter the Galapagos Islands, Darwin noticed something peculiar about the finches – although they were all clearly from the same species, each island’s population had developed various adaptations to help them survive in the different environments. This observation was the spark that would develop into his most famous and controversial theory: Natural Selection.
Darwin did not compile and publish his observations and theories until 24 years after his original journey to the Galapagos Islands. In 1859, after much discussion with other like-minded scientists, he released “The Origin of Species.” By then, he had already gained much acclaim as a naturalist, and his book immediately caught the attention of the masses.
While many falsely credit Darwin with theorizing evolution itself, that idea originally owes to Jean Baptiste de Lamarck (who died at the age of 85, two years before young Darwin set sail with the Beagle). While Lamarck concluded that some kind of evolution of species must take place, he could not figure out how it happened. That’s what Darwin was able to solve with his theory of natural selection.
Natural selection, or survival of the fittest, is the idea that only the animals with the best adaptations to their environments will survive and pass on their genes to their offspring. After centuries or millennia in a certain environment, different populations of the same species may evolve entirely unique adaptations that allow them to survive in their specific habitat. Or, in the words of Darwin himself, “One general law, leading to the advancement of all organic beings, namely, multiply, vary, let the strongest live and the weakest die.”
This theory was considered blatant heresy – at the time, the powerful Church supported the idea of Creationism, in which all creatures were designed by God exactly as they are today. When Darwin set sail in 1831, already vaguely familiar with Lamarck’s ideas on evolution, Darwin too was a creationist. The overwhelming evidence of evolution that he witnessed in the Galapagos Islands, however, compounded with his own theories of natural selection, were enough to change his mind.
Though it caused quite the controversy when he originally published his theories, within about a decade, most of the scientific community had agreed to it, and today even the Church acknowledges evolution as the origin of species.
Darwin himself did not feel that his theories conflicted with the Church’s beliefs, saying:
“There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.”
Evidence of Evolution in the Galapagos Islands
While Darwin’s observations in the Galapagos Islands focused primarily on the finches (later named for him), there are many other examples of natural selection and evolution that visitors today can observe:
- Giant Tortoises: The undisputed icons of the Galapagos Islands, the Giant Tortoises showcase natural selection most prominently with their distinct carapaces.
- Marine Iguanas: Cousins of the land iguanas and the mainland green iguanas, marine iguanas are the only sea-faring lizard in the world, capable of using their paddle-like tails to swim and dive deep, sharp claws to grip lava rock under the water, and specially adapted stomachs that can digest seaweed. Their jet black color helps them absorb sunlight to heat their bodies before diving into the cold depths of the water to scavenge for food.
- Flightless Cormorant: Unlike other cormorants which are very capable flyers, the aptly named flightless cormorant has sacrificed its ability to fly in favor of the more practical ability to dive and swim in order to catch fish.
With a keen eye and a good naturalist guide, you’ll learn about and see hundreds of other adaptations various animals have made in order to survive in the Galapagos Islands too!