Evolution

The Importance of the Galapagos Islands in Explaining Darwins Theory of



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Two months before he turned 23, Charles Darwin left his parents' home in England to set out on a three-year sea voyage that not only changed his life, but also altered the course of science and spawned a debate that continues to this day.

The grandson of a famous scientist, Darwin grew up in an arts-centered home. When he was recommended as a good man to join the HMS Beagle on a journey to map the east and west coasts of South America, it took lobbying from both young Darwin and other family members to convince his father to let him go.

Had he not taken that trip - or had his father known that the three-year mission would become a five-year expedition - he would likely never have published "the Preservation of Favoured Races in the Struggle for Life," a theory now commonly known as "evolution."

On September 16, 1835, Darwin's ship reached the Galapagos islands, a cluster of islands off the coast of Ecuador. During his five weeks on the islands, he was awed by the variety of species that lived on the islands - and by the obvious differences in certain species from one island to the next. Darwin said that if someone had spent time on the islands and saw a giant tortoise swimming off the side of a passing ship, they would immediately be able to tell which of the islands was home to the turtle. The variations were that dramatic.

Likewise, Darwin noted that there were two different types of iguana that appeared to have evolved from the same species. One had a pointy tail and was adept at living on land - feeding on sharply-spined cactus. The second had a flattened tail to help in swimming, strong claws to help climb out of the water, and a shortened snout that allowed it to find food by scraping rocks for algae. It became known as the marine iguana. On other islands, he noted that even more varied versions of these lizards lived - each with characteristics that made it able to survive on that specific island.

Surely these lizards hadn't consulted a realtor to find an island to fit their peculiarities. Instead, the lizards must have, through a process Darwin called "natural selection," have gradually changed into the creatures he saw during his stay.

Natural Selection, as Darwin explained, meant that all creatures occasionally mutate - change physically - on an almost random basis. But when a mutation actually made the creature superior to its predecessors and peers, it was more likely to survive whatever conditions in which it was forced to live. Slowly - or sometimes quickly - those without the mutation died off, leaving only those perfectly equipped to survive. This seemed to make sense, as it would provide some explanation as to how animals in arctic climates, like polar bears and wolves, just happened to be equipped with warming coats, and why animals often had coloring that helped them blend in with the environment. According to Darwin's theory, the first snow owls were likely not white. That happened as a result of mutation. But since the white owls were able to stay hidden among the snow, they were not as easily caught and eaten as their brown predecessors.

But why were the Galapagos islands so important? Some might argue that Darwin could have stumbled across this theory anywhere. But the Galapagos islands are unique in the incredible variety of creatures that live there - from sea lions, iguanas and sea turtles to penguins and rare insects. In fact, because the islands are so isolated from the mainland - and often one another - there are countless species of animal that live only on one particular island - and nowhere else in the world. That, above all else, made Darwin aware of the way environmental characteristics have literally shaped these animals.

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