Richard Dawkins: Distribution of Life: The Iguanas of Galápagos

Jun 5, 2014

Richard Dawkins explains how the distribution of life on Earth’s continents and islands is exactly as we should expect if life evolved, and exactly how we should NOT expect if it had been created.

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“In May 2007, I went to Galapagos with a large group from the
Center for Inquiry. As a small group of us walked with the guided
parties over the island, occasionally I would take the opportunity to
film the wildlife and speak about their significance. The result are
these ‘vignettes’, which were unscripted.”


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Both the marine and land iguanas of Galápagos resemble land iguanas found on the South American mainland, about 600 miles to the east. No doubt it was a freak accident that delivered them first to the newly formed volcanic islands of Galápagos. Thereafter, the fact that there were several different islands in the archipelago enabled them to diverge. The marine iguana, which is found nowhere but on Galápagos, presumably evolved on one island only at first, then later spread to the other islands, where they later diverged into all the different varieties that are now found.

This is a land iguana. It was land iguanas that first colonized the Galápagos Islands and then evolved separately into the modern land iguanas here and the marine iguanas, on the separate islands. The original colonizers would have been land iguanas that floated across, probably on maybe a fallen tree or something like that, perhaps in a hurricane. This has been known to happen in the West Indies, it’s actually been recorded: Fallen trees in a very, very high wind, blown across from one island to another, bearing a great load of iguanas which then, immediately, as soon as the tree is blown ashore, rush out and start to colonize the new island. So it’s actually been seen to happen on another species in another place, but it’s pretty clear that something like that is what would have happened here.

If species were individually created to fit their environment, we should expect islands and continents to have the same animals and plants as similar islands and continents on the other side of the world. But this is exactly what we do NOT find. The distribution of animal and plant species over the islands and continents of the world follows exactly the pattern we should expect if they have evolved, and exactly the pattern we should not expect if they had been created.

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