Great Thinkers: Charles Darwin and Evolution 

May 04, 2014

Charles Darwin developed the theory of how living things develop from simpler organisms over long periods of time.  That theory is known as evolution through natural selection.

How do new kinds of [bad word] into existence?  For much of recorded history, people have believed that organisms were created.  Few people believed that living things changed.  What process could make such change possible?

These were some of the questions Charles Darwin asked himself over years of research in botany, zoology and geology.  He was not the first person to ask them.  His own grandfather, Erasmus Darwin, believed that species evolved.  And others, like the French naturalist Jean-Baptiste Lamark, had proposed ways this could happen.  But it was Darwin who identified and explained the process, natural selection, that causes life to evolve.

BARBARA KLEIN:  Charles Darwin was born in Shrewsbury, England on [bad word] twelfth, eighteen-oh-nine. His father Robert Darwin was a doctor.  Charles' mother Susannah Darwin was the daughter of the famous potter, Josiah Wedgwood.  She died when Charles was only eight years old.

Young Charles was intensely interested in the natural world from an early age.  But his father wanted him to be a doctor.

At age sixteen, Charles was sent to study medicine at the University of Edinburgh.  But he did not like it.  He found medical operations especially horrible.  He later went to Cambridge University.  His father now hoped that Darwin would [bad word] a clergyman. But at Cambridge, Charles continued to follow his own interests.  There, he met John Henslow, a plant scientist and clergyman.  The two became friends.

STEVE EMBER:  John Henslow suggested that Charles Darwin take the unpaid position of naturalist for a trip on the British ship H.M.S. Beagle. It sailed around the world from eighteen thirty-one to eighteen thirty-six. The main goal was to make maps of the coastline of South America.  The British government paid for the voyage.  But another purpose of the trip was to collect scientific objects from around the world.

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BARBARA KLEIN:  The Beagle’s first stop was one of the Cape Verde Islands near the coast of Africa.  There, Darwin noted that levels of rock extending high above the sea contained the fossil remains of shells.  He thought that this was evidence that the bottom of the ocean had been lifted up by powerful geological forces over long periods of time.

The Beagle continued to the coast of South America.  In Valdivia, Chile, Darwin experienced an earthquake.  He collected examples of plants and animals.  He also collected the fossil remains of animals that had disappeared from the Earth.

But it was on the Galapagos Islands off the coast of Ecuador that Darwin found creatures that made him wonder about how species develop and change.  There, he saw giant tortoises and noted that the reptiles were different on each island.

He collected birds, each with different beaks.  Later, after he had returned to England, he would be shocked to find that these very different birds were all finches. Darwin found lizards called iguanas that lived on land and ones that fed in the sea.

Darwin noted that all these species were similar to those found in South America.  But, they all had differences, or adaptations, that helped them survive in the environment of the Galapagos Islands.

STEVE EMBER:  Darwin sent much of what he collected back to England on other ships the Beagle met along the way.  By the time he returned to England in October of eighteen thirty-six, he was already a well known geologist and naturalist.  Within a few years, he would be accepted into scientific organizations like the Geological Society and the Royal Society.
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