Download Charles Darwin and natural selection

3f: Darwinism
Lesson 1: Student Resource Sheet 1
Charles Darwin and his theory of evolution through natural selection
Charles Darwin in 1880
Charles Darwin (1809-1882) was born into quite a well-to-do
family in Shropshire. When he had completed his early
schooling, he went to study medicine at Edinburgh University.
He dropped out from this course in 1827 and went off to
Cambridge to study to become a clergyman in the Church of
England. It was here that he gained a special interest in the natural world
and began to collect specimens to study. He left university in 1831 and set
off on a voyage of discovery on a ship named ‘HMS Beagle’ and began his
career as a naturalist on a scientific expedition.
HMS Beagle from a watercolour by
Owen
Stanley 1841
Darwin’s close observations of both animal life and
rock formations while he was travelling led him to
consider that natural forces had been acting on these things over an
extremely long time. The earth and everything on it had taken a very long
time to arrive at where it was now! Many people at the time believed that the
earth was actually quite young and that the different species of animals had
been created by God in the beginning when the world had been made. This
of course is one way of reading the creation story in the Bible. Therefore,
Darwin’s thinking was beginning to concern him as he saw a conflict between
his ideas and those who took the Biblical account literally.
Science and Religion in Schools – 3f: Darwinism
What Darwin noticed next was crucially important. In the
Galapagos Islands off the coast of South America there
were finches, mocking birds and thrushes but they differed
slightly on each of the islands. In other words, each island
had its own slightly variant form of these birds. As Darwin
was leaving the islands, the governor of one of the islands,
Nicholas Lawson, told Darwin, who had not observed the
fact himself, that he could tell by inspecting a tortoise from which island it
came. Darwin was struck by this remark because this is also what he had
begun to think whilst collecting the birds.
When he returned to England,
Darwin was able, with the help of ornithologist John Gould, to establish which
of his finch specimens were genuinely different species and which were
variants of the same species. So the governor telling him about the tortoises
provided Darwin with an important clue, but the testing of the idea of natural
selection came later via the birds. Although Darwin was arriving at his basic
theory for all this by 1838, it was not until 1858 that it was made public and
a year later that his book ‘On the Origin of Species’ was published.
Essentially, Darwin suggested that animals compete for
survival because of food supply problems. The young
animals that survive best and go on to reproduce have
slight advantages such as longer legs or better
camouflage, more teeth or stronger stomachs! These
advantages enable them to survive more effectively in their particular
environments. As these animals breed they pass on these advantages to the
next generation. Over time, each generation will gradually change in small
ways as they adapt to their living conditions and pass on these adaptations
to their young.
This is evolution through natural selection.
Science and Religion in Schools – 3f: Darwinism