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The Origin of Species- Explaining the Diversity of Life on Earth
By Charles Darwin
Few people have changed the world with the power of an idea. Charles Darwin, the
British naturalist who lived during the 1800s, was one of them. Darwin’s legendary
book, On the Origin of Species by Means of Natural Selection; or, the Preservation of
Favoured Races in the Struggle for Life, is frequently listed as one of the greatest
books ever written. The two critical ideas he developed in it are:
 The fact that evolution occurs.
 The theory of natural selection is the driving force or mechanism behind the
process of evolution.
Darwin began developing these ideas as a result of his experiences during a fiveyear voyage on the ship H.M.S. Beagle, which sailed around the world on a
expedition during the early 1830s. Darwin wanted to record information about the
geology, sea life, land animals and plants, and people that the Beagle would
discover. When he set sail in 1831, Darwin was twenty-two years old, fresh out of
college, fascinated with science, and deeply interested in geology and natural
history.
Darwin allowed himself to wonder if species were fixed or prone to evolution. One of the
clues that moved Darwin to totally accept the principle of evolution involved a group of small
birds called Finches. Finches are unspectacular animals with a wingspan of about 10 inches.
They live in many habitats in North, Central, and South America. Darwin observed and
collected them on the Galapagos Islands, a cluster of small islands off the coast of Ecuador.
The Galápagos Islands have species found in no other part of the world, though similar ones
exist on the west coast of South America. During his voyage to the Galapagos, Darwin was
struck by the fact that the birds were slightly different from one island to another. He realized
that the key to why this difference existed was because species live in different kinds of
environments.
On returning to England, Darwin identified 13 species of finches that he had collected on the
Galápagos Islands. This was puzzling since he knew of only one species of this bird on the
mainland of South America where they had all presumably originated. He observed that the
Galápagos species differed from each other in beak size and shape. He noted that the beaks
were associated with diets based on different foods. He concluded that when the original
South American finches reached the islands, they dispersed to different environments where
they had to adapt to different conditions. Over many generations, they changed anatomically
in ways that allowed them to get enough food and survive to reproduce.
ANSWER USING COMPLETE SENTENCES AND IN YOUR OWN WORDS
1. The two critical ideas that Charles Darwin developed are
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2. While visiting the Galapagos Islands, Charles Darwin was surprised by the 13 different
finches because
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3. Charles Darwin noticed the finches different in the following characteristics (traits):
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4. Here are some of the finches that Darwin saw. What is the significance of the finch in the
center?
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