Biology (B)

Other Influences on Darwin

How did Darwin come up with his theories? Some of Darwin’s idea conflicted with widely held beliefs, included those from religious leaders, such as:

• All organisms never change and never go extinct, they are fixed.
• The world is only about 6,000 years old.

It was because of these widely held beliefs that Darwin delayed in presenting his findings.

Charles Darwin was influenced by the ideas of several people.

Before his voyage on the Beagle:

1. Jean-Baptiste Lamarck proposed the idea that evolution occurs. However, Darwin differed with Lamarck on several other points. Lamarck proposed that traits acquired during one’s lifetime could be passed to the next generation.
2. Darwin’s grandfather, Erasmus Darwin, wrote a book called Zoonomia. Charles Darwin was influenced by many of his grandfather’s ideas including his descriptions of how species change (evolve) through artificial selection. During artificial selection, people choose specific traits to pass to the next generation, such as with horse or dog breeding (see below).
3. Charles Lyell, a well-known geologist and one of Darwin’s instructors. Darwin learned about geology, paleontology and the changing Earth from Lyell. These findings suggested the Earth must be much older than 6,000 years.
4. Thomas Malthus: Darwin’s ideas of natural selection were inspired by reading an essay by Thomas Malthus, an economist who suggested that humans could overpopulate and potentially exhaust food supplies. Darwin thought this must be especially true for animals, as they have a tendency to have more offspring than people have. There would therefore be a competition for survival.
5. Charles Darwin came upon some of his ideas about natural selection and adaptations from reading about artificial selection and breeding dogs. All dogs, from Chihuahuas to St. Bernards are part of the same genus as wolves (Canis lupus). Humans created the different breeds of dogs by selecting dogs with specific traits to breed together. For example, greyhounds were created by selecting the fastest runners and breeding them together.
6. After the Voyage of the Beagle: Alfred Russel Wallace, another naturalist, also developed a theory of evolution by natural selection. Alfred Wallace toured South America and came up with a very similar theory of evolution by natural selection at the same time that Darwin did. Darwin and Wallace presented their theories and evidence in public together. Because of the vastness of Darwin’s data, and his book, he is mostly credited and associated with this theory.