Lecture on Charles Darwin and the Theory of Evolution

Charles Darwin and Natural Selection

• Charles Darwin is pivotal in the development of the theory of evolution.
• Notably, he did not use the term "evolution" but focused on natural selection.
• Conducted experiments and gathered evidence to support his theory of natural selection.

Early Life and Education

• Darwin began his career at age 16-17, studying medicine at the University of Edinburgh.
  • Found medical practices distasteful, particularly surgeries without anesthesia.
• He left medicine and pursued theology at Cambridge University.
  • Studying theology was essential for teaching natural history as a parson in the Church of England.
  • Graduated at the top of his class.

Voyage on the HMS Beagle

• Darwin was recommended as the naturalist for the HMS Beagle, which began its voyage in December 1831.
  • This was a survey expedition that required the naturalist to pay their own way, a unique opportunity to explore and collect specimens.
• The ship initially aimed to stop at the Canary Islands but changed course due to health concerns, proceeding to South America instead.
• Darwin spent substantial time collecting specimens and sending them back to England via other ships, akin to a postal service.
• He wrote letters documenting his experiences, which were published back home, making them popular.

Discoveries in the Galapagos Islands

• In 1835, Darwin visited the Galapagos Islands, where he developed the concept of adaptive radiation.
  • Observed different finches and their adaptations to various islands.
  • Realized that environmental conditions played a critical role in shaping the organisms.
• Observed extreme diversity among species in the islands compared to his earlier life in England.
  • Noted differences in features such as tortoise neck lengths and leg sizes adapted for reaching higher vegetation.

Influences on Darwin's Thinking

• Darwin came from a family with a background in science; his grandfather, Erasmus Darwin, had speculated on common ancestry.
• Influenced by earlier evolutionary thinkers:
  • Charles Lyell: Emphasized geological changes and Earth's age, which suggested a long history of biodiversity.
  • Jean-Baptiste Lamarck: Proposed the inheritance of acquired characteristics, which Darwin later corrected through natural selection.
  • Georges Cuvier: Suggested extinction through the fossil record, contributing to Darwin's understanding of life's diversity.
  • Thomas Malthus: Introduced the Malthusian dilemma, arguing that population growth would outpace resources, leading to a struggle for existence which natural selection would govern.

Collaboration with Alfred Russel Wallace

• Wallace independently outlined principles similar to Darwin's natural selection.
• Wallace's letter spurred Darwin to publish his own findings.
• In 1859, their joint paper on natural selection was published, leading to Darwin's famous book.
• Darwin faced both acceptance and controversy; his work gained significant traction within 15 years.

Legacy and Continued Relevance

• The theory of natural selection sparked discussions and controversies that evolved in the following decades.
• Post-1900s, genetic advances further solidified Darwin's ideas, enhancing understanding of natural selection's mechanics.
• Darwin’s work has had a long-lasting impact on biology and our understanding of evolution, anchoring it in both scientific thought and public discourse.