Lecture Notes on Evolution and Charles Darwin

Introduction

• Diversity of Life: Question posed - Why is there such a stunning diversity of life?
• Answer: Evolution.
• Darwin's Contribution: Charles Darwin's theory explains how species adapt and change, hailed as one of the best ideas ever.
• Current Research: Extraordinary science is now uncovering the mechanisms behind evolution.

The Tree of Life

• Species Diversity: Examples of diversity in species:
  • 9,000 species of birds
  • 350,000 kinds of beetles
  • 28,000 types of fish
  • Approximately 2 million living species.
• Understanding Evolution: Darwin sought to understand the extraordinary diversity of life on Earth.

Darwin's Journey

• Early Life: Influenced by nature, Darwin had a keen interest in collecting specimens from a young age.
  • Struggled in school, initially sent to medical school but left due to discomfort with surgeries.
  • Eventually studied at Cambridge, focusing on natural history.
• HMS Beagle Voyage: Darwin was invited to join the Beagle as a naturalist.
  • The voyage lasted nearly five years, traveling from Cape Verde to the Galapagos Islands.

Significant Discoveries

• Fossils in Argentina: Found extinct giant mammals, leading to thoughts on their relationship with living animals.
• Galapagos Islands: Key location for observations:
  • Unique species like marine iguanas and giant tortoises.
  • Notable observation: Different tortoise shell shapes based on island.

Finches and Tortoises

• Bird Collection: Collected various birds, later realized they represented 13 different species of finches based on beak shapes.
• Insight on Species Change: Noticed that species changed according to their environment - similar to the tortoises.

Evolutionary Theory Development

• Challenging Prevailing Views: Darwin's ideas contradicted the belief that species were created perfect by God.
  • Proposed that species evolve and adapt over time.
• Fossil Evidence: Discovered fossils that resembled modern animals, indicating species transformation.

Embryonic Evidence

• Embryo Studies: Observations of embryos revealed similarities across species.
  • Snakes had leg rudiments that did not develop, hinting at a common ancestor.
  • Whales and humans showed similar embryonic structures to fish, suggesting descent from fish.

Conclusion

• Darwin's Bold Idea: Concluded that all life is connected through evolution and shared ancestry.
• Legacy: His work laid the foundation for modern understanding of biological diversity.