Key Question: Why is there such a stunning diversity of life?
Answer: Evolution, as proposed by Charles Darwin.
Darwin's Theory: Explains how species adapt and change.
Key Problem: How does evolution actually work?
Extraordinary Science: Currently uncovering hidden mechanisms of evolution.
The Tree of Life
Diversity:
9,000 species of birds
350,000 types of beetles
28,000 types of fish
2 million living species and counting
Celebration of Darwin: 200 years since his birth and 150 years since his pivotal publication.
Darwin's Journey
Darwin’s Curiosity:
Developed interest in nature during childhood.
Poor student who disliked formal education.
Sent to Edinburgh Medical School, but was horrified by surgery.
Shift in Focus:
Transferred to Cambridge to study for the clergy.
Found direction in natural history, leading to an invitation on the HMS Beagle.
The Voyage of the Beagle
Significance:
Voyage lasted nearly five years, leading Darwin to significant discoveries.
Notable locations: Cape Verde Islands, Brazil, Argentina, and the Galapagos Islands.
Key Discoveries:
Fossils of giant extinct mammals in Argentina
Unique wildlife of the Galapagos Islands (e.g., marine iguanas, giant tortoises).
Insights from the Galapagos
Marine Iguanas: Symbolize the Galapagos; described by Darwin in his diary.
Giant Tortoises:
Differentiated by island-specific shell shapes.
Local knowledge about tortoises indicated that their shells were distinct based on origin.
Bird Collection:
Collected various birds that appeared similar but represented 13 distinct finch species.
Differences in beak shapes correlated with specific islands.
Theoretical Breakthroughs
Mental Rioting: Darwin’s thought process was chaotic but eventually led to major insights about species diversity.
Key Realizations:
Species change over time; a single type of finch diversified into many kinds.
Tortoise variations also exemplified change depending on environmental factors.
Challenge to Prevailing Views:
Contrary to the idea that God created unchangeable species.
Fossil Evidence
Discoveries of Extinct Species:
Noted similarities between extinct giant creatures and their living relatives in South America.
Suggested that species change over time, evident from fossils.
Embryonic Development
Victorian Era Studies: Examination of embryonic stages revealed surprising connections.
Findings:
Snake embryos show rudimentary leg structures.
Whales show teeth in embryos, suggesting ancestry with toothed mammals.
Human embryos display features similar to fish (gills in fish vs. ear bones in humans).
Conclusion
Bold Idea: Darwin concluded that all life is interconnected through evolutionary processes, with unexpected relationships like humans sharing ancestry with fish.
Significance of Darwin’s Work: Laid foundational understanding of the diversity of life and the mechanics of evolution.