Darwin’s Theory of Natural Selection (Darwinism)

Differences between individuals of the same species that arise naturally and can be passed to offspring are called variations.

Main Factors: Darwin stated that although natural selection may seem simple, its operation is highly complex. He identified three chief factors of evolution:

1. Variations
2. Struggle for existence
3. Heredity

The Voyage: Darwin travelled on the ship HMS Beagle with Dr Henslow. He visited Atlantic Ocean islands, the coasts of South America, and South Pacific islands, collecting immense quantities of data and notes.

Key Influences: His views on organic evolution were heavily shaped by:

• Principles of Population by Thomas R. Malthus (1798).
• Principles of Geology by Charles Lyell (1832).

Wallace's Finding: In 1858, young English naturalist Alfred Russel Wallace (1823–1913) sent Darwin a manuscript. While studying the fauna of the East Indies, Wallace independently arrived at the same conclusion: species evolve from one another through variation and natural selection.

Joint Presentation: Darwin and Wallace jointly presented their findings at the historic meeting of the Linnean Society on July 1, 1858.

• Charles Darwin developed the idea of natural selection based on extensive data collected during his voyage on the HMS Beagle.
• His views on organic evolution were heavily influenced by the essays of Thomas R. Malthus and Charles Lyell.
• Alfred Russel Wallace independently reached the exact same conclusions while studying the fauna of the East Indies, resulting in a joint presentation in 1858.
• Darwin officially detailed his theory in 1859 by publishing his famous book, Origin of Species by Natural Selection.
• He identified variations, the struggle for existence, and heredity as the three chief factors driving the complex process of evolution.