Influences on Darwin's Theory of Natural Selection

Charles Darwin's groundbreaking theory of evolution by natural selection was significantly shaped by the work of other thinkers. The correct option highlights two key individuals whose ideas provided foundational concepts for Darwin's work.

Key Influences Identified

• Charles Lyell: A geologist whose work, particularly Principles of Geology, popularized the concept of uniformitarianism. Lyell argued that geological processes acting slowly over immense periods could explain the formation of Earth's features. This provided Darwin with the concept of deep time necessary for gradual evolutionary change.
• Thomas Malthus: An economist and demographer whose essay "An Essay on the Principle of Population" observed that populations tend to grow exponentially while resources grow arithmetically. This leads to a "struggle for existence," a concept Darwin directly applied to nature, suggesting that organisms with advantageous traits are more likely to survive and reproduce.

Why Other Options Are Incorrect

• Watson and Crick: Famous for discovering the double-helix structure of DNA in 1953, which occurred long after Darwin developed his theory.
• Meselson and Stahl: Known for their experiment confirming the semi-conservative replication of DNA in 1958, also well after Darwin's time.
• Miller and Urey: Conducted an experiment in the 1950s simulating early Earth conditions to investigate the origin of life (abiogenesis), which is related to but distinct from Darwin's mechanism of evolution acting on existing life.

Therefore, Lyell's geological concepts and Malthus's ideas on population dynamics were crucial intellectual precursors to Darwin's theory of natural selection.