The Origin of Species · Chapter
Special Difficulties of the Theory of Natural Selection explained
Darwin addresses specific challenges to his theory, including the evolution of complex organs like electric and luminous organs in distantly related species, and the problem of neuter insects.
What happens
Darwin addresses specific challenges to his theory, including the evolution of complex organs like electric and luminous organs in distantly related species, and the problem of neuter insects. He argues that such organs can arise independently through convergent evolution, as natural selection works on different variations in different lineages. He emphasizes that nature does not make leaps, and that the imperfection of the geological record explains the rarity of transitional forms.
Themes in this chapter
Natural Selection and the Struggle for Existence
Darwin explains how natural selection can produce complex organs through gradual steps, using examples like electric organs and air-breathing adaptations in crustaceans.
Adaptation and the Utilitarian Doctrine
The chapter discusses how organs serve specific functions and how similar functions can be achieved through different structures, supporting the utilitarian view of adaptation.
Variation and Inheritance
Darwin emphasizes that variation provides the raw material for natural selection, and that inherited changes accumulate over generations to produce complex adaptations.
Characters to notice
- Fritz Müller
Müller's study of air-breathing crustaceans led him to accept natural selection, as he found that similar functions were achieved through different structures in distinct families.
- Milne Edwards
Quoted for the maxim 'Nature is prodigal in variety, but niggard in innovation,' supporting the idea that natural selection produces gradual change.
- Charles Darwin
Darwin presents and defends his theory against difficulties, arguing that apparent obstacles can be explained by natural selection acting on slight variations over long periods.
Key passages
“Nature is prodigal in variety, but niggard in innovation.”
Nature creates many variations but rarely introduces entirely new structures.
Milne Edwards' maxim is used to support the idea that natural selection works by modifying existing structures rather than creating new ones from scratch.
“Why should not Nature take a sudden leap from structure to structure? On the theory of natural selection, we can clearly understand why she should not; for natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by the short and sure, though slow steps.”
Nature does not make sudden jumps because natural selection only works through small, gradual changes over time.
Darwin explains the gradual nature of evolution, countering the creationist argument that complex organs must have been created fully formed.