On the Origin of Species

Character Guide

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Charles Darwin (the author)

The narrator and arguer of the book, a naturalist who lays out, chapter by chapter, the accumulated evidence for descent with modification through natural selection.

Charles Lyell

A geologist whose principles of gradual, slow-acting natural change (uniformitarianism) Darwin repeatedly invokes as a foundation for his own theory.

Thomas Malthus

Referenced as the source of the population principle—organisms produce more offspring than can survive—which Darwin applies to all of nature to explain the 'struggle for existence.'

Georges Cuvier

Named among the era's most eminent paleontologists who held to the immutability of species, representing the established scientific opinion Darwin is arguing against.

Richard Owen

A leading anatomist and paleontologist of the period cited as one of the authorities who maintained that species do not change.

Louis Agassiz

A prominent naturalist mentioned as another authority upholding species immutability, against whom Darwin measures his own claims.

Hugh Falconer

A paleontologist whose detailed work on mastodons and elephants is used by Darwin to discuss the ordering of extinct forms.

Edward Forbes (E. Forbes)

A naturalist noted for independently arriving at conclusions similar to Darwin's regarding the intermittent nature of the geological record.

Glossary

Natural Selection

Darwin's central mechanism: individuals with slight advantageous variations survive and reproduce more successfully, gradually shaping species over time.

Struggle for Existence

Darwin's broad, metaphorical term for the competition among organisms—and with their environment—for survival and reproduction, borrowed from Malthusian population theory.

Natura non facit saltum

Latin maxim meaning 'nature does not make a leap,' which Darwin cites to argue that evolutionary change proceeds through many small gradations rather than sudden jumps.

Palæontological / Palæontologists

Older spelling of 'paleontological'; relating to the study of fossils and ancient life forms.

Silurian strata

A specific ancient geological rock layer/period; Darwin uses the puzzling absence of fossils below it as a major challenge his theory must address.

Rudimentary organs

Vestigial body parts that appear reduced or functionless, which Darwin explains as remnants inherited from ancestral forms where they were once useful.

Divergence of Character

Darwin's principle that descendants of a common ancestor tend to become increasingly different from one another over time as they adapt to different niches.

Tangled bank

The famous closing image of the book—a densely overgrown natural scene—used by Darwin to illustrate the complex, interdependent web of life produced by natural laws.

Batrachians

An older term for amphibians (frogs, toads, and relatives), used by Darwin when discussing the biogeography of islands.

Denudation

The geological process of erosion wearing away land surfaces over long spans of time, used by Darwin to argue for the immense age of the Earth.

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