Darwinism

Darwinism refers to the scientific theory of biological evolution developed by Charles Darwin and his contemporaries in the nineteenth century. It centres on the idea that species arise and develop through natural selection, a process in which inherited variations that enhance survival and reproductive success become more common in successive generations. Although the term originally encompassed a broad set of evolutionary ideas, its meaning has shifted over time in both scientific and public discourse. Darwinism today is often used informally to describe evolutionary theory, though many modern biologists consider the term outdated for describing contemporary evolutionary science.

Terminology and early development

The term Darwinism was introduced by the English biologist Thomas Henry Huxley in 1860, shortly after the publication of On the Origin of Species in 1859. At that time it was used to describe Darwin’s theory of evolution by natural selection, as well as earlier concepts of species change, such as those discussed by Herbert Spencer. In the nineteenth century Darwinism therefore denoted a collection of evolutionary views, with Darwin’s own ideas placed alongside competing mechanisms that had not yet been tested by genetics.
Darwin himself accepted some ideas, such as the inheritance of acquired characteristics, that were later shown to be incorrect. Many early supporters of evolution—Huxley among them—welcomed Darwin’s emphasis on common descent but were initially sceptical about whether natural selection alone was powerful enough to generate new species.
As evolutionary research progressed, additional scientific principles became associated with the term, including the Weismann barrier—August Weismann’s argument that hereditary information flows only from germ cells to body cells—and, much later, the central dogma of molecular biology, which describes the directional transfer of genetic information from DNA to RNA to protein.

Eclipse and revival

From the 1880s to the early twentieth century, evolutionary biology entered a period known as the eclipse of Darwinism, in which alternative theories attempted to explain evolutionary change. These included orthogenesis, mutationism and various forms of neo-Lamarckism. Natural selection was not widely accepted as the dominant evolutionary mechanism during this period.
The revival of Darwinism occurred with the development of the modern synthesis in the early twentieth century. Incorporating Darwin’s ideas with Mendelian genetics and population-level analysis, the synthesis established natural selection acting on heritable variation as the central explanation for evolutionary change. This updated framework—rather than Darwin’s original nineteenth-century ideas—forms the basis of modern evolutionary biology.

Usage and interpretation in the nineteenth century

In the late nineteenth century, Darwinism was often interpreted beyond a strictly biological context. The idea of “survival of the fittest”, a phrase coined by Herbert Spencer in 1864, became widely associated with Darwinism even though Spencer’s evolutionary philosophy predated Darwin’s work and was more Lamarckian in character. Social and political movements appropriated Darwinian concepts: social Darwinism applied notions of struggle and competition to human societies, often to justify inequality or oppose philanthropic efforts. Francis Galton, Darwin’s half-cousin, interpreted Darwinism as a rationale for eugenics, arguing that natural selection was weakened in modern societies.
In Germany, Ernst Haeckel popularised a version of evolutionary theory known as Darwinismus, which differed substantially from Darwin’s own thinking and blended natural selection with broader philosophical claims about progress and development. Meanwhile, Alfred Russel Wallace—the co-discoverer of natural selection—advocated what he called pure Darwinism, emphasising the primacy of natural selection and rejecting supplementary mechanisms such as the inheritance of acquired traits. His strict selectionism contrasted with the views of George Romanes, who argued for a combination of selection and acquired inheritance.

Core principles

Darwin’s explanation for evolution by natural selection rests on several foundational ideas:

• More offspring are produced than can survive.
• Individuals vary in their traits, and these differences are heritable.
• Individuals with advantageous traits are more likely to survive and reproduce.
• Over many generations, these selective pressures lead to adaptation.
• When populations become reproductively isolated, they can diverge into new species.

These principles remain central to contemporary evolutionary biology, though modern theory integrates insights from genetics, ecology, developmental biology and molecular biology that were unknown in Darwin’s time.

Contemporary usage and public debate

While scientists often refer to evolutionary biology rather than Darwinism, the term persists in public discussion. Some science communicators—including Olivia Judson, Eugenie Scott and Carl Safina—argue that Darwinism is misleading because modern evolutionary theory substantially extends beyond Darwin’s nineteenth-century proposals. Darwin lacked knowledge of Mendelian inheritance, chromosomal genetics, mutations and genetic drift; none of these concepts formed part of his original framework.
In the United States and parts of the United Kingdom, the term Darwinism is frequently used by creationists and proponents of intelligent design as a pejorative label. It is employed to portray evolutionary theory as a rigid ideology, sometimes conflated with atheism or metaphysical naturalism. This rhetorical usage contrasts sharply with the scientific understanding, in which evolutionary theory is a broad, evidence-based field rather than a doctrine tied to Darwin personally.
Creationist writers have used the term to imply that evolution is adhered to dogmatically by scientists or that it excludes religious belief. This strategy can be traced historically to critiques such as Charles Hodge’s 1874 work What Is Darwinism?, although Hodge himself acknowledged that some supporters of Darwin, such as Asa Gray, reconciled evolutionary science with Christian faith.
In modern public debates—from books to films such as Expelled: No Intelligence Allowed—the term continues to be used polemically to refer to evolutionary scientists as “Darwinists”, despite the fact that contemporary evolutionary biology relies on a wide range of concepts not present in Darwin’s original theory.

Significance

Darwinism, as originally understood, transformed biological science by providing a naturalistic explanation for the diversity of life and the adaptive fit between organisms and their environments. Although the term today may be used inconsistently or controversially, Darwin’s core insight—that natural selection acting on heritable variation drives evolutionary change—remains one of the foundational principles of modern biology.