The founding text of natural selection
This entry is a later edition of Darwin's 1859 work, which sets out the argument that species change through natural selection. Darwin establishes that individuals within a population vary, that variation is heritable, that populations produce more offspring than can survive, and that those individuals whose variations suit their circumstances leave more descendants, which alters the population over generations.
His argumentative method proceeds from the familiar to the contested. He begins with variation under domestication, where breeders had produced enormous change in pigeons, dogs and crops within recorded time. He then establishes variation under nature, then the struggle for existence following Malthus on population, and only then states natural selection. Two chapters address the difficulties with his own theory directly, including the absence of transitional forms in the fossil record, the origin of complex organs, instinct, and the sterility of hybrids.
Darwin revised the text across six editions, and the later ones respond to critics in ways that weakened some formulations, including increased concessions to inheritance of acquired characteristics. Readers seeking Darwin's argument in its cleanest form are generally directed to the first edition.
He had no correct account of inheritance and stated this as a genuine problem. Mendel's work was published in 1866 and remained unknown until 1900, and the reconciliation of selection with genetics came only with the modern synthesis. The accumulated observational detail is extensive and dense. The reason to read it now is the method rather than the biology, since Darwin states the strongest objections to his own position at length before answering them.
Readers who want the primary text as a model of how to make and defend a contested argument, with modern sources used for the biology itself.
Chosen by shared topics, the entries that hold them, and the people who recommended both.