What does epigenesis mean?
Epigenesis is the biological principle that an organism develops gradually from an undifferentiated starting point, with new structures forming step by step rather than being present, fully formed, from the beginning. The word is best known from the history of embryology: for much of the seventeenth and eighteenth centuries it stood opposed to preformationism, the rival theory holding that embryos were merely miniature versions of adults waiting to unfold. Aristotle had already argued something like epigenesis from his observations of chick development, and later microscopists and anatomists — notably Caspar Friedrich Wolff — supplied evidence that organs arise successively out of initially homogeneous material. Beyond embryology, the term can be applied figuratively to any process that unfolds in successive stages toward greater complexity. Though largely confined today to scientific, historical, and philosophical writing, epigenesis remains a precise and evocative way to describe genuine creation of new form, as distinct from mere expansion or revelation of what was already there.
nounThe theory, originally in embryology, that an organism develops progressively from an undifferentiated embryo by the gradual formation and differentiation of new structures, rather than by the simple enlargement of a preformed miniature. More broadly, any process of development through successive stages from simpler to more complex forms.
- (Biology) The progressive development of an organism from an undifferentiated state through the successive formation of new parts, as opposed to preformation.
- (General) Development or emergence through a sequence of stages from simple to complex.
"Aristotle championed epigenesis, arguing that the organs of the chick emerge one after another during incubation rather than existing fully formed in the egg."
"In the seventeenth century, Harvey's observations of the developing deer embryo lent strong support to the doctrine of epigenesis."
"Critics described the city's growth as a kind of urban epigenesis, with each neighbourhood emerging organically from what came before."
Rarely pluralised; the plural follows the Greek-style -es ending but is seldom needed since the concept is usually discussed in general terms.
"Comparative biologists studied the epigeneses of several vertebrate species side by side."
For centuries scientists believed a tiny preformed human sat curled inside every sperm cell — until epigenesis won the argument that we build ourselves piece by piece.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of epigenesis
Epigenesis derives from Greek roots: epi- meaning 'upon' or 'after', and genesis meaning 'origin' or 'creation'. The term entered English in the mid-seventeenth century as anatomists debated how embryos acquire their form. It shares its genesis root with words such as genetic, generate, and parthenogenesis, all pointing back to the Greek idea of coming into being.
Related word forms
How epigenesis is actually used
A technical term used chiefly in biology, history of science, and philosophy; rare in everyday conversation. It is most often encountered in discussions of early embryology, where it is contrasted with preformationism. The adjective 'epigenetic' now more commonly evokes modern genetics than the older developmental doctrine.
Easily confused with epigenesis
Epigenesis is the embryological doctrine of gradual, step-by-step development of form, whereas epigenetics is the modern study of heritable changes in gene expression that occur without altering the DNA sequence.