extragi

Extragi is a term used in speculative biology and some science fiction to denote external biological agents or phenomena that influence living organisms from outside cells or organisms, without direct cellular infection. The usage is not standardized, and the concept varies across authors and media.

In proposed frameworks, extragi operate through three broad modalities: molecular extragi (biochemical signals released into the environment that interact with receptors or transporters on target cells); informational extragi (data or signaling cues that alter gene expression via regulatory networks); and ecological extragi (environmental or ecosystem-level factors that shape development indirectly). Some models include physical conduits such as extracellular vesicles, nanotube-like structures, or abiotic factors acting as regulators.

Within fiction and speculative discourse, extragi serve as devices to examine how organisms respond to external pressures, the ethics of manipulation, and the limits of individual autonomy in shared environments.

Extragi is not recognized in mainstream biology as a distinct category. Real-world concepts such as epigenetic regulation, the microbiome, exosomes, and environmental signaling are sometimes invoked in attempts to analogize extragi, but they are scientifically distinct and described with conventional terminology.

See also: epigenetics, extracellular vesicles, environmental signaling, horizontal gene transfer.