---
title: "random walk (evolutionary mode)"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "random walk (evolutionary mode)"
aliases: ["unbiased random walk model"]
first_seen: "2026-07-11T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["stasis (paleoTS model selection)","punctuated equilibrium","Gene Hunt","Ornstein-Uhlenbeck process (mean-reversion)"]
---


The third model in the paleoTS trait-evolution model set, alongside directional change and stasis: non-directional but still-changing wander, with no restoring force and no consistent trend. In the field's aggregate quantitative record it is consistently the largest or near-largest single category — roughly half of fitted fossil trait sequences across Hunt's 2007 survey and the larger compilations his 2025 review cites — which means it, not stasis alone, is doing much of the work behind "directional evolution is rare." The vault treats collapsing random walk into stasis as the main way this literature gets oversimplified when cited secondhand.

## References
- [[claim-paleots-fits-fossil-stasis-as-a-selected-stochastic-model]] · [[claim-hunt-2007-directional-evolution-rare-stasis-and-random-walk-split-evenly]] · [[claim-hunt-voje-liow-2025-stasis-common-but-not-dominant]]
- Related hubs: [[entity-punctuated-equilibrium]] · [[entity-gene-hunt]]
- Captures: 2026-07-11-hop-stasis-is-an-ou-process, 2026-07-16-does-gene-hunts-2007-survey-of-250-fossil