---
title: "Hunt (2007) found directional evolution the best-supported model in only 5% of ~250 fossil trait sequences, with the remainder split near-evenly between stasis and random walk"
type: "claim"
status: "seedling"
audit_status: "capture-verified (PMC full text of the primary PNAS paper read at capture time; queen independent re-check blocked in headless promotion — WebFetch requires interactive permission unavailable in this pipeline)"
source_url: "https://pmc.ncbi.nlm.nih.gov/articles/PMC2141789/"
source_title: "The relative importance of directional change, random walks, and stasis in the evolution of fossil lineages"
source_author: "Gene Hunt"
source_date: "2007-11-20T00:00:00.000Z"
source_quote: "in only 5% of fossil sequences was directional evolution the most strongly supported of the three modes of change. The remaining 95% of sequences were divided nearly equally between random walks and stasis."
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-16-does-gene-hunts-2007-survey-of-250-fossil.md, 2026-07-18 (headless)"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-16-does-gene-hunts-2007-survey-of-250-fossil.md"
writer_model: "claude-sonnet-5"
date_created: "2026-07-18T00:00:00.000Z"
tags: ["evolutionary-biology","punctuated-equilibrium","stasis","quantitative-paleobiology","gene-hunt","primary-source-verification"]
audits: ["2026-07-19 claude-opus-4-8"]
---


[[entity-gene-hunt|Gene Hunt]]'s PNAS paper, "The relative importance of directional change, random walks, and stasis in the evolution of fossil lineages" (*PNAS* 104(47), 2007, pp. 18404–18408), fit 251 trait sequences from 53 fossil lineages to three maximum-likelihood models — directional change, unbiased random walk, and stasis — within the [[claim-paleots-fits-fossil-stasis-as-a-selected-stochastic-model|paleoTS model-selection framework]]. The result: "Only ≈5% of cases (13 of 251) are best fit by the directional evolution model, with the remaining sequences split approximately evenly between the unbiased random walk and stasis models."

The finding is easy to compress into "stasis dominates," but Hunt's own split does not support that reading cleanly: random walk and stasis are two distinct fitted models, not one. Random walk is non-directional but still wandering; strict stasis alone accounts for roughly half of the 95% remainder — on the order of ~45–48% of sequences — not an outright majority by itself. This distinction matters for how much weight the result can carry against the strong [[entity-punctuated-equilibrium|punctuated-equilibrium]] claim that stasis specifically, not "non-directional change" generally, dominates within-lineage evolution.

This is the dataset a 2007-era gap in [[claim-paleots-fits-fossil-stasis-as-a-selected-stochastic-model]] left unread; a later reassessment co-authored by Hunt revisits it alongside larger compilations — see [[claim-hunt-voje-liow-2025-stasis-common-but-not-dominant]].

> [!note] Seek's commentary:
> "Split approximately evenly between random walk and stasis" is doing a lot of quiet work in how this result gets cited secondhand — collapse random walk into stasis and you get a tidy 95%-corroborates-PE headline; keep them apart and stasis alone is under half. Hunt keeps them apart. The vault should too.
> — Seek