---
title: "Desai, Fisher & Murray (2007) found that under clonal interference the speed of evolution rises only logarithmically in population size and mutation rate"
type: "claim"
status: "seedling"
audit_status: "capture-verified (the 2026-07-11 hop session read the primary via WebFetch verbatim from the PubMed record; an independent headless re-check of the verbatim phrasing was not run — no web-fetch tool is available in this promotion pipeline). [Audit 2026-07-12 (big-opus-3, same-model): re-fetched PubMed 17331728 via WebFetch. Title, authors, journal, year, and the logarithmic-scaling claim (speed of evolution rises only as the logarithm of population size and of mutation rate) all CONFIRMED. Provenance caveat: the PubMed abstract's verbatim wording is '...increases as the logarithm of the population size and logarithm of the mutation rate and thus yields a similar logarithmic increase in the speed of evolution' — the recorded source_quote is a faithful close paraphrase, not verbatim from the PubMed record; the paywalled Current Biology full text was not checked for an exact-match sentence.]"
source_url: "https://pubmed.ncbi.nlm.nih.gov/17331728/"
source_title: "The speed of evolution and maintenance of variation in asexual populations"
source_author: "Michael M. Desai, Daniel S. Fisher, Andrew W. Murray"
source_date: "2007-03-06T00:00:00.000Z"
source_quote: "the speed of evolution increases only as the logarithm of the population size and the logarithm of the mutation rate"
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-11-hop-population-scale-diminishing-returns.md, 2026-07-12 (headless)"
origin: "batch"
writer_model: "claude-opus-4-8"
derived_from: "10-inbox/raw/2026-07-11-hop-population-scale-diminishing-returns.md (id 20260711-1351-hop-population-scale-diminishing-returns)"
date_created: "2026-07-12T00:00:00.000Z"
tags: ["population-genetics","clonal-interference","evolutionary-rates","diminishing-returns","asexual-populations","scaling-laws"]
audits: ["2026-07-12 claude-opus-4-8"]
---


"The speed of evolution and maintenance of variation in asexual populations"
(Michael M. Desai, Daniel S. Fisher & Andrew W. Murray, *Current Biology* 17:5,
2007) analyzes what happens when a large asexual population generates beneficial
mutations faster than any one of them can fix. Multiple favorable lineages then
compete simultaneously — **clonal interference** — and most are lost even though
they are advantageous, because a fitter competitor sweeps first. The consequence
is a hard limit on how fast adaptation can proceed: "the speed of evolution
increases only as the logarithm of the population size and the logarithm of the
mutation rate."

Logarithmic dependence is a severe diminishing return. Multiplying the population
by a factor of ten does not multiply the adaptation rate by ten; it adds a roughly
constant increment. The extra individuals overwhelmingly supply mutations that
interfere with, rather than accelerate, the fixation of the best variant. The
result extends the Gerrish & Lenski (1998) clonal-interference lineage into an
analytic scaling law.

This is the biology instance of the same brake economics found in
[[claim-bloom-2020-ideas-are-getting-harder-to-find]]. It closes the loop on the
population-as-engine story: the acceleration mechanism of
[[claim-kremer-1993-technology-growth-proportional-to-population]] and
[[claim-hawks-2007-human-adaptive-evolution-accelerated-recently]] — more agents,
more variation, faster improvement — is not free in either domain. Beyond a point,
scaling the generating population yields sub-linear returns, and the friction is
not an economics artifact but a general property of populations generating
variation. The cross-domain pattern is drawn together in
[[observation-population-scaled-improvement-hits-a-sublinear-brake-across-domains]].

> [!note] Seek's commentary:
> The elegant part is that clonal interference gives the *same functional form* —
> logarithmic — that growth economics reaches empirically. Two fields, one working
> from selection theory and one from productivity data, land on "scale helps, but
> only logarithmically." That coincidence of form is what makes the bridge more
> than a metaphor. — Seek