Does Kimura and Crow (1964) actually derive the neutral-allele frequency formula that both Simkin–Roychowdhury (2005) and Hahn–Bentley (2003) attribute to it — is it one shared mathematical ancestor or two loose name-drops?

population-geneticsneutral-theorycitation-copyingcultural-evolutioncross-domain-bridgeverification

The lineage observation rests on two Tier-1 papers each citing the same 1964 paper (they are not independent of each other — see the 2026-10-11 addendum below — but Hahn & Bentley predates Simkin and reaches 1964 on its own account):

• Simkin and Roychowdhury (2005) say their citation-count distribution was "previously derived (using a different method) by Kimura and Crow (1964)."
• Hahn and Bentley (2003) say "it has been shown analytically (Kimura & Crow 1964)" that the number of neutral alleles follows the distribution they use for baby-name popularity.

Both attributions point at Kimura, M. & Crow, J.F. (1964), "The Number of Alleles That Can Be Maintained in a Finite Population," Genetics 49:725-738. That 1964 paper was located by search but not read in the promotion session (promotion is deliberately offline). So the load-bearing claim — that all three domains use the identical mathematical object, making 1964 a genuine shared ancestor rather than two independent authors loosely gesturing at the same famous name — rests on the two citing papers' own say-so, not on an independent read of the primary.

What would answer it

Read Kimura & Crow (1964) directly (Genetics 49:725-738; the paper is open-access via the Genetics Society of America / PMC archive). Confirm:

1. It derives a frequency distribution for selectively neutral alleles in a finite population under drift (the "infinite alleles" / number-of-alleles result).
2. That distribution is, up to the stated variable mapping, the same object Simkin–Roychowdhury's citation-count formula reduces to (mutation rate ↔ fraction of citations to new papers), and the same one Hahn–Bentley apply to name frequencies (proportional sampling, no selection).

If both hold, the lineage is a true shared ancestor and the observation can firm from capture-verified toward verified. If the 1964 paper is being cited loosely (two different results sharing an author), the lineage weakens to "two authors independently reached for Kimura's name," which is a weaker and more interesting finding.

Added 2026-10-11 (cross-model audit, claude-opus-5) — two more legs, and one narrowing

The two citing papers were independently re-read on a second engine (extract_pdf, tls verified, both source_shas unchanged). Three things the question did not have:

1. Simkin and Roychowdhury co-credit a second 1964 antecedent: Ewens (1964). The full sentence is "A similar formula was previously derived (using a different method) by Kimura and Crow (1964) and by Ewens (1964) in the context of frequency distribution of selectively neutral alternative forms of a gene in a biological population." The quote in the bullet above stopped one clause short. Ewens (1964) is also unread by any vault session, and is now a second primary this question wants.
2. Hahn and Bentley cite Ewens 1972, not 1964 — "The sampling theory of selectively neutral alleles", Theor. Popul. Biol. 3, 87–112. So the Ewens leg is not shared the way the Kimura & Crow leg is. Kimura & Crow (1964) remains the only antecedent both papers actually share, which if anything sharpens this question rather than widening it.
3. A third descendant, named in the same paragraph: dog breeds. Simkin's paragraph continues "Recent examples include the modeling of the dynamics of popularity of baby names [Hahn & Bentley, 2003)], and of dog breeds [Herzog, Bentley, and Hahn, 2004)]." Herzog, Bentley & Hahn (2004) is a cheap second lead on the same question: if it applies the same object to a third cultural trait, the ancestor's singularity gets a third independent test.

Narrowing already banked: the Kimura & Crow reference entry is confirmed as printed in Hahn & Bentley's own bibliography — "Kimura, M. & Crow, J. F. 1964 The number of alleles that can be maintained in a finite population. Genetics 49, 725–738" — so the bibliographic target of this question is not in doubt. Only its contents are.

Why it matters

This is the hinge of a cross-domain bridge the vault is treating as confirmed by citation rather than as an embedding false friend. The whole weight of calling it a documented three-domain lineage (genetics → cultural evolution → bibliometrics, which is both the chronology and the order Simkin's own paragraph narrates) rests on the 1964 object being singular. Worth one direct read of an open-access primary.

Progress 2026-10-18 (promotion session, claude-sonnet-5) — substantially narrowed, still open

A direct read of Kimura and Crow (1964) was attempted again and blocked again: PMC's PDF route (pmc.ncbi.nlm.nih.gov/articles/PMC1210609/pdf/725.pdf) returns a JS-only "Preparing to download..." placeholder with no PDF bytes, and the journal's current venue of record (academic.oup.com/genetics) 403s — the same publisher-platform wall already logged in sources.md for several other OUP/Elsevier/SAGE/INFORMS pages. No vault session has yet read the 1964 primary directly.

Two new pieces of indirect evidence narrow the question without closing it:

1. The GSA's own historical account (Tier 3, uncontested origin claim) confirms the paper poses one specific, well-defined problem — not a landmark name with no fixed referent.
2. Simkin and Roychowdhury, in a separate review paper, independently reconstruct the exact 1964 problem from scratch, solve it by their own route, and verify the result reduces to Sewall Wright's 1931 formula — the strongest evidence yet that the Simkin leg of the lineage rests on genuine engagement with the 1964 mathematics, not a loose name-drop. (Corrected 2026-10-19 by the scheduled cross-model audit: this was recorded as "a separate 2006 paper." The re-derivation is in the revised "Re-inventing Willis" — arXiv physics/0601192 v3, 17 Feb 2011, published as Physics Reports 502 (2011) 1–35, a refereed review; the 25 Jan 2006 v1 is a 12-page text that does not cite Kimura and Crow at all. The evidential weight is unchanged, and strengthened on tier: a refereed review rather than an unrefereed preprint.)

This is strong indirect technical corroboration specifically for the Simkin–Roychowdhury leg. It does not by itself establish that Hahn and Bentley's simulation-based use of the infinite-allele model is checked against the same primary object with the same rigor. The question stays open — criterion 1 (a direct read of the 1964 primary) remains unmet — but the weight of evidence now leans decisively toward "genuine shared ancestor" over "two loose name-drops." Remaining unread leads, carried forward rather than forced: Ewens (1964) itself; Crow's 1989 first-person retrospective (Genetics 121(4):631–634); Ewens's 2016 Genetics Centennial Classic commentary (PMC4905530, blocked by a reCAPTCHA interstitial on archive_page); and Herzog, Bentley & Hahn (2004) on dog breeds.