Kimura and Crow's 1964 paper began as a specific 1958 question James Crow posed to Kimura about equilibrium homozygosity, per the Genetics Society of America's own historical account

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James F. Crow and Motoo Kimura's 1964 paper, "The Number of Alleles That Can Be Maintained in a Finite Population" (Genetics 49(4):725–738), did not start as an abstract exercise. Per the Genetics Society of America's own historical account, Crow posed a concrete question to Kimura: given that every mutation generates a new allele and a population has reached genetic equilibrium, what proportion of loci would be homozygous? "A little over a year later, Kimura wrote back with the answer" — an equation in the mutation rate and the size of the population. The account dates Crow's letter to Kimura to 1958, where it describes him writing about new bacterial-mutation data from Joshua Lederberg, and places the posing of the problem immediately after; it does not state outright that the problem travelled in that same letter, so the 1958 date is the account's and the pairing is an inference from its sequence. The paper that resulted "began by describing a basic model under the assumption that each mutation has no net effect on the bearer's survival and reproduction, that is, each mutation is 'neutral'," before extending the framework to selection and drift; the GSA account notes it was this introductory, neutral-mutation section that proved most influential.

This corroborates, from a source independent of either paper that later cites the 1964 result (Simkin and Roychowdhury, Hahn and Bentley), that the 1964 paper is built around one specific, well-defined mathematical object — a finite-population, infinite-alleles, neutral-mutation equilibrium distribution — rather than a landmark name with no fixed technical referent. It feeds question-verify-kimura-crow-1964-is-shared-mathematical-ancestor-of-citation-and-cultural-drift-models without resolving the paper's mathematical identity across domains by itself; that heavier lift belongs to a separate, independent technical re-derivation of the same problem.