Descent, contact, and convergence are distinguishable in practice only by sequence-level parallels, attested corridors, and tree/areal congruence — never by motif resemblance alone
Bare resemblance between two myths carries almost no transmission information; the descent/contact/convergence verdict the vault assigns to every motif can be discriminated empirically only by three tests, in descending strength: (1) sequence-level, near-verbatim parallels (shared order of arbitrary sub-elements) signal textual dependence — contact or within-lineage descent; (2) a dated physical transmission corridor (texts, trade, migration) is required before contact can be asserted, never merely assumed from similarity; (3) congruence between a myth's distribution-tree and an independent tree (genetic, linguistic, geographic) is the only positive signal for deep descent — and its absence, combined with no contact route, is what licenses a convergence verdict.
1. The vault's own strongest verdict already runs on test (1): Genesis depends on Gilgamesh XI because they share sequence (warned hero → sealed vessel → animals → mountain → serial bird release → sacrifice → the divine smelling the offering), exactly as Gilgamesh XI's dependence on Atra-ḫasīs is shown by shared sequence — not because both mention a flood. great-flood
2. Tehrani's quantitative "Little Red Riding Hood" study and d'Huy's Polyphemus/Cosmic Hunt trees demonstrate test (3) working in both directions: the toolkit can separate a single descent lineage (European Red Riding Hood) from an independent look-alike tradition (East Asian Tiger Grandmother), and can flag congruence with migration geography. dhuy-phylomemetics-mythology
3. Berezkin's areal method supplies the distributional evidence for test (3) at continental scale — flood motifs are dense along Asian–Pacific–American corridors and sparse in flood-prone Africa, a non-uniform pattern that resemblance-counting alone could never detect and that argues distribution carries historical (not merely environmental) signal. berezkin-motif-database
The steelman is that the discriminators degrade exactly where the vault most wants them. Horizontal transmission is pervasive in myth and makes a borrowed trait indistinguishable from an inherited one inside any parsimony or Bayesian tree — so test (3)'s trees can be confidently wrong. Character coding (what counts as "the same motif") is analyst-chosen with no agreed protocol, so two researchers can build incompatible trees from the same corpus. And test (2)'s "no documented contact route" is an argument from absence: the Megiddo and Ugarit finds themselves show how a corridor invisible in 1850 becomes attested later. Hence prehistoric reconstructions stay class 3, and convergence is a default under current evidence, never a proof.
- Emic (traditions' own account): most traditions narrate their sacred stories as primordially given or divinely revealed — neither borrowed nor invented — so the emic frame offers no transmission data and is recorded as belief, not evidence.
- Etic (scholarly analysis): transmission is an inference from the structure and distribution of attested versions, calibrated against independent (linguistic, genetic, archaeological) timelines; the verdict is only ever as strong as the dated evidence behind the strongest applicable discriminator, which is why the vault scopes verdicts (e.g. flood: contact for the Near East, unresolved globally — Q5).