Ancient Astronomical Calendars and a Newly-Discovered Transgenerational Reproductive Parameter: Exploratory Evidence for Cultural Calibration

Abstract

A recent pre-registered study (Angulo & Sheretova, 2026; N = 1,366 families, 17 cultural groups, 1500–2000 CE; preprint DOI: 10.21203/rs.3.rs-8959120/v1) established that the transgenerational window (TW) — the sum of maternal ages at childbirth across two consecutive generations — clusters within [55, 65] years at 37.0% (95% CI: 34.4–39.5%) versus 13.2% expected (chi-squared = 673.6, p < 0.001, Cohen's h = 0.56). The TW mean is 55.0 years, with cultural modes ranging from 50.3 to 62.0 years. This exploratory follow-up investigates whether cultures with stronger ancient astronomical traditions show tighter alignment between their TW modes and known astronomical periods. We find that cultural TW modes correlate with the regional density of 56 catalogued ancient astronomical sites (Spearman rho = 0.733, N = 9 cultural groups, 95% bootstrap CI [0.15, 0.95]). The Middle Eastern TW mode (60.3 years) approximates three Jupiter-Saturn conjunction periods (59.6 years, 1.2% deviation), consistent with the Mesopotamian calendrical tradition. The overall TW mean (55.0 years) approximates three Metonic cycles (55.8 years, 1.5% deviation), the foundational period of ancient luni-solar calendars. We derive a testable prediction: migrant populations crossing between calendrical traditions should show TW drift toward the host culture's mode within 2-3 generations. We report all astronomical comparisons including poor fits and compute chance expectations. This paper is framed as hypothesis-generating; we propose a pre-registered migrant study as the confirmatory follow-up.

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