Hunch Not checked yet AD 1576

Cocoliztli broke out in wet years in central Mexico

Tested 25 October 2026 (exploratory, not the pre-set test). Drought atlas: epidemic years wetter than normal (all 14, p 0.008; the 4 major, p 0.008); 1576 struck in a wet decade after the 1572-73 drought. Fits a rodent boom after rain, but equally waterborne enteric fever (Salmonella Paratyphi C was found in 1545 victims). Not seen in the Puebla maize record (epidemic years mean -0.07), so it needs a third proxy (for example the Queretaro baldcypress record or written rainfall reports) before trusting it. The 2002 paper already noted that 1545 and 1576 began in rainy years; the tests across all 14 epidemics and the northern-only megadrought look new.

Third record (Queretaro bald cypress, 25 October 2026): no year-by-year wet signal (all 14 p 0.40). The year-level result rests on the drought atlas alone, so downgraded to OPEN. What holds across records is the decade-scale picture: the great epidemics struck in the long wet era (1540 to 1580) that followed the worst central-Mexican drought of the last 600 years (1514 to 1539).

How it connects

This hunch is about What caused the cocoliztli epidemics that killed most of Mexico's people (1545, 1576 and later)?

This hunch we read it in Acuna-Soto, Stahle, Cleaveland and Therrell 2002, Megadrought and megadeath in 16th century Mexico, Emerging Infectious Diseases 8:360

This hunch is argued against by Puebla maize record: good harvests in the 1570s, poor in the 1540s, no signal in epidemic years no signal in the maize record; 1540s poor harvests

This hunch is argued against by Queretaro bald cypress: the worst drought in 600 years ended in 1539; 1540 to 1580 was the wettest stretch no year-by-year wet signal

This hunch is supported by Drought atlas: cocoliztli years were wet in central Mexico; the 16th-century megadrought was northern epidemic years wetter than normal

This hunch came from this step Tested the cocoliztli epidemics against the Mexican Drought Atlas