Low- and high-hookworm areas may have differed in other respects like crops grown, suitability for slavery, wealth and education, undermining geographic natural-experiment identification strategies.
Evidence
COMMENT: THE IMPACTS OF HOOKWORM ERADICATION IN THE AMERICAN SOUTH (GiveWell)
Categorization
- corroborated: 2 independent passages support this claim
- XREF: connects to: Iodizing salt in 1924 closed a 15-point IQ gap cheaply; The definition of natural agriculture becomes questionable under experimental conditions. — Nicholson Baker, Baseless- My Search for Secrets in the…, 857