Domestication and lowland adaptation of coastal preceramic maize from Paredones, Peru

Abstract

Archaeological cobs from Paredones and Huaca Prieta (Peru) are phenotypically indistinguishable from modern maize. This contrasts with the earliest Mexican macro-specimens from Guila Naquitz and San Marcos, which are phenotypically intermediate even though they date more recently in time. These observations suggest at least two alternative scenarios, one in which maize was domesticated earlier than previously thought in the lowland Mesoamerica, followed by rapid lowland dispersal to Peru, and another in which maize was independently domesticated in South America and subsequently lost, as current evidence supports a single origin for all modern maize. To gain insights into the origins of ancient Peruvian maize, we sequenced DNA from three Paredones specimens dating 6775 to 5000 calibrated years before present (BP) and conducted comparative analyses with two teosinte subspecies (Zea mays ssp. mexicana and parviglumis) and extant maize, including highland and lowland landraces from Mesoamerica and South America. We show that Paredones maize originated from the same domestication event as Mexican maize and was domesticated by 6775 BP, implying rapid dispersal followed by improvement. Paredones maize show minimal levels of gene flow from mexicana, smaller than those observed in teosinte parviglumis. It also harbors significantly fewer alleles previously found to be adaptive to highlands, but not of alleles adaptive to lowlands, supporting a lowland migration route. Our overall results imply that Paredones maize originated in Mesoamerica, arrived in Peru without mexicana introgression through a rapid lowland migration route, and underwent improvements in both Mesoamerica and South America.

Two teosintes made modern maize

“…By this time, however, maize had already reached Panama (by ~7,800 cal BP) ( 33 ), and even farther into S. America (by ~6,900-6,700 cal BP) ( 34 – 36 ). Samples from S. America that reflect dispersal events prior to maize colonization of the Mexican highlands should not exhibit evidence of admixture with mexicana .Indeed, tests of admixture find no evidence of mexicana ancestry in N16, a ~5,500 cal BP maize cob from northern Peru ( 37 ).…”

“…Samples from S. America that reflect dispersal events prior to maize colonization of the Mexican highlands should not exhibit evidence of admixture with mexicana. Indeed, tests of admixture find no evidence of mexicana ancestry in N16, a ~5,500 cal BP maize cob from northern Peru (37).…”