Pre-Columbian corn Recent decades have seen an explosion in knowledge of the early agriculture of lowland South America. Knowledge of the highlands is scarcer, but much to be desired, given that the Andes were home to the Incas and other pre-Columbian cultures. Perry et al. report on maize and other plant remains going back 4,000 years from Waynuna, an archaeological site in the highlands of southern Peru. This extends the record of maize back by at least a millennium in the southern Andes and provides direct evidence for the deliberate movement of plant foods by humans from the tropical forests to the highlands. Over the past decade, increasing attention to the recovery and identification of plant microfossil remains from archaeological sites located in lowland South America has significantly increased knowledge of pre-Columbian plant domestication and crop plant dispersals in tropical forests and other regions.sup.1,2,3,4. Along the Andean mountain chain, however, the chronology and trajectory of plant domestication are still poorly understood for both important indigenous staple crops such as the potato (Solanum sp.) and others exogenous to the region, for example, maize (Zea mays).sup.5,6. Here we report the analyses of plant microremains from a late preceramic house (3,431 [plus or minus] 45 to 3,745 [plus or minus] 65 .sup.14C bp or ~3,600 to 4,000 calibrated years bp) in the highland southern Peruvian site of Waynuna. Our results extend the record of maize by at least a millennium in the southern Andes, show on-site processing of maize into flour, provide direct evidence for the deliberate movement of plant foods by humans from the tropical forest to the highlands, and confirm the potential of plant microfossil analysis in understanding ancient plant use and migration in this region.