Key 103 dating

1) date to 6,200 years ago and reinvigorate support for a model in which groups living in the Southern Highlands had already domesticated maize by 6,000–7,000 years ago and later diffused its cultivation to groups living at lower elevations in the valley of the Balsas River and coastal lowlands (4).

This report presents a long record of maize cultivation from the Veracruz coastal plain that is similar in terms of sedimentary sequence to the key Tabasco record, corroborating some of its attributes but forcing the conclusion that no evidence exists for maize cultivation as early as 7,000 years ago from the Gulf Coast Lowlands. 2) derives from an 8.5-m sedimentary core recovered with a Livingston-type corer from a small freshwater lake at the lowest point in an extensive belt of wetlands that covers the coastal plain between the dunes and the piedmont, some 24 km northwest of the port of Veracruz.Sedimentation subsequently aggraded those lagoons: by the mid-Holocene, they had become brackish estuaries; by late Holocene they had become a coastal plain marked by freshwater lakes surrounded by wetlands, crossed by streams with flanking levees, and edged along only the seaward margin with lagoons, estuaries, and mangrove forests.Previous research has shown that levees and the fringing Tertiary piedmont and Pleistocene dunes have for millennia provided settlement sites above the floodwaters with which the strongly seasonal precipitation regime inundates the coastal plain (12).Yet before the recent report of 7,000-year-old maize pollen from Tabasco, the direct evidence for maize cultivation outside of the Southern Highlands was more recent than the macrofossils from Tehuacán, even assuming they might be only 5,500 years old (1, 7).The Tabasco pollen record reported in 2001 (1) has thus provided key support for a domestication hearth outside of the Southern Highlands because it contributed the first direct evidence for maize cultivation elsewhere that was at least contemporaneous with and possibly much older than that from Tehuacán.

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