Table of Contents
Most of what is known about prehistoric Oaxaca comes from work in the Central Valleys region. Domesticated squash dated to 8750 ±350 has been found in the Guilá Naquitz cave near the town of Mitla, according to Mexico’s nomination file to UNESCO. This area was recognized as a UNESCO World Heritage site in 2010. In the listing’s words: “Ten thousand-year-old Cucurbitaceae seeds in one cave, Guilá Naquitz, are considered to be the earliest known evidence of domesticated plants in the continent, while corn cob fragments from the same cave are said to be the earliest documented evidence for the domestication of maize.” (UNESCO World Heritage Centre, whc.unesco.org/en/list/1352, short excerpt for review and study)
The UNESCO listing is the Prehistoric Caves of Yagul and Mitla in the Central Valleys of Oaxaca, inscribed under criterion (iii). The seeds it names are squash, from the gourd family.
Guilá Naquitz Cave
Guilá Naquitz Cave, located in present-day Oaxaca, Mexico, is one of the most important archaeological sites in Mesoamerica. It provides significant insights into early human habitation in the region. However, the occupation of the cave was neither continuous nor year-round, as the inhabitants used it primarily during specific times of the year.
Mexico’s nomination file to UNESCO, prepared by CONACULTA and INAH, places the cave at (6,319 feet) above sea level, in the area of Tlacolula de Matamoros. Kent V. Flannery of the University of Michigan excavated it in the 1960s and published the results as Guilá Naquitz: Archaic Foraging and Early Agriculture in Oaxaca, Mexico (Academic Press, 1986).
The nomination file also summarizes Flannery’s work. In its account, the people of this period were nomadic hunter-gatherers who used the caves as seasonal camps and temporary shelters. It names Flannery’s earliest archaic phase the Naquitz phase and dates it to 8900 to 6400 BC. It places the first evidence of domesticated local plants, including gourds, squash, beans and corn, toward the end of that phase, citing Flannery 1986. It also gives a date of 8750 ±350 for domesticated squash (Cucurbita pepo) at the cave (CONACULTA and INAH, The Prehistoric Caves of Yagul and Mitla in the Central Valleys of Oaxaca, nomination file 1352, chapter 2 and chapter 3).
The maize cobs
Corn came much later. Dolores R. Piperno of the Smithsonian Tropical Research Institute and Kent V. Flannery dated three maize cobs from the cave by accelerator mass spectrometry.
The cobs are the oldest known in the Americas.
…produced dates of 5,400 carbon-14 years before the present (about 6,250 calendar years ago), making those cobs the oldest in the Americas.
D. R. Piperno and K. V. Flannery, "The earliest archaeological maize (Zea mays L.) from highland Mexico," PNAS 98(4): 2101-2103 (2001), abstract, copyright 2001 National Academy of Sciences (short excerpt for review and study)
The same abstract notes that no maize fossils turn up in the older layers. In the authors’ account, the domestication of maize “probably occurred elsewhere in Mexico,” and the cave holds the earliest macrofossil evidence for both squash and maize, not proof that either was first domesticated there.
