The roots of a staple crop

June 03, 2020

About 9,000 years ago in the Balsas River Valley of southwestern Mexico, hunter-gatherers began domesticating teosinte, a wild grass. Fast-forward to the present, and what was a humble perennial has been turned into the world's biggest grain crop: maize.

Humanity deeply relies on maize, or corn, but just when it became a major food crop in the Americas has been a source of mystery and dispute.

Now, a UC Santa Barbara researcher and his collaborators, by testing the skeletons of an "unparalleled" collection of human skeletal remains in Belize, have demonstrated that maize had become a staple in the Americas 4,700 years ago.

In a new paper, "Early isotopic evidence for maize as a staple grain in the Americas" in the journal Science Advances, Douglas J. Kennett, a UCSB anthropology professor, details how the discovery of human skeletons buried in a rock-shelter over a period of 10,000 years opened a window on maize consumption nearly three millennia before the rise of Maya civilization.

"What this paper shows is that by 4,700 years ago," Kennett said, "there is a significant shift towards maize cultivation and consumption, exceeding what we would consider to be a staple grain. And by 4,000 years ago maize was a persistently used staple and its importance continues through the Classic Maya period and until today."

Kennett, the paper's lead author, said the breakthrough came with the discovery of two rock-shelters with remarkably well-preserved skeletal remains in the Maya Mountains of Belize. Bones in the Neotropics typically degrade because of heat and humidity, but these rock shelters preserved the skeletal material well enough to measure stable isotopes revealing the diets of these people prior to death.

"The lowland Neotropics is not kind to organic material," Kennett said. "Bones degrade quickly if left out in the open. But these are special sites because they provide dry shelter from the elements that helps preserve bones that we were able to extract collagen from for nitrogen and carbon isotope analysis."

Maize synthesizes carbon using a distinctive photosynthetic pathway, which is evident isotopically in people that consume this important cultigen. There are very few plants in the lowland Neotropics that synthesize carbon in this way, so it's clear isotopically when people start eating substantial amounts of maize.

Skeletons dated to older than 4,700 years ago show minimal or no maize consumption. Some individuals dated to 4,700 to 4,000 years ago, however, show about 30% of maize consumption -- what Kennett calls a transitional period. By 4,000 years ago the carbon isotopic evidence indicates that maize consisted of more than 70% of the diet of individuals in the Maya lowlands.

"If you measured the isotopic composition of Maya people today," he said, "they would look very similar because they're consuming a great deal of maize on a daily basis. In terms of broader significance, this is the earliest evidence for the use of maize as a staple in the Americas that we're aware of so far."

The transition to agriculture in the Neotropics, as evidenced by the use of maize as a staple, has tantalizing implications for the rise of Maya civilization. As Kennett notes, where the Maya came from and when they moved into the area are still open questions. Classic Period Maya society didn't start to develop until about 2,000 years ago.

"So the question is, when do Maya people first move into the region and are they the earliest agriculturalists?" he said. "It is possible that the early agriculturalists identified in our study moved into the area and that they are somehow related to the Maya that we associate with emergence of Maya civilization later in time."
-end-
In addition to UC Santa Barbara, the study was conducted by researchers from the University of New Mexico, Penn State University, University of Exeter, Central Identification Laboratory, University of Mississippi, Northern Arizona University and the Ya'axche Conservation Trust in Belize.

University of California - Santa Barbara

Related Maize Articles from Brightsurf:

European and American maize: Same same, but different
German researchers decoded the European maize genome. In comparison to North American maize lines, they discovered variations that underlie phenotypic differences and may also contribute to the heterosis effect.

European maize highlights the hidden differences within a species
Maize is one of our major staple foods and is cultivated around the world, showcasing a broad range of genetic adaptations to different environmental conditions.

Site-directed mutagenesis in wheat via haploid induction by maize
Site-directed mutagenesis facilitates the experimental validation of gene function and can speed up plant breeding by producing new biodiversity or by reproducing previously known gene variants in other than their original genetic backgrounds.

Research reveals regulatory features of maize genome during early reproductive development
A team of researchers led by Andrea Eveland, Ph.D., assistant member, Donald Danforth Plant Science Center, has mapped out the non-coding, 'functional' genome in maize during an early developmental window critical to formation of pollen-bearing tassels and grain-bearing ears.

UNM researchers document the first use of maize in Mesoamerica
international team of researchers investigates the earliest humans in Central America and how they adapted over time to new and changing environments, and how those changes have affected human life histories and societies.

Climate-smart agricultural practices increase maize yield in Malawi
Climate change creates extreme weather patterns that are especially challenging for people in developing countries and can severely impact agricultural yield and food security.

Maize, not metal, key to native settlements' history in NY
New Cornell University research is producing a more accurate historical timeline for the occupation of Native American sites in upstate New York, based on radiocarbon dating of organic materials and statistical modeling.

New aflatoxin biocontrol product lowers contamination of groundnut and maize in Senegal
Recently a team of plant pathologists have developed an aflatoxin biocontrol product, Aflasafe SN01, for use in Senegal, which includes four atoxigenic isolates native to Senegal and distinct from active ingredients used in other biocontrol products in Africa and elsewhere.

A genetic map for maize
Researchers have decoded the genetic map for how maize from tropical environments can be adapted to the temperate US summer growing season.

'Lost crops' could have fed as many as maize
Grown together, newly examined 'lost crops' could have produced enough seed to feed as many indigenous people as traditionally grown maize, according to new research from Washington University in St.

Read More: Maize News and Maize Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.