Researchers document the first use of maize in Mesoamerica

Date:
June 3, 2020
Source:
University of New Mexico
Summary:
Researchers investigated 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.



FULL STORY ========================================================================== [Corn varieties (stock | Credit: (c) Akarawut / stock.adobe.com] Corn
varieties (stock image).

Credit: (c) Akarawut / stock.adobe.com [Corn varieties (stock | Credit:
(c) Akarawut / stock.adobe.com] Corn varieties (stock image).

Credit: (c) Akarawut / stock.adobe.com Close An international team of researchers investigated 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.


========================================================================== Almost any grocery store is filled with products made from corn, also
known as maize, in every aisle: fresh corn, canned corn, corn cereal, taco shells, tortilla chips, popcorn, corn sweeteners in hundreds of products,
corn fillers in pet food, in soaps and cosmetics, and the list goes on.

Maize is perhaps the most important plant ever domesticated by people,
topping 1 billion tonnes produced in 2019, double that of rice, according
to University of New Mexico Anthropology professor Keith Prufer, Principle Investigator of a team that just released new research that sheds light
on when people started eating maize.

Recently published research from his team in the journal Science Advances reveals new information about when the now-ubiquitous maize became a key
part of people's diets. Until now, little was known about when humans
living in the tropics of Central America first started eating corn. But
the "unparalleled" discovery of remarkably well-preserved ancient human skeletons in Central American rock shelters has revealed when corn became
a key part of people's diet in the Americas.

"Today, much of the popularity of maize has to do with its high
carbohydrate and protein value in animal feed and sugar content which
makes it the preferred ingredient of many processed foods including
sugary drinks. Traditionally it has also been used as fermented drink
in Mesoamerica. Given its humble beginnings 9,000 years ago in Mexico, understanding how it came to be the most dominant plant in the world
benefits from deciphering what attracted people to this crop to begin
with. Our paper is the first direct measure of the adoption of maize as
a dietary staple in humans," Prufer observed.

Prufer said the international team of researchers led by UNM and
University of California, Santa Barbara is investigating 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.



==========================================================================
"One of the key issues for understanding these changes from an
evolutionary perspective is to know what the change from hunting and
gathers pathways to the development of agriculture looked like, and the
pace and tempo of innovative new subsistence strategies. Food production
and agriculture were among most important cultural innovations in human history.

"Farming allowed us to live in larger groups, in the same location,
and to develop permanent villages around food production. These changes ultimately led in the Maya area to the development of the Classic Period
city states of the Maya between 3,000 and 1,000 years ago. However,
until this study, we did not know when early Mesoamericans first became farmers, or how quickly they accepted the new cultigen maize as a stable
of their diet. Certainly, they were very successful in their previous
foraging, hunting, and horticultural pursuits before farming, so it is of considerable interest to understand the timing and underlying processes,"
he said.

Radiocarbon dating of the skeletal samples shows the transition from
pre-maize hunter-gatherer diets, where people consumed wild plants and
animals, to the introduction and increasing reliance on the corn. Maize
made up less than 30 percent of people's diets in the area by 4,700
years ago, rising to 70 percent 700 years later.

Maize was domesticated from teosinte, a wild grass growing in the lower
reaches of the Balsas River Valley of Central Mexico, around 9,000 years
ago. There is evidence maize was first cultivated in the Maya lowlands
around 6,500 years ago, at about the same time that it appears along
the Pacific coast of Mexico.

But there is no evidence that maize was a staple grain at that time.

The first use of corn may have been for an early form of liquor.



==========================================================================
"We hypothesize that maize stalk juice just may have been the original
use of early domesticated maize plants, at a time when the cobs and seeds
were essentially too small to be of much dietary significance. Humans are really good at fermenting sugary liquids into alcoholic drinks. This
changed as human selection of corn plants with larger and larger
seeds coincided with genetic changes in the plants themselves, leading eventually to larger cobs, with more and larger seeds in more seed rows," Prufer explained.

To determine the presence of maize in the diet of the ancient individuals, Prufer and his colleagues measured the carbon isotopes in the bones and
teeth of 52 skeletons. The study involved the remains of male and female
adults and children providing a wholistic sample of the population. The
oldest remains date from between 9,600 and 8,600 years ago and continues
to about 1,000 years ago The analysis shows the oldest remains were
people who ate wild plants, palms, fruits and nuts found in tropical
forests and savannahs, along with meat from hunting terrestrial animals.

By 4,700 years ago, diets had become more diverse, with some individuals showing the first consumption of maize. The isotopic signature of two
young nursing infants shows that their mothers were consuming substantial amounts of maize. The results show an increasing consumption of maize over
the next millennium as the population transitioned to sedentary farming.

Prufer noted, "We can directly observe in isotopes of bone how maize
became a staple grain in the early populations we are studying. We know
that people had been experimenting with the wild ancestor of maize,
teosintle, and with the earliest early maize for thousands of years, but
it does not appear to have been a staple grain until about 4000 BP. After
that, people never stopped eating corn, leading it to become perhaps
the most important food crop in the Americas, and then in the world." Excavations were directed by Prufer along with an international team
of archaeologists, biologists, ecologists and geologists. Numerous UNM
graduate and undergraduate students took part in the field research
as well as collaborators with the protected area co-management team,
a Belizean NGO the Ya'axche' Conservation Trust.

Conditions weren't easy for the excavation teams, Prufer noted: "We
did five years of fieldwork in two very remote rock shelter sites in
the Bladen Nature Reserve in the Maya Mountains of Belize, a vast
wilderness area that is a two- day walk from the nearest road. To
work in this area we had to camp with no electricity, running water,
or even cell service for a month at a time each year." Analysis was
conducted at Penn State University, UNM Center for Stable Isotopes, UCSB,
and Exeter University in the UK. Prufer was the project director along
with his colleague Doug Kennett from UCSB. The project was funded by the Alphawood Foundation and the National Science Foundation. The study was conducted by researchers from UNM, UCSB, Pennsylvania State University, University of Exeter, The US Army Central Identification Laboratory,
University of Mississippi, Northern Arizona University, and the Ya'axche Conservation Trust in Belize.

Now that the research is published, the team will advance it to the
next stage.

"New technologies allow us to look even deeper into molecular analysis
through studies of ancient DNA and isotopic analysis of individual amino
acids that are involved in turning food into building blocks of tissues
and energy. We already have a Ph.D. students working on expanding our
work to the next generation of analysis," Prufer said.


========================================================================== Story Source: Materials provided by University_of_New_Mexico. Original
written by Mary Beth King. Note: Content may be edited for style and
length.


========================================================================== Related Multimedia:
* YouTube_video:_When_did_people_start_eating_corn? ========================================================================== Journal Reference:
1. Douglas J. Kennett et al. Early isotopic evidence for maize as
a staple
grain in the Americas. Science Advances, 2020 DOI:
10.1126/sciadv.aba3245 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200603151158.htm https://www.sciencedaily.com/releases/2020/06/200603151158.htm

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