Corn: It's Not for Cocktails -- Michael Balter @ ScienceNOW

Corn: It's Not for Cocktails -- Balter 2009 (323): 2 -- ScienceNOW

Michael Balter reports for Science Now on the recent discovery of the oldest known signs of maize domestication in the Americas - as this article will only be online for 4 weeks from the publication date, I'll include some extensive quotes for posterity, beginning with this introduction by the author...

Pity the first corn eaters. The ancestor of the plant that gives us its succulent yellow kernels is an unappetizing grain known as teosinte, whose ears harbor only five to 12 rock-hard grains. Scientists have now found the earliest known traces of corn--or maize--at a site in central Mexico dated to nearly 9000 years ago. And although this ancient plant was probably tough on the teeth, the find suggests that early farmers did indeed eat it--rather than turn it into alcoholic beverages, as some researchers have suggested.

If the evidence from the attached image is anything to go by, the food item on the left looks most unappetising, and gives further proof that our ancestors didn't always get to eat prime cuts of meat on the hoof, or a nice basket of freshly gathered fruits and nuts - at least I'm assuming it was hunger rather than gastronomic considerations that prompted people to partake of this food item. The hunt for the earliest origins of maize - or corn as it's more commonly known this side of the Atlantic - has been under way for many years, as we see in this excerpt...

Scientists have spent decades trying to figure out where maize (Zea mays) was first domesticated and why. Many researchers suspected a link between teosinte and today's corn, but the evidence was not conclusive. In 2002, a team led by geneticist John Doebley of the University of Wisconsin, Madison, found the smoking gun. They used genetic testing to show that maize is a very close relative of a variety of teosinte that grows today in Mexico's Balsas River area. What's more, Doebley's team found that maize had been domesticated only once, about 9000 years ago, and then spread throughout the Americas.

This date of around 9,000 years ago accords roughly with the dates for the ealriest known domestication of other agricultural resources, namely squash, peanuts and cotton, the latter of which was largely responsible for maintaining the lifestyles of the citizens of Caral, a few millennia later. Back to the article for further detail of the maize research...

That and other discoveries led Dolores Piperno, an archaeobotanist at the Smithsonian Institution in Washington, D.C., and her co-workers to begin searching for archaeological evidence of the earliest maize in the Balsas River region. Until then, the earliest known maize cobs, found near Oaxaca, Mexico, had been dated to only 6200 years ago. Piperno and her colleagues began using new techniques to identify early domesticates using microscopic plant fossils, called phytoliths, as well as starch grains, both of which are often preserved on the stone tools used by early farmers in the humid tropics.

In 2005, a team led by Piperno and Anthony Ranere, an anthropologist at Temple University in Philadelphia, Pennsylvania, hit pay dirt: Under a giant boulder in the Balsas River region, called the Xihuatoxtla Shelter, the researchers discovered a trove of prehistoric grinding stones to which phytoliths and starch grains from maize were still adhering. Radiocarbon dating of charcoal found with the earliest of the stones pegged the corn as 8700 years old, bearing out the genetic dating by Doebley's group.

The study of phytoliths seems to be a comparitively new area of archaeological research, and one that has far proven to be very useful indeed, as traces of ancient stone tool use can be traced back many thousands of years, and has even been used to try and determine whether archaic humans were exploiting acacia wood 1.5 million years ago, and from the more recent Clovis site of Cactus Hill.

Back to the article for some surprising revelations concerning the use to which this early foodstuff was put, contrary to previous thinking on the matter...

The findings, which the team reports in two online papers today in the Proceedings of the National Academy of Sciences, also appear to discount a leading hypothesis for why early farmers would bother domesticating the unappealing teosinte plant in the first place. Several researchers, including Michael Blake, an archaeologist at the University of British Columbia in Vancouver, Canada, have suggested that the plant was valued not for its tough kernels but for its sugar-laden stalk, which might have been used to make early alcoholic drinks.

Only later, after it had come under cultivation, did teosinte undergo the genetic changes that turned it into maize and a staple food crop, according to the hypothesis. But none of the phytoliths and starch grains at Xihuatoxtla come from the stalk; even at this very early period of domestication, the team found, the people who used the shelter were grinding the kernels.

This period of domestication appears slightly later in the Americas than Anatolia, where the earliest signs of large-scale agriculture appear to coincide with the extraordinary phase of construction at Göbekli Tepe, a site which has turned all previous thinking about the emergence of monumentalism after the advent of agriculture on its head. As far as I can tell, there have been no similar contemporary discoveries in the New World, demonstrating that although societies began crop cultivation in earnest within a few millennia of each other, the circumstances, motives and resulting move to sedentary lifestyles were quite strongly contrasted.

Here's the final paragraph from the linked essay...

Blake concedes that the new findings do not support his idea and that the "primary interest" of the Xihuatoxtla people appears to have been the maize kernels rather than the stalks. Nevertheless, he argues, it is still possible that the farmers squeezed the juice out of the stalks while they were still in the fields and fermented it there rather than taking it back to the shelter.

But most importantly, Blake says, the new discovery raises hopes that researchers will eventually find larger, visible fragments of cobs, kernels, and stalks at early farming sites, which would provide critical insights into how they were processed and domesticated.

See also :: Teosinte - Maize's Wild Ancestor (PDF)

There are a couple of suggested links to related articles by Michael Balter, namely...

Early Chinese May Have Eaten Millet Before Rice

Michael Balter (25 March 2009)
ScienceNOW 2009 (325), 1.
| Full Text »

In Science Magazine

NEWS FOCUS
PLANT SCIENCE: Seeking Agriculture's Ancient Roots

Michael Balter (29 June 2007)
Science 316 (5833), 1830. [DOI: 10.1126/science.316.5833.1830]
| Summary » | Full Text » | PDF »

image:: Traces of the oldest known corn were found under this boulder in Mexico. Early farmers domesticated unappetizing teosinte (left in inset), transforming it into edible form (right).

Credit: (rock) Anthony Ranere; (teosinte/maize) John Doebley