Washington, June 30 : New analysis by scientists has suggested that maize may have been domesticated in Mexico as early as 10,000 years ago.
According to a report in Science Daily, the ancestors of maize originally grew wild in Mexico and were radically different from the plant that is now one of the most important crops in the world.
While the evidence is clear that maize was first domesticated in Mexico, the time and location of the earliest domestication and dispersal events are still in dispute.
Now, in addition to more traditional macrobotanical and archeological remains, scientists are using new genetic and microbotanical techniques to distinguish domesticated maize from its wild relatives as well as to identify ancient sites of maize agriculture.
These new analyses suggest that maize may have been domesticated in Mexico as early as 10,000 years ago.
Dr. John Jones and his colleagues, Mary Pohl, and Kevin Pope, have evaluated multiple lines of evidence, including paleobotanical remains such as pollen, phytoliths, and starch grains, as well as genetic analyses, to reconstruct the early history of maize agriculture.
While macrobotanical remains such as maize kernels, cobs, and leaves have been found in dry mountain caves, such remains are not preserved in more humid lowland areas.
Much smaller parts of the maize plant, like cellular silica deposits, called phytoliths, and pollen and starch grains, are preserved under both humid and dry conditions.
Phytoliths are another type of plant microfossil that is preserved for thousands of years and can be used to distinguish domesticated from wild maize.
These microscopic bodies are silica or calcium oxalate deposits that accumulate in the intercellular spaces of plant stems, leaves, and roots and have characteristic shapes depending on genus and species.
They are preserved even when the plant is burned or disintegrated.
Scientists have found that it is possible to distinguish the microliths of teosinte from those of maize and other grasses, thus allowing them to identify the approximate dates and locations of early agricultural activity.
Phytoliths are also preserved on ceramic and stone artifacts used to process food.
Jones and his co-workers analyzed the sediments from San Andres, in the state of Tabasco on the Mexican Gulf Coast.
Analysis of area sediments revealed phytoliths of domesticated varieties of maize as well as those of agricultural weeds.
These data, along with evidence of burning, suggested that agriculturalists were active in that part of the Yucatan Peninsula around 7,000 years ago.