|17 April 2004
Humans took 1000 years to tame wild plants
Remnants of ancient barley, wheat, figs and pistachios nearly 10,000 years old are helping to solve the mystery about how and when nomadic hunter-gatherers became sedentary farmers. A team led by Australian archaeologist Dr Phillip Edwards of Melbourne's La Trobe University said its findings in the Middle East suggested humans went through a 1000-year phase of cultivating wild plants before they began breeding plants in earnest.
The team has been investigating remnants at a site near the Dead Sea in Jordan that represents what archaeologists call the Pre-Pottery Neolithic A (PPNA) period, when humans began to establish settlements. Scientists have dated the site to about 9600 to 9300 years old. Until relatively recently, the PPNA was also generally accepted as the time when humans began to domesticate plants. But Edwards said the major flaw in this argument was that any archaeological evidence of plants from PPNA sites were not conclusive evidence of domesticated varieties. "That left us with a puzzle," said Edwards. "Villages really intensified and grew in this period, and if it wasn't due to a new food base then everybody was left with the question of what caused it."
The La Trobe team's archaeobotanist, PhD student John Meadows, studied ancient barley seeds from the Dead Sea site. While they were larger than wild types, they were not as large as fully domesticated types found in the next archaeological period, the Pre-Pottery Neolithic B (PPNB). This was one piece of evidence, argued Edwards, that suggested there was a period before domestication called "pre-domestication cultivation".
"They were still hunters, still collected plants but what we now think is that they had added part-time cultivation of wheat, barley and some legumes," Edwards said. He added the fact that the site was very flat and had an ancient spring suggested the grains of barley and wheat found there were grown there. Mortar and pestles and other grinding equipment were also found there. Edwards said other research from a PPNA site in Syria had found weeds associated with cultivation. Together with this evidence of a sedentary life, other evidence suggested the people at the Dead Sea site were also part hunter-gatherers.
Numerous figs and pistachios remnants found there were unlikely to have grown there because the site would have been very dry and saline at the time, said Edwards. Instead, he said, they would have been gathered from the hills in season. The La Trobe team's research has also added to archaeologists' understanding of when exactly the PPNA ended. The period is generally regarded as starting at 8,350 BCE and ending at 7,650 BCE. But Edward's team suggested an ending of about 7,350 to 7,250 BCE.
Source: ABC Science Online (13 April 2004)
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