he first farmers raised barley and wheat in the Middle East more than 10,000 years ago. Sometime later, Chinese began cultivating rice, Mexicans corn and beans and South Americans potatoes. Indians in what is now the eastern United States grew crops of sunflower seeds.
In all five regions, scholars concluded years ago, agriculture developed independently of outside influences and then spread, changing forever the way people lived.
Now another region, the highlands of New Guinea, can be added to the roster of originating heartlands of agriculture. Australian scientists reported last week in the journal Science that they had found some signs that crops were cultivated there 10,000 years ago and strong evidence this was happening 7,000 years ago and onward.
Exploring Kuk Swamp, in a mountain valley in central New Guinea, the researchers uncovered plant crystals, pollen and starch grains that they said were part of the "substantial evidence for deliberate planting and incipient domestication" of two valuable food crops, taro and banana.
The taro remains, including starch grains preserved on the cutting edges of stone tools, were revealing because that species did not grow naturally in the highlands and must have been brought there from the lowlands. Although wild bananas are still plentiful on the island, the scientists said, the large amounts of banana microcrystals found in grassland sediments "are interpreted to be diagnostic of deliberate planting."
The findings appeared to settle a longstanding debate on the origin of New Guinea agriculture: whether it was strictly homegrown or a transplant from Southeast Asia. Previous claims for an independent origin of New Guinea agriculture had been considered largely unsubstantiated.
The researchers, led by Dr. Tim P. Denham, an archaeologist at Flinders University in Adelaide, Australia, said the sediment samples and other evidence of farming were dated at 6,950 to 6,440 years ago. Other studies have indicated that no domesticated plants from Southeast Asia entered New Guinea until after 3,500 years ago.
"The evidence from Kuk confirms that New Guinea was a primary center of agricultural development and plant domestication prior to any known Southeast Asian influence," the research team concluded.
Dr. Denham and his collaborators also reported clues to a gradual emergence of agriculture there beginning around 10,000 years ago. The evidence included widespread clearing of forests, charcoal from burned-over grasslands, networks of drainage ditches and levees and traces of cultivated plants.
Dr. Katarina Neumann, an archaeologist at J. W. Goethe University in Frankfurt, said the research contributed to the changing picture of New Guinea as an independent homeland of agriculture. The research failed to yield a clear understanding, she said, of how significant agriculture was in the culture compared with hunting and foraging.
The only other contender for a place on the list of independent agricultural innovation is sub-Saharan Africa, where millet, sorghum and African rice apparently originated. "It remains unclear," Dr. Neumann said, "whether African plant domestication was triggered by the arrival of Near Eastern crops."
Dr. Neumann, also writing in Science, noted that recent biomolecular studies suggested that taro, bananas, yams and sugar cane were domesticated in New Guinea or the islands of Melanesia. "The new data from Kuk," she said, "indicate that New Guinea is more likely, at least for banana and taro."
Dr. Neumann pointed out that the evidence attested to cultivation "but not necessarily domestication of banana and taro." But Dr. Denham's group said the two crops were "potentially the most significant food staples" in the New Guinea highlands before the introduction of the sweet potato by European explorers 300 years ago.
Scholars said the new research challenged assumptions about the consequences to human society that were thought to follow inevitably from the domestication of plants and animals. Early and independent agriculture was often linked to rapid population growth, social stratification and the rise of "civilization."
Yet in the New Guinea highlands, Dr. Denham's group noted, none of these consequences has ever come to pass. The societies are still egalitarian and relatively simple.
In the journal article, the researchers concluded, "The evidence for
early agriculture in Highland New Guinea signifies the potential diversity
of prehistoric trajectories following the inception of agriculture, and
challenges unilinear interpretations of human prehistory."