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These squash seeds were determined to be cultivars, not wild plants, and are more than 9,200 years old.
These squash seeds were determined to be cultivars, not wild plants, and are more than 9,200 years old. (Image Courtesy Of Tom D. Dillehay)

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Monday, July 2, 2007

Agriculture's New World Start

Domestication of food and fiber plants in the New World -- as well as the emergence of communities built around farming -- appear to have occurred earlier than previously believed.

Researchers from four institutions, including the Agriculture Department, reported Friday in the journal Science that they have determined certain cultivated plant material from northern Peru to be 9,240 years old.

The researchers, led by Vanderbilt University anthropologist Tom D. Dillehay, dated both newly found and previously excavated material from the Nanchoc Valley, which is about 1,500 feet above sea level on the Pacific slope of the Andes. They studied a few squash seeds, part of a peanut shell, and a virtually intact cotton boll from the floors and hearths of ancient dwellings.

Radiocarbon dating put the squash seeds at more than 9,200 years old, the peanut hull at 8,000 and the cotton at 5,500. All bore evidence of being cultivars -- plant varieties intentionally selected and maintained through cultivation -- rather than wild plants. None was closely related to nearby species, suggesting that they had been domesticated elsewhere.

The archaeological context in which these vegetable remnants were found strongly suggests that horticulture was already well established by at least 6,000 to 7,000 years ago. The communities included canals for water management; mounds associated with the production of lime, which was used in preparing coca extracts; and personal garden plots.

Agriculture first appeared in the Fertile Crescent of the Near East 12,000 to 10,000 years ago. These discoveries suggest that crop cultivation began not long after that in the Western Hemisphere.

-- David Brown

Cooling Crust Is Another Threat

If global warming and rising ocean levels do not put many major American cities underwater, then the cooling of the rock beneath North America eventually will, a new study suggests.

Researchers at the University of Utah have learned that the elevation of various regions is determined, in part, by how hot Earth's rocky crust is beneath them. While the movement and collision of tectonic plates shape the landscape and form mountains, land elevation also depends on the composition and temperature of the rock that is moved, the scientists found. Less-dense crustal rock thickens and grows warmer when tectonic-plate collisions occur; the heat, in turn, makes the rock more buoyant.

"If you subtracted the heat that keeps North American elevations high, most of the continent would be below sea level, except the high Rocky Mountains, the Sierra Nevada and the Pacific Northwest west of the Cascade Range," said Derrick Hasterok, a doctoral student and co-author of the study, published in this month's Journal of Geophysical Research-Solid Earth.

As rock beneath North America cools and becomes denser, the continent will sink. Atlanta, now 1,000 feet above sea level, would be 1,416 feet below sea level if the crustal rock beneath it cooled to 750 degrees Fahrenheit, the temperature of the coldest crustal rock in North America at the moment, the scientists calculated. Other cities, including Albuquerque, Chicago, Dallas, Las Vegas, Phoenix and St. Louis would be well below sea level, as well.

Don't panic, though. Billions of years will pass before it happens.

-- Christopher Lee

Ships Rerouted to Avoid Whales

Ships traversing waters where whales nurse and feed in the Gerry E. Studds Stellwagen Bank National Marine Sanctuary off Massachusetts Bay began taking modified routes this month on their way to and from Boston Harbor to reduce the risk of collisions. The National Oceanic and Atmospheric Administration mapped out the new routes and said the change marked the first time that shipping lanes have been changed specifically to protect whales.

The modification follows years of monitoring ship traffic and whale behavior. NOAA said the shift will reduce the risk of a ship hitting one of the great whales by as much as 81 percent.

The lane shift will increase travel time by 10 to 22 minutes for the roughly 3,500 ships that pass each year through the sanctuary -- an 842-square-mile area that stretches between Cape Ann and Cape Cod.

The area is unusually hospitable to sea creatures, providing feeding and nursing grounds for more than a dozen whale species, including the endangered humpback, northern right and fin whales. It is home to more than 30 species of seabirds, more than 60 species of fish and hundreds of types of marine invertebrates.

Whale strikes have become increasingly common along the Atlantic coast and are now among the most frequent causes of whale injuries and deaths.

-- Marc Kaufman


© 2007 The Washington Post Company

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