Keith Thomas wrote on Sunday, September 28, 2003 10:22 PM -- <<and this would, by definition exclude all foods native to the Americas, because there were no humans on these continents before this time>>

--------------see ref. below -- Dedy

Scientists investigating how humans spread across the world have found evidence that Japan was the launch pad into the New World 15,000 years ago. http://old.smh.com.au/news/0108/02/world/world15.html

But recent discoveries point to an earlier colonization of the Western Hemisphere. A campsite known as Monte Verde in southern Chile was occupied 12,500 years ago. At the Cactus Hill site in Virginia, scientists found stone tools and charcoal that may date back 15,500 years. 
http://www.trussel.com/prehist/news115.htm

There seem to be some sites in South America which predate the North American Clovis boundry of 12,000 years. It seems to me that this would suggest that people were inhabiting the America's before 12,000 years ago, and possibly as early as 50,000 years ago. Also, the fact that the earliest sites are found in South America seriously conflicts with the traditional Beringia entry model. http://www.anatomy.usyd.edu.au/danny/anthropology/anthro-l/archive/february-1995/0115.html

 Based on radiocarbon dating techniques, the Arlington Woman, as she is known, appears to have lived at least 13,000 years ago. That makes her the oldest skeleton ever found in North America. It also means that she lived there during the end of the last ice age, which lasted from 125,000 to 10,000 years ago. http://www.oceansonline.com/chumash.htm

For much of the 20th century, scientists have scoured remote parts of Alaska for clues to North America's first inhabitants-paleoindians...This showed that some of the artifacts from the Mesa site, as it was called, were in fact nearly 12,000 years old. http://www.ak.blm.gov/ak930/1stamericans.html

Excavations at the Page-Ladson site yielded flaked-stone and a proboscidean tusk with chop marks, radiocarbon dated between 13,130 and 10,520 B.P.  http://www.clovisandbeyond.org/clovisexhib.html

Archaeological evidence suggests that people were already living in the Americas well before the initial appearance of Clovis. For example, people were living at a site called Monte Verde (in Chile) at least 12,500 years ago (and perhaps as much as 30,000-plus years ago). http://www.cabrillo.cc.ca.us/~crsmith/anth7_hist1.html