Observatoy: Ancient Morsels[NY Times]
By HENRY FOUNTAIN
Researchers digging in the remains of an ancient settlement in Panama have 
uncovered microscopic buried treasure: tiny grains of starch that they say 
are the earliest direct evidence of the cultivation of root crops in the 
Americas. 

The researchers, from Temple University and the Smithsonian Institution, 
found the starch grains, which are generally less than 30 microns long — less 
than half the width of a human hair — at an archaeological site near the 
Pacific coast of Panama. The grains were identified as coming from manioc, 
yams and arrowroot and were found on milling stones in sediments that date 
from 5,000 to 7,000 years ago.

By comparing the size and other characteristics of the grains to those from 
modern domesticated and wild versions of the same root plants, the 
researchers were able to determine that the ancient grains came from 
domesticated plants. The researchers, who described their work in the journal 
Nature, also found maize starch at the archaeological site, meaning that 
these ancient peoples were cultivating seed plants along with root plants.

Whether tropical forest areas like this site were early centers for 
domestication and cultivation has been a subject of debate. Given that 
forests are home to wild versions of these plants, it would seem to make 
sense that domestication began in or near forests. But evidence has been hard 
to come by, because remains of roots and tubers easily decompose in the humid 
tropical environment. The relatively few grains obtained by the researchers 
in Panama were found by scraping them from nooks and crannies on the stones, 
where they had been able to beat the heat and humidity.