POSTED 17 MAY 2007
Food on the coals: The Why Files (Memorial Day edition)
In the United States, Memorial Day (May 28, 2007) is a time for patriotic parades to honor soldiers who died defending the country -- and a weekend for barbecues. As a tradition, cooking food over the open fire may be as old as Homo sapiens ourselves.
Where did cooking arise, and how has it changed us, socially and physically? How else did fire help the emergence of humans? And now that we have stoves, what explains the continuing allure of the barbecue and other outdoor fires?
Let's go back a couple of years. Long before Memorial Day, before the wars that it commemorated, even before charcoal was sold in bags, humans were throwing food on the fire.
Firepits, known as "hearths" in the archeology trade, have played a critical role in ancient human settlements and the study of same. Firepits were often the settlement's center, and thus became a focus for finding the bones, tools, remains of dwellings, and scraps of food that record ancient culture. And the carbon in charcoal can be radioisotope dated. In some places, hearths are also the tell-tale signal of a settlement, says Robert Goodby, an associate professor of anthropology at Franklin Pierce College in New Hampshire. "Hearths are one of the most visible things we have." Even if the site was later plowed by farmers, the reddened, fire-cracked rocks are often found just beneath the surface. As the photo shows, some hearths were never disturbed by plows, and look much as they did when the embers went dark.
Courtesy Robert Goodby, Department of Anthropology, Franklin Pierce College.
Is it burning, man?
It's much easier to confirm that signs of an old fire represent a hearth if the remains are from the last few thousand years, rather than 100,000 or more years old. Ancient remains may have decayed or been disturbed or eroded, says Sissel Schroeder, an associate professor of anthropology at the University of Wisconsin-Madison.
© David Tenenbaum
Even those tell-tale fire-cracked rocks can be misleading, since fire can be sparked by natural causes like lightning, she warns. Concentrated remnants may indicate a well-used hearth -- or the stump of an ancient tree that burned. You can discount the possibility of an ancient tree by identifying multiple species of wood in the remains, she says, but that is "Difficult because the cell structure of plants becomes really distorted when burned."
To prove that signs of fire such as charring came from a fire made by people, archeologists try to assemble several lines of evidence, Schroeder says. These signs are highly suggestive of a cooking fire:
A ring of stones: Most ancient people contained the fire with stones. Although they may have been moved from their original position, the reddened, fire-cracked appearance will remain.
A good assortment of food remains that were cooked in the fire -- not just the odd wishbone or bird's beak.
Knife-marks on bones (a sign of butchering).
If you add it up, you can reach a solid conclusion, especially if you have those tell-tale butchering marks. "If all these elements are present you can say, definitively, that you have evidence that humans were using the fire to cook," Schroeder says. But as we'll see, the old evidence is ambiguous, and the earliest date of a controlled fire is uncertain.
© David Tenenbaum
Archeologists are finding that many of our ancestors were sophisticated gatherers, says Nina Versaggi, director of the Public Archaeology Facility and an adjunct associate professor of anthropology at Binghamton University. During studies in New York State, she says, soil from the firepits is "put into flotation machines, to recover bone and charred botanical remains: nutshells of different varieties, and wild plants such as seeds that could be ground into flour. Sometimes we see seeds from the grasses they were collecting for baskets or mats, and the tough rinds of wild carrots and aquatic tubers that grew around the edges of wetlands."
These studies of early New Yorkers "dispelled the myth of man the hunter," she added. "They were not hunting mammoths or mastodons, but migratory birds and small animals, and later gathering plants, and fishing. They definitely did not eat just meat."
Courtesy ©Louisa Medaris
Ancient fire: Can we get down to the who, what, when, where and why?
Megan Anderson, project assistant; Terry Devitt, editor; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive