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Flotation machine in use at Hallan Çemi, southeast Turkey, c. 1990. Note the two sieves catching charred seeds and charcoal, and the bags of archaeological matrix waiting for flotation. Photo: Mark Nesbitt

Paleoethnobotany, also known as archaeobotany in European (particularly British) academic circles, is the archaeological sub-field that studies plant remains from archaeological sites. Major research themes are recovery and identification of plant remains, the use of wild plants, the origins of agriculture and domestication, and the co-evolution of human-plant interactions.

Paleoethnobotanists use a variety of methods to identify and recover plant remains. One method used to recover macroremains is to sieve excavated material manually in a water bath in order to allow the organic material to float to the surface. This method is known as flotation. The matrix (the soil from a suspected archaeological feature) is slowly added to agitated water. The soil, sand, and other heavy material, known as heavy fraction, will sink to the bottom. The less dense organic material such as charred seeds, wood and bone will tend to float to the surface. The material that floats to the top, called light fraction, is gathered with a sieve. The organic light fraction is then available for examination. Samples of the heavy fraction are also gathered for later analysis. Other types flotation processes include machine-assisted flotation and froth flotation.

Paleoethnobotanists also recover and analyze microremains phytoliths, pollen palynology, human paleofeces (sometimes called coprolite), and impressions in ceramic sherds (such as the imprint of grains in mixing bowl).

Palynology is a mature and distinct scientific discipline that studies pollen, typically in the context of reconstructing past environments.

Dendrochronology, the study of growth rings on trees relating to study of past environments, is another scientific discipline useful to paleoethnobotanical study.

The work done in paleoethnobotany can be divided into field work, collections management, systematic description of species, and theories into the origins of human and plant interaction. Some examples of this analysis:

A paleoethnobotanist may find discrete concentrations of burned or dried remnants of seeds in an area of discolored soil (a possible hearth feature). If later analyses indicates that the remnants were of only mature wild seeds of a type of plant that grows locally, it could be inferred that the site was only visited seasonally. Such an inference could be supported by a lack of other features that would suggest that no permanent shelters were built at the site.

Alternatively, a paleoethnobotanist may find that a fire pit feature contains concentrated remnants of a wide variety of edible wild plants that mature throughout the year. An archaeologist may find features at the site that indicate some sort of semi-permanent dwellings (such as post holes and middens). The middens may have concentrations of animal remains, identified by a zooarchaeologist as those of wild game, with a variety of species-specific maturity levels. In that case, a more permanent settlement may be inferred, perhaps to the level of a village. Such an analysis of the archaeological features could suggest a society of hunter-gatherers who inhabited the site on a more-or-less year-round basis.

A paleoethnobotanist may also find concentrated remains of plants that typically are only grown through active cultivation (such as corn, beans, and squash). At the same site, an archaeologist might identify features such as stone walls surrounding enclosures arrayed in a pattern, and deep, layered middens with concentrations of domesticated animal remains such as goats or pigs. An analysis of the site, set within the context of the archaeological features and animal and plant remains, would suggest a settled agrarian community.

• Pearsall, Deborah M, Paleoethnobotany: A Handbook of Procedures, Second Edition, Academic Press, San Diego (2000), ISBN 0-12-548042-3.

• Christine A. Hastorf (Editor), Virginia S. Popper (Editor), Current Paleoethnobotany : Analytical Methods and Cultural Interpretations of Archaeological Plant Remains (Prehistoric Archeology and Ecology series), University of Chicago Press (January 15, 1989), ISBN 0-226-31893-1.

• Kristen J. Gremillion, People, Plants, and Landscapes: Studies in Paleoethnobotany, University of Alabama Press (February 1, 1997), ISBN 0-8173-0827-X.

• List of prominent paleoethnobotanists

• Association of Environmental Archaeology
• Steve Archer, "About Phytoliths": http://research.history.org/Archaeological_Research/Collections/CollArchaeoBot/PhytoFAQs.cfm .
• Terry B. Ball, "Phytolith Literature Review": http://www.ou.edu/cas/botany-micro/ben/ben282.html .