Paleoethnobotany
Paleoethnobotany, or archaeobotany, is the study of past human-plant interactions through the recovery and analysis of ancient plant remains. Both terms are synonymous, though paleoethnobotany is generally used in North America and acknowledges the contribution that ethnographic studies have made towards our current understanding of ancient plant exploitation practices, while the term archaeobotany is preferred in Europe and emphasizes the discipline's role within archaeology.
As a field of study, paleoethnobotany is a subfield of environmental archaeology. It involves the investigation of both ancient environments and human activities related to those environments, as well as an understanding of how the two co-evolved. Plant remains recovered from ancient sediments within the landscape or at archaeological sites serve as the primary evidence for various research avenues within paleoethnobotany, such as the origins of plant domestication, the development of agriculture, paleoenvironmental reconstructions, subsistence strategies, paleodiets, economic structures, and more.
Paleoethnobotanical studies are divided into two categories: those concerning the Old World and those that pertain to the New World. While this division has an inherent geographical distinction to it, it also reflects the differences in the flora of the two separate areas. For example, maize only occurs in the New World, while olives only occur in the Old World. Within this broad division, paleoethnobotanists tend to further focus their studies on specific regions, such as the Near East or the Mediterranean, since regional differences in the types of recovered plant remains also exist.
Macrobotanical vs. microbotanical remains
Plant remains recovered from ancient sediments or archaeological sites are generally referred to as either 'macrobotanicals' or 'microbotanicals.'Macrobotanical remains are vegetative parts of plants, such as seeds, leaves, stems and chaff, as well as wood and charcoal that can either be observed with the naked eye or the with the use of a low-powered microscope.
Microbotanical remains consist of microscopic parts or components of plants, such as pollen grains, phytoliths and starch granules, that require the use of a high-powered microscope in order to see them.
The study of seeds, wood/charcoal, pollen, phytoliths and starches all require separate training, as slightly different techniques are employed for their processing and analysis. Paleoethnobotanists generally specialize in the study of a single type of macrobotanical or microbotanical remain, though they are familiar with the study of other types and can sometimes even specialize in more than one.
History
The state of Paleoethnobotany as a discipline today stems from a long history of development that spans more than two hundred years. Its current form is the product of steady progression by all aspects of the field, including methodology, analysis and research.Initial work
The study of ancient plant remains began in the 19th century as a result of chance encounters with desiccated and waterlogged material at archaeological sites. In Europe, the first analyses of plant macrofossils were conducted by the botanist C. Kunth on desiccated remains from Egyptian tombs and O. Heer on waterlogged specimens from lakeside villages in Switzerland, after which point archaeological plant remains became of interest and continued to be periodically studied from different European countries until the mid-20th century. In North America, the first analysis of plant remains occurred slightly later and did not generate the same interest in this type of archaeological evidence until the 1930s when Gilmore and Jones analysed desiccated material from rock shelters in the American Southwest. All these early studies, in both Europe and North America, largely focused on the simple identification of the plant remains in order to produce a list of the recovered taxa.Establishment of the field
During the 1950s and 1960s, Paleoethnobotany gained significant recognition as a field of archaeological research with two significant events: the publication of the Star Carr excavations in the UK and the recovery of plant material from archaeological sites in the Near East. Both convinced the archaeological community of the importance of studying plant remains by demonstrating their potential contribution to the discipline; the former produced a detailed paleoenvironmental reconstruction that was integral to the archaeological interpretation of the site and the latter yielded the first evidence for plant domestication, which allowed for a fuller understanding of the archaeological record. Thereafter, the recovery and analysis of plant remains received greater attention as a part of archaeological investigations. In 1968, the International Work Group for Palaeoethnobotany was founded.Expansion and growth
With the rise of Processual archaeology, the field of Paleoethnobotany began to grow significantly. The implementation in the 1970s of a new recovery method, called flotation, allowed archaeologists to begin systematically searching for plant macrofossils at every type of archaeological site. As a result, there was a sudden influx of material for archaeobotanical study, as carbonized and mineralized plant remains were becoming readily recovered from archaeological contexts. Increased emphasis on scientific analyses also renewed interest in the study of plant microbotanicals, such as phytoliths and starches, while later advances in computational technology during the 1990s facilitated the application of software programs as tools for quantitative analysis. The 1980s and 1990s also saw the publication of several seminal volumes about Paleoethnobotany that demonstrated the sound theoretical framework in which the discipline operates. And finally, the popularization of Post-Processual archaeology in the 1990s, helped broaden the range of research topics addressed by paleoethnobotanists, for example 'food-related gender roles'.Current state of the field
Paleoethnobotany is a discipline that is ever evolving. Since the 1990s, the field has continued to gain a better understanding of the processes responsible for creating plant assemblages in the archaeological record and to refine its analytical and methodological approaches accordingly. For example, current studies have become much more interdisciplinary, utilizing various lines of investigation in order to gain a fuller picture of the past plant economies. Research avenues also continue to explore new topics pertaining to ancient human-plant interactions, such as the potential use of plant remains in relation to their mnemonic or sensory properties. Interest in plant remains surged in the 2000s alongside the improvement of stable isotope analysis and its application to archaeology, including the potential to illuminate the intensity of agricultural labor, resilience, and long-term social and economic changes.Archaeobotany had not been used extensively in Australia until recently. In 2018 a study of the Karnatukul site in the Little Sandy Desert of Western Australia showed evidence of continuous human habitation for around 50,000 years, by analysing wattle and other plant items.
Modes of preservation
As organic matter, plant remains generally decay over time due to microbial activity. In order to be recovered in the archaeological record, therefore, plant material must be subject to specific environmental conditions or cultural contexts that prevent their natural degradation. Plant macrofossils recovered as paleoenvironmental, or archaeological specimens result from four main modes of preservation:File:Charred Plant Remains.tif|thumb|301x301px|Charred Plant Remains. Clockwise from top left: bitter vetch ; barley ; glume wheat glumebases and spikelet; olive stones ; grape pedicels ; and grape pips.
- Carbonized : Plant remains can survive in the archaeological record when they have been converted into charcoal through exposure to fire under low-oxygen conditions. Charred organic material is more resistant to deterioration, since it is only susceptible to chemical breakdown, which takes a long time. Due to the essential use of fire for many anthropogenic activities, carbonized remains constitute the most common type of plant macrofossil recovered from archaeological sites. This mode of preservation, however, tends to be biased towards plant remains that come into direct contact with fire for cooking or fuel purposes, as well as those that are more robust, such as cereal grains and nut shells.File:Waterlogged Plant Remains.tif|thumb|302x302px|Waterlogged Plant Remains. From left to right: bog pond weed ; birch ; and common scurvygrass.
- Waterlogged: Preservation of plant material can also occur when it is deposited in permanently wet, anoxic conditions, because the absence of oxygen prohibits microbial activity. This mode of preservation can occur in deep archaeological features, such as wells, and in lakebed or riverbed sediments adjacent to settlements. A wide range of plant remains are usually preserved as waterlogged material, including seeds, fruit stones, nutshells, leaves, straw and other vegetative matter.
- Desiccated: Another mode by which plant material can be preserved is desiccation, which only occurs in very arid environments, such as deserts, where the absence of water limits decomposition of organic matter. Desiccated plant remains are a rarer recovery, but an incredibly important source of archaeological information, since all types of plant remains can survive, even very delicate vegetative attributes, such as onion skins and crocus stigmas, as well as woven textiles, bunches of flowers and entire fruits.File:Mineralized Plant Remains.tif|thumb|303x303px|Mineralized Plant Remains. Left to right: grape endosperms ; and fig seeds.
- Mineralized: Plant material can also preserve in the archaeological record when its soft organic tissues are completely replaced by inorganic minerals. There are two types of mineralization processes. The first, 'biomineralization,' occurs when certain plant remains, such as the fruits of Celtis sp. or nutlets of the Boraginaceae family, naturally produce increased amounts of calcium carbonate or silica throughout their growth, resulting in calcified or silicified specimens. The second, 'replacement mineralization,' occurs when plant remains absorb precipitating minerals present in the sediment or organic matter in which they are buried. This mode of preservation by mineralization only occurs under specific depositional conditions, usually involving a high presence of phosphate. Mineralized plant remains, therefore, are most commonly recovered from middens and latrine pits – contexts which often yield plant remains that have passed through the digestive track, such as spices, grape pips and fig seeds. The mineralization of plant material can also occur when remains are deposited alongside metal artefacts, especially those made of bronze or iron. In this circumstance, the soft organic tissues are replaced by the leaching of corrosion products that form over time on the metal objects.