Reference Work Entry

Encyclopedia of Global Archaeology

pp 305-310

Archaeobotany

  • Dorian Q. FullerAffiliated withInstitute of Archaeology, University College London Email author 
  • , Leilani LucasAffiliated withInstitute of Archaeology, University College London

Introduction and Definition

Archaeobotany is a composite discipline, combining botanical knowledge with archaeological materials. Archaeobotany is also known as palaeoethnobotany (or paleoethnobotany). It focuses on the study of preserved plant evidence from archaeological sites and the reconstruction and interpretation of past human-plant relationships. The term “archaeobotany” emphasizes the archaeological nature of the evidence, with its recognition of site formation processes and sampling issues. The term paleoethnobotany, especially prominent in North America, recognizes the importance of modern ethnobotanical studies in contributing to interpretations of the past. This needs to be kept distinct from the term palaeobotany, which is the study of past plants, their adaptations, evolutionary relationships, and communities, from the fragmented remains that are preserved in old sediments. While palaeobotany takes in the whole history of plant life on land (approximately 415 Ma), archaeobotany focuses on the plant evidence relating to past human environments of the Pleistocene and Holocene.

Like many other specialist subdisciplines of archaeology, archaeobotany has evolved from a side-line pursuit of scientists outside of archaeology to something that is very much a part of archaeological research (for histories, see Hastorf 1999; Pearsall 2000; Fuller 2008). The origins of this field of research can be traced back to the nineteenth century, especially to a prominent expert on fossil plants, Oswald Heer, who carried out the first studies of archaeological plant remains recovered from waterlogged Swiss Neolithic and Bronze Age lake-side sites. His detailed monograph on these, in 1865, had a major impact on the discipline of archaeology and the early development of evolutionary biology; see by extension, summaries in Charles Darwin’s Variation in Animals and Plants under Domestication (1868) and John Lubbock’s Prehistoric Times (1872), which introduced to archaeology the term “Neolithic.” For much of the subsequent century, recovered plant remains were sent by archaeologists to botanists for study, for instance, specialists working at natural history museums. However, specialist archaeobotanists taking part in archaeological fieldwork only began to be staples of archaeological research from the 1960s onward. Particularly important for this trend was the advent of improved systematic sampling of plant remains through the flotation method, first carried out in the USA and the Middle East in the 1960s. Flotation, a key method in archaeobotanical research, uses water to separate light organic remains (especially charcoal and carbonized seeds) from heavier archaeological material and the sand component of sediment (details of various systems in Pearsall 2000).

Key Issues /Current Debates

Research Themes

In general terms, archaeobotanical research questions relate to both past food-related practices/foodways, and past landscapes. A central concern of archaeobotany is the recovery of evidence for food plants exploited by past populations, where these plants came from, and how they were processed. In the study of hunter-gatherer societies, there are often challenges of preservation; yet, research on plant subsistence is crucial to examining issues of seasonal scheduling of activities, intensification of plant use and processing, storage, and niche construction (e.g., Mason & Hather 2002; Wollstonecroft 2011). Another major focus of archaeobotany is the transition to, and spread of, agriculture, including research on cultivation systems, arable weeds, and plant domestication traits (e.g., Fuller 2007; Piperno 2011). In contexts where agriculture existed, archaeobotanical research focuses on issues of diversification and intensification of agricultural systems and the organization of production and consumption of crops in relation to social hierarchy (e.g., Gumerman 1997; Fuller & Stevens 2009). When it comes to landscapes, archaeobotany has contributed to the reconstruction of past environments as well as to studies of environmental change due to climate change and/or human impact. In this area, wood charcoal, on-site and off-site palynology, and phytolith studies are especially prominent.

Archaeobotanical Datasets and Subfields

Given that the various datasets define subfields of the discipline, few archaeobotanists practice research on all lines of plant evidence. Macro-remains analyses tend to focus on the study of seeds only, whereas wood charcoal and the analyses of phytoliths and starches are specializations in their own right. Still these various datasets are largely complementary and gain strength from integration. The sections below, and Table 1, summarize the main lines of archaeobotanical evidence and their respective potentials. The study of Palaeofaeces, i.e., the analysis of exceptionally preserved human coprolites and gut contents, is another source of archaeobotanical data that may combine several lines of evidence (Hillman 1986).
Archaeobotany, Table 1

Archaeobotanical datasets, preservation environments, and typical spatial resolution

Data sets:

Preservation

Spatial resolution (typically)

Macros: remains of seeds and other fruit fragments

Charred

Local, biased by human procurement

Waterlogged

 

Desiccated

 

Mineralized

 

Macros: wood charcoal

Charred

Local, biased by human procurement

Desiccated

 

Waterlogged

 

Macros: parenchyma fragments

Charred

Local, biased by human procurement

(Potentially desiccated)

 

Plant impressions in pottery/ mud-brick

In pottery or hardened clay, therefore all environments where pottery or mud-brick is used

Local or nonlocal (traded), biased by human procurement and tempering preferences

Pollen

Fine sediments, especially acidic (alkaline and oxidizing conditions destroy pollen)

Regional

Phytoliths

Fine sediments, minimal bioturbation (of most pH levels except very high alkalinity (>9) and high temperatures).

Local plant use activities (on-site)

Regional vegetation (when part of off-site studies, as with pollen)

Starch Grains

Preserved in dental calculus

Components of human/ animal diet

From artifact surfaces (groundstone, ceramics)

Plant parts and taxa processed on these tools or vessels

Palaeofaeces (i.e., preserved feces or coprolites, and gut contents from mummies or bog bodies)

Mineralized

Local diet, but may contain regional pollen

Waterlogged

 

Diatoms are sometimes examined in archaeobotanical research

 

Regional aquatic environment

Macro-Remains: Crops, Chaff, and Weeds

Macro-remains refers to plant remains that are visible to the naked eye (larger than 0.25 mm), but which still require microscopy to identify. Seeds, which are the most common evidence studied by archaeobotanists, can be preserved by numerous means, including mineralization, waterlogging, metal oxide preservation (sometimes called pseudomorphs), or as impressions in pottery. The most common means of seed preservation encountered, however, are charred seed remains. Generally, charred macro-remains can be identified by examination of their external morphology through a low powered binocular microscope (i.e., 6x–40x). It has now become possible to extract fragmentary ancient genetic information (i.e., aDNA) from ancient seeds, and the prospects of this technique are immense (Palmer et al. 2012).

In general, charred assemblages sample only a very limited range of the floristic diversity of local flora. This came to be recognized in Europe in the 1970s. It was observed that most archaeobotanical samples consisted of a similar range of taxa that are dominated by grain crops (seeds and chaff) and wild species known from modern field studies as weeds of cultivation or weeds of habitats that are disturbed by humans (Jones 1985). However, by far, the best represented remains were those of cereals, in part due to the good preservation of grain and chaff. Thus, aside from the remains of a few wild fruits likely collected for food, most of this fossil evidence can be interpreted as deriving from arable plant communities rather than the environment at large. Therefore, the associations of grains, chaff, and weed seeds can be used to infer aspects of crop-processing (Hillman 1984; Jones 1987; Fuller & Stevens 2009). After crops are harvested, they must be processed in predictable ways, to remove inedible husk (and weeds) and to separate the grain products. Through ethnographic studies, archaeobotanists have developed predictive models about sample composition, which allow the stages of crop-processing represented to be inferred. Most studies have been on the crop-processing of Mediterranean wheat and barley (e.g., Fuller & Stevens 2009), but one can also find studies of millets (e.g., Reddy 1997; D’Andrea & Wadge 2011), rice (Thompson 1996), and some new world crops (e.g. Lopez et al. 2011). These ethnoarchaeological models have made it possible to interpret crop-processing, which can be divided into two basic sets of activities: those that break apart the crop-plant and those that separate out the various freed components. The first activity includes threshing to break apart cereal ears, or separate the pods of some pulses. Another later stage, for hulled crops, is de-husking, which removes the hulls and glumes that are still attached to the grain. In simplified terms, the early stages produce waste that is rich in chaff (especially of free-threshing cereals, like bread wheat and barley) and weed seeds, especially smaller, lighter weed seeds that are removed by winnowing. Later stages will have a higher proportion of grains, fewer weeds that are generally larger and heavier, and will only have chaff from hulled cereals (like the glumes of emmer or einkorn wheat).

Parenchyma, the starchy storage tissue of plants, which predominates in tubers and other underground storage organs, can also be preserved by charring. Such material has not traditionally been searched for in archaeobotanical samples, but studies from a number of regions have found it to be fairly common among seeds and charcoal (Hather 2000), and this line of evidence has the potential for identification of wild or cultivated roots and tubers. This approach should be an important part of research on the origins and development of Vegeculture. Identifications of this material requires the high magnifications and depth of field provided by scanning electron microscopy (SEM).

Macro-Remains: Impressions

Another source of evidence of seeds and chaff is preserved impressions of plants. Plant impressions, often preserved in pottery, are one of the traditional sources of archaeobotanical information. However, today, the study of impressions is often eschewed when charred remains recovered through flotation are available from a site. Impressions can be studied at lower magnifications and often latex casts are prepared from the molds, which can then be analyzed by SEM. Most cereal parts, such as chaff, are preserved in pottery since these readily available by-products of grain production were often used for tempering pottery. In some cases, this provides early evidence for crop domestication, such as in West Africa (e.g. Manning et al. 2011).

Macro-Remains Wood Charcoal

Wood charcoal is the most abundant component of archaeobotanical flotation samples. Given the centrality of fire in human cultures, wood charcoal is among the most abundant of cultural by-products. In contrast to seed remains, which represent chance/incidental burning, wood is generally considered to be the product of intentional burning. Wood can also be preserved under other circumstances, such as waterlogging. It is identified by looking at anatomical characters in transverse, tangential, and radial sections. This kind of study requires higher magnifications, generally 50x–150x, but sometimes as high as 400x, and beyond, which is aided by SEM. Since most fuel is likely to come from the vicinity of the site, it should provide some reflection of the surrounding vegetation. Numerous studies have utilized changes in the composition of wood taxa to examine changes in the landscape, but fuel choice may also reflect social and political concerns (Asouti & Austin 2005; Marston 2009).

Micro-Remains: Phytoliths, Starch, and Pollen

There are a number of lines of archaeobotanical evidence that are beyond the range of human vision and must be extracted from sediment samples, mounted on slides, and examined under high magnification. These lines of evidence are micro-remains, and include phytoliths, pollen, and starch grains. The most widely studied micro-remains in archaeology are phytoliths (sometimes called “plant opals,” silica skeletons, or spodograms), which are the silica casts of plant cells formed by the evaporation of silica-laden water through plant transpiration (Pearsall 2000). Being an inorganic glass, these have a high potential for preservation in many sedimentary environments, although they are likely to be destroyed by mechanical processes. The study of these remains requires magnifications from 200x to 1,000x. Phytoliths are invisible in cross-polarized light. Phytolith identification is complicated by the fact that any given plant produces numerous different forms of phytoliths and similar phytoliths forms may be produced by unrelated species. Nevertheless, some phytolith forms are diagnostic. Because of the high preservation potential of phytoliths, they have proved particularly important for examining plant exploitation prior to agriculture in the Palaeolithic (Madella et al. 2002), and for tracking crops in tropical environments with poor on-site preservation of macro-remains (e.g., Piperno 2011).

A more recently expanding line of research are starch grains; the intracellular storage of starch by plants. The form of starch grains appears to be taxonomically determined, allowing separation of families, and sometimes genera and species (Torrence & Barton 2006). There also seems to be some indication of domestication in some taxa (e.g., Piperno 2011). Most often starch grains are extracted from the surfaces or residues of artifacts, such as groundstone, but they also become trapped in dental calculus and, as such, reflect human diet. Starch grains have been central to the archaeological study of past Chimpanzee archaeology (Mercader et al. 2007). Some traditional archaeobotanists still regard starch grains with suspicion and there is on-going research and debate on issues of taphonomy, preservation, and identification, as there is with other lines of archaeobotanical evidence.

Pollen is usually collected from off-site geological sediments (palynology) for examining palaeoecology, which is often of relevance for archaeological interpretations. Of particular interest are approaches to identifying the introduction or intensification of agriculture through pollen. In addition, pollen is sometimes preserved in archaeological sediments (archaeological palynology), which can help fill-out reconstructions of past vegetation (e.g., Dimbleby 1985; Pearsall 2000). Pollen is studied at similar high magnifications as phytoliths.

International Perspectives and Future Directions

The growth of archaeobotany has been uneven internationally. As reviewed in Fuller (2008), several regions of the Old World have seen different chronologies for the development of this field. It was earliest in Europe, quite early but small-scale in India, and early in the Near East. Development in Africa has been slow, and the majority of sub-Saharan countries have had no archaeobotanical research. The USA has a long tradition of archaeobotanical research, but for much of the Neotropics, developments have been more recent and are spatially uneven (cf. Piperno 2011). Japan has had a longer tradition of studying waterlogged macro-remains, using flotation, and undertaking phytolith research, whereas such developments are quite recent in China or Korea. Most of Southeast Asia is un-sampled and understudied (Castillo & Fuller 2010). Thus, while archaeobotany has potential application anywhere – all human societies have used and consumed plants – its adoption has been uneven, partly biased toward countries with better funded research institutions and partly focused on regions deemed to be centers of origins of agriculture and civilization (e.g., Mesoamerica or Southwest Asia). Archaeobotany has greatly expanded internationally and across a range of subfields. It is set to continue to do so in the future.

Cross-References

Agrarian Landscapes:​ Environmental Archaeological Studies

Agriculture:​ Definition and Overview

Agroforestry:​ Environmental Archaeological Approaches

Animal Domestication and Pastoralism:​ Socio-Environmental Contexts

Archaeobotany

Archaeobotany of Early Agriculture:​ Microbotanical Analysis

Landscape Domestication and Archaeology

Maize:​ Origins and Development

Multiple Microfossil Extraction in Environmental Archaeology

Near East (Including Anatolia):​ Origins and Development of Agriculture

Northern Asia:​ Origins and Development of Agriculture

Phytolith Studies in Archaeology

Vegeculture:​ General Principles

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