9.1: Reconstructing Environments

ENVIRONMENT

To understand and interpret past human behavior, archaeologists need a complete understanding of the past natural environment and regional climate at a site. Reconstructing the environment and climate allows archaeologists to identify the plants and animals with which humans shared the landscape and examine how humans at the time adapted in response to the resources available to them. This chapter reviews a few of the ways archaeologists can use data to reconstruct the environment and climate at the time a site was occupied and identify food resources in terms of the flora (plants) and fauna (animals) that would have been available to the site’s occupants.

The Climate

Archaeologists try to reconstruct the climate of the time period during the occupation of a site whether it was one occupation or many occupations over many years. As we know, the earth has undergone cycles of warm and cold throughout its history. Much of the archaeologist's research can give us clues about the climate in which humans of the past lived including examining the geology, flora, and fauna of the time period and region. For example, tree rings can provide useful information about regional variations in climate, particularly in terms of the amount of rainfall at the time. For many types of trees, each ring in a cross-section of the trunk identifies one year of growth with the widest rings during unusually wet years and thinnest rings during severe drought years. Individual tree species respond differently to climatic conditions and thus provide somewhat different data. Archaeologists trained in dendrochronology can “read” the tree ring data and obtain information about the climate that existed when the rings were created, including changes in the climate over time.

Figure \(\PageIndex{1}\): Tree rings of a 200 year old douglas fir indicating a period of drought.

The Geology

Geoarchaeology plays a large role in reconstructing past landscapes and environments. There are several ways in which archaeologists rely on research techniques and knowledge from the Earth sciences for their own research. We have already covered some of these techniques in other chapters of this textbook, such as: the use of remote sensing devices to identify sites and features, studying site-formation and artifact deposition, and relative dating sites through stratigraphy, using palynotology to reconstruct the environment (Fagan, 2006). Sedimentology, which analyzes how sediments, such as sand, silt, and clay were deposited. This is another tool archaeologists use to analyze past environments and climates. The size and shape of deposits and the texture, size, and shape of the material they contain all give archaeologists clues about how the sediment ended up at a particular location. For example, a glossy, rounded sediment that’s relatively small in size was likely carried a long distance by water before being deposited. Scattered fields of rocks and other debris of various sizes and shapes, on the other hand, point to transportation by a glacier.

geoarchaeology

The branch of archaeology that uses techniques and subject matter from geography, geology, and other Earth sciences to inform archaeological research.

sedimentology

The study of sediments and the processes that result in their formation, transportation. and deposition.

 

The Flora

Other large plant remains, called macrobotanicals, are also useful in reconstructing environments. Archaeologists can identify plant species at a site even when they are no longer present in the fossil record such as imprints left behind by seeds and fruits in sediment and from charcoal left behind from burning wood in a fire pit. Reconstructing the environment helps determine whether plants found at a site were native to the area or likely came from another region and environment, indicating travel and/or trading relationships. By examining the associations between macrobotanical remains and other artifacts, we gain information about how the plants were used by humans in the past.

macrobotanicals

Plant remains that can be seen with the naked eye such as seeds, nuts, and wood fragments.

Small microbotanical remains include items such as pollen grains, which are microscopic, and small seed and plant structures. They are often abundant in archaeological sites but are not always studied because collection requires fine screening techniques such as water flotation. Palynology refers to the study of pollen grains, which has been an integral part of archaeology since the early twentieth century. Their size, shape, and structure can be used to identify the genus of plant that produced the grains. Like all organic matter, pollen grains are best preserved in dry environments such as caves and in anaerobic conditions such as those found in peat bogs.

microbotanicals

Ancient fragments or structures of plant tissues that are not visible to the naked eye, such as pollen and phytoliths.

palynology

The study of pollen grains and other spores, especially as found in archaeological or geological deposits.

Pollen is collected using a tool similar to an auger probe. Archaeologists extract long vertical cores of soil and sediment and examine carefully measured segments of the cores under a microscope to view and identify the pollen. Sometimes a more-involved chemical process is needed to remove the pollen grains from the matrix. In that case, the task is turned over to a palynologist. Once the grains are visible, each type of pollen in the sample is identified (typically at the genus level only) and counted. The results can be presented graphically to show how plant species present at the site changed over time or during its occupation.

Phytoliths are another type of microbotanical remains. They are minute particles of silica (silica also makes up sand) from plant cells that can survive long after all other parts of a plant, including pollen, decompose. Plants produce these particles in large quantities, and phytoliths are commonly found in the remnants of hearths, in layers of ash, inside pottery that at one time contained plants, and wedged in the crevices of animal teeth. Phytoliths can, in many cases, identify plants at the genus and species level and are used to confirm pollen sequences determined from core samples.

phytoliths

Fossilized particles of plant tissue.

Diatoms are a type of plant microfossil that consist of single-celled algae found in water that have silica cell walls instead of the cellulose cell walls found in plants. Thus, like phytoliths, diatoms survive long after cellulose plants decompose. Diatoms have been studied for more than 200 years, and many varieties, each with a unique structure, have been identified and classified. Their well-defined shapes allow archaeologists to identify the specific diatoms uncovered at a site, and the assemblage of diatoms present can be used to answer questions about the salinity (salts), alkalinity (bases), and nutrient content of the water in which they formed.

diatoms

A single-celled algae that have a cell wall of silica.

Figure \(\PageIndex{2}\): Pollen grains of common hazel, magnified 1200x.

Figure \(\PageIndex{3}\): Image of phytolithes from Elephant Grass.

Figure \(\PageIndex{4}\): Image of diatoms magnified 2400x.

The Fauna

When archaeologists study animal (fauna) remains at a site, they are particularly interested in how the animals wound up there—whether they were raised there by occupants, were wild and occurred naturally at the site, or were brought there by the occupants or by predators. Generally, large animal remains (macrofauna) are not as useful to archaeologists when reconstructing an environment as small animal remains (microfauna). Animals such as deer, buffalo, and boars often occupy large territories that shift with changes in the environment. Small animals such as rodents, bats, and other insectivores tend to be associated with localized geographic features such as caves and swamps. Burrowing animals present a challenge, however, because remains found at a site could represent animals present when the site was occupied or animals that burrowed down to that location hundreds or thousands of years later.

macrofauna

Animals that are larger than 2mm in size.

microfauna

Microscopic and organisms that exhibit animal-like qualities.

Figure \(\PageIndex{5}\): Dissection of an owl pellet.

Another example of microfauna remains that can be useful in reconstructing an environment is owl pellets—something you might have dissected in school. The pellets are the regurgitated remains of the owl’s meal, consisting of the bones, teeth, claws, and fur that they cannot digest. Owls do not travel far when hunting so their pellets provide a snapshot of the microfauna available at the time within a radius of just a few kilometers.

Remains of birds and of land and marine mollusks (snails) are also good indicators of climate change and the local environment. Both species are generally fairly well preserved, and the particular species present reflect the local climate. Birds, for example, occupy different types of climates in terms of annual average temperature and the presence or lack of fresh and saltwater. Archaeologists compare modern species of mollusks and the habitats they prefer with changes in the percentage of various marine mollusks in the past to reveal interesting information about shifts in coastal micro-climates that determine whether a shore is rocky or sandy.

Whatever type of animal species archaeologists study when reconstructing a past landscape, it is important not to rely on a single species indicator. Basing a reconstruction solely on the calcium carbonate of land mollusks, for example, would likely miss important details represented by other animal remains at the site.

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REFERENCES

Fagan, B. M. (2006). Archaeology: A brief introduction. Upper Saddle River, NJ: Pearson Prentice Hall.

Images

Figure 9.1.1 Tree rings. (2010). By Jason Hollinger under CC BY via flickr.

Figure 9.1.2 Pollen grains of common hazel. (n.d.) By Doc. RNDr. Josef Reischig, CSc. under CC BY-SA 3.0 via Wikimedia Commons.

Figure 9.1.3 Phytoliths are extracted from plant material (Elephant Grass) by dry ashing method. (2013). By Benjamin Gadet under CC BY-SA 3.0 via Wikimedia Commons.

Figure 9.1.4 Various diatoms. (n.d). By Doc. RN Dr. Josef Reischig, CSc. under CC BY-SA 3.0 via Wikimedia Commons.

Figure 9.1.5 Inside the owl pellet. (2017). By Art Siegel under CC BY-NC via flickr.

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A derivative work from

"Digging into Archaeology:A Brief OER Introduction to Archaeology with Activities" by Amanda Wolcott Paskey and AnnMarie Beasley Cisneros, Faculty (Anthropology) at Cosumnes River College & American River College, ASCCC Open Educational Resources Initiative (OERI), 2020, under CC BY-NC 4.0.