Phytoliths and Archaeology; an Amazing Field That Never Gained Popularity (with Good Reason)

Phytoliths are a durable floral microfossil formed by silica absorbed by a plant during its life. Although the usefulness of phytoliths in archaeology has been known for nearly a century, the field (independently) has not attained much popularity. Despite the fact that the yields of evidence and information from phytoliths are truly amazing, the field itself is at times more tedious than dendrochronology, causing a delay in the development of the use of phytoliths, as well as the lack of recognition. Phytoliths have been proven to be useful in a number of studies, ranging from paleo-environments, ancient agriculture, ancient technology, even the diet of particular cultures and their livestock. The largest problem with phytoliths tends to be the inability to identify certain phytoliths or the need to correlate the phytoliths with a different chronologies or reference collections. With all of the uses phytoliths have, these problems seem to be recurrent. However, in order to understand the use of phytoliths, one must first come to a better understanding of what they are.

Numerous sources have different terms for phytoliths, and even go so far as to separate phytoliths into two groups (Schiffer 1983: 227). This is not the case in this paper. The term phytolith will refer to a general definition that is broad and encompasses both of these groups; a phytolith is an opal or silica plant cell (Rapp and Hill 1998: 93). No source is completely sure of the biological purpose of the silica in the plant cells. Phytoliths occur from silica in ground water being absorbed through plants roots and integrated into the living plant (Hertz and Garrison 1998: 55). This silica fills the spaces in the cell and hardens. These cells can endure long after the life of the plant, even through decay and burning (Renfrew and Bahn 2004: 249). However, phytoliths are susceptible to highly alkaline soils, erosion, corrosion, mechanical wear (ploughs) and water damage (Schiffer 1983: 234). The general cell morphology, as well as density and cell wall thickness can affect the durability of phytoliths (Schiffer 1983: 235). Phytoliths first were realized for their usefulness in 1908 by Schellenberg, who noticed phytoliths in archaeological soils from North Kurgan (Herz and Garrison 1998: 55), however it was not again recognized until the 1950’s with Helbaek’s and Watanbe’s work regarding cereals (Herz and Garrison 1998: 55). Although phytoliths have been recognized as useful in examining many areas such as human and animal diet, agricultural technologies and crop exploitation, and paleo-environments, in the near century that work has been done with these microfossils the entire field of study has not reached popularity, and in many ways it seems like this is so for a good reason.

The environment throughout history has been of particular interest to archaeologists. The environment dictates how human beings will live, what kind of food they will eat, and similarly what kinds of resources are available. One way of looking at the paleo-environment is through the use of phytoliths. Phytoliths can provide many insights as to what the environment may have been like at a particular time; they can tell if the weather was humid or dry, if it was windy and what direction the wind was going in, or if seasons were particularly hot or cold.

In 1984, Dwight Brown presented his research that looked at the various types of grass phytoliths. Brown was particularly interested in looking at the migration rates of particular species of grass. He felt that the rates could indicate weather conditions. Brown looked at three shape classes of grass phytoliths: bilobates, saddles and trapezoids (Brown 1984: #4, 345). From his studies, Brown concluded that fluctuations in the ratios of phytolith shapes could indicate shifts in the environment to which the phytoliths belonged (Brown 1984: #4, 345). He also concluded that it was practical for one to be able to use phytolith analysis to obtain a better understanding of (flora) species migration and to be able to find the ancestors of major flora species (Brown 1984: #4, 345). Despite these truly intriguing results of Brown’s study, he did come across particular problems inherent in phytolith study; namely, he had difficulties identifying the different species from the phytoliths. Brown realized that species tend to have within species variation, and as a result multiple samples of the same species (as well as others) would be needed in order to provide a measurement for this possible variation. As a result, large comparative collections would be required. Prior to this, in 1970 Philip Armitage (mentioned later in this paper) realized that the phytoliths of grass species tended not to contain silica that was unique to the species, making them hard to identify (Armitage 1970: #3, 194). Another example would be a study done by Folger in 1967. Folger discovered