#phytoliths

Phytoliths as a tool for investigations of agricultural origins and dispersals around the world

by Terry Ball, Karol Chandler-Ezell, Ruth Dickau, Neil Duncan, Thomas C. Hart, Jose Iriarte, Carol Lentfer, Amanda Logan, Houyuan Lu, Marco Madella, Deborah M. Pearsall, Dolores R. Piperno, Arlene M. Rosen, Luc Vrydaghs, Alison Weisskopf and Jianping Zhang

“Agricultural origins and dispersals are subjects of fundamental importance to archaeology as well as many other scholarly disciplines. These investigations are world-wide in scope and require significant amounts of paleobotanical data attesting to the exploitation of wild progenitors of crop plants and subsequent domestication and spread. Accordingly, for the past few decades the development of methods for identifying the remains of wild and domesticated plant species has been a focus of paleo-ethnobotany. Phytolith analysis has increasingly taken its place as an important independent contributor of data in all areas of the globe, and the volume of literature on the subject is now both very substantial and disseminated in a range of international journals. In this paper, experts who have carried out the hands-on work review the utility and importance of phytolith analysis in documenting the domestication and dispersals of crop plants around the world. It will serve as an important resource both to paleo-ethnobotanists and other scholars interested in the development and spread of agriculture” (read more/open access).

The economic and ritual utilization of plants at the Raqefet Cave Natufian site: The evidence from phytoliths

by Robert C. Power, Arlene M. Rosen and Dani Nadel

"The Natufian culture marks a dramatic in the cultural evolution of our species, the shift from mobile to sedentary communities. Within this framework, analysis of their use of plants is pivotal for social and economic reconstruction. While most researchers believe the Natufians collected the grains of grasses, little direct evidence (e.g. macrobotanical remains) has been found. This current study uses phytoliths (opal silica bodies) to interpret Late Natufian plant use at Raqefet Cave (Mt. Carmel, Israel). We analyzed a wide range of sediment samples for microbotanical phytoliths remains. This analysis, of an assemblage of 35 samples, was aimed at exposing plant use at the site both in burial contexts and hewn bedrock features (e.g. mortars, cupmarks).

The results indicate economic use of grass seeds, including both small-seeded varieties and large-seeded grasses such as barley and wheat. They also suggest an opportunistic approach to grass seed collection. Phytoliths found in the burials of Homo 19 and Homo 22 may be the remnants of a final meal. The phytolith assemblages from burial contexts also show abundant morphotypes from dicotyledons that are rare elsewhere in the cave. The evidence suggests that a multi-species layer of vegetation including flowering plants and Phragmites lined the graves, accompanying the dead. This adds new insights to the range of known Late Natufian mortuary practices" (read more/open access).

Table 1 & 2: Examples of the descriptors found within the International Code for Phytolith Nomenclature (ICPN), 2005, for use of naming phytoliths. Figure 1: A bulliform phytolith under a microscope, ©Henri-Georges Nation.

Quick Tips: Use of Phytoliths in Archaeology.

Phytoliths are a very important identification tool in identifying plants within ancient environments, often even classifying down to the species of the plant.

But firstly, what are phytoliths? As the name phytolith suggests, coming from the Greekphyto- meaning plants and lith- meaning stone, they are tiny (less than 50µm) siliceous particles which plants produce. These phytoliths are commonly found within sediments, and can last hundreds of years as they are made of inorganic substances that do not decay when the other organic parts of the plant decay. Phytoliths can also be extracted from residue left on many different artefacts such as teeth (within the dental calculus), tools (such as rocks, worked lithics, scrapers, flakes, etc.) and pottery.

Phytoliths can form numerous striking shapes within the plant cells (figure 1), which gives them a characteristic shape, thus aiding the identification of plants. Due to the vast number of shapes and sizes that phytoliths can come in, researchers compiled theInternational Code for Phytolith Nomenclature (ICPN), 2005. The ICPN was developed to create a standard protocol which is to be used during the process of naming and describing a new or known phytolith type, as well as a glossary of descriptors to help aid with the naming.

Click here to read the whole blog post on All Things AAFS! 

Stephanie again, and our Modern Phytolith Reference Collection has reached 500+ samples!

#500 was from Sporobolus heterolepsis, or the prairie dropseed (grass), and had a particularly good yield.

Selena and I processed the very first sample, a Zamia leaf, on October 26th, 2009. It was disappointingly unproductive.

We're not certain that's a phytolith.

Stephanie again, and Happy Chinese New Year everyone!

Counting days are microscope days, where I'm sorting through a slide full of dirt and debris at 1000x magnification:

in search of some elusive phytoliths (microscopic plant silica body; see my previous post for background info). In the above view, there are ~6 obvious objects, but only the upper rightmost one is likely a phytolith. Just glancing at it, I can tell that it's some kind of grass silica short cell (GSSC), and is probably from a C3 Pooidae grass. But what type of GSSC is it?

A conical rondel? A broken bilobate? Perhaps a crenate from end-view:

GSSC's all look similar from the side, and you often need to see the phytolith from multiple angles before its obvious what it is. There's too much debris on this one to make a definite identification, so I'll have to move on.

Here's an easy one:

The spiky ball in the middle is a palm phytolith. While pretty rare in this sample, its presence suggests a warm and moist environment, or perhaps a sub-habitat like a forest understory. Palm phytoliths are my favorite.

Stephanie here with my first post on the wonders of phytoliths!

As some of you may know, phytoliths are microscopic plant silica bodies that form within/between plant cells. They can form a diverse set of shapes and textures, which we group into morphotype  classes to use in identifying the plant taxon that it originated from. This is particularly useful for paleoecological questions about past vegetation structure and evolution.

(Click on the photo to resize it) Here are some grass-diagnostic phytoliths from Calamagrostis purpurascens Cool, huh? Phytoliths come in a huge range of morphotypes and its up to researchers to describe and categorize them so we can use fossil phytoliths to answer archeological and paleontological questions.

^Some phytoliths produced by the arrowroot family, Marantaceae. Scale bar= 10µm for left-most two pictures, 20 µm for all others. 

One of my current projects is creating an online database of the phytoliths of modern Montana ecosystems as part of the Montana Project. We're using phytolith assemblages to reconstruct the vegetation of past Montana ecosystems, but we also want to see what today's Montana looks like from a phytolith perspective. More info on that soon!

An international team of archaeologists and paleoecologists analyzing records of pollen, charcoal and other plant remains like phytoliths spanning more than 2,000 years has created the first detailed picture of land use in the Amazonian savannas in French Guiana. 

The study, published in the journal Proceedings of the National Academy of Sciences, shows that indigenous people, living in the savannas around the Amazonian forest, farmed without using fire and practiced ‘raised-field’ farming, which involved constructing small agricultural mounds with wooden tools.