Wednesday, July 24, 2013

Day 17: Paleoethnobotany and Starbucks Coffee

Day 17- Paleoethnobotany, People and Plants in the Past

Talk about your alliteration! Get it? Well, I enjoyed it. Yes, Paleoethnobotany is the study of ancient peoples through the study of the plants remains, which have survived in archaeological contexts. Paleoethnobotany is an archaeological sub-field of study which uses the identification of plant remains, in combination with the ecological and cultural information we have thanks to modern plants, are able to study the use of wild plants, origins of agriculture and domestication, and the co-evolutionary nature of the human-plant interactions across time.

For this lecture, Dr. Kandace Hollenbach from the University of Tennessee at Knoxville was kind enough to come to Monticello to shine the light of paleoethnobotany on us field school students. Dr. Hollenbach's studies focus on the prehistoric foodways among hunting-gathering and agricultural peoples of the southeastern US, gender and identity roles, and the use and meaning of landscape among those hunting-gathering peoples as well.

Dr. Hollenbach's lecture focused on the rituals, use, and ancient peoples' thoughts of plants, her bottom line to us was, "people effect plants and in return the plants effect the people as well." People use plants for a multitude of reasons, they procure, process, prepare, consume, discard them, and frequently they are not preserved. The fact that they are not preserved leaves no evidence for paleobotanists and archaeologists. In terms of plant (either in the form of pollen or phytoliths) preservation, dry conditions are best, and wet conditions are destructive. Wet conditions can result in water logged, anaerobic conditions, meaning there is not enough oxygen for microbes to live and destroys the botanical remains completely. Plants can also be carbonized, this occurs when botanical remains become trapped and squeezed between sediments, are turned into carbon as they deteriorate, and since animals and plants get zero energy from carbon, the plant is left alone.

The preservation of micro/macro-botanical remains are then left to procurement. Procurement assumes the food item was gathered, harvested, or purchased.
Procurement = eating = digesting = paleofeces (coprolites)
Harvesting = food processing = eating = coprolites
OR Harvesting = processing = byproduct, then burned for fuel or trash disposal
Harvesting can also lead to the byproduct simply decaying on its own, whether it is simply disposed of, or as spill.

In the field of paleoethnobotany, certain biases are necessary to consider when reviewing a sample, these include:

  • byproducts being over-represented relative to the edible portions
  • items not cooked with fire are under-represented 
  • items that burn to ash (e.g. leaves) or unrecognizable mass (potatoes, etc.) are under-represented. 
  • small, fragile items that don't burn well and do not withstand mechanical damage (freeze/thaw and recovery techniques are under-represented
One also cannot go directly from numbers of remains located to the importance of crops in any civilization's lives. Instead, cross-reference your finds (i.e. a high number of corn remains) with the ethnohistorical accounts of crops and diets to enforce the located evidence. However in the reality of the historical record, white European men (early colonial settlers) simply do not write about the native's crops or dietary practices.

The recovery stage of both macro and micro-botanical remains is accomplished a process known as flotation, which can either be mechanized through a "float tank," or by hand. The next step is to analyze the remains under a microscope and identify them. The use of a modern comparative collection can come in handy during this stage and most collections collect and burn modern samples for precise references.

The interpretations of micro and macro-botanical remains focuses in on the subsistence and foodways of ancient peoples, the procurement, processing, storage, preparation/cooking, consumption, and discard practices offer a picture of how people are living on the site. For example, plant domestication can be followed by the changes through time and across location (regional patterns) to the crop. Paleoethnobotanists are finding that people are choosing larger seed sizes as time moves forward as well as a thinning of the seed coat. Wild seeds need their coating in order to survive the winters but domesticated seed are preserved through storage, resulting in the eventually thinning of their coats. Thin coats also sprout first and produce the most seeds for the next season's harvest as well. The importance of the coat lies not only in the agricultural value, aids in the successful identification and separation of wild seeds and domesticated seeds, since coats can be used to differentiate between the two. Plants co-evolve as people interact in their lives and there are changes in both the plants and people. People get tied down to spots with agricultural plots, going from a once continually moving, hunting-gathering society, to a settled, stable one illustrates the mutual domestication plants had on people as well!

Dr. Hollenbach then transitioned into the second portion of her lecture, which surrounded her research involving human behavioral ecology, arguing the costs and rewards of walking to gather or hunt a food source. The central place foraging theory is used to mathematically point out characteristics in people's behaviors, by solving for the return rate of the energy spent to collect the food item, with the energy obtained from the item, in consideration with the time spent to find, collect, or hunt the item. This is achieved through ethnohistorical accounts of the individual peoples, in combination with experimental archaeology, which Dr. Hollenbach admits to sending her grad students on a walking expedition to achieve.

*handling cost outweighs carrying cost
Squirrel = High handling cost (30kg)

  • walking cost (tied to slope and distance of specific landscape)
  • amount of time it takes to actually catch a squirrel
  • minimal gain in energy obtained
  • travel cost doesn't matter as much
Spawning Fish = Low handling cost (30kg)

  • assume the people know their surrounding landscape and know the location and the worth of the river where this resource can be continually found. 
  • travel cost matters
Given this mathematical breakdown of the cost vs. reward of various food sources, Dr. Hollenbach can hypothesis that most campsites of ancient people are made with a low cost food source close in distance. For example, fish are a reliable food source, they can always be found in a nearby river, whereas deer could be anywhere, and would therefore cost more to locate and carry, but if found would outweigh fish in the energy gained category. So it all comes down to how much energy you are willing to spend in the hopes of gaining equal or more energy in return for a specific food source/item.

Back to the micro and macro remains, these can also be used to identify the social and political organization of people, or any socio/politcal shifts which occurred throughout time within that society as well. In today's world think about your own personal reactions when you notice someone walk passed you holding a Starbucks coffee cup rather than a local, fair trade coffee brand/cup, certain social and economic assumptions are made on your end, and a social status signal is put out by the other person (the one holding the coffee cup). Certain aspects of our personal identity can be based on our favorite foods. MIND BLOWING! Think about that the next time you are going to treat yourself to a cup of brew- will you go commercial or local?

I promise to keep catching up on my blog updates- it is such a commitment!

Sunday, July 7, 2013

Day 16: A Tale of Sex, Love, and Romance

Day 16- The Role of Pollen in Archaeology

First, a huge thank you goes out to Dr. John G. Jones, Associate Professor of Anthropology at Washington State University, who was our guest lecturer for this lesson. He exuded energy and passion for the topic of palynology, opening his lecture as a tale of sex, adventure, and romance all about pollen. Needless to say, this gentleman was a true character, and equally kind to us students as he was to the professional staff.

Pollen is essentially and simply plant sperm with an outer shell made out of the genetic material, sporopollenin, which is the tough outer walls of spores and pollen grain, which is chemically very stable and is usually well preserved in sediments. Pollen is capable of being extracted from coal, and a 310 million year old pollen sample was found from a shale fragment from Mongolia, pollen will last. The only exceptions to this are when fungus or bacteria destroy the pollen.

Insect pollination is the most effective- plants attract bugs with pheromones from flowers, some plants make very little pollen and use their pretty flowers or fragrance to attract the insects to carry their pollen, or in the case of the pine tree, the plant may make a ton of pollen, pine trees make a billion polygrains in order to reproduce. Pollen wears and weathers out of rocks and people then breathe them in (allowing for location of bodies for example).

Pollen studies are used in fields such as the oil industry, medicine, bee keeping, forensic science, and of course, archaeology. In the oil industry, the oil has to be a certain age and maturity before it produces, so it is necessary to know how old the maturity of the sediment is, and whether it holds oil or just gas. Approximately 91% of all palynology worldwide is for various oil industries, which pays about $500 a sample, with about 4,000 samples requested a day as “rushed work,” and the lab receives 10% of the profits. Pollen is used in medicine for allergy testing. For example, a single vile of ragweed is $450 and is needed for all main allergy testing done by doctor’s offices. Forensics uses pollen testing just as you have probably seen in any criminal drama television show, such as Law and Order, or Bones.

Most importantly pollen is used in the field of archaeology, mostly coprolites (fossilized feces), and as Dr. Jones likes to say, “Pull up a stool, I’ll tell you all about it.” As in many cases, the bathroom holds the key to the way a society ate and lived. A stool can tell us the origins of agriculture, deciphering the earliest crop dates, and agriculture style (burning, fertilization, etc.). The sediment at Monticello perfectly conserves the pollen from oxidization which kills pollen, and the thick red clay also coats the pollen grains, keeping fungus from killing the pollen. Palynologists have, for example, taken pollen samples from ground stone to tell what people were harvesting, preparing, and eating.

The process of pollen soil sample is extremely complicated. The first step is to dissolve the soil away, leaving the pollen. Hydrochloric acid is used to isolate the pollen, then sands, silts (silicas) are removed with hydrochloric fluoride, the sample is then washed in potassium hydroxide, which can dissolve skin, but leaves the pollen, and in order to remove the organics acetolysis is used, it is explosive in water, but leaves the pollen, the minerals then need to be removed, a pyrite and tourmaline causing the minerals to sink and the pollen to float. The Monticello soils are very difficult to clean, due to the thickness of the clay, and not all pollen collected is identifiable.

Corn (maze) barley, oats, and wheat, along with all grass have similar looking pollens. The oldest maze pollen to have been located to date goes back to 52000 BCE and was produced by plants which did not produce corn cobs, yet still produce a sugary rich stem. Maze in the new world was possibly first domesticated to make sweet beer brew (honey was in Mesoamerica and cocoa), sweets from corn is brewable from the stocks.

Pollen in archaeology is taken with soil cores, samples from parts of the ground never exposed to oxygen, and core samples, used for radiocarbon dating (the chronological record of changes in pollen throughout time). A vibracore collection allows for the soil to be brought to surface without disrupting the sediments. Pollen samples are also collected from sidewalls (profiles) of the strata of a quadrat, what is known as a profile pollen sample, which means that every 5cm of the sidewall a pollen sample is collected from the bottom-up, and then a pollen diagram is created to illustrate the break-down of certain pollens.

Aside from pollen, phytoliths (siliceous plant remains) can also be useful in archaeology. Phytoliths are produced within cells of plants, and are strong in areas where pollen is weak. Whereas with pollen, grass could not be identified, with phytoliths grass is identifiable. The smaller the sample of phytoliths, the better the integrity, and these samples should be taken from the center of your feature (i.e. sub-floor pit found in quadrat). Both pollen and phytoliths are simply more key pieces to the historical puzzle which archaeologists are charged with attempting to solve over years of collecting and putting together piece after piece- slowly but surely. 

Day 15: In Archaeology, Geology, Rocks!

Day 15- Geology and Rocks on Site at Monticello

My apologies, due to the rain and the hectic schedule of the last couple of weeks, my blog updates have fallen behind. But I can quickly update you on the lectures and experiences of the field school- it has been unbelievable!

The first thing you need to know about geology, which may seem simple, but often gets over looked- rocks vary regionally. The second step to understanding geology is being knowledgeable about the Wilson cycle. The Wilson cycle refers to theopening and closing of ocean basins caused by movement of the Earth's plates. The Wilson cycle begins with a rising plume of magma and the thinning of the overlying crust. As the crust continues to thin due to extensional tectonic forces, an ocean basin forms and sediments accumulate along its margins. Subsequently subduction is initiated on one of the ocean basin's margins and the ocean basin closes up. When the crust begins to thin again, another cycle begins. 

In the specific case of the field school, Monticello is located in the Blue Ridge Mountains of Virginia, which have eroded into the coastal plain. A long time ago, when ancient Africa and North American collided, Atlantic fills with lava flows forming black basalt build ups, forming the mountains, the mountains then erode, island chains slams in, thus causing a continual series of mountain forming events. This black basalt build-up was then squashed with heat and pressure and morphed into greenstone. The Atlantic Ocean then erodes these mountains to form modern-day Virginia. The lava continues to build, spills out, and forms tiny payers between basalt, forming beach dunes and various landscapes. Silt stones formed together with heat and pressure to produce quartz. This information is important due to the fact that greenstone and quartz are the most common rocks found at Site 8 on the dig at Monticello. Quartz is also resistant to weathering and the most common and resistant mineral on the planet. It is capable of surviving chemical weathering since it does not oxidize at all.

The teaching assistant who gave this lecture, Devin Floyd, explained to us that rocks in archaeology make up everything that came before the people and the buildings and the history. He also explained that we, as archaeologists need to question what is and is not a rock artifact, and we can answer this question with another question: Has the rock been altered (or worked) by humans? This is how archaeologists know if the rock fragment is an artifact which needs to be kept or simply thrown away.

At Monticello quartz sand has formed into quartz and mineral massive quartz cannot be tested or replicated. Seems and cracks form in the parent material, then groundwater passes through, and silica accumulates and fills the space with quartz crystals, the parent material decomposes, leaving the quartz vein to grow. Along with quartz deposits, Goethite, named after the German polymath Johann Wolfgang von Goethe, has been found. The mineral was used for devil’s dice (the mineral breaks in perfect cubes) and was used to make game pieces and toys at Monticello.

Back to knowing whether or not a piece of quartz has been worked or not, quartz has similar properties as glass, it creates sharp edges when broken and was primarily used for projectile points (weapons, knives, etc.) for prehistoric peoples. Local quartz found on Monticello have lots of heat fractures and small pieces were worked til thick and blunt before they break with concloidal fractures (cone of energy breakage), and the bulb in the rock can tell us if it was struck or worked in any manner to be cut down and used. Slate and soapstone are also very important artifacts which can be found at Monticello. Slate gives off a high-pitched ring if struck and we used in chimney chinking and soapstone is metamorphic and as its surface is refined, it turns black (steatite) and can then be used as gun flints which have been found on slave sites. This is a key piece of evidence which has recently been discovered by archaeologists and has led to the interpretation that the slaves on Monticello (and other sites where the steatite has been found) had access to guns- most likely for hunting. These are the important developments in archaeology which geology has led to and one of the many reasons it is an important aspect of the historical record.