Understanding Climate Change with Baobab Trees

Understanding the environment is an essential aspect of an archaeologist’s job to understand the context in which societies formed and lived and artifacts are found.  More specifically, trees can serve as valuable records that describe the climate of an area over the period of hundreds or thousands of years.  Researchers in Southern Africa are using the analysis of radiocarbon dating and tree rings in Baobab trees to interpret how the climate has changed in Southern Africa over the past thousand years, and to use these interpretations to try to form ideas about the societies that developed in these areas.

A Baobab tree in northeastern South Africa

Since tree growth is dependant upon the environment, it can be a good indicator of the climate at a specific time.  Tree growth is a complex process, but temperature and soil moisture temperature can be the leading factors contributing to tree growth, thus tree growth can tell us a lot about the temperature and soil moisture of an area at a specific time period, among other things.  


Radiocarbon dating is a common process of evaluating the age of a tree, and radiocarbon samples can also be taken from a tree and can be used to determine such things as the moisture and temperature of tree cellulose at a given time period.  Radiocarbon dating works by measuring the amount of carbon-14 in an object relative to other carbon isotopes in the object and measuring the amount it has decayed over time.  


Tree rings can also usually be used to determine the age of tree, and act as a record of the quality of the tree’s health throughout its lifespan.  Tree ring growth varies with the climate, and thus it can be strong in the spring or weak in the winter and used to determine differences in tree health and of the wider climate’s condition at specific time spans.


Researchers analysed the Baobab trees from Northeastern South Africa for the amount of waterfall in the region and included the timeframe of the Kingdom of Mapungubwe in the period of time they studied.  The group of researchers from Britain, Romania, and South Africa determined that, “The wettest period was AD1075 or [1075CE] in the Medieval Warm Period, and the driest periods were AD1635, AD1695 and AD1805 during the Little Ice Age.”1

A map of Limpop-Shashe Basin

The data collected can also be used to try to better understand the region at the time the first Bantu-speaking farmers settled the land.  Better understanding the environment in which these farmers developed their land can be valuable knowledge in determining the political and economic systems of the area, of which were based upon the success of agriculture to allow for specialization at the time.2


Recognizing the importance of evaluating the environment in interpreting the context in which people lived and artifacts are found can help better fathom our perceptions of an area at a specific time.  The analysis of radiocarbon dating and the use of tree rings are important tools that researchers can use in their experiments, and this reality is manifested in the importance researchers placed on their analysis of Baobab trees to understand how the climate changed – and how people might have adapted to its change – in the South Africa.  



1,2: http://mg.co.za/article/2015-05-28-silent-giants-unlock-story-of-climate-change

Picture 1: http://media-cdn.tripadvisor.com/media/photo-s/01/77/88/b6/african-baobab-tree.jpg

Picture 2: http://www.sanparks.org/images/conservation/transfrontier/lstfca_combined.png


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How the Incas Defied their Environment

The environment can reveal a lot about a culture. If the environment is favorable for agriculture, people take up a sedentary lifestyle. If it is the opposite, or people have access to additional resources, agriculture is less likely to be a focus. Yet this general rule is challenged by the Inca Empire, and their persistence to pursue agriculture in a region unfavorable to crops.

The basic process of creating terraces.

Mountain climates do not inherently support agriculture. Little precipitation falls in the Andes. Steep slopes also prevent growth of plants as what little precipitation that does fall erodes soil and thus washes plants away. Mountain temperatures fluctuate, often becoming much colder at night and shortening the growing season.
However, the Incas found a way around these problems, with terrace agriculture. By cutting flat planes into the mountain, the Incas were able to create areas of suitable farmland. Bounded by stone walls, these areas are able to withstand the problems associated with Mountain climates. Along with domesticated species of plants suited to harsh conditions, the Incas were able to farm.
Yet why would the Incas put in the tremendous amount of work to make an area unsuitable for sedentary life, suitable? The answer lies within the environment. Cultures that struggle with agriculture often have earlier examples of rock art (signs of praying to the Gods). As religion is spurred by a harsh environment, it becomes even more central to the culture.
In the case of the Incas, religion played a huge role in their culture, likely due to the environment. As to why they would have stayed, or even continued higher; (major areas like Machu Picchu and Cuzco are over 7,000 ft. above sea level) this is likely due to being closer to heaven (the Inca highly revered their sun God, Inti). As religion led to the Incas moving up in altitude, the environment only became tougher for a sedentary lifestyle. Yet the practice of terrace farming shows the Incas dedication to their lifestyle, and persistence as a people.


A ruin of an Inca temple in Pisac, Peru.

Though harsh in terms of climate, the Andes region is bountiful concerning precious medals. The existence of the precious metals gold and silver would have confirmed that they were in a holy area of the world, and that their connection to their Gods would only be improved as they increased in altitude. The use of these metals in Inca throne rooms and temples shows the influence the environment had upon their lives.
Through just the knowledge of the environment, a lot can be seen about a culture. What environmental challenges are presented determine what kind of lifestyle inhabitants will lead. In the case of the Incas, their harsh conditions resulted in creativity and adaptation against the natural environment, so as to pursue their religious lifestyle. Understanding how environmental conditions pressure and shape a human life is imperative to understanding a culture.


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Animal Domestication: How Our Ancestors Became Sedentary

Transportation, agriculture, and companionship—Humans are significantly affected by interactions with animals. Our modern lifestyles would not be possible without the domestication of animals. When did humans start to have pets? Why did pets and other domestic animals begin to matter? How were they used? These are questions that archaeologists ask themselves and have done their best to answer.

Pets of our ancestors are significantly different than ones we keep today. Using a dog jaw found in Switzerland as evidence, archaeologists have estimated that dogs were first domesticated around 14000 to 14600 years ago, but humans have selectively breaded for

Dog jaw found in Swiss cave (c. 14000 years ago)

Dog jaw found in Swiss cave (c. 14000 years ago)

desired traits, causing dramatic changes in the physical structure of animals. Different societies selected for different characteristics, including  fur color, ability, and shape. The same qualities are found in cat remains, though cats are estimated to be domesticated around 7500 B.C. While most would like to hear more about the exciting shift of our furry friends from wild hunter to companion, the most striking information regarding the domestication of animals is looking at farm domestication and how groups of people shifted from nomadic bands to pastoral, sedentary groups.

The first animals thought to be domesticated for agricultural endeavors were sheep between 11000 and 9000 B.C., and goats were domesticated shortly after. These animals were used for meat, milk, and fur. Bands of people at this time were still primarily nomadic. Remains for sheep were first found in the Middle East, where there are high proportions of bones of one year old sheep. Dating for the domestication of these animals is possible by looking at the remains of those who lived in the area and finding when human beings were able to process lactose. There was an incredible advantage for those who could digest lactose because of high amounts of calories available from milk. Evidence is also available about milk use through 7000 year old perforated pottery that was used for cheese production. Use of this type of potter was proven by experimental archaeology and chemical analysis of the clay, which found milk fats inside the pottery.

Pottery that was used for cheese straining, found in  Poland

Pottery that was used for cheese straining, found in Poland

Pigs and cattle were domesticated slightly later, around 7000 B.C., but these remains are usually found with societies that were more sedentary.

One of the main reasons to domesticate animals is because there is always a constant, readily available, and reliable source of food. If one goes hunting, there are no chances that he or she will return with meat for his or her community. If one hunts too many animals, the food will spoil, and the food will be wasted. Domesticating animals also provided for suitable manure for farming, hides and wool for coats, and bones for tools. Through the domestication of animals, the concept of staying in one place was a viable option for people. The need to constantly move for a steady supply of food was outdated, and we see the rise of civilizations and larger social organizations as animals domestication begins.








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