From trees to… charcoal?

Did you know that the origin of trees goes back to the Devonian period, around 400 million years ago Yup, that long. Since then, the trees have always occupied a central place in the evolution of life on earth since the earliest hominid groups, to the appearance of the first civilizations (around 7000 BC), when animal and plant domestication, writing, and the first organized villages began to emerge and even within these days, as you probably already know.

We can say that they were used firstly as a point of reference, a source of food, a refuge against predators, and a good shadow. Later, for the Stone Age communities, wood was indispensable in the form of weapons such as thrusters, tools, fuel, lighting, warming, and construction material. Trees have always been part of our lives and played a key role in the process of human evolution as well as in modern human cognition.

My name is Roxane Matias, I’m a Ph.D. student at the University of Algarve in collaboration with the University of Wits, Johannesburg, South Africa. Since my BA I’m interested in Archaeobotany, more specifically on anthracology – the study of charred wood (charcoal) in archaeological context. Currently, I’m developing a research project about the role of fire across time, the management of wild woody resources, and past landscape inhabited by Later Stone Age (LSA) communities settled in Magaliesberg mountain, South Africa (Map 1). For this, I will use charcoal remains collected in seven sequenced hearths, spanning the Later Stone Age (c. 8500 BP.) to Later Iron Age (c. 1550 BP.) (Fig. 1) in the archaeological site of Jubilee Shelter located in that area.

Map 1 – Jubilee Shelter location. A) South Africa, B) Gauteng Province and C) Magaliesberg Mountain.
Figure 1 – Jubilee Shelter: Schematic representation of the radiocarbon dates made in charcoals from hearths (symbols). Source: Wadley, 1986, p. 56.

Since 1980 the LSA research in South Africa has increasingly integrated paleoenvironmental data to better understand how humans adapted their behaviors and culture to the changing environments, and how it may have affected them. In this sense, several archaeological sites in southern Africa (mainly located in coastal areas) have shown peaks of moisture/dryness fluctuations for the Holocene being commonly associated with multiple processes of cultural, economic, technological, and demographic reorganization across space and time.

As such, this study becomes important as it is one of the few inland archaeological sites in South Africa with charcoal assemblages and human occupation before and after the first contacts between local hunter-gatherers and the new arrivals, the Bantu agriculturalist communities, coming from the north. Furthermore, the Magaliesberg is inserted in the Cradle of Humankind region, world-famous for its archaeological sites, human remains related to the origins of humankind, and the oldest trace of the use of fire dated to over 1 million years ago (Swartkrans cave).

But how can I identify woody species through charcoal remains? This is because each woody species has its own anatomical cell structure and when charred it’s possible to identify species through microscopic analysis (Fig. 2).

Figure 2 – A) An example of how to analyze charcoal fragments under a reflected light microscope and B, C, D) Diospyros sp. An archaeological charcoal specimen.

So, stay tuned to our blog to know more about anthracology! For my next post, I will contextualize the LSA in South Africa and show you where I am analyzing the charred wood for my Ph.D. project and which procedure I will use.

Author: Roxane Matias

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