A micro-contextual approach to pyrotechnologies of Middle and Later Stone Age foragers in central Africa

MicroAsh

B. Nkosi demonstrating how to start a fire with a twig of the Kachere tree, or common wild fig. Drawing by A. Barbieri. With permission.

Poster presented at INQUA Roma 2023: the 21st congress of the International Union for Quaternary and Archaeological Sediments

Photomicrographs of experimental ashes and phytoliths in thin section

»The use and control of fire has shaped who we are today, and virtually all human populations depend on fire both culturally and biologically«

Mount Hora is a prominent landmark. Around its lower middle are several rockshelters with prehistoric archaeology, including Hora-1, which was discovered and first explored by Desmond Clark and his colleagues in the 1960s. Photo by J. Thompson.

Benjamin Inkosi is cutting reeds for experiments to create reference samples.

»Pyrotechnology«

We tend to take our ability to produce and control fire for granted. Sure, we use fire every day, and most people will agree that this technological development was a game-changer for our evolution. But how did this happen? Was it just a matter of a discovery, with humans leapfrogging any technological evolution process, or is there more to it?

In MicroAsh, I study the the ways in which fire has been implemented and how it evolved as a technology during the Middle and Later Stone Age (MSA-LSA) by analyzing ash-rich, anthropogenic, sediments from three rockshelter sites in northern Malawi, Africa.

Can the variability in fire features tell us something about MSA and LSA hunter-gatherer life: their behaviors, and how they used the landscape with its natural resources?

MicroAsh is a 2-year (2021-2023) EU-funded project, supervised by Vera Aldeias, which operates in close collaboration with the archaeological project led by Jessica Thompson: the Malawi Ancient Lifeways and Peoples Project (MALAPP).

During the course of the project, I will post updates and start creating an "Atlas" of plants and ashes documented within the MicroAsh to provide a - hopefully - useful lasting archive with relevance to anyone interested (e. g. hobby botanists, ecologists, anthropologists...).

At Hora-1 with geoarchaeologist David Wright.

Preliminary work: producing ashes of different plant types for reference. Kondwani Mwafulirwa performing burning experiments in a brick oven. (Photo added with permission of KM).

Map of the study area, showing the Kasitu river and the three archaeological sites: Hora-1 at 1450m AMSL, Kadawonda-1 at 1700m AMSL, and Mazinga-1 at 1395m AMSL. Map by Alvise Barbieri using AW3D30 data.

Collecting samples from a deep sounding at Mazinga. Tight and ashy!

Profile description and sample collection in a river bank in front of Mazinga.

»The Kasitu valley«

Three MSA-LSA rockhelters in the Kasitu Valley in northern Malawi will serve as case studies to investigate the pyrotechnological repertoire of prehistoric hunter-gatherers.

The rockshelters are located in inselbergs and collapsed blocks from magmatic intrusions, providing an acidic environment with very poor preservation potential for organic materials. However, the archaeological deposits are so rich in ash (with calcium carbonate as its main component), that the local conditions in the archaeological deposits are much more alkaline and many materials have been preserved which usually would not, including faunal and macrobotanical remains, shells, bone and lithic tools, several human burials, and a partial cremation.

The deposits span several key climatic changes such as the time before, during and after the Late Glacial Maximum, Heinrich Events 1 and 2, and the African Humid Period, providing opportunities to explore changing human-environment relationships.

The sites also include different time slices covering much of the LSA at all sites and reaching back to at least 30 ka at Mazinga-1. This last age overlaps with terminal MSA assemblages from open-air sites in northern Malawi, dated to as recently as 21 ka (e. g., Wright et al., 2014; Nightingale et al., 2019).

Swallows use clay to build their nests against the rock walls. Collecting fragments of abandoned nests helps build a reference collection and detect the origin of clay aggregates inside the archaeological deposits. On the right is a scan of a thin section.

Different parts of termite mounds are sampled for reference. This is a fungal comb from an abandoned mound.

The archaeological deposits are rich in ash (aa) and contain different types of clay aggregates (ca). Articulated plant ash in thin section will be compared with reference samples of different plants growing in the Kasitu valley today. By comparing clay aggregates with reference samples, their origin may be reconstructed, possibly informing about the human activities that took place in the rockshelters.

A small shelter of sekele grass for guarding crops (against baboons).

Sekele is used for building fences against the wind: here for the camp kitchen with local (Inkosi) crew members of MALAPP.

House constructed using sekele grasses. Example of the modern-day use of this versatile plant.

A freshly dug latrine pit in the valley in from of Mount Hora offers an opportunity to collect a reference sample. Are clay aggregates found in the archaeological deposits brought in from the valley? How?

In brief, MicroAsh has four main objectives:

Establish natural and anthropogenic site formation processes and characterize fire features.
Investigate the (two-way) relation between the use of fire and environmental changes.
Explore spatial and chronological changes in pyrotechnology.
Reconstruct site-use intensity.

The stems of the Matete reed is used for making mats (for example used for drying cassava), baskets and construction.