Hunter-gatherers. Picture: ISTOCK
Hunter-gatherers. Picture: ISTOCK

New technologies are shedding light on SA’s ancient past and the development of humanity’s cognitive abilities. Recent academic papers have been published that plot paths to understanding this forgotten history in terms of technology use and artistic development.

A pilot study has shown that it is possible to unravel the ancient alchemy of hunter-gatherer poisons. Thousands of years before the Sumerians developed writing in 3,000 BC or Egyptians began building their first dynasty, people in southern Africa were developing the first forms of technology. Researchers consider the use of poisons on arrow tips to be an important milestone in human cognitive development.

An arrow light-weight enough to travel relatively long distances would not have the force to do a large animal much harm, which is why the poisons are useful. But little research has been conducted on what plants were used in the poisons.

"Now, with the availability of new, more advanced, sensitive and reliable chemical detection techniques, we may be able to identify plant-based toxins present on archaeological artefacts," write the authors in their paper published in the latest issue of the South African Journal of Science.

"More subtle innovations within hunting systems, such as the introduction of poisons, also have the potential to inform on past cognitive frameworks and the time-depth of indigenous knowledge systems."

To detect the poisons, the researchers analysed a poison-tipped 100-year-old bone arrow from northern Namibia, a concoction of their own and fresh plant extracts, to test whether their technique worked.

The researchers used ultra-performance liquid chromatography to identify and quantify the different components that make up a mixture. But reconstructing poisons is not easy: they are often used in small quantities and time degrades organic compounds — the researchers have to reconstruct the compounds from the fragments that remain.

The pilot study had three phases: the researchers took 11 plant species, collected mainly from the Walter Sisulu Botanical Gardens, which are known to contain toxic compounds of known chemical structures. They were analysed and used to form the basis of poison recipes known to have been used by the San.

The resulting resin-like concoction was "blind-tested" — the person testing it was kept in the dark about what plants were used in the recipe. Finally, they applied their technique to a 100-year-old bone arrow, which was thought to have been used by the Hei||om people.

"We could identify organic plant-based compounds that are known to exist, but which we do not know were used as arrow poison ingredients in the past — that is the ultimate goal of our research," says Justin Bradfield, a postdoctoral researcher at the University of Witwatersrand’s Evolutionary Studies Institute and a co-author of the study.

"The next stage would be to analyse poisons from a wide variety of arrows, some of which may be hundreds of years old. In fact, we have some archaeological artifacts that are a few thousand years old.

"What I hope to achieve eventually is the identification of specific genera of plants that may have been used in the deep past. This would improve our understanding of indigenous knowledge systems and the continuity and diversity of plant-use patterns by indigenous people in the past."

Although working on a different aspect of — and time period in — southern Africa’s past, David Pearce, director of the Wits University’s Rock Art Institute, and colleagues have developed a way to directly date rock art.

Southern Africa has some of the best studied rock painting in the world, but they have not had dates until now.

Researchers have directly dated three sites in southern Africa, with results published in the journal Antiquity. They show that some of them were painted up to 5,700 years ago.

We know relatively little about these groups because of the paucity of archaeology

Rock art is notoriously difficult to date: to remove samples to test would destroy the paintings and they need to contain carbon in order to carbon-date them.

"What we’ve been doing previously existed out of time," says Pearce. "We know a lot about what the paintings mean, but traditionally there has not been a lot of scientific — chemistry and physics — techniques applied to archaeology here."

In southern Africa, ochre and white pigments dominate the rock art and unfortunately make them impossible to date directly. While there are black paints, these have traditionally been thought to be made of manganese-based compounds and are thus undateable.

However, the research shows there is carbon in some of the region’s rock art and this will allow researchers to put dates to the remarkable paintings. Armed with the dates, researchers can then answer questions about SA’s past.

About 2,000 years ago, Bantu-speaking farmers began moving into the region and rock art is the only historical record of when exactly this happened and what happened during that time.

"We know relatively little about these groups because of the paucity of archaeology," Pearce says.

There are a handful of dates for some southern African sites, but these were obtained indirectly by measuring the carbon in the mineral crust coating the art works or through dating artefacts at the rock art sites.

In 2010, a site Pearce was working on began collapsing. "We collected about 300 paint chips that had fallen off, and thought we’d take a look at composition," he says.

Adelphine Bonneau, at that time an archaeometry masters student at the University of Bordeaux, was an intern at the Research Laboratory for Archaeology and the History of Art at the University of Oxford, where Pearce was a research fellow. "So, the subject of my internship was simple. ‘We want to know what were the recipes of each paint used to create these paintings and we want to know how old they are. You have six months’," says Bonneau, who is now a postdoctoral candidate at Laval University in Canada and was lead author on the recent research paper.

They applied their technique to rock art sites in SA, Lesotho, and Botswana. They plan to date more sites the in region.

"It gives a better idea of what people are like, rather than this very narrow history that we have of the past couple of hundred years up to now. In this country, I think it’s very important," Pearce says

"We’ve got hundreds of thousands of years of people living in this country, doing all sorts of things, which people mostly don’t know anything about. That real story of SA is so vast and so complex and most people don’t know anything about it.

"There was this incredibly complex dynamic and we’ve had various groups of people arriving in southern Africa for the last 2,000 years, interacting with each other in a whole vast array of ways and the Europeans arriving is just the latest chapter in the arrivals and fits into the ongoing politics and
situation that was here."

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