Wilma den Hartigh
Recent analysis and dating of archaeological material discovered at a rock shelter in South Africa reveals that modern human behaviour, as we know it, developed much earlier than previously thought.
The findings of a multi-disciplinary research team made up of scientists from all over the world has shed new light on this topic, providing answers to the crucial question of when in prehistory human cultures similar to ours emerged – something that human evolution scientists have grappled with for many years.
Dr Lucinda Backwell, a senior researcher in palaeoanthropology at Wits University says until now, many archaeologists believed the oldest traces of San hunter-gatherer people in South Africa dated back 10 000 to 20 000 years, at the most.
However, when researchers analysed objects retrieved from archaeological layers at KwaZulu-Natal's Border Cave, they discovered people lived at this site as far bar back as 44 000 years ago.
"This find is important because it shows the earliest evidence of modern human behaviour as we know it," Backwell explains.
"What we found there shows that people made use of symbolism, they were innovative and had cognitive ability.
"It reveals that we are more like than we think we are."
More alike to our ancestors
Prof Francesco d'Errico, leader of the international team and director of research at the French National Research Centre, says their results confirm that when people in southern Africa developed a lifestyle similar to that of hunter-gatherers, it remained almost unchanged for 40 000 years.
He believes this adds a new dimension to the definition of modern cultural adaptation.
"We often consider modern behaviour as synonymous with rapid cultural turn over," D'Errico says.
"The results show that even among modern humans, as among previous human species, culture can remain almost unchanged for very long, when there is no need to change."
What they found
The site is a treasure trove for archaeologists as it records well preserved organic remains from that time. By using radio carbon methods, microscopic and chemical analysis, the team was able to identify how the artefacts were manufactured, used and what they were made of.
"We were able to show in this way that already 44 000 years ago the inhabitants of this site manufactured and used many artefacts that until recently were an integral part of Kalahari Bushman culture," Backwell says.
Many of the discoveries, such as the ostrich egg and marine shell beads used as jewellery, show that even 44 000 years ago early humans had great aesthetic sense.
"This shows that the first focus of aesthetic behaviour was the human body," D'Errico explains.
Backwell adds that people also used beads as part of a gift exchange system, just as modern people give and receive presents from each other.
"It is similar to bartering, but this system was reciprocal and not just a business transaction," she says.
They also used notched bones for counting purposes and the stone tools discovered in the same archaeological layers show a gradual evolution in stone tool technology.
"They fashioned fine bone points for use as awls (long pointed spikes) and poisoned arrowheads," Backwell says. "One point is decorated with a spiral groove filled with red powder, comparable with similar marks made by Bushmen to identify their arrow heads when hunting."
Complicated chemical analysis
Using only a grain of material smaller than a pinhead, chemists based in Italy made extraordinary discoveries about the use of natural materials to manufacture poison and glue.
A closer look at the artefacts revealed the earliest evidence for the use of poison. Chemical analysis of residues on a wooden stick decorated with incisions shows it was used to hold and carry a poison containing ricinoleic acid found in castor beans.
The oldest known use of beeswax as an ingredient in glue was also discovered at the cave. Backwell says the lump of beeswax, mixed with the resin of Euphorbia (a plant with poisonous milky sap), and possibly egg, was wrapped in plant fibres made from the inner bark of a woody plant.
The beeswax product was used as a binding agent to make stone tools such as arrowheads using a hafting technique, a process which involves attaching bone, metal or stone to a handle or shaft. Through this process, early humans could make tools that were more useful and stronger, such as a spear or an axe.
"This is a complicated list of ingredients used to make tools with impact," she explains.
Once the arrowhead was attached using the binding agent, it was reinforced with twine or animal ligaments.
The inhabitants of the cave also shaped warthog tusks into awls and possibly spear heads. "The use of small pieces of stone to arm hunting weapons is confirmed by the discovery of resin residue still adhering to some of the tools," she says.
The Italian chemists identified the resin to be suberin, a waxy substance produced from the sap of yellowwood trees, also used in the hafting process.
She says the variety of ingredients indicate the ability of early human cultures to adapt to their geographical surroundings and use any available materials.
Backwell says there are still many unanswered questions, such as why there appears to be a different rate of cultural development of early humans.
"There are clear signs of a punctuated evolution," she says.
There are many theories as to why this happened, ranging from communities moving to another site, population growth, or even a loss of interest in a particular innovation.
"Innovations came, were used and were lost again. This shows that human evolution was not entirely gradual," she says. "There is also a possibility that entire communities could have been wiped out by illness or disease."
According to D'Errico, their research further demonstrates that Bushmen technology and lifestyle emerged abruptly, and remained relatively unchanged until recent times.
"This represented an extremely successful and flexible cultural adaptation, able to cope with changing African environments," he says.
He believes their results have implications for the origins of language and the relationship between genetic and cultural heritage.
Backwell anticipates that more archaeological material will be discovered at Border Cave. "At the same cave, the oldest child burial site was discovered, dated 80 000 years ago," she says.
She explains that the excavation, analysis and interpretation of the artefacts found at Border Cave demonstrate the value of interdisciplinary collaboration.
She's also consulted with Kalahari Bushmen in the Botswana and Namibia regions. ""They have shed new perspectives of what we've found," she says.