Friday, 30 January 2015

Seminar report: "Early modern human behaviour in South Africa from 100 000 years"

On the 29th of January 2015, the society welcomed Dr. Riaan Rifkin from Witwatersrand University and the University of Bergen. His doctoral research looked at the use of pigments in Prehistory. He gave his seminar on early modern human behaviour from 100,000 years ago, a topic derived from his work excavating and researching Blombos cave and Klipdrift shelter, both in South Africa.
He started his talk discussing the fact that we all have African origins. These origins are in our DNA and, using his own DNA as an example, mentioned how his genetic origins can be traced to Africa on both sides of his family and has both 2.7% Neanderthal DNA and 4% Denisovan DNA.

He focused on a period during the Middle Stone Age, from 100,000 years ago to 30,000 year ago as it saw a very interesting development in modern human behaviour. This period saw a change in subsistence strategy, with evidence for a more marine based diet with the collecting of shell fish and diving for fish. There is also evidence to suggest that these humans had developed some idea about tides and used this to their advantage to obtain fish. There was also technological innovations during this period, such as the likes of pressure flakes and scrapers. There is also evidence for a change in social and symbolic behaviour. Evidence for these changes is present in Blombos cave and Klipdrift Shelter.

Between 80,000 and 35,000 years ago expansion took place with site distribution clustering along coastal zones. There is only two known sites in endemic malaria zones. It seems that they chose to avoid these types of areas. Blombos Cave was described as a “very unassuming, small” cave on the Indian Ocean. Excavations allowed for very accurate dates, with parts of the cave deposit dating from 72,000 ±4000 years ago. The lowest reached part of the deposit dates to around 110,000 years ago. The bottom of the cave has not yet been reached due to the work having to be done slowly but part of the cave deposit dates to 140,000 year ago. Blombos Cave contains the very first forms of art produced from around 100,000 years ago. The site contains features seventeen ochre engravings. These engravings had no functionality. This is the first time we see humans with complex capability’s to create art and creating paint. Finds of 1cm beads with ochre residue suggests that people covered their bodies with ochre as the beads seem not have been covered in it. The residue probably got on to the beads from rubbing against the body of the wearer.

Klipdrift Shelter had the earliest microlithic tool technology dating from around 65,000 years ago. Microscopic analysis suggests they were stuck into a wooden shaft with mixture of heated gum and red ochre. The size and shape of these microliths suggests they were possibly used for arrows.
Excavations at the Shelter also revealed several engraved ostrich egg containers from 65,000 years ago. It is the second known site in Africa with finds of these. They are often engraved with a geometric pattern.

Ochre is one of the most common archaeological finds from the Middle Stone Age. It often appears to have had symbolic purposes, such as people covering their entire bodies with it. Ochre, also, had many functional purposes, such as hide preservation and was definitely a common ingredient in hafting mastics. It is still used by some people in parts of Africa and still has symbolic purposes. As part of his PhD research, Dr. Rifkin visited the Ovahimba in Northern Namibia and Southern Angola, many of whom have their bodies, including their hair, always covered in red ochre. They mine the ochre themselves. The women publicly process ochre in similar way to maize or corn by grinding it on a grinding stone. The ochre is applied to the skin by being mixed with ghee or clarified butter. The women of the Ovahimba said they also wore the red ochre as their skin never burned and they were not bitten by mosquitos.

Dr. Rifkin and some of his colleagues preformed an experiment to test these hypothesis about ochre regarding sunburn and mosquito bites. Using lab breed mosquitos, several experiments were done with one arm being treated with ochre (mixed with clarified butter, ghee or animal fat) and the other arm untreated.  The ochre treated arm would not be bitten badly due to the clay particles that get stuck to the mosquitos’ mouths, they can’t feed again and it leads to their death.  Apart from the animal fat treated ochre (which drove the mosquitos mad and will bite at a ferocious rate), as a repellent the ochre was nearly as efficient as commercial products.

As a sunscreen, dry ochre proved to have a SPF of 11.1 – 9.9 and in some cases and SPF of 12 or 14. This is good enough for those of darker skin tones to be functioning sunscreen.These are most likely the same results that would have been achieved 100,000 years ago. The same ingredients were used then as in the experiments. The symbolic use of ochre is of undeniable value and similar symbolic values appear not just in Africa but in areas, like the Philippines.

By Sarah Delaney

No comments:

Post a Comment