Unearthing our human ancestors

Hagai Ron of the Hebrew University in
Jerusalem collecting samples from the
cave for dating.

A small stone tool excavated from the
Wonderwerk cave.

The Wonderwerk cave in 3D, mapped by
Professor Heinz Ruther of Cape Town
University’s Department of Geomatics. The
expanded section is of the front part of
the cave where the discoveries were made.

(All images: Michael Chazan)

Janine Erasmus

A team of researchers from South Africa, Israel and Canada, led by Canadian anthropologist Professor Michael Chazan and Dr Liora Horwitz of Jerusalem’s Hebrew University, has found man-made artefacts, thought to be at least 2-million years old, in a cave in the Northern Cape.

The Wonderwerk (Afrikaans, meaning “miracle”) cave, located 45km from Kuruman in the Northern Cape province, is a huge structure that has yielded a significant record of human history spanning hundreds of thousands of years. Ancient tools discovered in the cave are similar in age to those found at the bottom of Tanzania’s Olduvai Gorge.

The 30 artefacts, mostly small tools, are among the oldest known items of their kind and provide evidence that our ancestors lived in caves even earlier than was previously thought. This important South African find is the result of more than 60 years of work on the site.

Because of the key role it has played in providing clues to our human existence, the Wonderwerk cave and its surroundings were proclaimed a national heritage site in 1993 and are currently on the Unesco World Heritage tentative list for South Africa. Although it is a valuable research site the cave is open to the public on an appointment basis.

A shelter for many

Bushman paintings on the Wonderwerk cave’s walls have been dated back some 10 000 years. The cave was first inhabited by white settlers in the early 20th century, when the farmer P.E. Bosman and his family lived there between 1909 and 1911 while he was building the present homestead. He later used the cave as a shelter for stock.

Later, other farmers exploited the cave’s abundant bat guano for commercial purposes. Although the mining unfortunately destroyed much of the natural sediment in the upper levels it also led to the discovery of the first artefacts, alerting the archaeological community to the potential importance of the site. The first excavations began in 1940.

The cave was owned by the Bosman and Nieuwoudt families until 1993 when they generously handed it over to the McGregor Museum in Kimberley, an institution that is active in a range of fields including archaeology and military and cultural history. The museum now oversees all scientific activity at the site.

Ancient cave-dwellers

The 30 most recently found artefacts were found at the bottom-most level of the Wonderwerk cave and are believed to have been left in the cave by its former dwellers, not washed into it from the outside. The deeper the excavation, the older the layer, and the bottom level has been dated back two million years by researchers using a combination of methods, including palaeomagnetic and cosmogenic burial dating techniques.

Palaeomagnetic dating is based on a global time scale that tracks changes in the orientation and intensity of the earth’s magnetic field over time, while cosmogenic burial dating is based on radioactive decay of a pair of cosmogenic nuclides. Unlike the similar technique of carbon dating, it can measure extremely old dates.

While the oldest known stone tools, found in Ethiopia, date back 2.4-million years, those found inside Wonderwerk provide clues to the oldest known intentional cave dwelling by human ancestors, or hominids. Out of the numerous hominid species that lived in the area at the time, the most likely manufacturer of the tools, say researchers, is Homo habilis.

Compared to modern humans, Homo habilis was short in stature and had unusually long arms, with a skeletal structure similar to that of today’s primates. The species was unknown until a specimen, consisting of bone from the head and hand, was discovered in Olduvai in 1960 by the Leakey team.

Shortly afterwards a multidisciplinary team comprising Kenyan archaeologist Louis Leakey, British primatologist John Napier, and South African palaeoanthropologist Phillip Tobias studied the specimen extensively before making their announcement in 1964 that it belonged to a new species of man.

The name, meaning “handy man” in reference to its tool-making abilities, was suggested by Raymond Dart, the renowned Australian anthropologist. Dart is best known for his discovery of the skull of the little Taung Child in the same region as the Wonderwerk Cave, which led to his subsequent announcement of the new species Australopithecus africanus.

The work of millions of years

At 139m in depth horizontally, Wonderwerk is big enough to shelter many families and their livestock. The cave is a solution cavity, which means that it was filled with water millions of years ago. Located in the Kuruman Hills, erosion on the hillside has exposed one end of the cave, and today the only permanent water source is the Boesmansgat (Afrikaans, meaning “Bushman’s hole”) sinkhole some 12km away, and a seep on Gakorosa Hill 5km south of the complex.

Geologically, the structure consists of stratified dolomitic limestone belonging to the 2.3-billion year old Ghaap Plateau Dolomite Formation. The almost perfectly flat Ghaap Plateau sits some 1 130m above sea level and extends 150km from east to west, between the Harts River valley and the Kuruman Hills.

The plateau is made up largely of calcrete, a mix of sand, gravel, clay and other materials cemented together by calcium carbonate. The calcrete is covered with sparse soil and sits on bedrock of dolomite or calcium manganese carbonate, containing numerous caves, sinkholes and underground waterways.

The Ghaap Plateau is notable as the location of the underground freshwater cave known as Boesmansgat, the scene of many a world deep diving record. The 13-year-old men’s world record for cave diving is held by South African Nuno Gomes, with Gauteng resident Verna van Schaik holding the women’s record. It is also the place where the plant Hoodia, currently fashionable as an appetite suppressant and diet-aid, is primarily found.

The bedrock in the front of the cave is covered by 4m of almost horizontal deposit layers. Research reveals that the uppermost metre spans the past 300 000 years, while the bottom layer reaches back to 2-million years. Investigation of the layers shows human occupation at all levels.

All archaeological material brought out of the Wonderwerk cave is now held by the McGregor Museum. These items include decorated ostrich eggshells, pollen dating back about 400 000 years, animal bones and remains including those of a now extinct species of horse, engraved stones, and stone implements such as Acheulean handaxes, which belong to the Acheulean tool industry from the Lower Palaeolithic era.

The area’s renowned rock paintings were crafted in a variety of media ranging from red and yellow ochres of local origin to crushed plant roots and blood.

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