Karela Fry

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Ancient cultures: really ancient

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connections between climate change and human development

The Indus valley culture essentially died off about 3000 years ago. Our current culture, therefore cannot be older than about 3000 years. Really ancient and long-lived cultures are now being discovered. Nature carries a small review of current work in a site in South Africa:

The Still Bay culture was one of the most advanced Middle Stone Age groups in Africa when it emerged some 78,000 years ago in a startlingly early flourishing of the human mind. [Chris] Henshilwood’s excavations at Blombos Cave have revealed distinctive tools, including carefully worked stone points that probably served as knives and spear tips, and bits of rock inscribed with apparently symbolic designs. But evidence of the technology disappears abruptly in sediment about 71,000 years old, along with all proof of human habitation in southern Africa. It would be 7,000 years before a new culture appeared, with a markedly different toolkit, including crescent-shaped blades probably used as arrowheads.

Multiple teams are now racing to determine the part climate might have played in driving human evolution during this period. Blombos Cave, with its detailed archaeological record of the Middle Stone Age, could become a key testing ground. With Francesco d’Errico, an anthropologist at the French National Centre for Scientific Research (CNRS) in Bordeaux, Henshilwood has assembled a team of archaeologists, climate modellers and palaeoclimatologists for a five-year, €2.5-million (US$3.3-million) project to look at correlations between climate and culture during the eventful span of prehistory that includes Still Bay, and the beginnings of modern human behaviour.

Palaeoclimate records from marine sediment and ice cores suggest that around the time the Still Bay culture disappeared, global temperatures dropped and the polar ice sheets grew. Ocean levels fell, and the Still Bay people may have followed the sea onto the continental shelf, which would have become a productive plain.

If this idea is accurate, most of the evidence would have been submerged as the ocean returned over the past 15,000 years. [Archaelogists are] beginning excavations on a site called Klipdrift Shelter, west of Blombos, that could allow him to look at the rise of Still Bay’s successor: the Howiesons Poort culture, which appeared 65,000 years ago and persisted for about 5,000 years.

Once the site has been dated, the researchers will add it to environmental and cultural records from southern Africa and Europe. To construct a climate record, Henshilwood’s team is sampling cave deposits, in search of clues to ancient rainfall and temperatures. They are also testing ocean sediment cores for pollen and traces of charcoal that hint at vegetation, rainfall and the frequency of fires.

The palaeoclimate data will allow a team at the CNRS to build a high-resolution model of climate in Europe and southern Africa, beginning with the time spanning the Still Bay and Howiesons Poort cultures. The last step is to overlay the climate and cultural data onto an ecological model to analyse the environmental space occupied by specific cultures throughout time. The team can then look for links. Was one industry, for example, always associated with a particular environment? Do similar cultures occupy similar landscapes or respond to climatic shifts in similar ways?

[Curtis] Marean and a team of researchers have already produced an assessment3 of historical sea levels around Pinnacle Point, and now they have received money from the National Geographic Society in Washington DC and the US National Science Foundation to build a detailed geophysical map of the continental shelf. Marean thinks that the exposed shelf would have been a diverse shrubland ecosystem with edible roots, big game for hunting and marine resources. His goal is to reconstruct the vegetation, and then use models to analyse how people might have exploited those resources.

“We need to develop a thick empirical record and put that into a really tight timescale,” says Marean. “Once we have that, we can start debating the whys.”

Alison Brooks, director of the Center for the Advanced Study of Hominid Paleobiology at the George Washington University in Washington DC, says that Henshilwood and others are producing much-needed data and hypotheses, but she warns against the dangers of oversimplification. Brooks is co-authoring a forthcoming publication that aligns palaeoclimate data with archaeological data throughout Africa, and she says that each region of the continent seems to have has its own story. “There’s a lot of complexity here,” she says.

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