The dawn of ironworking in Africa is a hot anthropological topic. My own interests in demographic growth and dispersals depends very closely on the chronology of ironworking in Africa, because the advent of iron may have enabled faster conversion of land to agriculture.
Many anthropologists believe that the dispersal of the Bantu languages may be traced to an agricultural explosion driven by iron technology. Others dispute this connection, raising doubts about whether the ironworking chronology can match the timing this dispersal. Both these have some wiggle-room in their dating, as do the times of introduction or domestication of various crop species.
For the purposes of our paper last year, it was sufficient to know that populations grew in Africa after roughly 2000 BC. But to test hypotheses about gene dispersal and selection among African populations -- data that are now available -- we have to be a bit more precise.
Last week's Science includes a summary article by Heather Pringle, which discusses the controversy over the chronology of African ironworking.
Now controversial findings from a French team working at the site of Ôboui in the Central African Republic challenge the diffusion model. Artifacts there suggest that sub-Saharan Africans were making iron by at least 2000 B.C.E. and possibly much earlier--well before Middle Easterners, says team member Philippe Fluzin, an archaeometallurgist at the University of Technology of Belfort-Montbéliard in Belfort, France. The team unearthed a blacksmith's forge and copious iron artifacts, including pieces of iron bloom and two needles, as they describe in a recent monograph, Les Ateliers d'Ôboui, published in Paris. "Effectively, the oldest known sites for iron metallurgy are in Africa," Fluzin says.
Some researchers are impressed, particularly by a cluster of consistent radiocarbon dates.
And, as you might expect:
Others, however, raise serious questions about the new claims.
The article casts the debate as an opposition between a diffusionist hypothesis (metallurgy entered Africa from the Near East) and local development. That's appropriate, since this pattern of opposition is one of the oldest stories in archaeology. But I'm more interested in the dates and resulting population dynamics. How did technology relate to demographic growth, and how were genes affected by these processes?
The article makes the early development of ironworking in Africa seem very credible, particularly if the only other option is a late introduction via Carthage or the Nile corridor. It is not obvious how much of the apparent controversy is about the early dates from this one site in particular, and how much is about the presence of pre-first-millennium BCE ironworking generally. Critics raise various scenarios for the contamination of radiocarbon dates by old carbon. This always reminds me about how much error may lie within Paleolithic dates if we have to worry about contamination in Iron Age sites!
Well, more on this issue later.
Pringle H. 2009. Seeking Africa's first Iron Men. Science 323:200-202. doi:10.1126/science.323.5911.200