How it began
The Haya people live on the western shore of Lake Victoria in northwestern Tanzania. Research by anthropologist Peter Schmidt and metallurgist Donald Avery of Brown University showed that the Haya and their forebears practiced an advanced iron smelting technology based on preheating 1,500 to 2,000 years ago and produced carbon steel. Excavations on the lake shore uncovered the remains of 13 furnaces nearly identical in design to the traditional Haya furnace, and radiocarbon dating of their charcoal gave that age.
How it works
The furnace the Haya elders rebuilt was a cone about 1.6 meters high made of slag and mud, set over a pit packed with partially burned swamp grass. The charred reeds supplied carbon that combined with the iron. Eight ceramic blowpipes reached inside the furnace and were fed by goatskin bellows outside, so the air was preheated before it reached the charcoal fire. The furnace reached temperatures above 1,800 degrees Celsius, high enough to produce medium-carbon steel.
Who pushed back
The craft died out in the early 20th century. Because the Haya could buy inexpensive European-made steel tools and earn more from coffee and other crops, they stopped making their own steel about 50 years before the 1978 study. By then only very old men remembered the details, and the researchers wrote that the knowledge was threatened every day by death and infirmity among the shrinking group of expert smelters.
What lasted
Schmidt was led to the old smelting sites by Haya elders, who showed him a shrine tree marking the place. In 1976, working from memory at the scientists' request, the elders built a traditional furnace and smelted in it. The authors suggested the technology may have evolved as an adaptation to overexploited forest resources, and argued that the findings matter for the history of Africa and of metallurgy, which had been explained mainly from European evidence.
