5500 BP

We know mankind has used fire for more than 100,000 years. By 40,000 BP humans were baking clay figurines, presumably having made ovens to get an even high temperature. That blowing on a fire made it burn hotter was common knowledge; Otzi the iceman carried the hot embers of his fire when he moved, so as to start his next fire this way. And they will surely have known that fires are hottest and best for cooking when they have a thick bed of charcoal.

We also know that humans have quarried stone for at least the last 12,000 years, and probably the last 20,000. Shell and stone beads were used to make personal ornaments for which coloured stones, ores, would be favoured. And stones were regularly put into fires to heat them for cooking in leather or wood containers.

Yet it took until 5500 BP for a piece of copper ore to be placed into a bed of charcoal and be fanned by the wind or by hand, and to reveal that it is possible to produce copper.

So what are the scenarios to explain why smelting of metals took so long to start and then developed so rapidly?

The first and probably most obvious is that humans had no idea that there could be a substance that they could craft into useful tools by shaping it as a malleable material. They of course knew that gold could be shaped, and will have had plenty of experience in shaping mud - the earliest pottery figurines date back to some 30,000 years ago. They knew that a soft malleable substance like clay could then be baked and made hard but might not have been able to imagine a hard substance that could be softened by heat to be made malleable, that would then become hard again when cooled.

A second scenario is that there just wasn’t a need drive experimentation. Stone tools are remarkably effective if you know how to make them well. Flint knives and arrow-heads are very sharp and can be sharpened by careful pressure-flaking. A flint axe-head well mounted in a haft will chop down trees, maybe not quite as fast as a metal axe, but pretty quickly. For finer work a community would probably have access to a few obsidian blades. We know long-distance trade was happening by 40,000 years ago and obsidian blades have been found many hundreds or even thousands of miles from their source. An obsidian blade can be sharper than a metal surgeon’s scalpel.

A third scenario is that the leaders of the societies created a cultural and religious environment which made the kind of experimentation needed to smelt metals unacceptable. The speed with which agriculture developed rather suggests that an organised civilisation can be led to progress developments that the society’s leaders see as a priority. It is larger civilisations that make major developments, small groups and tribes tend to carry on living as their ancestors have before them. It is only when groups get big enough to enable some specialists to be tasked with certain tasks. If the leaders of the society use this effort to maintain a group of religious leaders who promote continuance of existing practices and who frown on development of new ideas, then there might have been quite strong pressure against the kind of explorations and inventiveness that led to copper smelting.

The point is that there was nothing to stop the smelting of copper starting much earlier than it did start, at least using veins of ore that reached the surface and were accessible. So we will have to decide which of the scenarios to explain why it took so long we think is most likely.

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