Fire shaped our oldest tools
flint.jpg
Fire-treated tools may have helped
modern humans to ascend and hastened
the demise of the Neanderthals, according
to the researchers.
Image: iStockphoto

If the old adage 'don't play with fire' had been heeded by early humans, our evolution out of Africa, via the colder climes of Europe and Asia, may have been aborted or severely hindered. Clearly, fire kept us warm on these vital migrations.

But fire may already have been put to far more sophisticated uses in those distant days, to heat treat stone used to craft early stone-age weapons, particularly the specialised, light, and efficient tools needed by hunting parties. All this at a time when, until now, it was assumed man lacked the knowledge for such technological methods of production.

The use of this early 'pyrotechnology' may also have hastened the end for Neanderthals and helped the ascent of modern humans, by enabling us to control our environment and even hone our higher instincts through the beautification of artifacts.

New research in caves and rock shelters at Pinnacle Point in South Africa has revealed heat-treated artifacts dating back perhaps 164,000 years. The work, led by PhD scholar Kyle Brown from the University of Cape Town, has just been published in the latest issue of the international journal Science.

In an introductory article in the same issue, two La Trobe University researchers, John Webb and Marian Domanski - both internationally recognised specialists in ancient stone tool technology - were asked to provide their perspective on the significance of the new discovery.

Dr Webb, Associate Professor in Earth Sciences, and Mr Domanski, a PhD scholar, also describe how fire was used by Australian Aborigines to improve the quality of a variety of local stone raw materials on this continent to make better use of scarce resources.

They say artifacts created by pyrotechnology are common in Europe between 14,000 and 10,000 years ago.  Although finds are rare before that, scientists have recognised that humans used heat treatment of stone materials for least 72,000 years to make more efficient tools.

'The recent research by Kyle Brown and others indicates that in coastal South Africa, the deliberate use of this technique may date back perhaps as long as 164,000 years, predating its use elsewhere.'

The La Trobe stone tool experts explain that heat technology enables easier and better quality stone shaping by using pressure rather than the well-known percussion, or striking, method which most people associate with stone tool or spear tip making.  It also allows a wider range of rock to be used for raw materials.

Dr Webb and Mr Domanski say Neanderthals in Europe appeared to lack this technique, perhaps giving early modern humans that had the capacity to use it an evolutionary advantage as they moved out of Africa into Eurasia.

'This was particularly important in the harsh tundra environments of the Northern Hemisphere, where deep snow cover, frozen ground, and often frost-shattered stone reduced access to suitable raw materials and caused seasonal shortages.

'Pressure blade techniques using heat-treated stone may have been invented by reindeer hunters in this area as an adaptation to the shortage of raw material.'

The La Trobe stone tool experts say producing flaked stone tools for hunting, food gathering and food processing requires not only special skills but also high quality stone materials.

'When such stones were unavailable, early humans developed the ability to improve their quality through controlled heat treatment by burying selected pieces beneath a fire at a campsite or specialized workshop, usually for a day or more.

'Hence, this use of fire as an engineering tool is an early step in the evolution of means by which humans could more effectively control their environment.'

Dr Webb and Mr Domanski say the new evidence for heat treatment in Africa appears at roughly the same time as widespread evidence for symbolic behaviour, signaling the development of increasingly complex cognitive ability.

In Australia heat treatment was practiced until recently in the Kimberley.

Kidja Aborigines built large fire pits in sandy soil in which roughly flaked blanks of white chalcedony were left under ash in the bottom of the pit for three to four days.

'The blanks were then worked into long, thin, two-edged "Kimberley points" by master craftsmen using pressure rather than the percussion method.

'This meant that up to four or five times as many blanks could be produced from the same volume of material.'

The researchers explain that heat treatment improved both the flakeability and aesthetic qualities of stone. Kimberley points were prized as beautiful objects, given as prestigious gifts, and exported along indigenous trade routes.

In a prehistoric twist on today's artificial diamonds, heat treatment meant that inferior quality stones could be made to flake more like the best quality stones, such as the desirable and widely traded obsidian.

They say heat treatment can also impart a desirable vitreous lustre to stone, cause colour changes, generally toward more reddish hues, and was sometimes deliberately used to enhance the beauty of objects.

For example, Indian bead makers have used thermal treatment for at least 4,500 years to improve the colour of agate beads. Heat treatment was also used by stone-age Indian cultures in North America to produce their small and distinctive grooved spear blades.

Dr Webb and Mr Domanski say they don't know how far back the use of the technique goes in Australia. However, the team that wrote the Science paper on Africa proposes to investigate the origins of heat technology throughout the world, including Australia, with the aid of a US National Science Foundation grant.

'We have been invited to be part of the expanded team for that project.'


Editor's Note: Original news release can be found here.