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'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle

Ennos, Antony Roland; Chan, Tak Lok

Authors

Antony Roland Ennos

Tak Lok Chan



Abstract

It is usually assumed that 'fire hardening' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-hardening process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-hardened tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-hardening would have been a mostly negative side effect, not its primary purpose.

Journal Article Type Article
Publication Date May 18, 2016
Journal Biology letters
Print ISSN 1744-9561
Electronic ISSN 1744-957X
Publisher Royal Society, The
Peer Reviewed Peer Reviewed
Volume 12
Issue 5
Article Number 20160174
APA6 Citation Ennos, A. R., & Chan, T. L. (2016). 'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle. Biology Letters, 12(5), https://doi.org/10.1098/rsbl.2016.0174
DOI https://doi.org/10.1098/rsbl.2016.0174
Keywords Wood; Spears; Fire hardening; Hardness; Mechanical properties
Publisher URL http://rsbl.royalsocietypublishing.org/content/12/5/20160174
Copyright Statement © 2016 The Author(s)
Published by the Royal Society. All rights reserved.
Additional Information Authors' accepted manuscript of article published in: Biology letters, 2016, v.12, issue 5, article no.20160174

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Copyright Statement
© 2016 The Author(s)
Published by the Royal Society. All rights reserved.





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