Biface

In archaeology, a biface is a two-sided stone tool and is used as a multi purposes knife, manufactured through a process of lithic reduction, that displays flake scars on both sides. A profile view of the final product tends to exhibit a lenticular shape (i.e., as a convex lens). Bifacial artifacts can be made on large flakes or blocks, and may be grouped into numerous distinct classes.

Terminology

For the purposes of this article, four classes are defined :

Class I consists of large, thick bifaces reduced from cores or thick flakes; these are referred to as blanks.
Class II consists of thinned blanks. While form remains rough and uncertain, an effort has been made to reduce the thickness of the flake or core.
Class III bifaces may be either preforms or crude formalized tools, such as adzes.
Class IV includes the finer formalized tool types such as projectile points and fine bifaces.

While Class IV bifaces are referred to as "formalized tools", bifaces from any stage of a lithic reduction sequence may be used as tools. (Also, other biface typologies make five divisions rather than four).

History

Examples of bifaces first appeared 1.6mya in the later Oldowan (Mode I), called the "developed Oldowan" by Mary Leakey,^[1] but became more abundant in mode II Acheulean industries that appear in what is now Southern Ethiopia around 1.4 million years ago,^[2] although some of the best examples come from 1.2 million year old deposits in Olduvai Gorge.^[3] They are also known in Mousterian industries. In North America, bifaces make up one of the dominant tool industries, starting from the terminal Pleistocene and continuing throughout the Holocene. For example, the Folsom point and Clovis point traditions (collectively known as the fluted points) are associated with Paleo Indians, some of the first people to colonize the new world (see Models of migration to the New World). Further, biface technology is almost unknown in Australian prehistory.

Oldowan bifaces appeared sometime between 1.6 and 1.4 million years ago. They are most closely associated with Homo ergaster. The average biface from H. ergaster was 15 cm (6 in), but some were as long as 30 cm (12 in). Unlike earlier stone tool technology, bifaces have three distinctive shapes; hand axes, cleavers, and picks. Hand axes were shaped like a tear drop, with two cutting edges and a sharp point. Cleavers were like hand axes, but with the point broken off and replaced with a cutting edge. Picks were thicker, more triangular bifaces. These three shapes are very uniform. For example, the ratio of the length and width of hand axes is fairly consistent across hand axes from this period. These bifaced tools were possibly used in five ways by H. ergaster.

1. Butchering hunted or scavenged animals
2. Digging for tubers, animals, water
3. Removing tree bark
4. Throwing at prey
5. Source for flake tools

References

Boyd, Robert (2008). How Humans Evolved. New York: W. W. Norton & Company. ISBN 9780393932713.

^ Leakey, M. D. 1972. Olduvai Gorge. Vol 3. Cambridge: Cambridge University Press
^ Asfaw, B., Beyene, Y., Suwa, G., Walter, R. C., White, T. D., et al. 1992. The Earliest Acheulian from Konso-Gardula. Nature, Vol 360. Pp. 732-5
^ Lewin, R., Foley, R. A. 2004. Principles of Human Evolution (2nd Ed.) Blackwell Science, UK. ISBN 0-632-04704-6