The broad spectrum revisited: evidence from plant remains

Abstract

The beginning of agriculture is one of the most important developments in human history, with enormous consequences that paved the way for settled life and complex society. Much of the research on the origins of agriculture over the last 40 years has been guided by Flannery's [Flannery, K. V. (1969) in The Domestication and Exploitation of Plants and Animals, eds. Ucko, P. J. & Dimbleby, G. W. (Duckworth, London), pp. 73-100] "broad spectrum revolution" (BSR) hypothesis, which posits that the transition to farming in southwest Asia entailed a period during which foragers broadened their resource base to encompass a wide array of foods that were previously ignored in an attempt to overcome food shortages. Although these resources undoubtedly included plants, nearly all BSR hypothesis-inspired research has focused on animals because of a dearth of Upper Paleolithic archaeobotanical assemblages. Now, however, a collection of >90,000 plant remains, recently recovered from the Stone Age site Ohalo II (23,000 B.P.), Israel, offers insights into the plant foods of the late Upper Paleolithic. The staple foods of this assemblage were wild grasses, pushing back the dietary shift to grains some 10,000 years earlier than previously recognized. Besides the cereals (wild wheat and barley), small-grained grasses made up a large component of the assemblage, indicating that the BSR in the Levant was even broader than originally conceived, encompassing what would have been low-ranked plant foods. Over the next 15,000 years small-grained grasses were gradually replaced by the cereals and ultimately disappeared from the Levantine diet.

Fig. 1.

Grain sizes of SGG occurring at Ohalo II and in contemporary agriculture; the Ohalo II species are indicated with ¶. The species are arranged in order of increasing grain volume (calculated using refs. –50). Length, breadth, and thickness are mean measurements in mm; volume is in mm³. Volume was calculated by multiplying length, breadth, and width. The cereals (wild emmer wheat and wild barley) included for comparison, highlight how large these grains are compared with the SGG.

Fig. 2.

Averages, per period, of the percentage of SGG relative to the total grasses at each site. Dates are median dates for each period [A, UP; B, Natufian; C, Prepottery Neolithic A (PPNA); D, Early PPNB; E, Middle PPNB; F, Late PPNB]. The graph shows a decline in SGG from the UP to the Early PPNA and their negligible significance thereafter.