Emerging economies: late Neolithic and Copper Age beads and pendants of the Portuguese Estremadura

This is an anthropological inquiry into how humans use beads and other personal ornaments, and what this can tell us about production, labor organization, regional traditions, and cultural exchange. Specifically, it examines the manufacture and provenience of 8,000 Late Neolithic and Copper Age (3500-2500 BC) beads from a group of closely related collective burials in the Sizandro River Valley of southwestern Portugal. Because these burials lie within five kilometers of each other and have access to similar geological landscapes, patterns of raw material consumption would be expected to be comparable. This period witnessed the rise of socially-complex, non-state societies, but there is still debate about how socially differentiated people were. One way archaeologists can shed light on this type of prehistoric social complexity is to examine how and why people produce things in the way that they do--how they work.

Beads in museum collections were measured and coded for shape, usewear, composition, and other traits. Analyses were conducted using microscopy, spectroscopy, petrography, and isotopic chemistry. The goal was to determine the extent of intra-site versus inter-site variation in the Sizandro, and to compare these results to other sites in the Estremadura in order to better understand craft production and interregional exchange in the context of the demographic transition to agriculture.

A number of striking patterns were found. The vast majority of beads (~90%) show a high degree of standardization and are made of abundant, locally-available materials. Discoid calcite beads in particular have low standard deviations in diameter and thickness, highly indicative of batch production. Because of their transportability, beads (perhaps sewn into garments) likely served not only a decorative but a semi-monetized function. This pattern is similar to the use of `wampum' beads as commodity money among chiefdom-scale groups in parts of pre-contact North America, and has numerous cross-cultural ethnographic parallels. Approximately 10% of the beads were much less standardized and made from a diverse range of non-local raw materials obtained via direct or down-the-line exchange from other groups in the Iberian Peninsula. The emphasis on rarified materials is similar to elsewhere in the Western Mediterranean, suggesting that the Estremadura participated in a wider system of shared symbolic values.