Selective Transport of Animal Parts by Ancient Hunters: A New Statistical Method and an Application to the Emeryville Shellmound Fauna

When deciding which parts of a prey animal to transport home, hunters may be more or less selective. In our vocabulary, unselective hunters are those who usually bring home most of the carcass; selective hunters are those who usually abandon all but the choicest (and/or lightest) parts. This paper uses the abcml statistical method to develop a means of estimating transport selectivity from the frequencies of skeletal parts in a faunal assemblage. It then applies the method to artiodactyl data from the Emeryville Shellmound in order to test the local depression and distant patch use hypothesis. This hypothesis predicts that selectivity should decline during the early part of the Emeryville sequence and rise during the later part. The initial analysis did reveal such a pattern, but this pattern disappeared when samples were pooled in order to produce acceptably narrow confidence intervals. Although this result weakens the hypothesis, it does not firmly refute it, because the model fits the data imperfectly in the critical middle portion of the sequence. Abcml also provides estimates of the intensity of attrition, which indicate that attrition was most severe in early strata and least severe in later ones. Substantial attrition (50% of bones surviving) is indicated even from samples that show no indication of attrition using conventional methods. These conclusions are based on assumptions about the processes of transport and attrition that are more reliable in qualitative outline than in quantitative detail. Consequently, the paper's qualitative conclusions are more trustworthy than its quantitative estimates.