Using obsidian transfer distances to explore social network maintenance in late Pleistocene hunter–gatherers

Abstract

Social behaviour is notoriously difficult to study archaeologically and it is unclear how large the networks of prehistoric humans were, or how they remained connected. Maintaining social cohesion was crucial for early humans because social networks facilitate cooperation and are imperative for survival and reproduction. Recent hunter-gatherer social organisation typically comprises a number of nested layers, ranging from the nuclear family through to the ~1500-strong ethnolinguistic tribe. Here we compare maximum obsidian transfer distances from the late Pleistocene with ethnographic data on the size of the geographic areas associated with each of these social grouping layers in recent hunter-gatherers. The closest match between the two is taken to indicate the maximum social layer within which contact could be sustained by Pleistocene hominins. Within both the (sub)tropical African and Subarctic biomes, the maximum obsidian transfer distances for Pleistocene modern humans (~200km and ~400km respectively) correspond to the geographic ranges of the outermost tribal layer in recent hunter-gatherers. This suggests that modern humans could potentially sustain the cohesion of their entire tribe at all latitudes, even though networks are more dispersed nearer the poles. Neanderthal obsidian transfer distances (300km) indicate that although Neanderthal home ranges are larger than those of low latitude hominins, Neanderthals travelled shorter distances than modern humans living at the same high latitudes. We argue that, like modern humans, Neanderthals could have maintained tribal cohesion, but that their tribes were substantially smaller than those of contemporary modern humans living in similar environments. The greater time taken to traverse the larger modern human tribal ranges may have limited the frequency of their face-to-face interactions and thus necessitated additional mechanisms to ensure network connectivity, such as the exchange of symbolic artefacts including ornaments and figurines. Such cultural supports may not have been required to the same extent by the Neanderthals due to their smaller tribes and home ranges.

Neutron activation analysis of 12,900-year-old stone artifacts confirms 450–510+ km Clovis tool-stone acquisition at Paleo Crossing (33ME274), northeast Ohio, U.S.A.

“…Given that the majority chert toolstone from only one Clovis site in western North AmericadEckles, Kansas (Hoard et al, 1992(Hoard et al, , 1993Holen 2010)dhas been geochemically verified to demonstrate longdistance stone acquisition, our results from eastern North America more broadly support the long-held but poorly corroborated assumption that Clovis foragers regularly depended on "exotic" stone for tool production. Furthermore, long-distance stone acquisition, either through direct or indirect acquisition of the stone, is also widely acknowledged to be evidence of geographically widespread social contact and territorial permeability (Bamforth, 2009;Ellis, 2011;Goodyear, 1989;Pearce, 2014;Pearce and Moutsiou, 2014;Sholts et al, 2012;Speth et al, 2013). Paleo Crossing thus provides strong inferential material evidence that the fast expansion of the Clovis culture, as already documented by chronometric evidence (Prasciunas and Surovell, in press;Waters and Stafford, 2007), occurred as a result of a geographically widespread hunteregatherer social network.…”

“…Given the low density of Clovis sites across North America, and thus presumably low population densities, empirical validation of long-distance acquisition of stone provides a unique opportunity for inferring geographically widespread social contact and territorial permeability among mobile hunteregatherer populations (Bamforth, 2009;Burke, 2006;Ellis, 1989;Kelly and Todd, 1988;Pearce, 2014;Pearce and Moutsiou, 2014;Speth et al, 2013). For example, in terms of tool flaking patterns, there appears to have been a continent-wide standardization of Clovis technology, perhaps reflecting Clovis knappers sharing their technical knowledge through direct transmission (Sholts et al, 2012).…”

The Middle/Later Stone Age transition and cultural dynamics of late Pleistocene East Africa

“…The strongest archeological data set available for this is the distribution of obsidian artifacts that can be tied to a known geological origin, which serves to outline the social limits of past populations who used this common source . Obsidian is volcanic glass.…”

Going the distance: Mapping mobility in the Kalahari Desert during the Middle Stone Age through multi-site geochemical provenancing of silcrete artefacts

“…The considerable distances over which silcrete was transported, as indicated by our geochemical provenancing results, could suggest the presence of widespread social contacts and an expansive range in the Kalahari during the MSA (also see Goodyear, 1979;Ambrose and Lorenz, 1990;McBrearty and Brooks, 2000;Bamforth, 2009;Ellis, 2011;Sholts et al, 2012;Speth et al, 2013;Pearce and Moutsiou, 2014;Pearce, 2014;Boulanger et al, 2015). Clearly, with what was undoubtedly a low population density, the limits or boundaries of these ranges or potential territories would have been open and permeable.…”