Shellfishing and human evolution

Abstract

Southern and northwestern Africa have provided the oldest known shell middens, dating from the Last Interglacial (MIS 5, ~128-71 ka) and the early part of the succeeding glaciation (MIS 4, ~71-59 ka). However, when and if older, suitably situated, stratified coastal sites are found, they are likely to show that routine shellfishing began much earlier, perhaps from the time that people first occupied coasts. Ethnohistoric records suggest that ancient people would have shellfished mainly during twice-monthly periods when the intertidal zone is maximally exposed. Caloric and nutrient return for coastal shellfishing effort can be quite high, but only when the intertidal is exposed, and archaeology implies that like ethnohistorically observed groups, ancient shellfish collectors depended more on terrestrial and marine vertebrates and on plants. Shellfishing can generate highly visible and durable archaeological signatures, and only a few collecting episodes each year could have produced the oldest middens, which span many millennia. Shell middens are so far unknown in European Neanderthal (Mousterian) and succeeding Upper Paleolithic sites, probably because suitably situated sites have yet to be found. Consistently large gastropod size in the oldest known middens suggests that human population growth cannot explain either the occasional presence of "symbolic" artifacts or the innovative burst that coincides with the spread of fully modern Africans to Eurasia 60-50 ka.

Neandertals on the beach: Use of marine resources at Grotta dei Moscerini (Latium, Italy)

“…It lacks significant upwelling by which wind-displaced surface waters are replaced by cold, nutrient-rich water; the intertidal areas on the coasts of South Africa supported a good number of large mollusks (limpets, mussels) and during spring low tides their maximal exposure allowed intensive shell fishing collection. But tidal oscillations in the Mediterranean are generally of the order of few cm while on the south coast of South Africa the difference between low tide and high tide is about 1 m. [26,49].…”

Shellfish exploitation during the Oakhurst at Klipdrift Cave, southern Cape, South Africa

“…It has been argued that the sizes of gastropods, and variation in shellfish species, from archaeological sites may provide an estimate of the extent and intensity of harvesting of these animals as food, which in turn can be used as a reflection of human population size. 4,25,26 The reduced size of gastropods in LSA sites relative to those from MSA localities in southern Africa has been used to imply intensified collection due to higher human population size during the LSA. 4,25,27 In addition, MSA assemblages tend to contain a smaller range of mostly larger species, and the few smaller species tend to occur in low numbers relative to LSA assemblages.…”

“…4,25,27 In addition, MSA assemblages tend to contain a smaller range of mostly larger species, and the few smaller species tend to occur in low numbers relative to LSA assemblages. 26 As such, gastropod size and species abundance have been used to argue for smaller human population sizes during the MSA. 4,25,27 Another argument is that the reduced gastropod size could be due to environmental factors affecting shell growth rates, particularly as non-food species are also reduced in size in the LSA compared to MSA.…”

From coral reefs to whale teeth: estimating mortality from natural accumulations of skeletal materials

“…As with the shells of live collected bivalves, sclerochronological techniques such as direct ageing of shells can also be employed on midden samples to extract a wealth of information regarding historical ecological and environmental conditions (see Andrus 2011 for review). A combination of these techniques could make middens a power ful tool in calculating historical fishery related mortality, which can also give important insight into the changes in foraging habits over the timeframe of human evolution (Klein & Bird 2016). …”