Opportunistic versus target mode: Prey choice changes in central-western Korean prehistory

Human decision-making processes are usually hierarchical in that higher-level decisions impose constraints on lower-level decisions. As a result, prey choices during individual foraging trips are governed to a large degree by higher-level decisions regarding how to supply resources to satisfy demands, with higher-level decisions typically made prior to foraging trips. Resource selectivity and search bias sometimes take place in this context. By dividing resource procurement modes into opportunistic and target, I discuss how choice of mode on the basis of an overall economic plan affects prey choice during foraging trips and faunal assemblage composition resulting from those trips. An analysis of taxonomic diversity in shellmidden assemblages from the central-western Korean Late Chulmun Period (3500–1300 BC) and Middle and Late Mumun Period (700–100 BC) shows that Late Chulmun people adopted a target mode, while Middle/Late Mumun people adopted an opportunistic mode in their exploitation of marine resources. A decrease in the importance of marine resource in Middle/Late Mumun produced a change in taxonomic diversity by increasing the opportunistic cost of marine resource exploitation.     

Stable isotope evidence of human diet at the Nukdo shell midden site,South Korea

Carbon and nitrogen stable isotope analysis was undertaken on bone collagen extracted from archaeological human (n = 48) and animal (n = 45) skeletons from the Nukdo site, Location I C, South Korea. This shell midden and grave site is dated from the late Mumun (550–300 BC) to early Iron Age (300 BC-1 AD) periods. The herbivorous mammals fell within the range of C₃ consumers, with average values of δ¹³C = −21.0 ± 0.5‰ and δ¹⁵N = 3.6 ± 0.5‰ for deer (n = 16) and δ¹³C = −20.6 ± 0.5‰ and δ¹⁵N = 4.5 ± 2.0‰ for wild boar (n = 17). Humans from this site averaged δ¹³C = −18.3 ± 0.4‰ and δ¹⁵N = 11.2 ± 0.7‰ for adults (n = 15) and δ¹³C = −18.7 ± 0.7‰ and δ¹⁵N = 12.5 ± 1.1‰ for juveniles (n = 33). These δ¹³C values indicate that there was no significant input of C₄ plants in the human diets and this may be associated with the spread of rice agriculture in the Mumun period. Human bone collagen δ¹³C and δ¹⁵N values indicate that there was some consumption of marine foods, although the main protein sources were from terrestrial foods. The isotope data demonstrate that the humans at Nukdo had mixed diets that included marine and terrestrial protein, including C₃ plants such as rice. Finally, the isotope results from the juveniles indicate that weaning occurred before the age of 1.5 years in this period.