Marine abundance and its prehistoric past in the Baltic

In a recent article, Lewis et al.1 advance the hypothesis that an increase in the marine fertility of Danish waters from ca. 7600 cal BP onwards fuelled an intensification in the marine economy and a fourfold population increase in the later Mesolithic period. This hypothesis is severely compromised by: (a) reliance on archaeological data from shell middens without reference to the multiple biases that operate differentially to distort quantitative inferences from such deposits, (b) selective use of stable isotope data obtained from human bone collagen and dates concerning marine technology, and (c) the assumption that human economic choices closely or necessarily track environmental change.

We conclude that these biases cast doubt on the case for Late Mesolithic intensification and population increase, and that investigation of the undoubtedly complex interactions between environmental change and human response requires wider multi-disciplinary collaboration, better integration and understanding of palaeoecological, archaeological, geoscientific and biomolecular datasets, better recognition of their limitations, greater attention to the differential taphonomic histories of archaeological sites and materials, and better articulation and evaluation of alternative hypotheses.