Reply to “Marine abundance and its prehistoric past in the Baltic”

In response to the comment by Hausmann et al.¹ we highlight here that a number of the key criticisms of Lewis et al.² are either misinterpretations of our paper or are speculative, requiring rigorous testing via empirical data (and subsequently are topics for further research). We would, therefore, like to take the opportunity to clarify these points, so that others do not misinterpret our study² in the same way. Hausmann et al.¹ provide no physical evidence or data that rebuke our hypothesis, and therefore in the spirit of critical scientific discussion and endeavour, we challenge them (or others) to disprove our hypothesis through high-quality data, and hope that our original paper² and this further discussion stimulate such work. The criticisms expressed by Hausmann et al. largely focus on the use of a summed probability distribution 14C curve based on oysters as a proxy for shell midden abundance, yet this is only a supportive dataset within the broader theme of this study, and we certainly welcome future research into improving how we quantify shell midden abundance and marine resource intensification in past cultures and societies. However, we highlight that the criticisms of this 14C oyster-derived dataset by Hausmann et al.¹ does not detract from the key point of this study, that population increased during periods of increased marine productivity (demonstrated by sediment pigment and other proxy data) and hence increased marine resource availability, when humans predominately consumed a marine-based diet³. Below we respond to the specific points raised by Hausmann et al.¹.