Is it all about elephants? Explaining prey size decline in the Paleolithic Southern Levant

Recently we (Dembitzer et al., 2022) found that the weighted mean body mass of faunal assemblages steadily declined over the last 1.5 million years of the Paleolithic Southern Levant. We used a large dataset comprising 83 species from 133 stratigraphic layers from 58 archaeological sites. We showed that this pattern of body size decrease holds in dozens of statistical analyses of multiple datasets, with and without controlling for factors such as paleorainfall, vegetation, hominin species, temperature, type of site (open-air, cave, rock shelter, or terrace), sampling methods, dating methods, and variation within and between archaeological sites. All our analyses had high explanatory power and pointed to a steep decline through time. We found virtually no relationship to any climatic or environmental predictors or climate change. Our results are thus consistent with the effects of the novel agent in the region, i.e., humans. We suggested that hominins preferentially (though by no means exclusively) targeted the largest species present. Orbach et al. (2022) instead suggest that 1. changes in prey mass through time are better explained by cultural preferences. 2. that hominins preferred smaller, not larger prey and 3. the archaeological record does not represent the identities and abundances of species that were present in the environment at a given time. The empirical data they raise to support their claims are scant or irrelevant. Crucially, they fail to explain extinctions that occurred in the region or their sequence. They take issue with one aspect of our analyses (log transformation of time), and with our interpretation that humans caused the size decline by preferentially targeting large prey. Orbach et al. (2022) offer no new data or analyses to support their conclusions, nor do they account for any confounding variables. Their statistical reasoning is flawed, their specific comments, while sometimes valid, do not detract from the overall picture we present, and hence do not change our interpretation, and their conclusions fail to explain the extinction that occurred in the region. We contend that, with no new evidence coming to light, the arguments of Orbach et al. (2022) can at best illuminate some of the unexplained variance in our analyses.