The effects of carnivore diversity on scavenging opportunities and hominin range expansion during Out of Africa I

Abstract

Numerous extrinsic hypotheses explaining Out of Africa I (OoA I), like faunal turnover and hominins following fauna, have been rejected based on paleoecological models. Others have explored the importance of the hominin intrusion into the carnivore guild. Here, I build on this latter research by proposing the complementary carnivore guild flexibility hypothesis (CGFH). In eastern Africa, carnivore richness peaked around 3 Ma and declined gradually until shortly after 2 Ma. This timeline coincides with the development of early lithic technologies and initial evidence of the butchery of large mammals, thus implying that increased hominin carnivory impacted endemic carnivore diversity through the transition from passive to confrontational scavenging. The CGFH posits that the relatively stable carnivore diversity and richness in Eurasia permitted hominin range expansion into Eurasian habitats after 2 Ma due to scavenging opportunities along continuously overlapping carnivore ranges. This study tests the CGFH by examining carnivore richness at African and Eurasian sites covering intervals before, during, and after the initial OoA I dispersals. This study builds on previous hypotheses about the role of carnivore guilds in hominin dispersals while tying in theoretical models on modes of early hominin carnivory and actualistic research on scavenging opportunities resulting from carnivore guild composition. In support of the CGFH, carnivore richness in Eurasia is higher than in Africa, which likely facilitated range expansion by hominins during OoA I. Furthermore, decreases in carnivore richness are evident in Eurasia at the end of the Early Pleistocene, which happen within a few hundred thousand years of sustained hominin presence in certain regions, like southwestern Europe and eastern Asia.