Results/Conclusions Significant shifts in Paleolithic human trophic characteristics occurred after 50,000 years ago, mostly from narrow to broader diets. Most of the changes in prey choice concern the use of supplementary animal resources, with more even emphasis on slow (high-yield) and quick (lower yield) small game animals in forager diets. Biomass-corrected data on prey choice also indicate increasing use of those species with higher reproductive efficiencies. The development of intensified techniques for extracting fat and bone grease from large game animals parallels the expansion of dietary breadth in some Mediterranean areas. The changes in human predator-prey relationships can be linked to increases in human population densities. Step-wise, apparently irreversible shifts began with the earliest Upper Paleolithic (ca. 50 kya) in the eastern end of the Mediterranean basin and spread northward and westward. Evidence of demographic pressure and greater use of resilient prey populations is followed by technological innovations to exploit these animals more efficiently. The zooarchaeological findings suggest that earlier (Middle and Lower Paleolithic) reproductive units were not robust at the micropopulation scale, due to the rather narrow set of behavioral responses that characterized social groups at the time. Localized extinctions at the micropopulation level were likely to have been common under these demographic conditions. Upper Paleolithic archaeological “cultures” have shorter histories of existence than those of earlier periods, but they were more widespread geographically. The demographic robustness of the Upper Paleolithic systems may stem from wholesale strategies for evening-out or sharing risk and volatility in technology. Micropopulations were larger and often denser on landscapes, more ultimately connected via cooperative ties, and thus more robust.