W. Andrew Barr, Briana Pobiner, John Rowan, Andrew Du, and J. Tyler Faith

PNAS February 1, 2022 119 (5) e2115540119

Significance

Many quintessential human traits (e.g., larger brains) first appear in Homo erectus. The evolution of these traits is commonly linked to a major dietary shift involving increased consumption of animal tissues. Early archaeological sites preserving evidence of carnivory predate the appearance of H. erectus, but larger, well-preserved sites only appear after the arrival of H. erectus. This qualitative pattern is a key tenet of the “meat made us human” viewpoint, but data from sites across eastern Africa have not been quantitatively synthesized to test this hypothesis. Our analysis shows no sustained increase in the relative amount of evidence for carnivory after the appearance of H. erectus, calling into question the primacy of carnivory in shaping its evolutionary history.

Abstract

The appearance of Homo erectus shortly after 2.0 Ma is widely considered a turning point in human dietary evolution, with increased consumption of animal tissues driving the evolution of larger brain and body size and a reorganization of the gut. An increase in the size and number of zooarchaeological assemblages after the appearance of H. erectus is often offered as a central piece of archaeological evidence for increased carnivory in this species, but this characterization has yet to be subject to detailed scrutiny. Any widespread dietary shift leading to the acquisition of key traits in H. erectus should be persistent in the zooarchaeological record through time and can only be convincingly demonstrated by a broad-scale analysis that transcends individual sites or localities. Here, we present a quantitative synthesis of the zooarchaeological record of eastern Africa from 2.6 to 1.2 Ma. We show that several proxies for the prevalence of hominin carnivory are all strongly related to how well the fossil record has been sampled, which constrains the zooarchaeological visibility of hominin carnivory. When correcting for sampling effort, there is no sustained increase in the amount of evidence for hominin carnivory between 2.6 and 1.2 Ma. Our observations undercut evolutionary narratives linking anatomical and behavioral traits to increased meat consumption in H. erectus, suggesting that other factors are likely responsible for the appearance of its human-like traits.

See https://www.pnas.org/content/119/5/e2115540119

Fig. 1.

Spatiotemporal distribution of zooarchaeological evidence synthesized in this study. (A) Regional map showing spatial distribution of major research areas. (B) Temporal distribution of zooarchaeological levels plotted according to their date on the vertical axis. Labels are color coded by major study area. The size of each circle is drawn proportional to the square root of the number of modified bones reported from the corresponding zooarchaeological assemblage. The position of each level on the horizontal axis is randomly jittered to improve legibility. (C) Schematic illustration of the temporal ranges of selected hominin species in eastern Africa over the temporal duration of this study.