Hominin diet shifted to C_4 plants more than 3 million years ago

摘要

According to one widely i held model, hominins acquired powerful grinding teeth to better process hard foods like nuts and seeds. Recent carbon isotope analyses of fossil tooth enamel, however, have shown that certain early human ancestors such as Paranthropus boi-sei consumed abundant quantities of C_4 plants. Julia Lee-Thorp et al. (pp. 20369-20372) analyzed carbon isotope ratios in the teeth of Australopithecus bahrelghazali from the Koro Toro fossil site in Chad, and found a significant enrichment in ~(13)C, suggesting that these individuals consumed a diet rich in foods derived from C_4 resources. The authors propose that based on the site characteristics of Koro Toro the most abundant source of C_4 biomass would likely have been seasonally available grasses and sedges, neither of which is usually considered standard great ape fare.