Bison death assemblages and the interpretation of human hunting behaviour

Bison kill sites on the North American Plains are well-studied archaeological examples of human communal hunting and mass killing of large ungulates. Assemblages of bison bones from these sites are dominated by the remains of prime adults, and younger animals are not as well represented as expected. We propose that predation by large carnivores preferentially removed calves and yearlings from some herds prior to the preferred seasons for communal hunts in the fall and winter, and that human hunters may have targeted herds depleted in this way. Some general models of human predation suggest that prime-dominated assemblages of large mammals are a unique human signature, caused by the ability of humans to target prime-aged prey, and thus exploit a niche that was under-used by non-human carnivores. Because mass kills of bison are also dominated by prime-aged animals, we propose that a prime-dominated mortality pattern need not be the result of targeted predation, and could equally well reflect the emergence of complex human behaviours required to conduct a mass kill.