Department of Human Evolutionary Biology, Harvard University
Friday 10:30-10:45, Ballroom B
Although meat has played an especially important role in hominin evolution, human molars are bunodont and thus thought to be poorly adapted to chewing raw meat. Here we explore the performance ability of humans chewing raw meat, and analyze the effects of mechanical and thermal food processing techniques on masticatory parameters. 10 male subjects chewed size-standardized samples of raw, sliced, tenderized, or roasted goat meat. Masticatory muscle EMGs were measured during the trials and then transformed into chewing forces using a force-EMG calibration trial. Subjects chewed until they would typically swallow, at which time the resulting bolus was collected. For each subject, we compared the number of chews, force used per chew, total masticatory force, and the degree of intraoral food breakdown per trial among the raw and processed samples (Wilcoxon signed-rank test, p≤0.05). The results indicate that raw meat does not fracture readily in the oral cavity. Slicing significantly decreased masticatory force (chew number 22% lower; force per chew 19% lower) and size of the largest particle in the chewed bolus was 48% smaller. Roasting to medium-well also improved comminution, reducing size of the largest comminuted particle by 25%. In contrast to the other processing methods, tenderizing did not affect food breakdown, and average force per chew actually increased 18%. These data illustrate the masticatory benefits of slicing and roasting meat prior to consumption, and suggest that food processing may have been necessary for hominins to efficiently masticate and consume large quantities of meat.
This study was funded by the National Science Foundation (DDIG # 0925688).