Meeting Abstract
The cooking of food is hypothesized to have played a significant role in human evolution by providing an increase in net energy gain from each meal. Cooking softens food thereby reducing the time and energy devoted to chewing and digestion. Hence, more food can be consumed at a lower cost, and more energy can thus be allocated to growth and reproduction. We tested this hypothesis by comparing the efforts of chewing and the energy expended on the digestion of raw versus cooked sweet potato and carrot for juvenile and adult bearded dragons (Pogona vitticeps). For juvenile and adult lizards, pieces of raw sweet potato and carrot required 2.4 and 3.5 times more chews, respectively, than cooked pieces. We used closed-system respirometry to compare peak postprandial metabolic responses and to quantify specific dynamic action (SDA) of raw and cooked meals equaling 5% of lizard body mass. Juveniles responded with a 25% greater metabolic peak digesting the raw meals, whereas adults experienced a 12% greater metabolic peak. The SDA generated from the cooked meals were significantly less than those from the raw meals. On average, lizards expended 35% less energy digesting and assimilating the cooked sweet potato and carrot meals compared to the raw meals. These results demonstrate the energetic benefits of consuming cooked versus raw foods and support the hypothesis that the advent of cooking had a significant impact in human evolution.
