Meeting Abstract

88.6  Wednesday, Jan. 7  Cooking and the net energy value of meat: implications for human evolution CARMODY, R.N.*; CONE, E.; WRANGHAM, R.W.; SECOR, S.M.; Harvard University; Harvard University; Harvard University; University of Alabama carmody@fas.harvard.edu

The emergence of Homo erectus ~1.9 MYA is characterized by energetically costly increases in body size and relative brain size, coupled with reductions in the gut and dentition. This suite of adaptations suggests that Homo erectus ate foods of higher energy density than did its australopithecine ancestors. Among anthropologists, the relative roles of increased meat-eating and the advent of cooking in supporting this energetic transition are debated. However the two are not mutually exclusive: if cooking improves the net energy value of meat, cooking may have played an important role regardless of the timing of its adoption or the extant degree of carnivory. Recent reviews of the diffuse literature suggest several positive effects of cooking, but no studies have addressed its net contributions experimentally in mammals. As a first test of the hypothesis that cooked meat provides more net energy than raw meat, we compared growth and caloric intake between two groups of weanling BALB/c mice (n = 24; 14.1 ± 1.2 g) that we reared for 40 days on diets comprised of ad libitum raw or cooked (microwaved) flank steak and a supplemental ration of chow equivalent to 30% of caloric requirements. Results appear to contradict our hypothesis. We observed no differences in the weight gain of cooked-fed mice (n = 12; 9.7 ± 1.0 g) compared to raw-fed mice (n = 12; 9.6 ± 1.2 g). Moreover, preliminary analysis of intake patterns suggests that more calories were consumed by cooked-fed mice (609.8 ± 34.3 kcal) than raw-fed mice (563.3 ± 34.8 kcal) to achieve a similar level of weight gain (p = 0.003). Freezing, desiccation and excessive lean protein consumption are evaluated as factors that limit the potential benefits of cooking, and their implications for the energetic significance of cooking in human evolution are considered.