Meeting Abstract

63.1  Wednesday, Jan. 6  Energetic significance of food processing: a test of the cooking hypothesis CARMODY, R.N.**; WEINTRAUB, G.S.; SECOR, S.M.; WRANGHAM, R.W.; Harvard University; Harvard University; University of Alabama; Harvard University carmody@fas.harvard.edu

Cooking has been hypothesized to support increased energy demands in human evolution, including growth in body size and relative brain size that occurred ~1.9 mya. Alternatively, non-thermal forms of food processing, such as pounding, could have supported the dramatic rise in energy requirements at this transition, with the effects of cooking limited to subsequent, more modest signals of dietary improvement. However the relative effects of cooking and non-thermal processing on the energy gained from key hominin foods like tubers are not known. In this study, we compared the relative effects of cooking and pounding on energy gain among mice fed jewel yams, a starch-rich tuber, using a balanced within-subjects study design. Adult male CD-1 mice (n = 17) were fed yams in four treatments: raw/whole, raw/pounded, cooked/whole, cooked/pounded. Each treatment was administered ad libitum for four days, followed by a washout period of six days during which time the mice received ad libitum chow. Repeated-measures ANOVA revealed that cooking, but not non-thermal processing, improved energy gain as indexed by change in body mass. Whereas mice lost weight on raw treatments (whole: -4.3 ± 0.4 g; pounded: -3.8 ± 0.6 g), they gained weight on cooked treatments (whole: 0.1 ± 0.4 g; pounded: 0.2 ± 0.3 g). Post-study preference tests further support the superior effects of cooking. Fasted mice presented with equal rations of all treatments concurrently and in random configuration preferred cooked treatments in 17 out of 17 cases as measured by first bite, and in 16 out of 17 cases as measured by total intake over a 3 h trial. Our results indicate that, in contrast to cooking, non-thermal processing would likely have provided little energetic benefit for ancestral hominins reliant on starch-rich plant foods.