The evolution of large human brain size has had important implications for the nutritional biology of our species. Large brains are energetically expensive, and humans expend a larger proportion of their energy budget on brain metabolism than other primates. The high costs of large human brains are supported, in part, by our energy- and nutrient-rich diets. Among primates, relative brain size is positively correlated with dietary quality, and humans fall at the positive end of this relationship. Consistent with an adaptation to a high-quality diet, humans have relatively small gastrointestinal tracts. In addition, humans are relatively "undermuscled" and "over fat" compared with other primates, features that help to offset the high energy demands of our brains. Paleontological evidence indicates that rapid brain evolution occurred with the emergence of Homo erectus 1.8 million years ago and was associated with important changes in diet, body size, and foraging behavior.

中文翻译：

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大脑进化对人类营养和代谢的影响。

人类大脑大的进化对我们物种的营养生物学具有重要意义。大型大脑的能量消耗很高，与其他灵长类动物相比，人类在脑代谢上花费的能量预算比例更大。人类大脑的高昂代价部分地由我们能量和营养丰富的饮食来支持。在灵长类动物中，相对大脑的大小与饮食质量呈正相关，而人类则处于这种关系的正向。与适应高质量饮食相一致，人类的胃肠道相对较小。此外，与其他灵长类动物相比，人类相对“肌肉发达”和“脂肪过多”，这些特征有助于抵消大脑的高能量需求。