Any change in the energetic cost of mammalian mastication will affect the net energy gain from foods. Although the energetic efficiency of masticatory effort is fundamental in understanding the evolution of the human masticatory system, nothing is known currently about the associated metabolic costs of chewing different items. Here, using respirometry and electromyography of the masseter muscle, we demonstrate that chewing by human subjects represents a measurable energy sink. Chewing a tasteless odorless gum elevates metabolic rate by 10 to 15% above basal levels. Energy expenditure increases with gum stiffness and is paid for by greater muscle recruitment. For modern humans, it is likely that mastication represents a small part of the daily energy budget. However, for our ancestors, before the onset of cooking and sophisticated food processing methods, the costs must have been relatively high, adding a previously unexplored energetic dimension to the interpretation of hominin dentofacial fossils.

中文翻译：

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咀嚼的代价：人类咀嚼的能量学和进化意义

哺乳动物咀嚼能量成本的任何变化都会影响食物的净能量增益。尽管咀嚼努力的能量效率是理解人类咀嚼系统进化的基础，但目前对咀嚼不同物品的相关代谢成本一无所知。在这里，我们使用咬肌的呼吸测量和肌电图，证明人类受试者的咀嚼代表了可测量的能量汇。咀嚼无味无味口香糖可将基础代谢率提高 10% 至 15%。能量消耗随着牙龈僵硬而增加，并通过更多的肌肉募集来支付。对于现代人来说，咀嚼很可能只占日常能量预算的一小部分。然而，对于我们的祖先来说，