Underlying the process is muscle movement throughout the system through swallowing and peristalsis. Each step in digestion requires energy, and thus imposes an "overhead charge" on the energy made available from absorbed substances. Differences in that overhead cost are important influences on lifestyle, behavior, and even physical structures. Examples may be seen in humans, who differ considerably from other hominids (lack of hair, smaller jaws and musculature, different dentition, length of intestines, cooking, etc.). COUNT 4
QSN1 What muscle movements are used for digestion? ANS1 swallowing and peristalsis QSN2 What does every stpe of digestion require? ANS2 energy QSN3 What does needing energy to digest impose? ANS3 an "overhead charge" QSN4 Over head charges influence what? ANS4 lifestyle, behavior, and even physical structures