CoachHuman teeth come in three kinds, each with its job:
- the incisors, flat and sharp at the front, cut — they slice into the apple;
- the canines, pointed, at the corners, tear — they grip and pull tougher food;
- the molars, broad and bumpy at the back, grind — they crush food into a paste ready to swallow.
示例
Example 12.2 (One bite of apple, three tools)
Eating a piece of apple uses the whole toolbox in order: the incisors slice off the bite, the canines help pull it free, and the tongue passes it back to the molars, which grind it up. Only then do you swallow.
Example 12.5 (The wobbly incisor)
A front tooth starts to wobble at the very age children start school. Under it, an adult incisor has been quietly growing and dissolving the baby tooth’s root, until the little tooth lets go. The gap is not an accident — it is a changeover.