The grain in wild grasses develops near the top of the stem. As it matures, the stem slowly breaks up—shatters, in the jargon—letting the seed dribble to the ground. In wild wheat and barley, a common single-gene mutation blocks shattering. For the plant the change is highly disadvantageous, but it facilitates harvest by humans—the grain waits on the stem to be collected. The discovery and planting of nonshattering grain is thought to have been integral to the Neolithic revolution in the Middle East.
