The buildup of cellular detritus isn’t merely wasteful but harmful, too. Out with the old and in with the new doesn’t just restock the pantry; it also clears away decay. Our ancient ancestors often ate only once a day or went for several days without any food, so our autophagy switches were constantly getting tripped.237 Today, in our three-meals-a-day world, our cells no longer need to look under the couch cushions for sustenance, and the trash heaps just pile higher.
