Since industrialization, maintaining such a slow cultural metabolism has been much harder, with the long midday meal shrinking to whatever could be stuffed into a lunch bucket or bought at a food stand.

since industrialization, maintaining such a slow cultural metabolism has been much harder, with the long midday meal shrinking to whatever could be stuffed into a lunch bucket or bought at a food stand.

For instance, there's a high energy cost in switching from a regular metabolism to an almost-no-water metabolism.

The big difference between "drought-tolerant" plants and these tough plants: metabolism.

They lack water-storing structures, and their existence on rock faces prevents them from tapping groundwater, so they have instead developed the ability to change their metabolism.

Yet once they start growing, such plants seem not to retain the ability to hit the pause button on metabolism in their stems or leaves.