fundamental ratios

1. There are no big cells.
2. There are no small animals in the polar regions.
3. Red wines are kept in small barrels for aging.
4. Grain dust is explosive but grain is not.
5. Larger ships are more efficient.

All of these seemingly unrelated phenomena stem from one single principle: As a three dimensional object gets uniformly larger, its volume grows faster than its surface area.

Going back to the listed phenomena:

1. After a certain size threshold, diffusion of molecules across the membrane can no longer handle the amount of traffic needed to sustain the cell metabolism.
2. Small animals have more trouble maintaining their body temperature.
3. Smaller barrels provide greater contact with the wood, allowing the wine to pick up the tannins faster.
4. Grain dust is smaller, and therefore has relatively more surface area that is available for chemical reactions.
5. Most of the steel used in the construction of a bulk carrier goes towards building the hull.