theme for a fantasy campaign

[Anthony]

Originally Posted by whswhs

Yes, it does. But within a humanoid size range, the error in using ST^2 is small enough to be disregarded, I think.

Working (as opposed to resting) metabolic rate is heavily influenced by the actual amount of work done, which means that the metabolic multiplier for a given critter is rather similar to the productivity multiplier for the critter. Due to the metabolic costs of sapience the work/metabolism ratio for intelligent creatures probably favors larger lifeforms, but it may not vary by a lot.

Significantly more important here is the cost of food. A meat-eater can generally maintain a higher metabolism (and work rate) than a plant-eater, and a plant-eater eating high value foods such as seeds does better than one eating low value foods such as grasses, but that tends to be compensated for by the much higher availability of the less concentrated foods. The big advantage of grains is that grasses produce large amounts of concentrated food (seeds) relative to their overall production. This makes desert and tundra even lower value than their gross primary production implies, as concentrated food sources are generally meats, and also produces problems for forests, which put a great deal of energy into production of relatively indigestible twigs and leaves.