It does make sense when you consider where the energy all comes from: the sun. Plants absorb solar energy and store it as chemical energy. Animals roam far and

It does make sense when you consider where the energy all comes from: the sun. Plants absorb solar energy and store it as chemical energy. Animals roam far and wide to eat those plants, collecting the chemical energy in one place- themselves. Then human hunters come along and simply 'pick' the energy from the dense source that is the animal. Now, the humans don't need to do much work because the energy is all in one place (they just need to find that one place). But the energy itself was collected over a huge area.