The underlying reason why this transition was piecemeal is that food production systems evolved as a result of the accumulation of many separate decisions about allocating time and effort. Foraging humans, like foraging animals, have only finite time and energy, which they can spend in various ways. We can picture an incipient farmer waking up and asking: Shall I spend today hoeing my garden {predictably yielding a lot of vegetables several months from now}, gathering shellfish {predictably yielding a little meat today}, or hunting deer {yielding possibly a lot of meat today, but more likely nothing}? Human and animal foragers are constantly prioritizing and making effort-allocation decisions, even if only unconsciously. They concentrate first on favorite foods, or ones that yield the highest payoff. If these are unavailable, they shift to less and less preferred foods.
( Jared Diamond )
[ Guns, Germs, and Steel ]
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