Food production systems evolved as a result of the accumulation of many separate decisions about allocating time and effort

From Guns, Germs, and Steel: The Fates of Human Societies by Jared Diamond, page 107. Running through the book so far is a sub-theme which has not emerged as anything explicit - that some complex outcomes are not arrived at via intent but through the evolutionary pressures of individual tactical decisions in a complex environment yielding an aggregate outcome that was not anticipated, might not even have been conceivable, in advance. It is essentially the sociological/economic equivalent of the human eye which was long a bugbear for evolutionary theory - how do you explain the intermediate evolutionary steps that get you to the remarkable human eye when there is no apparent value to the eye except as a complete and finished feature? That was eventually explained but Diamond is dealing with similar issues regarding the transition from hunter gather economies to settled agriculture.

I must say that I think this idea of (r)evolutionary outcomes arising from the aggregation of innumerable tactical decisions dealing with pressing short term problems is an intriguing one and one which I suspect has greater importance than we acknowledge.

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.

Many considerations enter into these decisions. People seek food in order to satisfy their hunger and fill their bellies. They also crave specific foods, such as protein-rich foods, fat, salt, sweet fruits, and foods that simply taste good. All other things being equal, people seek to maximize their return of calories, protein, or other specific food categories by foraging in a way that yields the most return with the greatest certainty in the least time for the least effort. Simultaneously, they seek to minimize their risk of starving: moderate but reliable returns are preferable to a fluctuating lifestyle with a high time-averaged rate of return but a substantial likelihood of starving to death. One suggested function of the first gardens of nearly 11,000 years ago was to provide a reliable reserve larder as insurance in case wild food supplies failed.

Conversely, men hunters tend to guide themselves by considerations of prestige: for example, they might rather go giraffe hunting every day, bag a giraffe once a month, and thereby gain the status of great hunter, than bring home twice a giraffe's weight of food in a month by humbling themselves and reliably gathering nuts every day. People are also guided by seemingly arbitrary cultural preferences, such as considering fish either delicacies or taboo. Finally, their priorities are heavily influenced by the relative values they attach to different lifestyles—just as we can see today. For instance, in the 19th-century U.S. West, the cattlemen, sheepmen, and farmers all despised each other. Similarly, throughout human history farmers have tended to despise hunter-gatherers as primitive, hunter-gatherers have despised farmers as ignorant, and herders have despised both. All these elements come into play in people's separate decisions about how to obtain their food.