(Note: After musing over his aerial photographs of trinchera
hill sites, Tom Baker takes the position here that they were fortified
farming villages. - L.B.)
Summary: The study of cerro de trinchera ("entrenched mountain") sites in the lower American Southwest and northern Mexico may shed light on the question of whether, as a number of researchers have speculated, early farmers operated amid a sea of hunter-gatherers, with the two lifestyles in occasional (if not constant) conflict. The trinchera hill sites appear to be fortified locations for growing food. Did early farmers have to defend their crops and storage bins from raiding nomads who had not adopted agriculture? Further investigation of these sites may support the idea.
Apparently so. Foragers (variously called "hunter-gatherers,"
"nomads," or just "hunters") and farmers ("agriculturalists,"
or more accurately "horticulturalists" at this stage
of the game) seem to have shared the same territories, voluntarily
or not, as agriculture developed. It appears to have been a common
situation worldwide. It could have happened when a cultural group
that had already adopted agriculture migrated into the territory
of hunter-gatherers (or vice-versa), or it may have evolved when
some element of a single nomadic people took up agriculture among
the rest who did not.
Drawing strict distinctions between the foraging and farming lifestyles is oversimplifying, of course, because as agriculture evolved there would have been a mixture of the two, and perhaps never a complete separation. Semi-sedentary groups could have foraged while also maintaining small gardens, and in fact this must have an intermediate step for those nomads who eventually became sedentary through increasing dependence on agriculture. But there were nevertheless groups who remained primarily nomadic foragers, while others became largely sedentary farmers, existing in the same territory. In historic times, we have only to look at the example of the U.S. Southwest, where the farming Pueblo towns were surrounded by nomadic Athabaskan tribes who migrated into their territory. And yet Puebloan farmers never completely abandoned hunting, while nomadic Navajos (for example) also tended gardens in watered canyons.
Some theorists visualize the two lifestyles as being economically dependent on one another, especially early on when the distinctions between them were more blurred, and trading their products (the meat and skins of the hunters, the cereals of the farmers) back and forth. Conflict would have become more common later on, when farmers became more efficient, and self-sufficient.
Up until the appearance of agriculture, of course, hunting and gathering was the natural lifestyle of all humans, the original legacy of our hominid ancestors, pursued since time immemorial. Small bands of humans had always roamed the landscape in seasonal cycles of foraging that were finely tuned to the rhythms and resources of the environment. Then, relatively recently and suddenly, the agricultural way of life evolved, triggering rapid cultural evolution leading to civilization. This happened independently and at different times in the Old and New Worlds, but why it should have occurred at all is still a question that gives anthropologists fits, and probably always will.
There is a school of thought that believes that an agricultural lifestyle, being an unusual development for humans, with definite drawbacks to it as well, would have been resisted by all but those unable to continue in the old hunter-gatherer way of life. Only people who could not, for some reason, continue to be hunters and gatherers would resort to gardening, this reasoning goes; the rest would go on as humans always have. The eventual result would be the two different lifestyles, foraging and farming, existing side by side, with conflict developing between them. The fortified hills we are interested in here may have been an outgrowth of such conflict.
Why should the two lifestyles have been in conflict?
It would have been simply the farmers defending their villages, crops and food stores from raiding nomads, the same way the Puebloans resisted the raiding of the Athabaskan tribes in later times. Besides the obvious temptations of a farmer's food gardens to hunter-gatherers (that is, after all, what they gather), farmers can amass food surpluses that they can store to tide them over hard times. Foragers, on the other hand, would be without such a safety net when the natural pickings grew slim, and at such times the crops or storage bins of the farmers would have become especially attractive to them. And when a group of humans wants something, especially hungry ones wanting food, they will take it by force if they can't get it by an easier means.
Thus, if a group of farmers in such a situation could keep their valuable seeds and surplus produce in an easily defended place, such as a walled hilltop, reason suggests that that is what they would do. If they could also locate their gardens in such a place (for at this time period we are talking more about truck gardens than waving fields of grain), or even park their entire farming village there, that would be even better. In our aerial photos we usually see a river or stream at the foot of a trinchera hill, which is where the farmers would have gotten water for their gardens (and themselves), carrying it back in waterproof baskets while waiting patiently for someone to invent pottery.
Is this, then, what the cerros de trincheras (fortified hills) really are: the early farmers' response to the raiding of larcenous hunter-gatherers? These hills appear, in our aerial photographs, to have stone walls for defense, terraces for planting gardens, and sometimes places where houses were located (see the especially obvious small circles, suggesting structures, in the Cerro Vidal photo). If these trinchera hills were actually fortified farming settlements, then archaeologists should find evidences of gardens on the terraces, and perhaps storage cists or bins as well. The many grinding stones and other plant food processing tools scattered about these sites which all observers, from Adolph Bandelier onward, have commented on make it clear that some sort of agricultural activity took place on these hills.
Note also, in John Roney's commentary on our photo of Cerro Juanaqueña, that he has found a lot of projectile points on these trinchera hills, and in fact that is one of his main methods of dating the sites, as well as by the presence (or conspicuous absence) of pottery. Are all these spearheads (this was too early for arrows) evidence of fighting? Perhaps so. And if so, it is all the more argument for these hills being prehistoric farm-forts.
It will be interesting to see if future archaeological work, both in the air and on the ground, supports this idea about what the cerros de trincheras were.