As I read about the US government pulling out of the Paris climate accord, I wonder what we can contribute to the conversation as archaeologists. Certainly, we can talk about human adaptation to climate and environmental change in the long term. It occurs to me that there are lessons from the past that might be very useful in the near future. The main lessons I see have to do with the nature of tradition and our place-based sense of identity. I think archaeology tells us fairly clearly that pre-Holocene tradition and identity must have been very different from those we know now. We may want to revisit some of their aspects.

Algorithmic vs Essentialist tradition

Our politically centralized, largely coastal, sedentary, agro-industrial societies have evolved over the past 8 millennia essentially under conditions of climate stability. We are adapted to life in a stable environment. We have densely populated the areas of our globe that are hospitable to our subsistence strategy, which is based on increasingly intensive sedentary agriculture. For the past 8000 years at least, this strategy, as it has spread around the world and been adopted by nearly the entire human population, has faced no serious environmental challenge.

Under conditions of environmental stability, both cultural conservatism and a concern for tradition are highly adaptive. What worked yesterday will probably work tomorrow. What our grand-parents did got us this far, and we should hesitate to change it. In terms of cultural evolution, Holocene conditions favour high copy-fidelity and low rates of innovation.

Because we are adapted to stability, our social systems are fundamentally conservative. This may not have been the case in most of the world between about 18000 and 10000 years ago.  The archaeological evidence is extremely scant of course, but this is a period during which humans went from living in full glacial conditions to living in a full inter-glacial. Not only did average temperatures and precipitation change radically, but global sea levels went up 125 m (about 400 feet). Shorelines moved, and plant and animal communities changed and moved very rapidly. The human populations that were making a living off them also changed very rapidly from  a very sparsely spread out, loosely connected network of highly mobile hunter-gatherers 12000 years ago to an almost universally dense, highly politically centralized, constantly warring collection of sedentary agricultural communities by 5000 years ago. The process was faster in some places than others, but it happened almost everywhere, and especially in environments to which this new strategy was best adapted.

The early Holocene, the period right after the last de-glaciation, was not a time of cultural conservatism. It was a time of rapid environmental and social change. If tradition was valued in the terminal Pleistocene and early Holocene, it was not the same kind of tradition that characterizes our later Holocene communities. Tradition at the end of the last ice age and in the period of intense change immediately following would have been what I will call an algorithmic tradition. It would not have been the kind of essentialist tradition that values the way things have been done in the past and advocates stability of practices and outlooks. It would have been the kind of tradition that values successful algorithms for deciding how things should be done in a particular, often unique, never before and never again to be encountered contexts.

Once climatic and environmental conditions stabilized in the mid-Holocene, there would have been increasing pressure to continue to do specific things that were done in the past and worked well. As the sedentary agricultural adaptation spread, this pressure would rapidly have extended to nearly all communities it touched. It is much easier and cheaper, both energetically and cognitively, to learn a practice and repeat it, than to learn a problem solving strategy that must be applied in any context to generate a unique solution each time. Later Holocene communities literally and justifiably hate re-inventing the wheel. We much prefer to learn how to make it, and we don’t generally worry too much about whether it is needed or why we should make it. We just make it, and it continues to work because the natural and social environment in which we are making and using it has not significantly changed since our grand-parents made and used it. Increased climate and environmental stability in the mid-Holocene led to the evolution of the kind of essentialist tradition we live with today.

The problem for us now is that in the post Holocene world, whether it should be called Anthropocene, or Neocene, or something else, adaptive algorithms rule, and essentialist tradition and stability of practice is a recipe for disaster.

Adaptation-based identity vs place-based identity

As human communities settled down and became less mobile in the early and mid-Holocene, they tied themselves to spatially discrete resource bases, such as the large and predictable cereal plant concentrations that eventually evolved into agricultural fields, or the very favourable estuarine fishing areas of the coast. This means they tied themselves, their subsistence and their very destiny to specific and sometimes very limited places. Place became tied not only to subsistence and survival, but overwhelmingly to identity.

Place has become important in another way. For mobile hunter-gatherers, the main method of conflict resolution is to walk away. This is possible because mobile hunter-gatherers tend to think of a place in terms of the resources that can be found there, and of the role it plays in a dynamic subsistence strategy. In any given landscape, there are usually a range of accessible places that can provide similar resources and play the same role in a strategy. People can use one place or another, and some are better than others, but generally speaking, the cost of moving to a slightly less favourable location that serves the same purpose is substantially less than the cost of inter-personal or inter-group conflict. Because mobile hunter-gatherers move around a great deal, their populations tend to be less dense. High mobility imposes constraints on birth spacing. A local group simply can’t physically carry a large number of toddlers over the distances required for even a moderately mobile adaptation. Populations that don’t approach the carrying capacity of the landscape can afford to move to slightly less favourable locations when they have to.

In settled populations birth spacing is free to decrease, leading to larger and denser groups that rapidly start to flirt with carrying capacity. While mobile hunter-gatherers spend some energy managing their environment and their resources, sedentary agriculturalist social networks invest massive resources into the intensive management of plant and animal populations (domestication, for example), and in modifying the landscape to make it suitable for these resources (e.g. irrigation, terracing), sometimes over generations. Communities that rely on agricultural fields and on domesticated herds that require very specific environmental conditions found in a very limited range of places tend to conclude that inter-group conflict is less costly than walking away from their substantial investment. Since agriculturalists can live much closer to carrying capacity, a residential move to even a slightly less favourable location could be disastrous for the entire community. This calculus, even if unconscious, selects for attachment to place in sedentary populations, and attachment to way of life in mobile groups. It creates the uniquely Holocene phenomenon of place-based identity. Place is highly valuable physically and symbolically, and that value is expressed as ownership. Loss of place is unimaginable and the worst trauma that can be visited upon a community. So while mobile hunter-gatherers use a range of locations to assemble a subsistence strategy and identify with the resources they use and the way they use them, sedentary agriculturalists survive by assembling a few key resources in one place and work at making the place viable for those resources. They identify with the places themselves, and less so with what is in them or what they do there. The first strategy is spatially flexible. The second is not.

In a post-Holocene world, this combination of extreme attachment to place, reliance on immobile resources, and populations on the edge of carrying capacity creates massive problems. When global sea levels went up 125 meters at the end of the last ice age, entire regions that had been available to human occupation disappeared. People moved. They were able to move because there were other similar places nearby where they could practice the adaptive strategy with which they identified and where they could run the algorithms that had helped them face challenges in a different context, not long ago, not far away.

Today, a rise in global sea levels of 50 centimeters will be catastrophic for entire communities that could vanish as a result of environmental disaster, or as a result of the great social disruptions that will result from what is really a very minor adjustment of sea levels. Many people will have to move. But where? And who will let them? Will they even want to? And if someone lets them, and if they accept to move, will they try to follow their essentialist tradition in a new place to which it is not suited?

A world of adaptability

Because our sedentary agricultural Holocene adaptation has been so successful for so long under such stable conditions, even very minor changes in climate and environment will have dire consequences for us and will lead to species-level disruption. Unless that is, we manage to learn something from a more remote past than our cherished Holocene tradition currently lets us. Key to our adaptation to these newly variable conditions will be the mobility and adaptability that made our ancestors successful in a period of intense change at the end of the last glaciation. After all, despite the very rapid changes taking place at that time, it is the period during which humans very rapidly and for the first time expanded their range to the entirety of the New World and re-occupied the northern third of the globe. Far from being severely challenged and on the edge of survival, humans seemed to thrive precisely when conditions were changing extremely rapidly. The very fact that Holocene communities see environmental change as such a deadly challenge says a lot about us.

We will have to learn how to let each other move without war, and we will have to learn to love to reinvent the wheel again, because the wheel we build in one context at one time will not work a little later and a little further on. But the algorithm that allowed us to build one that works in one context will allow us to build one that works in another. We will have to value problem solving algorithms rather than the specific solutions they generate, and we will have to be attached to a way of life rather than to the place where we live it. We will have to do this at late Holocene population sizes and densities, something our late glacial ancestors did not have to do.

The real Holocene catastrophe is not that our environment is changing or that we are facing climate tipping points. The real Holocene catastrophe is that we have become stability specialists. We can only hope that we have not overspecialized in too catastrophic a way. We could let selection take care of adapting us to our new climate reality, just as it adapted us to the Holocene 10000 years ago, but that is a costly strategy. There might be a cheaper one.

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