As the readers of this blog know, a big chunk of my research focuses on why complex societies go through cycles of alternating internally peaceful, or integrative, phases and turbulent, or disintegrative periods. In all past state-level societies, for which we have decent data, we find such “secular cycles” (see more in our book Secular Cycles).

What was a surprise for me was to find that pre-state societies also go through similar cycles. Non-state centralized societies (chiefdoms) cycle back and forth between simple (one level of hierarchy below the chief) and complex (two or more hierarchical levels) chiefdoms. But now evidence accumulates that even non-centralized, non-hierarchical societies cycle. The work by archaeologists, such as Stephen Shennan, showed that various regions within Europe went through three or four population cycles before the rise of centralized societies (see, for example, his recent book The First Farmers of Europe).

These cycles were quite drastic in amplitude. For example, last month at a workshop in Cologne, I learned from archaeologists working in North Rhine that population declines there could result in regional abandonment. Several hypotheses have been advanced, including the effects of climate fluctuations, or soil exhaustion. But there is no scientific consensus—this is a big puzzle.

One hypothesis, which, for some reason, doesn’t get much attention, is the role of warfare in all this (I’ve written about this curious bias in this post and others). For example, a recent, and otherwise excellent article by Hofmann et al. on the rise and collapse of Tripolye mega-settlements (Governing Tripolye: Integrative architecture in Tripolye settlements) doesn’t mention words “warfare” or “war” even a single time! I’ll return to this article in a bit.

To fill this theoretical gap, I am starting a project in which we will model the rival hypotheses, including the one focusing on warfare, and will do a systematic empirical test of their predictions using data on several Neolithic populations.

But back to the Tripolye article. Hofmann et al. integrated the data coming from high-resolution magnetometry surveys (it never ceases to amaze me how rapidly archaeological methodology is advancing) of 19 mega-settlements and discovered that they all had large communal buildings. Here’s a map from the article of one well-studied settlement, Maidanetske:

The big red square with numeral 1 appears to be the main meeting/ritual building. There are 12 more intermediate size buildings, which are much larger than residential houses, and were also “integrative buildings” where joint decision-making meetings could take place (followed, it goes without saying, by feasting). What is particularly interesting is that we have a three level hierarchy here:

1. Usual houses (around 3,000 of them, implying total population in excess of 10,000)

2. Mid-level integrative buildings (12 of them), probably used to govern each district

3. Top level integrative building to govern the whole settlement.

At least, this is the reconstruction by the authors, which makes a lot of sense to me.

What is particularly interesting is the dynamics between 4100 BCE, when these giant settlements formed, and 3600 BCE, when they collapsed. It is schematically depicted in this figure from the article:

The mega-settlement was formed by a number of groups moving together. Each of the groups probably occupied a separate district with its own integrative building, and then they added the top-level meeting hall to work out the issues affecting the whole community. Later, however, mid-level meeting halls disappear, and only the top-level integrative building remained. And soon after that the whole settlement collapsed.

The authors argue that “the non-acceptance of this concentration of power and the decline of lower decision-making levels might be a crucial factor for the disintegration of Tripolye giant-settlements around 3600 BCE”. Perhaps. But this conclusion leaves a lot of questions unanswered.

First, why did the different groups move together in the first place? From almost any point of view, except one, this was a really poor decision. Such crowding together resulted in serious problems with sanitation and disease. Additionally, farmers had to waste a lot of time traveling to their fields, because such huge settlement required a lot of land to support it. The only reason for such population concentration that makes sense to me is collective defense.

There are many signs pointing to warfare as the primary mover behind the rise of Tripolye mega-settlements. The Tripolye people constructed elaborate defenses with not just one but two concentric rings of ditches. Another indicator of external conflict is burned houses. Of course, wooden houses can burn as a result of an accident, but note the green-colored “houses burnt (settlement 1)”. These houses are outside the ditch, and quite spread out. Enemy action is more likely as the cause of burning then accidental fire leaping from house to house. Finally, the authors note that the size of mega-settlements increases as one travels in the southeastern direction, and thus towards flatter steppe region, where defense is more difficult.

The second question is that at the end of the mega-settlement period, the population didn’t simply disperse out; there was a very substantial population collapse. Again, what was the reason for this? In historical periods the usual answer is pervasive endemic warfare. Not only war kills people, its effect on demography is even more due to the creation of a “landscape of fear,” which doesn’t permit farmers to cultivate fields, so that the local population gradually starves, has fewer babies, and is further diminished by out-migration. Such landscape of fear is not easily detectable archaeologically, because few people die violently (they keep to fortified settlements and are afraid to venture out).

As I said earlier, this internal warfare hypothesis is just one of possible explanations for the Neolithic collapses. We will get better answers by comparing model predictions to the data, and it looks like Tripolye would make a great case study in this research.