Demography and Environmental Stresses
Social scientists have suggested that increasing populations and higher population density can lead to more warfare. Rapid population increases can create pressure by increasing demand in the economy and stressing the capacity of social institutions. Also, population increase provides a larger manpower pool to absorb the losses that more frequent combat entails and allows formation of larger war parties that are more likely to be successful. Another characteristic of growing populations is the development or introduction of new technologies in food production, transportation, and weaponry.
However, the ethnographic evidence indicates that the frequency of warfare and social violence is simply not a consequence of human density or crowding. Groups with smaller population densities are just as likely to engage in warfare in a given timeframe as groups whose densities are hundreds of times higher. A reasonable expectation to be drawn from the ethnographic record is that warring societies are equally common and peaceable ones equally uncommon at any level of population density. Archaeologists, then, need to be aware of signs of warfare whether the population densities of their prehistoric cases are high or low. It cannot be assumed that violent conflicts reach significant levels only when regional densities and social complexity have reached a certain threshold.
In some instances an increase in human density and social complexity has not been accompanied by any increase in violence. Between 13 000 and 11000 years ago, during the development of the Natufian culture, the Near Eastern Levant experienced a large growth in both regional and local human density, along with an increase in the sedentism of foraging communities. The period is marked by an absence of any indications for warfare at all. In contrast, the last Mesolithic foragers of Central Europe (c. 7500 BP), whose density is estimated to have been quite low and whose way of life was nomadic, seem to have been quite violent.
The food or resources on the territory, or lack of them, may be a significant factor that makes a region prone to warfare. Ethnographic and archaeological evidence indicate that environmental stresses related to hard times lead to outbreaks of violence and increase the likelihood of warfare in a region. While many societies are able to cope with small-scale hardships and disasters, violence often occurred after large-scale natural calamities such as severe drought. War-prone groups tend to initiate conflict when recouping losses due to calamities, to replace deteriorating pastures and fields by territorial expansion, and to cushion the effects of expected future losses. For example, the increase in fighting among South African Bantu tribes in the early nineteenth century seems to have resulted in part from years of decreasing rainfall following forty years of better conditions during which both human and cattle populations had increased. Archaeological evidence of disaster-driven warfare is discernible in the Crow Creek massacre in thirteenth century South Dakota. The violence followed shortly after a climate change. The bones of the victims showed signs of chronic undernourishment.
Borders and Frontiers
Some anthropological research maintains that frontiers between different cultural groups are peaceful. In this perspective, boundary regions serve as settings for the peaceful exchange of goods, labor, spouses, and information between two societies. However, frontiers are also places where resources and goods are displayed, resources that are just beyond the limits of one’s society. Should desperate times arise, the needy know where they must go to obtain required resources. Thus some studies indicate that frontiers, whether static or moving, can be places of conflict.
Frontier areas can be violent because cultural and social restraints mitigating violence are minimal or absent. Disputes in frontier areas have no recourse to adjudication by a higher authority, thus making outbreaks of violence more likely. Frontier zones tend to be less peaceful also because of their proximity to the outside and to potential enemies. Settlements along borders are very vulnerable to raids because they are less densely populated, easier to surprise, and easier to retreat from if resistance proves too great. The greater degree of vulnerability and volatility of frontiers explains why no-man’s-lands have often buffered them and why their settlements tend to be fortified.
Moving cultural frontiers can be especially violent places where the risk of warfare is much higher than within cultures or on static frontiers. A moving cultural boundary usually involves the expansion of one human physical type, language, culture, or economic system at the expense of another. Though there are cases of peaceful expansion, research shows that warfare often accompanies the movement of a frontier and occasionally may be the only mechanism by which it can advance. This is especially so when the movement of a frontier involves colonization by newcomers on a large scale, which leads to competition over land and resources. Historical examples include the Romans and Celts or Germans in Western Europe, the late medieval Spanish and the Gaunche tribesmen of the Canary Islands, and the medieval Japanese and the Ainu tribesmen on Honshu.
From the archaeological record, one example is the movement of Mississippian peoples into various regions of eastern North America between AD 900 and 1400. This migration was marked by the fortification of almost all new settlements in these areas. The Crow Creek massacre occurred on or near a fluctuating frontier between middle Missouri and Coalescent farmers between AD 1050 and 1300. In Western Europe some 7000 to 6000 years ago, colonizing Early Neolithic farmers appear to have encountered a hostile reception from indigenous Mesolithic hunter-gatherers, as evinced by the presence of fortified villages and no-man’s-lands. In the end, fortification of pioneer and border settlements provides strong indication that hostilities were more likely at moving cultural boundaries.
Trade and Conflict
A common assumption made by many researchers is that societies exchanging goods and marriage partners are likely to remain at peace with each other. Other researchers believe that this is generally true only for short timeframes, and that societies engage in cycles of trade and warfare. Modern cases, such as twentieth century American-Japanese interaction, clearly demonstrate how trading partners go through cycles of peaceful exchange and deadly conflict. The ethnographic record also yields examples of this phenomenon. For instance, the Tupinamba of coastal Brazil made periodic truces with their inland enemies, during which they traded coastal goods for inland commodities.
It is quite often the case that trading partners, due to logistical considerations, are societies that share a border. The closer two parties are, the easier the logistics to interact, whether those interactions take the form of trade or war. Hence, while not a sufficient cause for warfare, territorial contiguity and the forms of interaction it fosters can be a contributing factor. However, mere proximity does not explain why some interactions are benign while others are violent.
In most tribal economies, the bulk of commodities are exchanged through various forms of reciprocity and ‘gift-giving’ rather than by direct barter or purchase. Failure to reciprocate acts of ‘gift-giving’ can engender grievances that escalate into warfare. Thus in tribal societies, failure to reciprocate is equivalent to default or fraud in a more commercial system.
Another common source of warfare over trade arises when one social group holds a monopoly over a particular commodity, usually because the only source lies within its territory. Two commodities that serve almost universally as the foci of such tribal conflicts have been hard stone for tools and mineral salt.
The interchangeability between trade and warfare becomes clearer when we consider their ultimate physical results. Trade, intermarriage, and war all share a common overall effect of moving goods and people between social units. In warfare goods are moved as plunder, while people are moved as captives and slaves. In peaceful interactions of exchange and intermarriage, goods move as reciprocal gifts, trade items, and bride wealth, whereas people are moved as spouses. This is a particularly important observation for archaeologists, since some researchers automatically interpret the presence of exotic goods at a site as evidence of prehistoric trade and exchange, thereby ignoring the possibility that the goods may be spoils of war.
Political Consolidation and Dissolution
Many researchers have linked social violence and warfare with the development of large-scale, socially stratified, and politically centralized polities such as chiefdoms and states. Archaeologists and cultural anthropologists have noted that warfare increases during periods of political consolidation, for example, when tribes coalesce into chiefdoms, and chiefdoms into states, or small states into empires. Case studies from both the ethnographic and archaeological records seem to demonstrate a relationship between social complexity and warfare, though debates continue as to causal direction. Whereas some researchers believe only state-level societies participate in warfare, others hold that the formation of states occurs through conquest-related warfare. The material record offers evidence that ancient states have developed within regions of competing chiefdoms, and researchers maintain that the emergence of complex polities occurs through subjugation and conquest of other polities. Overall, it does appear that emergence of state-level society in many regions is highly correlated with the increased frequency and intensity of collective violence.
Conversely, warfare seems to have increased during the decline, collapse, or fragmentation of larger political units such as states and empires. External pressures are cited for the decline of societies, and they include increased threats or attacks by foreign groups. There are examples of collapsing state societies empirically linked to predatory non-state neighbors. According to researchers, the collapses of states throughout history are more likely to result from attacks by large numbers of predatory neighbors than from natural catastrophes. States not geographically vulnerable to conflict with non-state neighbors tended to enjoy greater stability and longer life spans. In Asia, for example, ancient states in northern Indian territory tended to last no more than a century or two without drastic changes, whereas Southeast Asian states lasted two or three times as long. The two regions shared many similarities in terms of environment, resources, population densities, and government institutions. The main difference was that the states of northern India were much more susceptible to attack by aggressive non-state neighbors (see State-Level Societies, Collapse of).
See also: Americas, North: Eastern Woodlands; American Southwest, Four Corners Region; Asia, West: Archaeology of the Near East: The Levant; Europe, Northern and Western: Mesolithic Cultures; Osteologi-cal Methods; Political Complexity, Rise of; State-Level Societies, Collapse of; Weapons and Warfare.