The other concept to which the word tribalism frequently refers is the possession of a strong cultural or ethnic identity that separates oneself as a member of one group from the members of another. This phenomenon is related to the concept of tribal society in that it is a precondition for members of a tribe to possess a strong feeling of identity for a true tribal society to form. The distinction between these two definitions for tribalism is an important one because, while tribal society no longer strictly exists in the western world, tribalism, by this second definition, is arguably undiminished. People have postulated that the human brain is hard-wired towards tribalism due to its evolutionary advantages. See Tribalism and evolution below.
Many tribes refer to themselves with their language's word for "people," while referring to other, neighboring tribes with various epithets. For example, the term "Inuit" translates as "people," but they were known to the Ojibwe by a name translating roughly as "eaters of raw meat." This fact is often cited as evidence that tribal peoples saw only the members of their own tribe as "people," and denigrated all others as something less. In fact, this is a tenuous conclusion to draw from the evidence. Many languages refined their identification as "the true people," or "the real people," dehumanizing the other people or simply considering them inferior. In this, it is merely evidence of ethnocentrism, a universal cultural characteristic found in all societies.
The anthropological debate on warfare among tribes is unsettled. While typically and certainly found among horticultural tribes, an open question remains whether such warfare is a typical feature of hunter-gatherer life, or an anomaly found only in certain circumstances, such as scarce resources (as with the Inuit), or among food producing societies. There is also ambiguous evidence whether the level of violence among tribal societies is greater or lesser than the levels of violence among civilized societies.
If nothing else, conflict in tribal societies can never achieve the absolute scale of civilized warfare. Tribes use forms of subsistence such as horticulture and foraging which, though more efficient, cannot yield the same number of absolute calories as agriculture. This limits tribal populations significantly, especially when compared to agricultural populations. When tribal conflict does occur, it results in few fatalities. Lawrence Keeley argues in War Before Civilization, however, that as a percentage of their population, tribal violence is much more lethal. Nevertheless, Keeley also admits that the absolute numbers are so low that it is difficult to disentangle warfare from simple homicide, and Keeley's argument does not ever cite any forager examples, save the anomalous Inuit.
Tribalism has a very adaptive effect in human evolution. Humans are social animals, and ill-equipped to live on their own. Tribalism and ethnocentrism help to keep individuals committed to the group, even when personal relations may fray. This keeps individuals from wandering off.
Thus, ethnocentric individuals would have a higher survival rate -- or at least, with their higher commitment to the group, more opportunities to breed. A more significant vector may be that groups with a strong sense of unity and identity can benefit from kin selection behavior such as common property and shared resources. The tendency of members to unite against an outside tribe and the ability to act violently and prejudicially against that outside tribe likely boosted the chances of survival in genocidal conflicts. Logically, a distinct divide between one's own group and other groups fosters the ability of the individual to interact with members of those groups in a manner that is equally distinct: one being altruistic (in the case of a group of unrelated members) or kin-selective (in the case of a group of more or less related members), the other being violent.
While it may be tempting to believe that racial conflict, ethnic cleansing, and genocide are the result of increased social pressures from relatively recent societal paradigms such as nations and empires, our understanding of early human history suggests otherwise. Acts of genocide are described in the Judeo-Christian Old Testament (Deut7:2), which is one of the earliest historical works, and clearly involving a state-level society. Genocide is also often used to explain the disappearance of Neanderthals in Europe shortly after the arrival of early humans in prehistorical times, though this has been largely discredited (see Neandertal interaction with Cro-Magnons). It is logical to assume that a predisposition to tribalism and specifically to genocide aided early humans in their expansion into Europe, though no evidence of such activity exists. Modern examples of tribalist ideologies, such as the Rwandan genocide, are often treated separately as many of the characteristics that define the tribes that existed prior to the Neolithic Revolution are largely not present, for example small population and close-relatedness which were not held by the Hutus and Tutsis of the Rwandan Conflict as they both numbered in the millions and were not defined by kin, but by European-created classes.
According to a study by Robin Dunbar at the University of Liverpool, primate brain size is determined by social group size. Dunbar's conclusion was that the human brain can only really understand a maximum of 150 individuals as fully developed, complex people (see Dunbar's number). Malcolm Gladwell expanded on this conclusion sociologically in his book, The Tipping Point. According to these studies, then, "tribalism" is in some sense an inescapable fact of human neurology, simply because the human brain is not adapted to working with large populations. Beyond 150, the human brain must resort to some combination of hierarchical schemes, stereotypes, and other simplified models in order to understand so many people.
Nevertheless, complex societies (and corporations) rely upon the tribal instincts of their members for their organization and survival. For example, a representative democracy relies on the ability of a "tribe" of representatives to organize and deal with the problems of an entire nation. The instincts that these representatives are using to deal with national problems have been highly developed in the long course of human evolution on a small tribal scale, and this is the source of both their usefulness and their disutility. Indeed, much of the political tension in modern societies is the conflict between the desire to organize a nation-state using the tribal values of egalitarianism and unity and the simple fact that large societies are unavoidably impersonal and sometimes not amenable to small-society rules.
In complex societies, this tribalistic impulse can also be channelled into more frivolous avenues, manifesting itself in sports rivalries and other such "fan" affiliations.
This work formed the foundation for primitivist philosophy, such as that advocated by John Zerzan or Daniel Quinn. These philosophers have led to new tribalists pursuing what Daniel Quinn dubbed the "New Tribal Revolution". The new tribalists use the term "tribalism" not in its traditional, derogatory sense, but to refer to what they see as the defining characteristics of tribal life: namely, an open, egalitarian, classless and cooperative community, which can be characterized as primitive communism. New tribalists insist that this is, in fact, the natural state of humanity, and proven by two million years of human evolution.
Whether life in this natural state was better or worse than life in modern society is a question that remains open to debate, and the answer may depend on each person's preferences as well as on the particular tribes that are used as a point of reference - because tribal life itself was not (and is not) the same for all tribes; the natural environment where a tribe lives has an especially important influence.