That's "Upper Paleolithic", not "Upper Peninsula." Barton et al. (1994) discuss the interpretation of Paleolithic art in Western Europe. A good short summary is this passage (p. 190):
Viewing art as a communication medium that monitors information flow allows us to propose an explanation for observed patterns in Palaeolithic and post-Palaeolithic art, and to model changing alliance networks in European forager populations from the late Pleistocene through the early Holocene.
They conclude that the tradition of parietal art in Southwest France and northern Spain reflects demographic pressures associated with increases in population density, stress on existing alliance networks, and claims for property rights.
The information exchange approach taken here argues that parietal art is an example of Wiessner's emblemic style; that emblemic style is, among other things, a monitor of demographic stress, and that the appearance of parietal art in late Pleistocene Europe resulted from the closing of social networks under increasing population density (ibid:199).
They suggest that this use of emblemic style is merely an archaeologically visible instance of a system based in archaeologically invisible referents, and that this visibility is a function of group size and resource availability:
As noted, both assertive and emblemic style almost certainly existed among prehistoric foragers, but are not usually recoverable archaeologically. Ethnographic data indicate that emblemic style in forager contexts is often associated with features of the landscale (e.g. Denbow 1984; Lewis-Williams 1984). That is, it functions to identify sacred localities, prominent topographic features, the boundaries of more or less exclusive economic territories and other geographic landmarks. Under conditions of low population density, changing group membership and open social networks, the significance of such landscape features is transmitted from one generation to the next by means of the oral traditions of small, fluid social units; the physical marking of such features is rarely necessary. With aggregation, however, the need for more effective means of both inter- and intra-group communication arises. It becomes necessary to reinforce oral tradition within larger social units, whose members might not participate in a single tradition nor interact with one another on a regular basis.
I wanted to note the contrast they draw between two "explanatory paradigms" for patterns in Paleolithic art:
Art and social interaction
The first sees distributional patterning in Paleolithic art, and more generally style, as a monitor of the degree of cultural affinity among social groups through time or in terms of shared cultural traditions. This 'social interaction' model has roots in both the Old and New Worlds. In North America, it dates back to A. L. Kroeber, Clark Wissler and the 'culture area' studies of the 1930s. Social interaction theory defined style in a strongly normative way as repetitive behavior that acts as a kind of psychological 'filter' to constrain variety and reduce information overload. Style functions at the level of the individual and is essentially passive; that is, it reflects normative constraints learned unconsciously through enculturation. In art and in artefact design, style is construed to exhibit modal properties taken to reflect, an a more or less direct way, group norms and values. These modal properties are often considered to be isomorphic with the temporal and spatial boundaries of identity-conscious social units -- in other words, an ideational definition of style, but with alleged material correlates (Clark 1993) (ibid.:186).
In other words, "style" in artifacts reflects the boundaries of meaning in the minds of people who made the artifacts. It is unintentional -- a byproduct of the process of learning a limited set of information. Because of a lack of intentionality, the analysis of style may uncover the social units themselves, consisting of individuals who shared boundaries of meaning. Style is therefore a marker of cultural affinity.
Art and information exchange
The second approach to art is essentially a functionalist one that views it as the remains of communication systems involving the exchange of information (Braun and Plog 1982). As employed here, the 'information exchange' theory of style originated with Polly Wiessner (1983, 1984, 1985), who views art as an act of social communication defined, at various levels and scales, by style. Style, in turn, as its behavioral basis in a fundamental human cognitive process: the personal and social identification of images through visual comparison. In sharp contrast to the pattern searches of social interaction theory, style is defined here by its determining processes, rather than by its material conditions.
In this paradigm, "style" is a functional element of artifacts that may or may not correspond to cultural entities. It has an adaptive function in the intentional transfer of information, such as information about social status or property. Since the imposition of style is deliberate, it does not mark cultural units in a straightforward way, but instead marks patterns of activity that may or may not be linked to cultural entities.
I like this second concept, because it assumes that people are intentional agents with respect to stylistic representation. But I think that elements of the first are also necessary, since there clearly are boundaries to meaning that are important in the function and interpretation of stylistic information. Indeed, without boundaries to delimit meaningful representations, there can be no transfer of information (The importance of these delimitations on meaning is well illustrated by modern art, which is often more about the placement of boundaries to meanings than it is about stylistic or representational elements).
Barton CM, Clark GA, Cohen AE. 1994. Art as information: explaining Upper Palaeolithic art in Western Europe. World Archaeol. 26:185-207.