I'm reading through the English translation of The Culture Historical Method of Ethnology by Wilhelm Schmidt -- one of the practitioners of the Vienna School in the early 20th century. This is in pursuit of my project describing early 20th-century diffusionism, the next logical point is the Kulturkreise, or "culture circle" theory.
While I formulate my thoughts on that topic, I thought it might be worth highlighting this passage, in which Schmidt considers the problem of reconstructing culture relations among prehistoric hunter-gatherers -- the kind with which Paleolithic archaeologists would now be concerned. The passage lies in a broader section about external causes of culture similarities, and the basic point seems to be that the vastness of time allows few distinctive similarities among the very ancient cultures of Paleolithic people:
On the other hand, the comparison of ethnological with the prehistorical periods, as is carried out by O. Menghin in his Weltgeschichte der Steinzeit, shows how long those periods of the food gatherers must have lasted, which without any noticeable "progress" (in external culture) cover thousands (and even tens of thousands) of years. We pass over in silence the astounding speed of the historical events of modern times, for neither could that profusion of events of "early historical" times have happened in the epochs with which we are here concerned, because there existed only very small human groups who lived thinly distributed over the earth, which was still so sparsely peopled. At any rate, the external course of events could by far not have been rich and developed, and the resonance of the individual events could also not by any means describe such broad circles and, if so, then only in a long course of time.
Of course, that does not decide the question of te plenitude and richness of psychic events of the peoples of that time, although also the small number of individuals in the single groups and the great distances separating the single groups restricted these to certain limits. The smallness of a group could especially increase the danger that the group received none of the leading individuals, who are of particular importance for the awakening and preservation of intellectual life (Schmidt 1939:251-252).
I find the last paragraph here to be quite modern in its conception of information transfer and storage within individuals. In the first paragraph, Schmidt concerns himself with the pace of culture change, with culture viewed as a reactive system in the face of external events. The long span of Paleolithic time has few extrinsic changes to which cultures might have obviously adapted, so that contrasts between cultures on an extrinsic basis might be expected to be minor.