Passage Summary: People usually think ice-age nomads were big-game hunters. However, an anthropologist argues they actually ate mostly plants and small animals because their groups were too small to risk losing members to dangerous big-game hunts.

Conclusion: Ice-age nomads likely obtained most of their food from small game and plants rather than big-game hunting.

Reasoning: Nomadic groups were small (15-20 people), and hunting large animals would have been too dangerous for such a small community to sustain.

Analysis: To identify the 'Role in Argument,' look at the transition words. The statement in question is introduced as something 'commonly portrayed,' which is immediately followed by the word 'but.' This is a classic LSAT setup: the author introduces a popular or opposing view specifically to knock it down. Therefore, this statement is a claim that the anthropologist's argument is intended to refute or provide an alternative to. It's the 'foil' that sets the stage for the author's main point.