Emphasis on cross-cultural testing, multiple currencies, multivariate analyses, and levels of explanation makes this an important paper. However, it does not distinguish current function from evolutionary origin; it lacks history. Rather than distinct alternatives, tolerated scrounging (TS), costly signaling (CS), and reciprocal altruism (RA) are likely to be sequentially evolved components of a single integrated system (and kin selection (KS) important only among very close relatives).