Fig. 2. Regression results for the “humans-only” models.
The left column (β0) indicates the model intercept (the mean level of the megafauna proxy when all other covariates are held constant at zero, which, in this case, has no substantive interpretive meaning); the central column (βHumans) indicates the effect of human population size on megafauna population size; and the right column (βTa) indicates the effect of taphonomy. If human population size was an important driver of megafauna extinction, the estimate(s) would differ (i.e., be non-overlapping) from zero (denoted by the vertical grey lines). Note that in each case, the human model (βHuman) posterior estimates overlap zero, which indicates no relationship between the radiocarbon-date proxies.