Carroll: Well, natural selections works
on very
tiny increments of differences in performance between organisms, and to measure those differences requires a whole lot of sampled life.
So, except for
tiny effects of convexity bias (due to earning or paying interest
on margin), futures and forwards with equal delivery prices result in the same total loss or gain, but holders of futures experience that loss / gain in daily
increments which track the forward's daily price changes, while the forward's spot price converges to the settlement price.