Usually, the argument runs that staying put in one place to wait for fermentation was one of the reasons people settled down, giving up a nomadic way of life. The argument George Will offers, based partly on Steven Johnson's book The Ghost Map, is slightly different and presupposes settled life and urbanization:
To avoid dangerous water [of crowded areas], people had to drink large quantities of, say, beer. But to digest that beer, individuals needed a genetic advantage that not everyone had -- what Johnson describes as the body's ability to respond to the intake of alcohol by increasing the production of particular enzymes called alcohol dehydrogenases...
Johnson suggests, not unreasonably, that this explains why certain of the world's population groups, such as Native Americans and Australian Aborigines, have had disproportionately high levels of alcoholism: These groups never endured the cruel culling of the genetically unfortunate that town dwellers endured. If so, the high alcoholism rates among Native Americans are not, or at least not entirely, ascribable to the humiliations and deprivations of the reservation system. Rather, the explanation is that not enough of their ancestors lived in towns.
Professor Bainbridge disagrees, arguing that wine, which is simpler to ferment and requires no "mashing" to convert starches to fermentable sugars, would have been discovered first. I think Professor Bainbridge is probably correct in pointing out that wines (including fruit wines and mead) likely pre-dated beer, and may have had more to do with the early settling down of nomadic tribesmen, but that seems to be a different point than Will's core claim.
As far as Will's point (and Johnson's) goes, it would follow that the dehydrogenase gene would be selected for most in areas of higher population densities, but we see a ready counter-example in East Asia. Furthermore, while I am sympathetic to any argument advancing beer as a pillar of civilization, it seems to me that according to Johnson's theory drinking beer is less a catalyst of civilization, and more a response to some of its post facto challenges.