ONE OF THE best ways to deflect criticism for even the worst habits is to ascribe them to scholarly endeavor. For this reason, I prefer to think of excessive beer drinking as a kind of cultural study, ethnobeerology, if you will. If you need to further rationalize this practice to yourself or others, simply remember that throughout the world beer is at least as common as, and often cheaper than, potable water. Some would argue that production of beer is one of the hallmarks of civilization. Indeed, such a vast record of beer production has been uncovered from ancient Egypt as to enable modern drinkers to effectively share a glass of home brew with the souls responsible for the 4,400-year-old tomb paintings that hold the recipes. The ubiquity of beer throughout almost all of recorded history and virtually every culture has led to my belief that a culture's beers are essentially the fingerprints of its civilization. Each beer has a distinct personality, and each is more representative of its country of origin than any diplomat. So tell anybody whining about your beer consumption to get bent. This is science.

On my most recent expedition, I decided to check out South and Central American beers, and with the veritable United Nations of restaurants representing the Americas in the Mission District, you can sample beers from Peru, Ecuador, Brazil, El Salvador, and Argentina within seven square blocks.

Panchita's No. 2 The menu offered Regia ($6.00) and Suprema ($2.75), two of the beers common to El Salvador. Why six bucks for the Regia? It comes in a 32-ounce bottle that looks like a depth charge. The Suprema is more conservatively bottled, and the size difference drew jeers from our server. The light golden color of both appeared nearly identical, but as they settled in the glass, some differences became evident. The Suprema maintained its head a bit with some uneven lacing (when remnants of the head stick to the side of the glass as it subsides and as the beer is consumed, it's actually a good thing). The Regia was as headless as a Sleepy Hollow horseman and very dry. While the Suprema wasn't full bodied, it was a bit more creamy than the light Regia, which was akin to Kirin, the Japanese lager. 3091 16th St. (at Valencia), S.F. (415) 431-4232.

Limón The selection of South American beers was broader than Panchita's. Quilmes, Cusquena Malta, and the Pilsner Callao (all $3.75) offered the most varied tasting. Quilmes, the lone Argentine beer of the day, was crisp and refreshing with a hint of citrus. The Pilsner Callao, from Peru, tasted virtually the same as Pilsner Urquell, a fairly common Czech beer that has a slightly corky flavor and a mildly woody or nutty aftertaste. The most unique beer of the entire day was the Cusquena Malta. Cusquena Malta has strong flavors of molasses and fig, coffee when swigged, and when you're licking the creamy head from your upper lip, it tastes like cinnamon. It's an excellent non-beer-drinker beer. The head cascades down the glass when poured, much like a Guinness, but with larger bubbles. 3316 17th St. (at Mission), S.F. (415) 252-0918.

Platanos Xingu, Brazilian Black Beer, and Pilsner of El Salvador in its ace of hearts-labeled bottle were on the menu. Again, the dark beer was sweet and deceptively light. The dark brown head gave way to a deep black brew that, even when held to the light, was impenetrable. The Xingu, chocolaty and creamy, was the evil twin of the Pilsner of El Salvador. The Xingu didn't share the flavors of the Pilsner Callao from Limón and wasn't as notable. 598 Guerrero (at 18th St.), S.F. (415) 252-9281.

El Majahual Steady beer drinking and appetizer sampling were beginning to take their toll, but there were Colombian beers left to taste, Aguila ($2.75) and Club Colombia ($2.75). The Aguila was extremely dry and tasted almost like soda water. The Club Colombia was crisp with light vanilla flavors. The light flavor and clean taste complemented the spicy foods we had with them, and although neither matched the complexity of the Cusquena Malta, they weren't made to. 1142 Valencia (between 22nd and 23rd Sts.), S.F. (415) 821-7514.

When it comes to beer, Central and South America ain't Belgium. The general feeling you get in tasting a number of the popular beers of the region is that the vast majority are utilitarian, like many popular U.S. beers. They are meant to cool off both body and tongue, slake thirst, and offer unpretentious, easy, fast drinking. They get the job done. Dark beers from warmer climates tend to be sweet and light when compared with many dark European or U.S. beers and don't share their bitter, black-licorice taste. Of the beers tasted in this batch, the most novel, by far, was the Cusquena Malta, which you may be able to find cheaper at Mi Lindo Perú, farther out on Mission Street. The Quilmes and Club Colombia had some distinctive flavors mostly notable in their finish. The Regia is an excellent choice for a platter of pupusas and a group of friends. It's often tough finding distinctions among lighter beers. Beer tasting with radically different beers is fairly easy because of the wide variation, but the subtlety of tasting several similar beers can help calibrate your palate. In any event, it's a sweet way to burn through a Sunday afternoon.