The Thing From the Swamp : A SOCIAL HISTORY OF THE AMERICAN ALLIGATOR, <i> By Vaughn L. Glasgow (St Martin’s Press: $29.95; 265 pp., illustrated)</i>

Alligators come from Canada. Did you know that? You probably didn’t, but it’s true:

The oldest ancestor of the modern alligator, as far as Vaughn L. Glasgow, author of “A Social History of the American Alligator,” can tell us, was a critter named Albertochampsa Langstoni , which cruised the swamps and marshes of Alberta some 70 million years ago, when a subtropical climate was featured thereabouts. That’s no longer true, of course, and the gators have moved along with the planetary sun belt into the bayous and car washes, drainage canals, restaurants and proprietary legends of Louisiana--which state is now, again according to the author, the only place it’s really at for Alligator mississippiensis .

Why? you might ask. Well, one answer is that Louisiana is where Glasgow lives and works as director of special projects for the State Museum. Not at all incidentally, it’s also where his late father, the distinguished Dr. Leslie Glasgow, did most of his work, which (also very un-incidentally) included crucial contributions to the restoration of the state’s and the nation’s threatened alligator populations and the setting up of a now-thriving American alligator industry. Glasgow junior knows his gators better than most, then, and the gators he knows best are right in his own back yard.

Now, if you live in Florida (or for that matter Texas, Alabama, Arkansas, Georgia, the Carolinas, Central America, northern Mexico, or eastern China’s Yangtze River Valley, where Alligator sinensis , the American alligator’s only surviving cousin, makes its home), this Louisiana chauvinism stinks. This reviewer, for instance, has experienced several quite spectacular Florida alligators, intentionally and otherwise, with degrees of intimacy ranging from distant to hands-on and outcomes from benign to terminal--usually for beast, but once for man too--and let me assure you, my gators haven’t been one infinitesimal increment less interesting for lacking Cajun credentials.

All the same, though, Glasgow does have a point. We do owe ‘em one for the great Louisiana alligator-protection/controlled-harvesting experiment. Life without alligators just wouldn’t have the flair it does.

They’re terrifically attention-getting creatures, of course, sitting up there astride the Southern-wetlands food chain and grinning at us in that godawful otherwordly ugly way, and so it’s not at all surprising that over the course of our time on their home continent we’ve involved ourselves with them frequently and variously enough to fill a well-stuffed book with a history that can accurately be termed “social.”

We’ve used their oil to make indigo dyes and lubricate steam engines and render soap for Confederate soldiery; their teeth for baby pacifiers and musket chargers, as well as for ornaments (and, ground up into powder, as aids to sexual potency); we’ve tanned their hides into belts and shoes and golf bags and Parisian portmanteaux and Czarist chaises longues. We’ve eaten them in all manner of ways, as well as being eaten by them in pretty standard fashion; we’ve used them to scare the dickens out of ourselves and our children, as well as amusing ourselves anthropomorphically with cute-gator toys, props, gadgets, cartoons, symbols and souvenirs; and of course we’ve slaughtered them almost to the point of extinction, and then granted them new life.

Now Glasgow and his assistants have corralled all this interaction into oodles of very interesting pictures (all, unfortunately, black and white), united them with solid, informatively workmanlike prose (some of it, unhappily though not offensively, somewhat plodding), and achieved a totality of well-organized, admirably academic thoroughness. Pretty much everything you need to know about alligators, and much of what you’d like to, is here in one form or another.

One has quibbles. You might, for instance, find yourself wishing the author could have abandoned himself from time to time to the sheer outrageousness of his material (though on the other hand, plenty of other folks already have; much of the alligator art and literature sampled here is lurid enough for anyone, B-movie addicts included) and, in a similar vein, you might wish that his dedication to the job of demythologizing such a feared and storied beast had been more circumspect. If, for instance, you were to rely entirely on this book, you might well form the impression that people are killed or mutilated by alligators only in their overactive imaginations, in which case you would be gravely mistaken.

Here again, though, it’s also good to see somebody genuinely sympathetic with the usual victim in the human/gator, predator/prey relationship, and it’s especially refreshing that despite his partisanship, the author also believes we should all enjoy as many pairs of stylish saurian shoes and tasty tail fillets as we can afford. Harvester/preservationists always make the most sense, and Glasgow is no exception: He knows that in this world, the best way to preserve a species--and thereby its natural habitat--is to make it legally valuable in cold, hard cash, then control access.

To the meat of the matter, then, and the question first and foremost in cutting-edge contemporary consciousness (and for that matter in the subsistence plans for many generations of rural Southerners black and white, and millennia of natives before them): Taking its very low fat and very high protein as nutritionally desirable givens, how does gator meat actually taste?

There is always some confusion here, and our author clears it up neatly by explaining that alligators, like us, are what they eat. Wild Louisiana gators and farm-raised gators everywhere, nourished primarily by the meat of the rat-like nutria, tend toward the veal/chicken/beef end of the spectrum, while gators caught in my part of the world suggest Nile perch, turtle and other mild freshwater-fishy flavors. In Miami, of course, they taste like poodles; in New York, there’s a hint of sewer worker; and so on.

Just kidding. Now that the subject’s out of the bag, though, let’s address it. Glasgow delves at moderate length into the New York City sewer-gators’ mystery so nicely deepened by Thomas Pynchon, among others, but while he claims to have demythologized the issue entirely--it’s all hooey, he says--he certainly hasn’t done so to my satisfaction.

There are albino alligators, he admits, and alligators with dark eyes but pure-white skin!--and long, long ago there were gator-like critters 50 feet in length and even “large flying reptiles that looked like alligators” (ugh!), so why can’t there be a few blind, mutating and probably rather truculent beasties slithering around beneath Times Square, pining for the alligator farms and tourist traps of their tot days in Dixie? Nobody trustworthy has ever reported actually seeing one, but really, if that were any criterion for open-minded inquiry . . .

All the same, warps and wonders abound in Glasgow’s book. Balloonists ascend over New Orleans on the backs of harnessed, semi-comatose show gators; Sarah Bernhardt’s first pet alligator, Ali-Gaga, succumbs to an overdose of Champagne; the pre-modern gator’s supposed preference for particular people succumbs to non-racist rationality, while its attraction to laundresses is confirmed thereby (hungry gators like any old meat--babies, poodles, laundresses, whatever--that plops into their bayou and wriggles).

In our own time, medical researchers find in the alligator a slow-motion model of human bioelectrical activity and, observing that temperature differentials control the gender of hatchlings from alligator eggs (cooler means females, warmer makes males), ponder the relevance of that fact to dinosaur extinction; and, as we have a right to expect, the origin of “see ya later, alligator” is revealed (it’s musician talk, wouldn’t you know), along with the fact that gators bellow in B-flat.

So now you’re up to speed. Go further for $29.95 or perhaps a more festive $75 for a limited edition bound in “mock croc.” St. Martin’s doesn’t, of course, offer the real thing. Wimps.