A New Zealand longfin eel, featured on Animal Planet's "River Monsters." Nature porn at its best. Animal Planet

I went to a bar with a friend the other night, one of those old-fashioned street-corner Irish dives that you still find in New York, specializing in draft Guinness and raucous conversation. In the men’s room, there was a poster depicting two over-muscled characters in imposing body armor. It was advertising something called Knights of Mayhem (the title was in Gothic script) which I assumed was just another new computer-generated action movie in the tradition of Wrath of the Titans. Then I looked at the small print: a National Geographic Channel production.

National Geographic? The folks who bring us the wonders of the Serengeti and the amazing world of big cats? I was intrigued enough to go online to see what other shows the channel was offering these days. Don’t get me wrong: National Geographic, like public television, still makes gorgeous documentaries, such as the highly acclaimed Great Migrations. But its current listings also include things like Beast Hunter, Python Hunters, Shark Men, Swamp Men, and Stormageddon.

This isn’t an isolated development, it turns out. Much the same thing is happening with programming on nature, environment, and wilderness topics across the cable TV spectrum, no matter how distinguished or how sleazy the pedigree of the particular broadcaster. The Discovery Channel, which began life as a bona fide competitor to PBS in the field of serious docs, spends a lot of its time now hanging out with hunky men with three-day stubble as they master the world’s toughest natural environments. The World’s Toughest Trucker hurtles across the waterless Australian Outback and slithers around ice-bound precipices in the Himalayas. In The Deadliest Catch, Alaska fishermen do constant nailbiting battle with the Perfect Storm, which seems to occur up there on a weekly basis. There’s Man vs. Wild, Out in the Wild, Hogs Gone Wild… in fact the word wild crops up in the title of five different shows. Clearly it market-tests well.

Animal Planet, meanwhile, which was launched as a documentary project with the BBC as a partner, now serves up Gator Boys, Call of the Wildman, and Skunk Whisperer, in addition to Animal Planet Extreme and My Extreme Animal Phobia. (The word extreme should probably be stricken from Webster’s at this point, having become such an advertising cliché that we now have to contend with newer variants such as extreem, extreeme, and xtreme. Perhaps Xtreme Power Stick deodorant is what all those tough truckers use.)

Not to say all this man-conquers-nature stuff is exactly new. Theologians may continue to debate the exact meaning of the original Hebrew, but the entrenched view (certainly in the Republican Party) is still that the King James version of Genesis, I:28, which urges us to "have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth," should be taken literally.

There’s always been a good bit of shock and awe along the way, of course. Violent struggle -- human versus the elements, human against animal, predator and prey -- is an intrinsic part of the drama.

In pop culture, the forms have changed over time. Men have always grappled with hostile creatures and boasted about their size. The celebrated explorer-writer-radio show host of the 1920s and 1930s, F. A. Mitchell-Hedges, who may have been the inspiration for the character of Indiana Jones, wrote a bestseller with one of my all-time favorite titles: Battles with Giant Fish. Now we have Python Hunters and Shark Men. (Men being the operative word: note the absence of gator girls and swamp women in my informal survey.)

We have also always loved the vicarious thrill of observing nature in all its redness of tooth and claw. When I was a kid in Britain, one of the most celebrated TV nature shows featured a Belgian scientist called Armand Denis and his blonde British wife Michaela, who looked a bit like Grace Kelly. Off we would all go on safari, and when we got there the heavily accented and much-parodied Armand would sit for hours in a baobab tree with his telephoto lenses until the magic moment when he could say, Und heer vee see a leopard engaged in a laife-or-deass shtruggle viss a helpless wildebeest.

But something fundamental has changed: we’ve kept the thrills but we’re losing the story. I don’t want to idealize those old books and TV and radio shows, because they carried cultural baggage that would make us cringe today. When Mitchell-Hedges traipsed off to do battle with the sharks of Central America, for instance, he would also deliver pep talks about the need for military dictators to keep the rowdy locals in line. When we went on safari with Armand and Michaela, it was usually in the company of faithful native bearers and their titillatingly bare-breasted wives. Even so, these travelers knew that their job was to tell us a story, one with context, history, a narrative arc. And the Belgian-British couple actually spoke passable Swahili.

I’m not saying the great environmental documentary is dead -- we will no doubt get more things like David Attenborough’s incomparable Planet Earth; the independently produced Koyaanisqatsi (a Hopi word meaning "life out of balance"), with its Philip Glass score; or the French-made Microcosmos, the extraordinary close-up study of the everyday lives of insects. But in places like Animal Planet, the barbarians are definitely storming the gates. When that channel announced its makeover in 2008, the logic was pretty overt: it said it wanted "an image with more bite … to tap into humans’ basic instincts." As one astute commentator on cable TV remarked at the time, "Think of it as swapping a drab narrator saying that a lion is about to kill its prey for the blood-curdling scream of the doomed creature as it meets its demise." Don’t expect any more Attenboroughs on that channel.

I’ll continue to hope that the better angels at National Geographic hold the line. Otherwise what we’ll be left with is the environmental equivalent of the baseball highlight reel: none of the longueurs, subtle tactical maneuvers, and intimate dramas of the three-hour game, just a pulse-pounding music track and an endless succession of diving catches, strikeouts, and home runs. Think of it as nature porn.