Biologists uncover a scurrilous sex trade on the most unlikely of continents"If they're going to have a quickie with another guy, they have to do it on the sly," observes Lloyd Spencer Davis, an ornithologist from the University of Otago in New Zealand, who with colleague Fiona Hunter recently titillated the world of science with a rather shocking discovery: After 1,700 hours of note-taking on some very cold antipodal ice, the biologists concluded that among Antarctica's Adélie penguins flourishes a lively and salacious sex trade.The hanky-panky begins with stones, the local nest-building material that also serves as the Antarctic equivalent of hard cash. When an Adélie couple discovers that it has an inadequate stone stash, the female waits for her partner to begin staring off into space — the penguin version of watching Monday Night Football — and then sneaks away to flirt the tuxedo off any bachelor who boasts a surfeit of stones. If he responds to her seductive head-bobbing and coquettish glances, they get down to business, and at the conclusion of the affair the courtesan is rewarded with a stone.Davis and Hunter recently published their revelations in Auk, a journal put out by the American Ornithologists' Union, which is typically known for less lascivious subjects (à la "Fat Storage in Male Willow Warblers"). The pair took an equally racy walk on the wild side in the June issue of the Australian bird journal Emu, with an exposé on penguin homosexuality. And in October, Davis will dash back to the ice cap for an even more nuanced analysis of Antarctica's oldest profession: He's wondering whether penguin promiscuity could be inspired by the prospect of early death.