You'll know that you've been tango'd; Dance

OF ALL the theories about the origins of the word "tango," the most convincing - and appealing - is the one that claims derivation from the Latin tangere, to touch. Dancing cheek-to-cheek is a coyeuphemism for what tango couples do. The contact is ferocious: temples pressed, cheeks crushed to the bone, jaws almost fused in what can look like an attempt to pursue a long, hard kiss while stalking big game. It takes more than two to tango: it takes carnal knowledge.

The joy of Forever Tango, the Argentinian dance-and-variety show, is that it goes far beyond the tea-dance parody of passionate melodrama most of us think of as tango. A two-hour show of alternating music and dance reveals the form as a vehicle for ingenuity, intrigue, wit, broad hu- mour and subtle character-acting, as well as a range of head-spinning gymnastics that would make a circus act look dour.

The style emerged in the 1880s in the swarming suburbs of Buenos Aires, where European immigrants had settled near the port. Like flamenco, the term applies equally to music, sung and played. Forever Tango presents both, and its two solo singers - the desperately glamorous Sandra and the histrionic Carlos - strike the only wrong note for a British audience. It's not that they're bad, but that they remind us of cabaret on the Costa del Sol. Unfair, I'm sure. By contrast the orchestral music, featuring four bandonens - the small Argentian squeeze-box - is utterly captivating. Despite some long musical interludes, we are never impatient to get on with the dance.

Sandor and Miriam, Roberto and Marcela, Diego and Natalia . . . there are six couples in all, and we get to know them rather well in the course of an evening of star turns. We find out their little ways, and their dynamic as a couple. Tango famously encourages speculation on what the dancers are like in bed together, but here we wonder what they're like in the kitchen, too.

Mayoral and Elsa Maria are the discreet older pair, he dapper, she elegant in ubiquitous sequinned black and towering spike heels. The rapid, complex steps make no allowance for age, but here the movements are economical. He tweaks his jacket during a short pause and mops his brow when she's not looking. She adjusts his hold away from the buttock, but warms up later, when he whispers in her ear.

Carlos and Inez are the wild ones, scooting on stage snorting and spitting, fighting like cat and dog. His style is rough, shaking his woman like a cocktail, forcing her into faster and more complex steps. She, dishevelled, gives as good as she gets, then suddenly turns and almost purrs as she wraps a leg around his torso and strokes his back with her thigh.

It's hot stuff, but there's plenty of fun blowing through the steam. My favourite couple kept up a front of propriety throughout: he clean- cut, she tall and prim, but with a small, knowing smile. Their insatiable appetite for dangerously fast, flicking steps (one false move and their legs would be severed at the knee) left the audience in no doubt as to what they did after hours. Forget champagne, oysters and rhino horn. See Forever Tango.

While age was proving unwitherable at the Strand, youth was going through its paces at Sadler's Wells, where NDT2, the youth company that feeds into the famous Nederlands Dans Theater, began a fortnight's residency. The dancers are aged between 17 and 21, a fact which makes itself felt through muscle-tone more than technique, which is flawless. The girls particularly have that smoothly lissom line that hardens in more experienced dancers, however slender. The group's founder and leading light, Jir Kylin, knows just how to exploit that freshness in the work he creates for the group. In Un Ballo, set to Ravel's gorgeous Pavane, five couples dance out their affections, tenderly, lyrically, ingeniously, each girl adapting her flowing skirt into a barrier, rope, winding sheet and, finally, secret tent to shelter her lover.

Petrol-Head Lover, the final piece, comes as a relief from too much sensibility. Gideon Obarzanek's cartoon number is the kind of brash, energetic, quasi-political effusion you would expect young dancers to take to their hearts. Dressed in motoring goggles and wearing toy cars as tutus, they jostle, shake fists, crash, and finally revert to the de- motorised simplicity of the jungle before rebuilding the social fabric. On this showing, NDT2 as a company has almost everything: energy, grace, precision. Perhaps it's too much to ask for depth.

'Tango': Strand, WC2, 0171 930 8800. NDT2: Sadler's Wells, EC1, 0171 713 6000, to Sat.