Dance: Siobhan's dance to the music of Conlon

IMAGINE, if you can, an octopus in steel-capped shoes playing a Steinway. Now imagine that octopus being tickled under the armpits and you get an inkling of the hair-raising, sometimes hilarious nature of Conlon Nancarrow's studies for pianola. No human hands can play this music, though some have tried. There are just too many notes, too fast, too crazily spaced. Manic. So your first thought is how very odd it is that Siobhan Davies, that most sensitive marriage broker of dance and music, a stalwart for keeping theatre music live, should want to match this mechanised madness to her human and humanising art.

Yet there is method in it, if you keep your eyes peeled. This new work, Eighty-eight, hits the ground running. David Buckland's black and silver set is flanked by monochrome prints (framed portraits of each of the dancers) and a set of giant chrome heating pipes swathed in steam. Peter Mumford's piercing searchlights swerve and dart in the darkness with menacing intent. Then the dancers appear, sprinting, dodging, revved-up. Davies's choreography isn't known for speed - this is new.

From the pit emanate furious tinklings of piano sound, like a crystal palace shattering into a thousand shards. Scraps of loud boogie-woogie assault the ear, a crashing tango, a frenzy of trills. Then sudden, deafening silence. The women, in more familiar Davies mode, scoop and shape great chunks of air, which gives a sense of sculpted negative space as much as positive presence. The more frantic the music, the calmer the moves: slow balances to a set of nursery tunes played at reckless speed; unearthly slow walking through an avalanche of glissandi, while a counterpoint group lurch, leap and run. They don't so much dance to the music as through it. As always with Davies's dance, you make your own stories (a parable of people seeking serenity through the busy-ness of life?). But any fixed interpretation is foolishly inadequate. It's too subtle for that.

If nothing more, Eighty-eight (a reference to the number of keys on a piano) is a vibrant exploration of dynamics, human versus mechanical . Yet ironically it's the machine element that seems the more erratic. In pre-recording days many composers, including Rachmaninov, Gershwin and Stravinsky, saw the beauty of transferring their compositions to piano roll for the sake of posterity. But only the nutty American hermit Nancarrow tried to bypass human intervention entirely by composing direct to pianola. His scores are meticulously punched in tiny perforations on to rolls of paper and relayed through a special device on to the keys of an ordinary piano, which at the performance in Oxford was hidden in the pit.

Might Davies not have saved herself a lot of trouble by using the same music on CD? Possibly. But during the interval when lingering patrons spotted pianola whizz Rex Lawson dismantling this bizarre machine, he was persuaded to give an impromptu demonstration, and revealed that strong calf muscles, flexible thumbs and a quick mind are essential to its operation. Even in Nancarrow's dehumanised music the fallible element prevails. That this one happened to possess lively repartee, a spectacularly hairless head and a two-foot beard was an entertaining bonus.

The Siobhan Davies Company marks its 10th anniversary this season; to celebrate, she has blown her entire Prudential Award on hiring two extra (splendid) dancers, bringing the number up to 10. This enables her to revive a work she made earlier for Rambert, Winnsboro' Cotton Mill Blues, which with its theme of factory work and human toil is a perfect match for Eighty-eight. The title comes from Frederic Rzewski's scrunchy piano blues (played here with superhuman force by Andrew Ball). But the music is imaginatively extended by the chunterings of Lancashire cotton looms, while the dancers form patterns of cogs and chains and coils which suggest - without anything so obvious as direct imitation - the oppressive drill of factory work as well as the action of machines.

For those who associate Davies with quiet and elegant introspection, this up-tempo programme will come as quite a stiffener: exhilarating stuff. But still it's far from show-off, "How do they do that?" dance. Unique in her field, Davies bends all her craft to penetrating human feeling and giving it form. When it succeeds as well as this does, it transcends its own medium to become something beyond theatrical performance. A kind of brain-food, perhaps.

Edinburgh Festival Theatre (0131 529 6000), Fri & Sat; Cambridge Arts Theatre (01223 503333),22 & 23 May; Blackpool Grand Theatre (01253 290190), 29 & 30 May.