Why are we walking this way? Rambert celebrates Charles Darwin

The opening raises hopes. In an all-black setting, with a reflecting floor, a collection of white cocoons, lovely objects, glows from within. In silence, for quite a while, we observe shapes moving, then hatching. The dancers are in parti-coloured all-over tights: seen from the front, they are white; from the back, black. If, however, we expect that "change" will involve a blossoming into full colour - the world of animals and birds - we never get it.

Anderson's music is squealy in the early sections; later, the texture becomes densely clotted. I found it trying on the nerves, distracting from the dance; and I thought fondly of Constant Speed, with the lovely melodies of dear old Franz Lehar.

The dance, like the music, is a series of episodes. Entrances and exits are made from and into a dark void. A blurred impression remains of sinuousness and rippling, changing formations, but none­theless an air of sameness. The movement builds in vigour. Meanwhile, one dancer is elaborately wrapped in silver foil, to make a "mould". This is then removed, placed centre stage like an idol, and glows gold: ah, a bit of colour. At the climax, when the dancers have changed into all-white or all-black, the figure is abruptly squashed - and your guess is as good as mine, if you have one.

The other new piece, Tread Softly, is Henri Oguike's first creation for Rambert. His title comes from a line from WB Yeats: "Tread softly because you tread on my dreams." Physically, though, what is trodden on is the abdomen. The piece opens with a woman recumbent and a man emerging from the blackness to step, very gently, on her midriff. Later, she returns the compliment. Later again, another girl trips lightly across the full length of three men lying end to end. The music is Schubert's String Quartet in D minor (Death and the Maiden), in Mahler's orchestration; and to its tense rhythms, Oguike bombards us with hyperactivity.

The dance is packed with quirky moves and gestures: wriggling and wagging, pelvic undulations, slaps, cantering processions with hands to backs, like wings. Three women on the floor, straining with legs apart, appear to be on the point of giving birth. Asalia Khadje's costumes gleam white in Yaron Abulafia's lovely, hazy lighting, which also makes line patterns along which the dancers tread. By the end, though, with all 10 dancers jigging, I was exhausted by the sheer busyness.

We get variety of pace and colour in Siobhan Davies's delicious Carnival of the Animals, which completed this programme. Her interpretation of Saint-Saëns's "zoo" is decidedly anthropomorphic, like a sophisticated series of charades at a party. The dancers wear white tails - in the sartorial sense, a visual pun - against David Buckland's decor, showing the painter "Le Douanier" Rousseau in his landscape with tiger.

Davies's witty dances make only sly hints at her animals' characteristics. Pieter Symonds, the convener of these revels, is also a rather suave elephant. The ensemble for the Aquarium number waltz in couples or swim in shoals. Four women bounce on an imaginary perch to the trilling bird music. The cuckoo, so sweetly lovelorn, fails to attract a mate; and Alexander Whitley is beautifully lithe and soulful in the swan solo. Altogether a delight. In the whole programme, the dancers are superbly watch­able, and the musical performance from the newly named Rambert Orchestra is admirable.

The same qualities shine from the Mark Morris Dance Group and their own regular musicians in everything they present. Morris's second programme at the Wells included another work new this year, Visitation, set to Beethoven's Sonata No 4 in C major, for cello and piano. Maile Okamura is the central figure, who inserts herself into various encounters with a group, but never fits in, and after several episodes is left alone, defiant. I found this made a rather bland opener, and Elizabeth Kurtzman's casual costumes are depressingly drab.

Going Away Party is one of Morris's jokey pieces, to Western swing songs from Bob Willis and His Texan Playboys. The dance is infectiously lively and inflected with the sense that not everything is hunkydory between three couples, until things are resolved in a hoedown. But one character, danced by Bradon McDonald - who has a solo to the title number - is given the brush-off by the rest. Another outsider. McDonald (with a beard and ponytail) had a star spot with a trio of short dances to catchy piano preludes by George Gershwin, which Morris himself used to dance, captivatingly, even when he was getting on the portly side. The slim McDonald, in his white gloves and spats, proved an excellent successor in the debonair choreo­graphy, with its jaunty, darting sallies, quick stops and starts, and intricate embroidery of footwork.

Then came the climax we had all been waiting for: the extraordinary Grand Duo, with Lou Harrison's eruptively propulsive music for violin and piano. The 12 dancers are a tribe in a ritual. In Stampede, there are rushes and withdrawals of two sides in confrontation. In A Round, they lope in a circle. The finale, Polka, knocks you out of your seat as they blaze round, arms shooting out madly, slapping thighs, stabbing legs, wagging heads in a mounting, manic frenzy. The power, gutsiness and precision rhythm are unforgettable.