Size really does matter for Saatchi & Co

It has been a good week for that ageing pack of artists known as the YBAs. Putting the lie to rumours of their imminent demise, the no-longer-quite-so-Young British Artists have staged a multiple comeback. At the Saatchi Gallery, "Ant Noises" - an anagram, if you hadn't noticed, of sensation - brings together variably new works by Damien Hirst, Sarah Lucas, Ron Mueck and Jenny Saville. Moving trendily eastward, two leading YBA dealerships have opened offshoots in Hoxton. Jay Jopling's White Cube has spawned White Cube² in a converted factory. The gallery's first show, "Out There", naturally includes Hirst, together with a clutch of those YBAs left out of "Ant Noises": Gary Hume, Gavin Turk, the Chapman boys et al. Sadie Coles, meanwhile, has opened Hoxton HQ. Her debut show also features Sarah Lucas - it's a small world, after all - alongside fillies from her private stable, like Angus Fairhurst.

Depending on your point of view, your reaction to all this may not be one of undiluted joy. The point of the Young British Artists was that they were all three of those things. Now that the first seems increasingly implausible, the point is lost. "Young" was a synonym for edgy, subversive, in-your-face - qualities that were always under threat from their own success, and appeared to meet their Establishment Waterloo at the Royal Academy. "Sensation" turned the YBAs into MABAs: "middle aged" is a synonym for well, for what, exactly?

The answer may be, maturity. The first thing that strikes you as you walk into the Saatchi is an unexpected air of poise. This is most apparent in Sarah Lucas' new work. Before, cigarettes were props in Lucas' tediously egocentric drama of aren't-I-a-bad-girl. Now they are an art material, woven and quilted and tessellated into a medium via which Lucas universalises her own experience. Her hand-rolled Malboros tell an allusive story of sex and death, sucking and drudgery. You can see the same kind of transformation in Jenny Saville's paintings. Where Saville's earlier work set out to shock, her new pictures are more introspective. Their subjects are still provocative - elephantine women, girls with lips like labia - but they are less relevant to Saville's new agenda, which is mark-making, working with paint, experimenting with abstract form.

Saville's pictures do raise another curiosity of mature YBA work, though, and that is its size. One particularly bitter school of thought holds that Charles Saatchi is so powerful a patron that he has actually shaped the kind of art that artists who aspire to catch his eye produce. Saatchi, note adherents of this school, is an ad man, with an ad man's taste for billboards; his gallery is a series of vast white rooms; ergo, Saatchi art is big art, for which read splashy, vulgar and self-promoting.

Critics of this persuasion will take dark comfort from White Cube², which apparently came about in part because White Cube¹ was too small to hold the more mountainous new YBA works. The dead hand of Saatchi, it seems, stretches even to N1. Actually, none of the works in "Out There" is particularly big. Hirst's dully jokey Rehab is for quitters - a skeleton crucified on a glass cross, its ping-pong-ball eyes goggling on columns of compressed air - is nine feet tall, Gavin Turk's Death of Che - a political Deposition in the manner of David's Marat - a stripling eight. Sadly for anti-Saatchists, most of the works in "Out There" are not just small but rather dull, Mona Hatoum's clinically elegant Untitled (wheelchair II) being one of the few to stick in the mind.

Saatchi-baiters will at least have their faith restored by "Ant Noises", whose centrepiece is Hymn, the punningly male anatomical doll which Hirst has blown up to twenty feet of polychromed bronze. Hirst has allegedly been particularly susceptible to Saatchian sizeism. Hymn is so high that it only just squeezes under the gallery's pitched roof, out-Saatchi-ing Saatchi himself. You find yourself wondering whether Hymn is a not very subtle dig at the collector, a portrait as Ozymandias meant to cut him down to size.

Actually, bigness and the Saatchi Gallery seem to me coincidental bedfellows. The point of the gallery's space is that it allows Hirst to play dollies with traditions of monumental sculpture. The real joke of Hymn isn't that it's big, but that it's bronze; the work is less about the skull beneath the skin than the material beneath the paint.

And playing is the right word. Scale is an aesthetic of childhood, and much of the art in "Ant Noises" is intentionally infantile. Walk into the room of works by Ron Mueck - another doll maker - and you find yourself alternately shrunk by Mask and magnified by his diminutive Angel and Pinocchio. My own feeling, for what it's worth, is less that the Saatchi Gallery forces artists to experiment with scale than that it allows them to do so: and that it is no coincidence that both the art and artists in "Ant Noises" should be growing up as a result.

'Ant Noises': Saatchi Gallery, NW8 (020 2328 8299) to 20 August; 'Out There', White Cube ², N1 (020 7930 5373) to 1 July; Sadie Coles Hoxton HQ, N1 (020 7434 2227) to 10 June