Monika Treut

The portrait of Monika Treut in the official Berlinale catalogue is only half of a set. In the original, the left-hand side shows Treut, stunningly made up, her hair swept back, earrings sparkling. It's labelled "Drag Queen". The right-hand side shows her in a leather jacket with her hair in a kind of quiff. There is a "wanna try something?" look on her face, an entirely convincing moustache and a cigarette dangling from her lips. "Drag King" is written underneath.

The Panorama has used the one on the right as the publicity shot to accompany her new film, Gendernauts. It is tempting to say "this year's film", since there is a Treut movie in the festival most years. But this one is a classic Treut subject, about a world that the mainstream media tends to treat as deviant. Take last year's unforgettable Didn't Do It For Love. It's about Eva Norvind, a former Norwegian showgirl who became a Mexican movie star and then went on to establish herself as the most famous dominatrix in New York.

Norvind has stayed in touch with Treut. "She calls me once a week," the Hamburg-based director says with a wry smile. "I've told her I'll have to start sending her bills. She's using me as her shrink." But it's said without malice.

Gendernauts is also about people Treut has known on and off for nearly a decade. One of them, Annie Sprinkle (née Ellen Sternberg) played a major part in her highest-profile film, Female Misbehavior. And besides, the new picture is like a logical extension of all Treut's earlier work: it's about "gender fluidity" in the Bay Area of San Francisco, where gender is surely more fluid than anywhere else on the planet. (Well, not so much fluid as flowing firmly in a direction determinedly different from whatever appears on one's birth certificate.)

Over the years, Gendernaut's subjects have undergone regular oestrogen or testosterone treatment, many of them under the supervision of the Transgender Clinic. The experience has made them what Treut calls "travellers who go quite far along the spectrum of where you say 'this is female, this is male'. They show us the way the journey goes. They provide us with a tremendous possibility of getting an insight into our own cocktail of possibilities of female and male."

The director, who regularly travels to San Francisco to make films, teach or simply hang out, decided to make the documentary because these changes had started to become really marked, particularly with the video artist Texas Tomboy. She was still quite female last time Treut saw her, but now adorns the poster for the film, standing there with cropped blond hair and stubble, staring out at the camera with piercingly aggressive blue-green eyes.

Texas Tomboy won't be coming to Berlin. He no longer does interviews, having become fed up with the sensationalist approach of the TV talk shows. But Stafford, who is also a graphic designer, will be here, along with Sprinkle. As will Sandy Stone, the "goddess of cyberspace" and author of The War of Technology and Desire at the Close of the Mechanical Age, who is the real authority on the subject and a reference point for the film.

"The synthesis of sexual hormones wasn't possible before the late 1950s," explains Treut. "The synthesis of oestrogen, the female hormone, has been possible much longer than it has for the male hormone, testosterone, which is relatively new."

Gene genies

"What I find very interesting is that the doctors in the Transgender Clinic in San Francisco are saying that there is almost no research being done on the use of testosterone in biological females," she adds. "They're quite curious about what's happening."

And so is Treut, but more as a film-maker than as a potential gendernaut. "I like to do cross-dressing sometimes," she says. "I have a lot of fun with that, but that's it. I was tempted by hormones about 10 years ago, but it's so much work. You have to focus so much on your own body. And I thought, I'm not that interested in myself. I think you'd have to make yourself the centre of your world for a lot of the time - I've seen it with friends."

In some ways, Gendernauts completes an unexpected circle for Treut and her production company Hyena Films. It existed long before this movie, producing Treut's films since the 1985 feature Verführung: die grausame Frau (Seduction: the Cruel Woman). Hyenas, it turns out, are the gendernauts of the animal kingdom. They are organised in a matriarchal society, in which the female hyenas have remarkably high levels of testosterone, not to mention a clitoris that looks more like a penis.

"But I didn't have a clue about this when I named the company," Treut says. "I just liked hyenas because they had such a bad reputation. I identified with them because they were outcasts and lived off garbage.

"And that's pretty much how we live in relation to the big film world," she concludes. "They're quite beautiful animals."