Nineteenth-century ethnographic photographs show stripped subjects, devoid of any sign of personal identity or culture, standing stiff against a gridded background, reduced to statistics, reduced to their "essence" - an essence that could be scientifically deciphered and catalogued. Medics, criminologists and fledgeling social engineers wielded photography as the scientific tool that would capture the features they believed signalled the mad, the bad, the diseased, and so protect society.
With historical foundations like this, is it any wonder that the photograph is still seen as a truth apparatus? That despite the knowledge that images can be retouched, airbrushed, posed, manipulated and morphed, we still have a sneaking suspicion that the camera can't lie. How many times have you dismissed that candid shot with a "it doesn't look like me at all", yet had the uncomfortable feeling that that is what you look like to others, reality somehow captured by a dispassionate lens?
But Southampton University cultural studies lecturer Russell Roberts says photography, with its shifting, ambiguous status as both document and art object (and sometimes simultaneously both), has been far from a passive objective recorder of life. Curator of "In Visible Light", opening next month at the Museum of Modern Art in Oxford, he says photographs conceal as much as they reveal and their objectivity is as much circum- scribed by agendas, techniques and interpretation as any art.
The documentary status of photography has been somehow unquestionable. Its power was in the fact that it seemed to duplicate the way that natural vision worked - it provided a document which appeared to mirror optical experience.
But what happens when photography shows aspects of the world that natural vision cannot apprehend. When you start to look at the institutions that set photography to work in the name of science and the individuals behind the camera and their agendas and subjectivities, the validity of a photograph as an absolute document of race, ethnicity, disease, normality or of some kind of pathology, is undermined.
And it wasn't only institutions, there were almost certainly more personal agendas, too. It's hard to say what gazes intersected with the clinical gaze in a lot of these scientific projects where the naked body was at the centre. I don't want to reduce visual anthropology to the sexual fantasies of the photographer, but in some of these photographs there's definitely something else going on - a simmering sexuality.
In official hands, the camera became an extension of colonialism, says Roberts, taking over, labelling, pigeonholing people and bodies, regulating them for public consumption.
Take Sir Francis Galton, for example. A cousin of Charles Darwin, in the 1880s he worked to highlight the common characteristics of the healthy, the tubercular and the "criminal" by fusing images of groups of people via multiple exposures on a single photographic plate. The resulting "composites" showed, he said, with "statistical constancy" that a person's inner character was writ in their face.
"Individual faces, villainous enough but in different ways, when combined their individual peculiarities disappear and common humanity of a low type is all that is left," he wrote.
Armed with this information, Galton believed it would be possible for society to control breeding and remove de- generate strains from the population, leaving it happier and healthier. Photography, said the father of eugenics, proved the scientific legitimacy of evolution.
But while the thoroughly modern technique of photography gave Galton's work scientific credibility, with the 20:20 vision of hindsight, interpretations of his apparitions were patently subjective, yoked to Victorian prejudices of social class and the anxieties that abounded as changes wrought by the industrial revolution continued to bring floods of people into increasingly dangerous and congested cities. His conclusions were as emotively coloured as an artist's, says Roberts.
If photographic typing offered a quick method for assessing the character and capabilities of strangers, it also gave governments and propagandists a powerful tool - the generic stereotype - which could be used to control and mould public impressions. Fear this face, a photograph could say, whether the prevalent thought was determinism which refuted any possibility that "bad blood" might be made good, or Nazi pseudo-science that upheld Aryan superiority.
Ironically, "In Visible Light" also shows photographs from an "atlas of social types" commissioned by the Weimar Republic in the Twenties from photographer August Sander which, far from supporting this racist myth, revealed a diversity that completely undermined the whole theory.
But it was not just the bad who could be identified by their image, the camera was also wielded by Victorian doctors grappling with ways to systematise and improve their diagnoses of both the physically and mentally ill.
Nor are we any less affected by photographic "truth". We may know, after the expose, that John Prescott was not sipping from a bottle of expensive champagne and Camilla Parker Bowles never wore that wedding dress or tiara but, nonetheless, the image sticks to colour our views.
Today, artists are exploding this 19th-century investment in photography with work that parodies its scientific attributes. In the exhibition, Roberts juxtaposes Galton's work, for example, with that of German photographer Christian Boltanski, whose randomly placed, captionless faces of murderers and victims cut out from popular crime magazines rubbish the idea that a photograph can reveal inner identity and leave the audience examining their own preconceptions.
Others, like Oxford University psychologist, computer scientist and physiologist Dr Philip Benson, believe the camera can still serve both art and science. His eerie pared-down composites produced by a combination of camera and computer are as clear and precise as Galton's were blurred and selective. But instead of trying to identify the mad or bad, Benson is searching for the essence of beauty.
"I use the facial image from experimental research as a metaphor for discussing sensory representation in the brain. If we can isolate aspects of facial attractiveness or gender in a face then, by stripping things out, we might finally be able to get a handle on what makes something look beautiful."
One of the things that can be stripped in or out is symmetry, he says. By using real faces with naturally defined left and right sides and others computer-manipulated to have two left sides, or two right sides, or mirror images, Benson has found a compelling preference for the left side of a face as we see it.
At a time when X-ray was still in the realms of the fabulous, the camera seemed to offer the possibility of making the invisible visible. Photographers set up in lunatic asylums like Saltpetriere in Paris, to record the fleeting expressions, movements and postures of the mentally ill in the hopes of at least mapping the mind's states, if not capturing an elusive cause.
These asylum images were used as teaching aids for diagnosis and as an early form of psychological therapy, to confront the deluded with the "truth" of their own image - a theory used somewhat more gently today by phototherapists such as Jo Spence who use their craft to help people reshape their image of themselves and to come to terms with disease. In the 19th century, however, photographic mapping meant again the individual stood in for something feared, says Russell Roberts. "The individual became the disease. You couldn't see the disease, but photography allowed them to pigeonhole it, to create order, to superficially control fear of the disease by putting a face to it."
Yet photography, with its qualities of close observation, also made significant contributions to scientific understanding. Eadweard Muybridge's studies of human locomotion in the 1870s helped physicians create effective artificial limbs by allowing intricate study of the act of walking. His split-second images of a horse in mid-gallop, showing all four hooves off the ground, tucked up toward the stomach, not outstretched front and back, not only changed forever the way artists drew horses but heralded the art of "moving" pictures.
And while it's easy to be horrified by apparently crude attempts to classify individuals by what they look like - it's worth remembering that we still search for "scientific" shortcuts to reveal character - witness the increasingly ubiquitous use of personality questionnaires for job seekers and the number of requests for handwritten applications.
The explanation for this is likely, not surprisingly given photography's continuing if uncomfortable place at the crossroad between art and science, to have more to do with the viewer than the viewed.
`In Visible Light' will take place from 16 March-22 June at the Museum of Modern Art, Oxford (01865 728608)Reuse content