A scientific exhibition examines what makes human beings individuals
WITH the construction of the railways in the 19th century, a new sociological phenomenon was born: the travelling criminal. Until then, police had relied on local communities to recognise a bad apple in their midst, but now the felons were on the move, wreaking havoc in communities which had no knowledge of their past and hence no reason to be wary. For law enforcers trying to contain the problem by sharing descriptions of known recidivists, it became imperative to answer one question: what is it that identifies someone as a particular person?
This question has long troubled humanity, of course, and it is explored in all its facets in a new exhibition at the Wellcome Collection in London. One practical application lies in the forensic arena. The first solution offered, branding, was simple and effective. But even in a society that preferred to believe that criminals were born and not made, this was soon deemed unacceptable. So there was a need to find something innate to human beings that remains constant from the cradle to the grave, and that is sufficiently differentiated in the population to make it useful in identifying individuals.
Alphonse Bertillon, who appears in one of the identity cards he invented, came up with a system that combined photography (the profile and face-on photos that police still use today) with a range of bodily measurements. His system was widely taken up until Sir Francis Galton, a colleague, rival and inveterate classifier, realised the individualising potential of fingerprints. These held sway for a century until, in 1984, Sir Alec Jeffreys of Leicester University stumbled on an even more powerful personal barcode: DNA.
Embedded in this short history is all the elusiveness of human identity; each new advance reveals the flaws in earlier systems. Go to the website of the New York-based Innocence Project to see the latest tally of exonerations that have taken place in America, after DNA evidence showed those convictions to be unsafe. At the time of writing, the figure comes to 246. Mistaken eyewitness identification is a major culprit, but fingerprint misidentification is cited too.
Ironically, our facility for recognising faces may be to blame. The brain has evolved to look for patterns, and when one is incomplete it will fill in the gaps, sometimes leaping to the wrong conclusion, as Brandon Mayfield, an Oregon lawyer, discovered when he was wrongly implicated in the 2004 Madrid bombings on the basis of a single, poor-quality fingerprint.
So what of DNA? Within hours of reaching a crime scene, police may now have information that helps identify suspects. In the courtroom, DNA trumps all other identifiers. But it has its limitations. With ever more minute quantities becoming detectable, contamination is a serious issue. The Phantom of Heilbronn murdered her way across Europe until, last March, she was discovered not to exist. The DNA found at each crime scene actually came from a female worker in the factory that manufactured the cotton swabs used to collect evidence.
There is another problem with DNA. When the technology allows for a person’s entire genome to be read from a single drop of blood, it may well constitute a gold standard for identification. But for now analysts work with a snapshot of that genome, represented by an arbitrary number of markers spaced along it. If there are gaps to be filled, the brain will fill them, which could make it vulnerable to the same kind of errors as its predecessors.
From the very real travelling criminal, via the Phantom of Heilbronn, the Wellcome exhibition returns to the central question. Perhaps identity, like beauty, lies in the eye of the beholder, and if people want to see one and not the other, they need to invent a new way of looking.