DNA barcoding was invented by Paul Hebert of the University of Guelph, in Ontario, Canada, in 2003. His idea was to generate a unique identification tag for each species based on a short stretch of DNA. Separating species would then be a simple task of sequencing this tiny bit of DNA. Dr Hebert proposed part of a gene called cytochrome c oxidase I (COI) as suitable to the task. All animals have it. It seems to vary enough, but not too much, to act as a reliable marker. And it is easily extracted , because it is one of a handful of genes found outside the cell nucleus, in structures called mitochondria.
Barcoding has taken off rapidly since Dr Hebert invented it. When the idea was proposed, it was expected to be a boon to taxonomists trying to name the world’s millions of species. It has, however, proved to have a far wider range of uses than the merely academic—most promisingly in the realm of public health.