http://www.newscientist.com/news/news.jsp?id=ns99996357
"Tracking the recent whereabouts of suspected criminals or uncovering the true origins of asylum-seeking immigrants might come down to a single hair, says a UK researcher.
Stuart Black and his colleagues at the University of Reading are testing a new method of determining where people have lived by measuring the ratios of oxygen and hydrogen isotopes in their tissues or fluids. They presented their results at the British Association for the Advancement of Science Festival in Exeter, UK.
The isotopes, absorbed into the body from water, have predictable values for different local areas and leave a telltale signature in tissues. "Hair is particularly good because it grows about a centimetre a month," says Black. "So it actually grows a record of not only where you have been but what you have been eating and drinking.""
