Cadaver dogs are trained to locate and follow the scent of decomposing human flesh.
Dogs' sense of smell is far more acute than that of humans – the nose of a German shepherd contains about 200 million olfactory cells, while a human nose has about 20 million.
In a recent study, the forensic pathologist Lars Oesterhelweg, then at the University of Bern in Switzerland, and colleagues tested the ability of three Hamburg State Police cadaver dogs to pick out – of a line-up of six new carpet squares – the one that had been exposed for no more than 10 minutes to a recently deceased person. Several squares had been placed beneath a clothed corpse within three hours of death, when some organs and many cells of the human body are still functioning. Over the next month, the dogs did hundreds of trials in which they signalled the contaminated square with 98 per cent accuracy, falling to 94 per cent when the square had been in contact with the corpse for only two minutes. The research concluded that cadaver dogs were an "outstanding tool" for crime-scene investigation.
In one study involving four dogs and their handlers, anthropologist Keith Jacobi of the University of Alabama says cadaver dogs were able to detect remains at all stages of decomposition. Performance varied between dogs, but some could locate skeletonised remains buried in an area of 300ft by 150ft. "The few single human vertebrae I used in the study were well over 25 years old, and dry bone," Jacobi says. "This made the discovery of one of these vertebrae, which we buried in dense woods 2ft deep, by a cadaver dog pretty remarkable."
Nobody really knows how they do it.
Mark Harrison, national search adviser for the UK National Policing Improvement Agency in Wyboston, Bedfordshire says: "If you ask me, 'Will a machine replace dogs?' I would say no."
This miracle of technology, beyond what any humans can devise or even understand, is an amazing testament to God's creation.