Distillations - What the Dog Knows - page 59

Although it has been around as long as we have, few researchers know much about the
scent of human death. For all the attention that a forensics show like Bones receives, and
as much as forensic scientists know about maggots, skin slippage, and the thermodynamics
of putrefaction, the work on the volatile compounds that vent of human decomposition is
just starting. Despite some early medical fascination and training with the smell of death, for
most modern scientists and chemists, “odor mortis” is a new frontier. Forensic anthropolo-
gist and research scientist Arpad Vass and his colleagues have identified nearly 480 different
volatile compounds coming off decomposing bodies. Arpad thinks it will be closer to 1,000
organic compounds (though not all of them volatiles) by the time they are finished creating
a DOA database—which in this case stands for “decomposition odor analysis,” not “dead on
arrival.” As Arpad noted with his slightly inflected German accent, the decomposing human
is “a pile of pollution.”
Why bother sorting out the chemicals from that messy pile? Because ultimately, the know-
ledge may help create a machine that can help detect the smell of death. It may help scientists
develop more effective pseudoscents for dogs to train on.
If it's a new frontier to figure out what compounds are in the air column from human de-
composition, it's another stratospheric leap to understand what the dog's nose is picking up
from that air column and translating as human remains. No one knows exactly what the dogs
are smelling. We can't ask them. Most likely, they are smelling a lot of things mixed together.
“It's a much more complex chemical composition than any other forensic sample, with the
possible exception of human scent,” said Florida International University analytical chemist
Kenneth Furton. He and a group of scientists, trainers, and law enforcement representatives
are trying to develop a national set of best practices for detection dogs. Creating a set of best
practices is a challenge, and understanding how best to train dogs to detect human decom-
position is one of the group's biggest challenges. “There are more knowledge gaps in human-
remains detection than anywhere,” Furton said.
The things that we humans invented—bombs, manufactured drugs, and land mines—are
chemically simple in comparison to our remains. Decomposing humans are not entirely a
black hole, though. While no one has yet nailed the perfect formula for what it is that good
cadaver dogs think is unique or interesting about dead people—as compared with, for in-
stance, garbage from a suburban household—we do know that solidly trained dogs can tell
the difference between dead human, dead deer, and aged goat cheese, or something equally
putrefied and odiferous. Arpad noted that cadaver dogs tend to alert on dead sheep more
than on other species; he thinks some dogs get confused by the generous dose of sulfur that
sheep emit after they die. We emit it, too.
Although sheep may be chemically close to humans, there are, he notes, several significant
chemical differences between us. Chemicals we ingest may play a role. Arpad's research labor-