With over twenty times as many olfactory cells as that of a human, the canine nose constitutes the most sensitive and most accurate sensory tool currently known, particularly when combined with a trained dog’s ability to distinguish and categorize a multitude of individual and mingled scents which even the most cutting-edge technical equipment frequently cannot recognize or differentiate[i]. Today specially trained canines aid in arson investigations by detecting accelerants; support law enforcement operations by sniffing out explosives, narcotics, and articles of evidence; and participate in search and rescue missions in a variety of contexts, from mountain wilderness to urban collapsed structures.
The branch of canine scenting work known as Human Remains Detection, or HRD, involves locating (by scent) burials, the remains of deceased individuals, or traces or fragments thereof. Human Remains Detection canines train to recognize and locate the scent of dead human tissue, ranging from trace splatters of blood or decomposition residue in soil to entire cadavers or even mass graves. If properly exposed to a variety of scent sources during training, a well-trained Human Remains Detection dog recognizes the distinctive scent of a deceased human in whole cadavers, different types of soft tissue, desiccated bone, blood, hair, cremated ashes, grave dirt, and other potential sources[ii]. This scent signature, as discussed below, also appears in even ancient human remains, as demonstrated by the work of the Institute for Canine Forensics in California.
As with other canine scenting disciplines, much of the value of dogs as a sensory tool lies in their ability to identify and distinguish among a multitude of unique odors. In addition to recognizing several widely differing states of deceased human scent, trained Human Remains Detection canines differentiate and “exclude”, or ignore, live human scent, remains of deceased nonhuman animals, and other irrelevant signals[iii].
No human-made instrument known to date can reliably identify the distinct chemical or olfactory signature of human remains material, scent or residue, let alone differentiate between human and nonhuman decomposition products if degradation or contamination rules out DNA testing, as it often does[iv]. Frequently, however, HRD canines can.
Dogs trained for human remains detection are making a difference worldwide in both search and rescue (such as searching for deceased victims of an urban disaster, missing persons presumed dead, or drowning victims) and law enforcement (location of clandestine burials or other suspected murder victims), as well as archaeology[v].
[i] Vass, Arpad A. , Rob R. Smith, Cyril V. Thompson, Michael N. Burnett, Dennis A. Wolf, Jennifer A.Synstelien, Nishan Dulgerian, and Brian A. Eckenrode. “Decompositional Odor Analysis Database.” Journal of Forensic Sciences. Vol. 49, No. 4. July 2004. p. 760-769.
[ii] Cen-Tex Search and Rescue. Training Comm. July 2007.
[iii] Cen-Tex Search and Rescue. Training Comm. July 2007.
[iv] Vass et. al. 2004.
[v] Morris, Adela and Donna Randolph. “Evolution of the Historical Human Remains Detection Dog: Choosing the Best Resource.” Paper presented at the Society for Historical Archaeology Annual Conference; Sacramento, CA, 11-16 January 2006. Institute for Canine Forensics. http://www.k9forensic.org/
This guest post was written by Kiona Strickland, who is an anthropologist, search & rescue volunteer, writer, Army wife, and the proud human companion of a border collie named Duke. You can read more on her personal blog, One Day at a Time.