The analysis of scent compounds from a person鈥檚 hand can reveal whether they are a man or woman, which could help police work out what happened at a crime scene.
Human odour is a complex mixture of volatile organic compounds (VOCs) secreted from the body. These chemicals are a product of genetics, the environment and body secretions.
To see what information can be gleaned from them, at Florida International University and his colleagues recruited 60 people 鈥� 30 who self-described as male and 30 as female 鈥� from a range of ethnicities.
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The researchers collected odour samples by asking the participants to squeeze cotton gauzes for 10 minutes in their hands, which had been left unwashed for at least an hour. After processing the gauze with some chemical reagents, Furton and his colleagues analysed the samples using gas chromatography and mass spectrometry to identify the individual chemicals.
They used a model, based on a technique called linear discriminant analysis, to analyse the data and found it could identify the genders the participants ascribed to with an accuracy of 97 per cent, getting 29 right from each group.
鈥淭he most interesting aspect of this paper is that they were able to reliably discriminate between male and female donors through advanced statistical methods (aka chemometrics),鈥� says at Indiana University-Purdue University Indianapolis.
鈥淎 big issue here is gender versus sex,鈥� says of Texas A&M University. 鈥淭his research did not report sex of individuals, so it is unclear how correlated gender versus sex-biased odours are. This may or may not matter and likely ties to whether the odours are part of innate odour production versus gendered differences in chemical exposure to hands.鈥�
Hands tend to be heavily involved in crimes like robbery and assault. In the absence of fingerprints and DNA, analysing chemicals left at crime scenes by people鈥檚 hands could help identify who was there, suggest the researchers.
Tarone raises questions about how well this might work in forensic science, though. What happens if a person holds the hand of someone of a different gender, he asks. 鈥淗ow much of these compounds can be transferred and how long would such a signal last? Similarly, how much do hobbies and professions impact hand profiles?鈥�
鈥淚 think the main barrier to broader adoption of this method in forensic science is that hand VOCs have not been proven to linger at crime scenes or on materials, like discarded gloves or other clothing,鈥� says Goodpaster.
PLoS One
