News in Science 
 
 Pubic hair bugs could help solve sex crimes 
 
 Pubic evidence DNA profiles of the bacteria that live on pubic hair could help identify rapists, according to preliminary research. 
 
 The study, published today in the journal Investigative Genetics, is the first to find that individuals have a unique profile of bacteria on their pubic hair. 
 
 "Everyone had something that was quite special to them," says forensic biologist, Silvana Tridico of Murdoch University in Perth. 
 
 Hairs are commonly found at crime scenes but they rarely provide human DNA unless they have been forcibly removed, leaving some part of their roots attached. 
 
 So Tridico and colleagues used a technique called metagenomics to do a "molecular audit" of bacteria living on human hairs to provide clues about the hairs' source. 
 
 "You get a DNA profile of the bacteria in that environment — a 'microbial signature'," says Tridico. 
 
 The researchers examined the DNA of bacterial communities inhabiting the scalp and pubic hair of seven study participants. 
 
 They examined the DNA profiles at three different times over a five-month period and found that while scalp hair samples had many common environmental microbes, pubic hair samples were much more specific to individuals. 
 
 "There were signature taxa that were specific to certain people," says Tridico. 
 
 This suggests that microbial communities on pubic hairs may be useful as 'microbial signatures' to identify individuals, she says. 
 
 The bacterial profiles were also able to identify whether the individual was a male or female. For example females had lactobacillus and gardnerella species of bacteria whereas these bacteria did not normally occur in the males. 
 
 Merging profiles 
 
 The most interesting results came from hair samples from two people who were a couple. 
 
 Over the period of the study, the bacterial profiles of the couple became more similar, says Tridico. 
 
 "At the last time point, I thought I'd made a mistake. I thought I'd looked at the woman's sample twice because her partner was showing lactobacillus species," she says. 
 
 "But then I reanalysed it and got the same result." 
 
 Tridico then asked the couple a "personal question" about their sex life and found out that they had actually had intercourse 18 hours prior to the collection of their pubic hairs. 
 
 "He works away a lot and it was his night off," she says. 
 
 The findings suggest that even without hair being transferred, DNA from the microbes on hair can be transferred during sexual activity. 
 
 If future research supports these findings, Tridico says it may be possible to check for transfer of bacteria between victims and suspects in rape cases. 
 
 "You could actually swab the victim's genital area and the suspect's genital area and see if the bacteria's transferred or not, or cut the pubic hairs and extract the DNA from them, she says. 
 
 "I can't believe that no one's thought about it before." ||||| When it comes to identifying a rapist, one of the main pieces of evidence police analyze are pubic hairs found at the crime scene. But most of these hairs are missing their roots and thus don’t harbor enough DNA for a proper match. Now, a new study suggests there may be a better way to finger the criminal: Look at the bacteria he left behind. 
 
 In addition to hair, police have relied heavily on semen samples to identify potential rapists, notes Silvana Tridico, a forensic biologist at Murdoch University in Perth, Australia. But criminals have gotten wise to genetic testing, she says, and are increasingly wearing condoms, which they take with them after assaults. She hoped to find a way to get around this problem by comparing bacteria that are present in the pubic hairs of the victim and suspects and then creating a microbial fingerprint that could nail the culprit. 
 
 Tridico and colleagues asked seven individuals—two of whom were living together—to collect their scalp and pubic hair for 5 months. The researchers then analyzed these samples in the lab, looking for bacterial populations present after 2 and 5 months. The scalp hair showed that 50 different varieties of microbes in males and 55 in females are found in this part of the body, but many of the microbes that were found were not specific to the individual carrying them. The pubic hair bacteria, however, turned out to be more distinct; in addition, each individual’s “personal” pubic bacteria stayed roughly the same during the 5 months. More kinds of bacteria live in these hairs: approximately 73 in males and 76 in females. A larger combination of different bacteria means it is more likely for people to carry a unique microbial signature on them, Tridico says. 
 
 Although each person’s pubic hair bacteria were distinct, the couple who were living together had greater similarity of bacteria on their pubic hairs at 5 months than detected after 2 months. The couple later revealed that they had sexual intercourse 18 hours before the collection of their hairs, the researchers report online today in Investigative Genetics. 
 
 Because the study included only one couple who were living together and only seven participants in total, the results are “far from conclusive,” Tridico cautions. However, the findings are encouraging, she says, and show that “it may be possible to differentiate between individuals on the basis of their bacteria.” 
 
 Max Houck, a lead forensic scientist at Consolidated Forensic Laboratory, a government organization based in Washington, D.C., agrees. But he also points out that it might be more difficult to use this method if there has been previous sexual contact between the victim and the subject, in the case of abusive ex-spouses, for example. “Human pubic hairs could be of potentially significant use in cases where the victim and subject have not had previous sexual contact.” 
 
 Rachel Fleming, a molecular biologist at the Institute of Environmental Science and Research Ltd., a government-owned research institute, who’s based in Auckland, New Zealand, says further research is needed before pubic hair bacteria can be used in forensic research. Experiments would need to determine how easily the bacteria are transferred between people, she says, and whether these microbes can be transferred by using the same bed sheets, clothing, or towels and how long transferred bacteria can stay on pubic hairs. 
 
 “I think this method has interesting possibilities for forensic science,” Houck says. “Forensic science is all about the associations between people, places, and things involved in criminal activities, and sexual assaults are among the closest associations we encounter.”
– Investigators routinely analyze pubic hairs found at crime scenes where rape is suspected, but it's rare that the hair has its root, and thus sufficient DNA to identify its former owner. Now researchers say that bacterial colonies on pubic hairs appear to be so unique to an individual that they could be used much like a fingerprint, reports Science. "I can't believe that no one's thought about it before," the forensic biologist who led the study—published this week in the journal Investigative Genetics—tells Australia's ABC. Silvana Tridico and her team analyzed the DNA profiles of bacteria that live in scalp and pubic hair, and found the microbes tied to the latter to be much more "specific to certain people." Further, one couple she studied who lived together had more similar profiles 18 hours after intercourse than they did two months after living together. "I thought I'd looked at the woman's sample twice," explains Tridico, "because her partner was showing lactobacillus species," which isn't typically found on males. ABC notes this could mean that the microbes can transfer even if hair doesn't. "You could actually swab the victim's genital area and the suspect's genital area and see if the bacteria's transferred or not," says Tridico. Still, results of the study are preliminary; only seven participants were analyzed and several questions remain, including how easily these bacteria transfer and how long they stay. But if future studies back up these findings, forensic scientists say they could identify even rapists who wear condoms. (Meanwhile, bite marks may be thrown out of court as evidence.)