Fingering the Answers

Sunday, June 05, 2005
RELATED TAGS: COMPUTERS

Personality traits digitized
Don’t judge a man by his handshake; look at his fingers instead. Psychologist Peter Hurd of the University of Alberta in Canada compared the second and fourth fingers, that is, the index and ring fingers, of 300 university students and found males with the longest ring fingers were most likely to get in fights.

“A longer ring-to-index finger ratio has been correlated with higher levels of prenatal testosterone exposure,” says Hurd. Previous studies suggest that men with longer ring fingers are better when it comes to sports and have especially developed male-pattern visuospatial skills.

“We originally started this study just to have fun,” says Hurd, who is now looking at the fingers and penalty records of professional hockey players to see if they confirm his results. But assessing a potential mate by his fingers would be premature. “Finger length explains only 5 percent of the variation in physically aggressive behavior between individuals,” says Hurd. “But it does suggest more of our personalities are determined in the womb than we thought.”
Jocelyn Selim

Seeing prints with X-ray eyes
As any crime-scene investigator can tell you, lifting fingerprints is not always easy. They don’t readily show up on porous paper, wood, textiles, leather, adhesives, plastic, or human skin. Children’s prints disappear quickly because oils in their hands don’t last long. And print-detection techniques can destroy evidence. Methods using powder, liquid, or fumes cover or react chemically with fingerprints, damaging DNA and other clues in the process.

In an effort to solve these problems, analytical chemist Christopher Worley and his colleagues at Los Alamos National Laboratory in New Mexico adapted an existing X-ray technique to capture fingerprints and analyze their chemical composition. Using it, investigators can find out what the fingerprint’s owner had been handling—bomb-making materials, for example. “It gives you not just the physical pattern but the information contained within it,” says Max Houck, director of the Forensic Science Initiative at West Virginia University. “They have essentially come up with a technique to make the evidence do double duty.”

Micro-X-ray fluorescence uses a tiny beam to agitate the atoms of the elements making up the print, causing each of them to emit a distinctive X-ray signature. Computer software then turns this into a multicolored fingerprint with different hues representing the intensity of any element found—sodium from sweat, for example. “It’s similar to what the Weather Channel does when they show heavy versus light precipitation on a map using color,” Worley says.

Don’t expect to see a portable version of the equipment at a crime scene anytime soon. It is the size of a footlocker and requires 30 hours to scan a single print. “It would be an expensive way to visualize prints on a regular basis,” says Houck, “but it’s good anytime you need to squeeze more information out of them.”
Jessa Forte Netting

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