Science Briefs

Hair dye ‘CSI’ could help police solve crimes

Criminals with a penchant for dyeing their hair could soon pay for their vanity. Scientists at Northwestern University have found a way to analyze hair samples at crime scenes to rapidly determine whether it was colored and what brand of dye was used. Their report appears in the American Chemical Society journal Analytical Chemistry.

Richard Van Duyne and Dmitry Kurouski note that analyzing hairs for forensic investigations, despite what TV shows would have you believe, can be a labor-intensive, time-consuming and flawed process. Testing samples for DNA requires an intact bulb or root, which isn’t always present.

The researchers turned to surface-enhanced Raman spectroscopy with a portable Raman spectrometer. SERS can detect minute amounts of illicit drugs, explosives, gunshot residue and body fluids. With this method, the team could rapidly confirm whether hair samples, even microscopic ones, were dyed and what brand of colorant was used. This highly sensitive technique could help forensic investigators analyze hair quickly in the field, the researchers say.

Study finds where ants go to ‘do their business’

Ants may use the corners of their nest as “toilets,” according to a study in the journal PLOS ONE by Tomer Czaczkes and colleagues from Germany’s University of Regensburg.

Little research has been done on ant sanitary behavior, so the authors of this study conducted an experiment to determine whether distinct brown patches they observed forming in ants’ nests were feces. They fed ants, living in white plaster nests, food dyed with either red or blue food coloring and observed the nests for the colorful feces.

They found that one or two corners of each nest started to fill with feces that was the same color as the food they were fed. The researchers found no other waste in these areas, suggesting that ants may use these areas as “toilets.” They also discovered that the ants didn’t just put their toilets anywhere: Almost all the ants placed their toilets in the corners.

Profiling nice guys by their finger lengths

Men with short index fingers and long ring fingers are on average nicer toward women, and this unexpected phenomenon stems from the hormones these men have been exposed to in their mother’s womb, according to a new study by researchers at Canada’s McGill University. The study, showing a link between a biological event in fetal life and adult behavior, was published in the journal Personality and Individual Differences.

Men’s index fingers are generally shorter than their ring fingers. The difference is less pronounced in women. Previous research has found that digit ratio – the second digit length divided by the fourth digit length – is an indication of the amount of male hormones, chiefly testosterone, someone has been exposed to as a fetus: The smaller the ratio, the more male hormones. The McGill study suggests that this has an impact on how adult men behave, especially with women.

“It is fascinating to see that moderate variations of hormones before birth can actually influence adult behavior in a selective way,” says Simon Young, a McGill psychology professor and coauthor of the study.