What are fingerprints good for, besides aiding police investigations? That’s the question that biomechanics researcher Roland Ennos recently set out to answer. This notion that human fingerprints (and presumably footprints) evolved because they act like tire or boot tread–increasing the friction against a smooth surface so we don’t slip or drop stuff–is a 100-year-old urban myth that, apparently, had never been put to the test [NPR].
To test the impact of fingerprints, Ennos rigged a machine that measured the amount of friction generated by a fingertip (belonging to study coauthor Peter Warman) when it was pressed against a piece of acrylic glass. Warman gradually increased the pressure, going from a light touch on the glass to a tight grip, but the corresponding friction didn’t increase as much as the researchers expected. Soon they realised that the skin was not behaving like a normal solid, where friction is proportional to the strength of the contact. Instead, it was behaving like rubber, where the friction is proportional to the contact area between the two surfaces [BBC News].
(more…)
Specialized cells found only on flower petals have the same basic function as nonslip mats that prevent people from slipping in the shower, a new study has determined. The bumpy cells, called conical cells, help bees come in for a landing on the flower petals and find their footing, so they can get down to the important business of pollination.
Conical cells had been something of a botanical mystery, with most researchers assuming they played a visual role. One hypothesis held that by modifying the spectral properties of the petal, the cells enabled the plant to appear brighter to pollinators [The Scientist]. In the study, will be published in a forthcoming issue of Current Biology, researchers showed that the conical cells’ main function is to provide friction, and that bees can detect them by touch. The first experiment used two kinds white snapdragons that looked identical to both human and bee eyes, but one was a mutant with flat cells instead of conical. The bees initially went to both flower types, but after 20 visits they chose the blossoms with conical cells more than 80 percent of the time.
(more…)
Scientists have found that manipulating a person’s sense of touch can confuse their sense of sight, an intriguing finding that suggests that touch and vision are integrated in the human brain…. For decades, instructors in medical schools have taught students that the senses —including vision, touch and sound — are interpreted in different, discrete parts of the brain, says Michael Beauchamp of the University of Texas Medical School at Houston. “Now it turns out what we’re teaching them is wrong,” he says. “There’s a lot more cross talk between the modalities” [Science News].
In the experiment, which will be published in an upcoming Current Biology, researchers used a postage stamp-sized device that used tiny pins to stroke the test subject’s finger in either an upward or downward direction. When subjects watched a stationary stripe on a computer screen after a machine stroked their fingertips, the motion of the stroking created the illusion that the stripe was moving [ScienceNOW Daily News].
(more…)
Everyone knows that scratching relieves an itch–but how? Neuroscientists now say they’ve found part of the answer in a new study of macaque monkeys. Previous research has suggested that a specific part of the spinal cord – the spinothalamic tract – plays a key role. Nerve cells in this area have been shown to be more active when itchy substances are applied to the skin. The latest work … found that scratching the skin blocks activity of nerve cells in the spinothalamic tract during itchiness – preventing the spinal cord from transmitting signals from the scratched area of skin to the brain [BBC News].
The findings could eventually lead to medical treatments for humans, says lead researcher Glenn Giesler. More than 50 conditions can cause serious itching, including AIDS, Hodgkin’s disease and the side effects of chronic pain treatment…. Some terminal cancer patients even cut back on pain medication just to reduce the itch, he said. Scratching can lead to serious skin damage and infections in people with chronic itch, he said. So scientists want to find ways for such people to relieve their distress “without tearing up their skin,” he said [AP].
(more…)
