Spiders are covered with fine hairs that can detect the faint movements of an enemy creeping closer, or a prey insect moving nearby. Scientists had long thought that these hairs functioned like the hairs humans have in our ears, which each tremble in response to a specific frequency and have to work together for us to hear sounds. But a new experiment suggests that each individual hair on a spider is capable of responding to a whole spectrum of sound, thus acting as an ear all on its own. As Dave Mosher writes at Wired:
The hairs responded best to sounds between about 40 Hz, a low rumble of bass, and 600 Hz, a car horn (humans ears can detect between 20 Hz and 20,000 Hz). That they picked up such a wide range of frequencies at all could overturn previous assumptions about how trichobothria [as the hairs are called] work.
“They operate like band-pass filters or microphones, not like the hairs in a human ear,” Bathellier said. In effect, each hair is its own ear that filters out background noise and zeroes in on biologically relevant information, such as an unwary cricket’s hopping or a spider’s sneaking.
How all these tiny “ears” work together, though, is still a mystery—further studies will have to investigate how the hairs’ vibrations affect spiders’ nervous systems.
It was a stroke of serendipity that may one day help those who hide under comb overs or wear wigs: scientists studying how mice bowels react to a stress-reducing chemical have inadvertently discovered a cure to baldness. But unfortunately, it looks like this cure won’t apply to genetic baldness, which is by far the main cause of most hairless pates. Still, researchers hope the lucky find will eventually be used to battle at least some of the bare heads of humans.
The story begins with mice that were genetically modified to produce too much corticotrophin-releasing factor, or CRF–a type of stress hormone. Normally, as these stressed-out rodents age, their backs lose hair. But a group of researchers from the Veterans Administration and the University of California at Los Angeles didn’t care about hair, they just wanted to study the effects of a chemical on the modified mice.
Researchers at the Salk Institute developed a peptide called “astressin-B”, which blocks the action of CRF, and the teams injected the peptide into the bald mice. They weren’t thinking about baldness at all — they wanted to test whether the astressin had any impact on the mice’s gastrointestinal tracts. The first injection did nothing, so the team gave the mice additional injections over five days, and then measured the effects on the newly de-stressed mice’s colons. [Popular Science]
With most of the experiment done, the researchers forgot about the mice for three months. Then they returned for some follow-up tests:
However far-fetched some of their science has been, the barrage of forensic science TV shows during the last decade has ingrained into people the idea that even the most cautious criminals (we’re looking at you here, Dexter) leave something of themselves behind at the scene of the crime. And thanks to the march of genetic science and sequencing, those bits of someone can tell more and more about them. Even their hair.
In a study coming soon to the journal Human Genetics, Manfred Kayser and colleagues identify genetic markers that can predict a person’s hair color.
The researchers studied DNA and hair colour information from hundreds of Europeans. They investigated genes previously known to influence the differences in hair colour. “We identified 13 ‘DNA markers’ from 11 genes that are informative to predict a person’s hair colour,” said Professor Kayser. [BBC News]
The problem: Scientists want to study our circadian rhythms, our bodies’ internal clocks, and they can do so on the genetic level by examining how gene expression changes throughout the day. But ordinarily that would require sampling a person’s blood or skin multiple times a day, an ordeal few of us would want to endure.
The solution: hair.
Makoto Akashi’s team reports today in the Proceedings of the National Academy of Sciences that hairs, be they from the beard or head, contain the telltale signature of RNA activity that shows when we humans are at our peak activity level for the day.
Have you seen this man? Probably not: He lived 4,000 years ago.
The image to the left is not a wanted poster, but rather an artist’s impression of Inuk, the name given to him by the scientists who sequenced his genome. It’s the first time the genetic code of an ancient human has been deciphered this completely, and the researchers published their results this week in Nature.
Inuk died on an island off Greenland called Qeqertasussuk. Researchers don’t know the cause of death, but they do know he left bits of hair and bone that the permafrost preserved. Scientists found the thick clumps of hair—which could be the remnants of a 4,000-year-old haircut—in the 1980s, and stored them in the National Museum of Denmark. Today’s DNA sequencing technology allowed them to look back in time at what he may have been like. Inuk’s genes reveal he was a fairly young man, robustly built to exist in a frigid climate, with A-positive blood, dark skin, brown eyes, and thick, black hair on a scalp genetically susceptible to baldness [San Francisco Chronicle].
The notion that stress can cause hair to turn gray isn’t entirely a myth: at least when it comes to genetic stress applied to laboratory mice. That’s what researchers found when they damaged mice’s DNA with ionizing radiation, according to a study published in the journal Cell.
Scientists already knew that cells known as melanocyte stem cells were responsible for youthful hair color. Each of these cells divides into two cells: One that replaces itself and another that differentiates into a pigment-producing daughter cell called a melanocyte, which imbues hair with its browns, reds and blacks. Earlier research has suggested that the depletion of these stem cells was to blame for grayness. But how exactly these stem cells disappeared was mysterious. With no more stem cells around to produce melanocytes, hair turns gray [Science News].