Friday, July 6, 2012
Juvenile delinquency among high school students may be partly linked to lack of sleep, researchers have found based on a new study. Although a handful of past studies have suggested such a link could exist, little detailed information exists. The new analysis found that more serious forms of delinquency appear to become more common in relation to the severity of youngsters’ sleep deficit. The study re-examined 15-year-old data from the National Longitudinal Study of Adolescent Health, a federally funded project that surveyed adolescent health in the United States in relation to a variety of risky behaviors. The survey sample used for the study on sleep and delinquency encompassed 14,382 high school students—half male, half female, 63.5 percent white. Students who slept seven or fewer hours nightly reported “significantly more property delinquency,” such as vandalism or theft, than students who slept the recommended eight to 10 hours, the authors of the new study reported. The findings appear in the Oct. 10 issue of the Journal of Youth and Adolescence. Those who slept five or fewer hours per night, meanwhile, “reported significantly more violent delinquency,” wrote the researchers, Samantha Clinkinbeard and colleagues at the University of Nebraska at Omaha.
at 12:39 AM posted by SCIENCE NEWS
Tiny green insects known as pea aphids have individual behavior patterns, or “personalities,” despite being clones of one another, scientists say. The researchers found differences in the way each individual responds to a threat. The study was part of a “burgeoning” of scientific interest in animal personality variation, noted the investigators, with the University of Osnabrueck, Germany. But despite this trend, they added, few studies have been done on invertebrates, or simple animals without backbones. Studies on “clonal invertebrates,” which are all genetically identical and would thus be expected to show limited differences in behavior, are “nonexistent,” they added, reporting their findings in the March 1 online issue of the journal Developmental Psychobiology. “This is surprising given the obvious advantages of using invertebrates/clones to tackle the crucial question why such consistent behavioral differences exist,” they went on. Personality differences not attributable to genes are generally presumed to be due to the environment in which an organism formed, though there is also a growing appreciation of epigenetic factors—chemical differences that are not genetic, but that influence gene activity. Pea aphids, scientifically named Acyrthosiphon pisum, are pale little insects typically less than a sixth of an inch (half a centimeter) long that feed on pea plants and their relatives. A cluster of aphids infesting a given plant is typically a genetically identical, or clonal, group produced by one mother without sex, although aphids can also reproduce sexually at certain phases. When a pea aphid is threatened by a predator—of which the species has several including wasps and grubs—it gives off a chemical alarm signal that alerts nearby aphids. They may respond in several ways: they can walk away, drop off the plant or seemingly ignore the signal. The researchers, Wiebke Schuett and colleagues, found that pea aphids can be divided into one of three categories: consistent “droppers,” consistent “non-droppers,” and some that behave unpredictably.
at 12:37 AM posted by SCIENCE NEWS
Next time you’re grumbling about a stale cookie or a steak that tastes “like cardboard,” count yourself lucky that you’re not Australopithecus sediba, the human ancestor who ate bark. At least, that’s what scientists say about A. sediba, a short, gangly South African species from two million years ago. Their study indicates the creature targeted trees, bushes and fruits for its diet, chomping on harder foods than other other known early hominids, or human ancestors. Virtually all others that have been tested from Africa—including Paranthropus boisei, dubbed “Nutcracker Man” thanks to its massive jaws and teeth—focused more on grasses and sedges, according to anthropology doctoral student Paul Sandberg of the University of Colorado Boulder, a co-author of the new study. The findings were published in the June 27 online edition of the research journal Nature. Scientists analyzed the A. sediba diet by zapping fossilized teeth with a laser, said Sandberg. The laser breaks off telltale carbon from the enamel of teeth, so researchers can pinpoint which types of plants the carbon comes from. The results show which of two groups of plants were consumed: so-called “C3” plants like trees, shrubs and bushes preferred by A. sediba, and “C4” plants like grasses and sedges consumed by many other early hominids. The teeth from both A. sediba individuals analyzed had levels of C3 outside the range of all 81 previously tested hominids, the researchers reported. “The lack of any C4 evidence, and the evidence for the consumption of hard objects, are what make the inferred diet of these individuals compelling,” said Sandberg. “It is an important finding because diet is one of the fundamental aspects of an animal, one that drives its behavior and ecological niche. As environments change over time because of shifting climates, animals are generally forced to either move or to adapt to their new surroundings,” said Sandberg.
at 12:34 AM posted by SCIENCE NEWS
Breeders have unknowingly bred the flavor out of tomatoes by favoring those with a nice uniform color, scientists are reporting. It’s hoped the finding could help growers recapture the old, sweet flavor of tomatoes—which, as they sit on supermarket shelves today, often seem not to taste much different from the packaging they sit in. The finding, reported in the June 29 issue of the journal Science, could have implications for the U.S. tomato industry, which harvests over 15 million tons of the fruit yearly for processing and fresh-market sales. “This information… provides a strategy to recapture quality characteristics that had been unknowingly bred out of modern cultivated tomatoes,” said Ann Powell, a biochemist at the University of California Davis and one of the lead authors of the study. For about 70 years, breeders have selected tomato varieties with uniformly light green fruit before ripening. These tomatoes then turn red evenly as they ripen, and they look nice in a supermarket display. Powell and colleagues say the gene at the heart of uniform ripening codes for the production of a molecule called GLK2, which is a transcription factor, meaning it governs genetic activity.
at 12:28 AM posted by SCIENCE NEWS