Random Samples

Science  19 Jun 2009:
Vol. 324, Issue 5934, pp. 1495
  1. Sorghum Hero

    CREDIT: COURTESY OF PURDUE UNIVERSITY

    Agronomist Gebisa Ejeta of Purdue University in West Lafayette, Indiana, last week won the $250,000 World Food Prize—the “Nobel Prize” for agriculture—for developing drought- and weed-resistant sorghum varieties in Africa. Ejeta, born in Ethiopia, spent 15 years looking for ways to defeat striga, a parasitic weed that devastates sorghum crops. He finally identified the chemical signal from sorghum that striga rootlets pick up and developed sorghum seeds in which the process would be interrupted.

    Ejeta has spent his whole career at Purdue, where he got his doctorate in 1978. He'll be honored at a 15 October ceremony in Des Moines, Iowa.

  2. Self-Confidence Genes?

    Brains alone don't make a star student. Motivation and self-confidence—what some psychologists call “self-perceived abilities” (SPAs)—are important, too. Now, psychologists report that not only IQ but SPAs as well are strongly influenced by genes.

    A team led by Corina Greven of the Institute of Psychiatry in London examined data from a large longitudinal study of British twins. For 1217 identical twin pairs and 1070 same-sex fraternal twin pairs, all 9 years old, the researchers compared school test scores, IQ scores, and results of a test in which the subjects ranked themselves on a five-point scale ranging from “not at all good” to “very good” at English, math, and science subjects.

    By comparing scores of identical twins (who share 100% of their genes) and fraternal twins (with 50%), the researchers estimated a heritability for SPAs at 51%. “Contrary to extant theories, SPAs are substantially influenced by genetic factors, … at least as much as IQ is,” they wrote online last month in Psychological Science. Heritability of IQ, which goes up with age, was estimated at .43 for the 9-year-olds.

    “I don't think anyone has looked at this before,” says Nicholas Martin, a twin researcher at the Queensland Institute of Medical Research in Brisbane, Australia. “It would be interesting to explore further what the roots of self-confidence are, since it seems to be semi-independent of true ability.”

  3. Underwater World

    Stones believed to have been used as caribou-hunting blind. CREDIT: JOHN O'SHEA AND GUY MEADOWS

    Some time between 10,000 and 7000 years ago, hunters herded caribou on what is now the bottom of Lake Huron. Now researchers are searching the site—a land bridge that once connected Michigan and Ontario when lake levels were about 100 meters lower—for clues about its inhabitants.

    Anthropologist John O'Shea and ocean engineer Guy Meadows of the University of Michigan, Ann Arbor, probed the waters with side-scan sonar and a remote operating vehicle to uncover what appears to be a former caribou hunting ground. They identified a long string of boulders, or “drive lane,” used to guide caribou to an ambush site with large boulders believed to be a hunting blind. Other signs are suggestive of a campsite, the team reported online on 8 June in the Proceedings of the National Academy of Sciences. The researchers plan to explore the area further with scuba divers and an autonomous underwater vehicle. O'Shea says the site may shed light on the transition from nomadic big-game hunters to a more settled society.

    “Some of the features they see are really intriguing,” says paleontologist Russell Graham of Pennsylvania State University, University Park. “If their interpretations are right, … we might find perishable remains,” such as bones and wood artifacts that are typically lost to the acidic soils of the northeast but that could be preserved in the water, he says.

  4. Making It Last

    CREDIT: JENNI KESANIEMI AND ANNE LEHTOVAARA

    Maybe size doesn't matter with fruit flies, but for the males, at least, longer is better.

    In the fruit fly Drosophila montana, females who are detained in lengthy copulations with males wait longer before going at it again, a team of European scientists reports in a paper in press at BMC Evolutionary Biology. It's to the males' advantage, as the longer they draw out the encounter, the greater the chance that they will father the ensuing offspring.

    In fruit flies, males and females seem to have different ideas about how long they want copulation to last. Not long after a female has permitted a male to mount her, she tries to kick him off, report researchers led by Dominique Mazzi of the University of Jyväskylä in Finland. The scientists found that the males who manage to hang on stayed on 50% longer than those who were successfully rebuffed.

    Protracted copulation didn't enhance fertility, the researchers found. Rather, it prevented females from hooking up quickly with competitors. If the scientists interrupted the linkage, the females quickly found someone new.

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