Citations
By Lydialyle Gibson
Photograph courtesy Susan Goldin-Meadow
Olfactory recall
After a long winter’s nap, Belding’s ground squirrels lose the memory of their littermates’ smell—a survival necessity in an environment where the animals must avoid inbreeding and rely on kin for protection—but they do relearn it. In a February 13 presentation at the American Association for the Advancement of Science’s annual meeting, biologist Jill Mateo said that during a six-month hibernation period, yearling squirrels forgot the scent of their siblings. But when the littermates were reintroduced in the spring, they re-established recognition by comparing their own smell to others’, a process Mateo describes as the “armpit effect.” Understanding animals’ capacity to remember kin is important, she said, for captive-breeding programs and plans to release endangered species into the wild.
Evolutionary echo
The mass extinction that killed the dinosaurs and countless other species some 65 million years ago still sends ripples through the fossil record. Taking a global census of marine bivalves, paleontologist David Jablonski, geophysical-sciences postdoc Andrew Krug, AB’99, AM’08, and University of California, Berkeley, biologist James Valentine found what Jablonski called “an echo of the big bang for evolutionary biology.” The researchers traced the geologic ages of 711 major bivalve lineages and saw an increase in evolutionary origination rates after the Cretaceous Period—when the dinosaurs died. What remains mysterious is the researchers’ discovery that origination rates hardly slowed, even after the first ten million years following the colossal die-off. “The tropics were the engine of recovery,” Jablonski said, “and they just kept pumping out new lineages.” The researchers published their findings in the February 6 Science.
Gesturing at 14 months leads to more words at age 4.
A small gesture
Toddlers who talk with their hands are better prepared to make the most of school. In the February 13 Science, psychologists Susan Goldin-Meadow and Meredith Rowe explain that children who use lots of gestures at 14 months have bigger vocabularies at 54 months than children whose hands stay quiet. They’re also better equipped to begin their education. The researchers found that early-childhood gesturing is connected to socioeconomic status. Videotaping youngsters from 50 Chicago-area families, Goldin-Meadow and Rowe found that 14-month-olds from wealthier, well-educated families used gestures to convey an average of 24 meanings during a 90-minute session, while low-income children averaged only 13. Once in school, higher-income children’s comprehension vocabulary measured 117 on a standardized test; poorer children’s was 93. Children begin gesturing at around ten months old, and it was “striking,” Rowe said, that socioeconomic status could become so clearly evident only four months later.
Priority check
Between 2006 and 2008, large numbers of Americans got on board with support for mass-transit spending, though they’re not keen on giving greater assistance to poor countries or big cities or space exploration. Released February 10, the most recent edition of the University-based National Opinion Research Center’s spending-priorities survey shows the effects of the past year’s spike in gas prices: in 2008 mass transit took tenth place on the list of priorities with a score of +40.8, up more than 15 points from 2002. Topping the list, as usual, was education at +68.4, with health in second place by a hair’s breadth. (Conducting the survey since 1973, researchers determine each score by subtracting the percentage of respondents who thought too much money was spent on a particular issue from the percentage who wanted to see more spent.) Interviewing 2,023 randomly selected Americans last year, NORC researchers also found the environment, the poor, and Social Security to be high priorities. Bringing up the rear: foreign aid, with a score of -52.3.