Stardust Insights Come From Earth-Bound Meteors
At first glance, studying dust would seem to promise all the excitement of watching dust collect. Unless, of course, that dust comes from outer space.
Researchers have long analyzed the chemical composition of cosmic dust. The work has yielded important insights into the evolution of stars. But questions remain about the sources of cosmic dust. By some accounts, it comes from stars whose atmospheres are cool enough for material to condense.
To help fill in the picture, researchers at Washington University in St. Louis analyzed dust found embedded in primitive meteorites. By measuring the levels of various isotopes in the grains, they've added two more candidates: red giant stars in the final stages of life, and supernovae - very massive stars that end their lives in a cataclysmic explosion.
Based on their findings in the lab and on current notions of stellar evolution, the team reckons that red giants form the grains as their atmospheres expand and cool. The supernovae generate the dust during the violent mixing of elements that takes place as the shock wave moves through what's left of the star's atmosphere and into space.
Bi-peds' swinging ancestor
Eighteen million years ago there was Proconsul, an early ape that walked on all fours. Three-and-a-half million years ago, there was Australopithecus afarensis, which walked on only two. But what happened in between? How did apes evolve to climb, hang, and swing? Researchers in Spain recently reported finding a nearly complete fossilized skeleton of the ape Dryopithecus laientanus, which dates 9.5 million years ago.
To gain insights into how locomotion evolved, researchers need to study the skeletal elements associated with movement. But these elements are extremely rare.
Hence the completeness of Dryopithecus is seen as a boon. According to the research team that discovered the fossilized ape, the skeleton is clearly adapted to the kinds of motions seen in today's orangutans, a distant relative of Dry's. Although other researchers had favored an upright posture for Dry, it was from more-fragmentary fossils. With its completeness, the find from Spain seems to settle the question.
The bees go marching two by two...
In the insect world, ants and termites have long been known to establish trails to and from their nests. Generally wingless, they have no other way to get around but to hoof it. Now, researchers from the University of Arkansas have added another type of social insect to the trail register: Amazonian bumble bees.
While most of the bees in the colony they studied flew, 8 to 10 percent of the bees were consigned by their station in life to roam the forest floor in search of nest materials. The ''thatchmakers'' hike in pairs along a well-defined trail to a pile of leaf litter that serves as building material. Along they way they poke at the soil with their mandibles, or jaws, and investigate odd plant fragments they encounter. From the pile, they fly back to the nest.
Why walk when you can fly? The researchers posit that the behavior may be a response to the rough conditions the bees face. The approach may be a more efficient way to look for building materials than using aerial reconnaissance. And the hiking bees may speed response times if the colony's territory needs defending. In any case, the species provides a striking example of an evolutionary convergence of behaviors.
Newton's big apple?
New York dominates the competition in the annual Westinghouse Science Talent Search, with two New York City high schools each producing more prize candidates than the next leading state has.The 300 semifinalists announced last week by the Westinghouse Foundation and Science Service included 136 from New York State, 90 of whom were from New York City. California, with 20 semifinalists, was second. Forty winners will be announced in Washington Jan. 23.