Study Backs Some Vaccination

A computer simulation indicates that it may not be necessary to vaccinate the entire U.S. population to stem an outbreak of smallpox if terrorists attack with the virus.

If people who come in close contact with those infected are vaccinated, that appears to be sufficient to keep the disease in check, according to the new analysis, which was based on a computer model simulating various scenarios for how a smallpox outbreak might spread through a community of 2,000 people.

The Bush administration is debating how widely to make the smallpox vaccine available. States have been instructed to begin making plans to vaccinate the entire population in the advent of an outbreak.

But M. Elizabeth Halloran of Emory University in Atlanta and colleagues found that may be unnecessary, assuming that Americans still had half of the "herd immunity" left over from before routine smallpox vaccination was discontinued in 1972. That could be supplemented by vaccinating police and other "first responders" and offering the vaccine on a voluntary basis, the researchers found.

"Although further research with larger-scale structured models is needed, our results suggest that increasing herd immunity, perhaps with a combination of preemptive voluntary vaccination and vaccination of first responders, could enhance the effectiveness of postattack intervention," the researchers wrote in the Nov. 15 Science.

Ancient Bones and Molecules

An international team of scientists for the first time has recovered two ancient biological molecules from a fossilized bone, a feat that they hope could be useful for studying evolution.

Christina Nielsen-Marsh of the University of Newcastle upon Tyne in England and colleagues from the University of Oxford, Harvard, and Michigan State University examined two 55,000-year-old fossilized bison bones.

The researchers isolated from the Siberian fossil a type of genetic material known as mitochondrial DNA, as well as a protein in all bones known as osteocalcin.

If such molecules can be recovered and studied from other fossilized bones, they may offer scientists a new way to learn more about how creatures evolve.

Studying physical attributes in bones can be very subjective and open to misinterpretation, the researchers said.

"By extracting biochemical information from fossils, scientists utilize tools that avoid these difficulties and offer more objective comparisons between ancient and modern species," said Nielsen-Marsh.

"Although temporal limits for DNA and protein survival are still unknown, their combined analysis may allow future molecular paleontological investigations to extend farther back in time," the researchers wrote in the December issue of the journal Geology.

Unsealing Their Fate

One way that harbor seals apparently can differentiate between the sounds made by whales that would eat them and whales that are friendly is by their voices, according to new research.

Volker B. Deecke of the Vancouver Aquarium Marine Science Center in Canada and colleagues used underwater microphones to play various sounds to wild harbor seals in British Columbia. When the seals heard the calls of killer whales they fled. But the seals did not flee when they heard the sounds of fish-eating whales that do not pose a danger to them.

The seals also fled, however, when they heard the sounds of unfamiliar fish-eating orcas from Alaska. That suggests the animals had learned which sounds not to fear, and fled from all others.

"By selective habituation -- learning what not to fear -- harbor seals pursue the more conservative, and thus more advantageous, strategy," the researchers wrote in the Nov. 14 Nature.

To Jump Farther, Weight

In ancient Greece, athletes competing in the long jump held weights called halteres, which they swung back and forth as they made their jumps. It's been unclear whether the weights helped the athletes jump farther, or whether the idea was to make the feat harder. Research has found the weights helped instead of hindered the long jumpers.

Alberta E. Minetti and Luca P. Ardigo of Manchester Metropolitan University in England used a computer model to test the effect of a jumper holding such weights, and took measurements when four subjects actually made jumps. The weights increased the power of takeoffs by about 6 percent, the researchers found.

"Halteres may therefore be the earliest passive tool that was devised to enhance human-powered locomotion," they wrote in the Nov. 14 Nature.

Synonymous Blue and Green

Many languages have no specific word for the color blue and do not distinguish between blue and green. Now, researchers think they may know why: High levels of ultraviolet B (UVB) exposure damage the eye in these countries, making many adults unable to perceive blue.

Delwin T. Lindsey and Angela M. Brown of Ohio State University reviewed 203 languages from around the world and levels of ultraviolet B, which rise closer to the equator, according to the November issue of Psychological Science. UVB can speed aging of parts of the eye to make it less able to distinguish blue from green.

In areas with low levels of UVB, languages tended to have a word for blue while areas with high levels tended not to, the researchers found. In addition, an experiment in the laboratory found that subjects tended to have difficulty recognizing blue when looking through a lens that simulated an eye that has been exposed to high levels of UVB.

-- Compiled from reports by Rob Stein