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Straight ahead on "Our World" ... Facing the possibility of a flu pandemic ... high-tech weather balloons ... And great new ideas for the world's poor...
GRANT: "With this technology the cost of the house is 40 percent cheaper just to build, and then the cost of the energy to heat the home is 75 percent cheaper."
Those stories, the challenge of teaching evolution, a Website of the Week for readers, and more. I'm Art Chimes. Welcome to VOA's science and technology magazine, "Our World."
There's new evidence that something out of today's headlines ? climate change ? may have been at work in the extinction of the woolly mammoth and other large mammals at the end of the last Ice Age. But as we hear from VOA's David McAlary, it is a controversial challenge to the traditional view that human hunters killed off the beasts.
McALARY: Scientists have long debated whether the cause was climate change or hunting by the human newcomers from Asia.
New scientific dating of 600 bones from that era from Alaska and Canada's Yukon Territory, including bones of humans, suggests that the warming climate was the culprit. scientist Dale Guthrie says it was a time when the landscape was changing from frigid grassland preferred by the large species to something less hospitable to them.
GUTHRIE: "What happened during this changeover time was that more moisture and warmer temperatures allowed trees and tundra to move in, a very unproductive landscape for large mammals but very dense greenery."
McALARY: The study of the bones' ages, published in the journal "," shows that the woolly mammoth was already declining in number when humans arrived in North America from Siberia over the Bering Strait, which was still frozen at the time.
McALARY: But others cling to the belief that humans forced the large mammal disappearance ? not only in North America, but everywhere. University of Arizona geo-scientist Paul Martin has long described how the pattern of large animal extinctions coincides with human expansion and big-game hunting technologies.
MARTIN: "The arrival of the first people into a landmass [has] everything to do with the extinction of large animals at that time in that landmass."
McALARY: Supporting this view is the dating of several burial sites of big Australian land mammals, reptiles, and birds in 2002. It revealed that the animals died off about 46,000 years ago, a few thousand years after humans arrived. That was far earlier than the North American extinctions. University of Melbourne researcher Richard Roberts says climate change cannot be the explanation for the loss of this so-called megafauna. If it were, extinctions would have occurred simultaneously everywhere.
At the University of Alaska, Dale Guthrie agrees that animals are vulnerable to human colonization.
GUTHRIE: "The story is more complex than any simplistic idea. So to have one simple solution to all of extinctions seems to be rather unwise."
McALARY: David McAlary, VOA News, Washington.
Public health officials across the globe want answers to the same urgent question: What will they do if the deadly H5N1 avian flu virus mutates and sparks a human pandemic? Since 2003, about 100 people have died as the virus has spread out from East Asia. Millions of birds have also died from the disease or have been slaughtered as a precaution against further spread of the virus.
VOA's Rosanne Skirble has this report on the latest computer-aided strategies to slow the spread of a possible human pandemic.
SKIRBLE: Researchers at Johns Hopkins University developed computer models to analyze a variety of public health emergency scenarios, including restrictions on travel, isolation of infected patients, stockpiling of antivirals and the use of less effective but more available generic vaccines.
The model simulated the spread of a pandemic across the United States and England using data based on population density, demographics and human travel patterns.
Researcher Derek Cummings says the model shows that no single response can control a pandemic, should one develop.
CUMMINGS: "We found that you really need suites of interventions in order to significantly alter the course of the pandemic."