Whether it’s a mugger or a friend who jumps out of the bushes, you’re still surprised. But your response — to flee or to hug — must be very different. Now, researchers have begun to distinguish the circuitry in the brain’s emotion center that processes surprise from the circuitry that processes the aversive or reward “valence” of a stimulus.

C. Daniel Salzman and colleagues published their findings in the September 20, 2007 issue of the journal Neuron.

“Animals and humans learn to approach and acquire pleasant stimuli and to avoid or defend against aversive ones,” wrote the researchers. “However, both pleasant and aversive stimuli can elicit arousal and attention, and their salience or intensity increases when they occur by surprise.

A team of researchers has determined through analysis of the earliest known hominid fossils outside of Africa, recently discovered in Dmanisi, Georgia, that the first human ancestors to inhabit Eurasia were more primitive than previously thought.

The fossils, dated to 1.8 million years old, show some modern aspects of lower limb morphology, such as long legs and an arched foot, but retain some primitive aspects of morphology in the shoulder and foot. The species had a small stature and brain size more similar to earlier species found in Africa.

"Thus, the earliest known hominins to have lived outside Africa in temperate zones of Eurasia did not yet display the full set of derived skeletal features," the researchers conclude.

A new study of finger-sized Australian lizards sheds light on one of the most striking yet largely unexplained patterns in nature: Why is it that some groups of animals have evolved into hundreds, even thousands of species, while other groups include only a few?

The study takes a look at Australia's most diverse group of vertebrates -- more than 252 species of lizards called skinks. Researchers at the Cornell Lab of Ornithology have found evidence that the "drying up" of Australia over the past 20 million years triggered this explosive diversification.

A win for embryonic stem cell research may be the kind of symbolic pyrrhic victory politicans engage in after bold action is no longer necessary.

It may not be necessary if research from Weill Cornell Medical College in New York City holds up. They say adult stem cells found in a male patient's testicles might someday be used to create a wide range of tissue types to help him fight disease -- getting around the need for more controversial embryonic stem cells.

Using spermatogonial progenitor stem cells (SPCs) obtained from the mouse's testes, the researchers were able to redirect the cells' development in the lab to form so-called "multi-potent adult spermatogonial-derived stem cells" (MASCs).

Biofuels are a wash environmentally and a negative economically because they requite subsidies to be competitive but there is one way they are a boon: the increase in world agriculture prices caused by the global boom in biofuels could benefit many of the world’s rural poor, according to a new book, Biofuels for Transport: Global Potential and Implications for Energy and Agriculture, written by the Worldwatch Institute.

“Decades of declining agricultural prices have been reversed thanks to the growing use of biofuels,” says Christopher Flavin, president of the Institute. “Farmers in some of the poorest nations have been decimated by U.S. and European subsidies to crops such as corn, cotton, and sugar.

Scientists believe that shortly after Earth was formed, it had a glowing surface of molten rock extending down hundreds of miles. As that surface cooled, a rigid crust was produced near the surface and solidified slowly downward to complete the now-solid planet.

Some scientists have suggested that Earth lost all of its initial gases, either during the molten stage or as a consequence of a massive collision, and that the catastrophically expelled gases formed our early atmosphere and oceans. Others contend that this early “degassing” was incomplete, and that primordial gases still remain sequestered at great depth to this day. New research by E. Bruce Watson, Institute Professor of Science at Rensselaer, supports this latter theory.