When a rabbit is scared, its hair stands on end.
When a human is scared, he or she calls the police.
Erector Pili and
The erector pili are smooth muscle fibers that give humans "goose bumps." If the erector pili are activated, the hairs that come out of the nearby follicles stand up and give an animal a larger appearance that might scare off potential enemies and a coat that is thicker and warmer. Humans, though, don't have thick furs like their ancestors did, and our strategy for several thousand years has been to take the fur off other warm looking animals to stay warm. It's ironic actually that an animal, sensing danger is near, would puff up its coat to look scarier, but the human hunter would see the puffier coat as a warm prize, leaving the thinner haired weaker looking animals alone. Of course, some body hair is helpful to humans; eye brows can keep sweat out of the eyes and facial hair might influence a woman's choice of sexual partner. All the rest of that hair, though, is essentially useless.
The science of melting ice just became a little more solid.
A new computer simulation shows that frozen water molecules, when heated up, vibrate until they start to spin. The swiveling motion causes the Mickey-Mouse-shaped particles to break free of their ice crystal home, bump into neighboring molecules and start a chain reaction of melting.
David van der Spoel, a computational chemist at Uppsala University in Sweden, said his team's computerized model is based on an actual 2006 experiment in which a laser melted ice, but could not provide the detail that the simulation offers.
"We want to see what's happening on an atomic level ... but experiments don't show that detailed structure," van der Spoel told LiveScience. "We've done that here with computer simulations, added the picture of how something moves from solid to liquid on a realistic time scale."