Guardians of the brain unmasked

Researchers have uncovered the secret identity of microglia, cells that patrol the human brain, protecting it from damage. Until now, they were thought to be dormant in the healthy brain. But using genetically engineered mice in which microglia glowed green, scientists were able to examine these cells in vivo. Though they have virtually immobile cell bodies, microglia have thin tentacle-like projections extending from their bodies that grow and withdraw randomly. They can patrol the entire volume of the extra-cellular environment of a healthy brain within hours, collecting harmful by-products given off by its cells and destroying deteriorated tissue.
-Jennifer Bates
Source: Science

I’ve been everywhere, man

Recent analysis of mitochondrial DNA in the aboriginal populations of southern India and southeast Asia has led to a controversial new theory about the initial exodus of Homo sapiens from Africa. It challenges the conventional wisdom that early humans entered the Near East and Europe from Africa through the Levant region about 45,000 years ago. The new findings suggest that early humans traveled from Africa, along the coast of the Indian Ocean to southern India 66,000 years ago, and reached Australasia relatively rapidly, within a few thousand years. Over time, human populations diffused from coastal areas into Asia, the Middle East, and eventually Europe.
-J. B.
Source: Science

A whiff of cosmic pixie dust

When the impactor from NASA’s Deep Impact probe slammed into the Tempel 1 comet on July 4, the resulting explosion threw up a 720-kilometer-wide plume of fine dust (see false-color image above), which suggests the comet’s surface contained little frozen water and was more porous than scientists had thought. Scientists are now analyzing the deluge of data from telescopes around the world to determine the comet’s composition. Comets are thought to contain material from the solar system’s primordial days, including water and compounds that may have helped establish life on Earth.
-Mike Ghenu
Source: Nature