New cells are born every day in the brain's hippocampus, but what controls this birth has remained a mystery. Reporting in Science, neuroscientists at the Johns Hopkins University School of Medicine have discovered that the birth of new cells depends on a protein that is involved in changing epigenetic marks in the cell's genetic material. 

If global warming projections turn out to be accurate, a rapidly warming climate would seriously alter crop yields in the tropics and subtropics by the end of this century and could leave half the world's population facing serious food shortages, according to new research.

Compounding matters, the population of this equatorial belt – from about 35 degrees north latitude to 35 degrees south latitude – is among the poorest on Earth and is growing faster than anywhere else.

The first people to arrive in America traveled as at least two separate groups to arrive in their new home at about the same time, according to new genetic evidence published Current Biology.

Everyday, all over the world, people assemble peacefully into crowds at places such as shopping malls, sporting events, concerts and tourist sites--but crowds can shift from peaceful to unruly, even riotous, in just a few minutes given the right conditions.

The factors that cause a "charged" crowd to reach a "tipping point" and erupt into violence are not well understood by scientists because crowd behavior is so difficult to study. No one wants to incite a riot for the sake of science and surveys of individuals about their behavior as part of a crowd have not been that reliable.

On Monday, Jan. 5, NASA issued a request for proposal for the Ares V rocket that will perform heavy lift and cargo functions as part of the next generation of spacecraft that will return humans to the moon. The request is for Phase I concept definition and requirements development for the Ares V rocket. Proposals are due to NASA's Marshall Space Flight Center in Huntsville, Ala., no later than 1 p.m. CDT on Feb. 9. 

The lowest ever levels of oxygen in humans have been reported in climbers on an expedition led by UCL (University College London) doctors. The world-first measurements of blood oxygen levels in climbers near the top of Mount Everest, published in this week's New England Journal of Medicine (NEJM), could eventually help critical care doctors to re-evaluate treatment strategies in some long-term patients with similarly low levels of blood oxygen.