As trade routes have criss-crossed the globe, plants and animals have hitched rides into new environments. Some immigrants have settled peacefully into their new homes. Others have become conquerors, wreaking ecological havoc and driving out native species. Many places are trying to rid themselves of invasive species. But occasionally, these alien invaders carry a hidden upside. VOA's Steve Baragona has more.
A U.S. astronaut and a Russian cosmonaut made an emergency return to Earth shortly after launching Thursday on what was supposed to be a mission to the International Space Station. Rescuers reached American Nick Hague and Russian Alexei Ovchinin after their emergency landing in Kazakhstan. VOA Pentagon correspondent Carla Babb recently sat down with Hague to talk about his future in space, a future now up in the air after his unexpected fall to Earth.
An estimated 44 million people 65 years and older worldwide have Alzheimer's, the most common cause of dementia. Alzheimer's is a degenerative brain disorder that causes memory loss, and impairs thinking, judgment and problem solving. So far, scientists have not found a drug that can stop the disease. But a research program in the United States is trying to prevent it by targeting the earliest changes in the brain while memory and thinking skills are still intact. VOA's Deborah Block has more.