Wildlife is becoming "globalized," biologists warn, as the spread of animals and plants makes species more homogenous at the expense of regionally unique varieties.
Europeans owe their ancestry mainly to Stone Age hunters, not to later incomers who brought farming to Europe from the Middle East, new research suggests.
As populations' distance from Africa increases, genetic diversity decreases, according to a global DNA study. Researchers say the finding suggests early humans settled the planet in small steps.
Two new genetic studies suggest modern humans left Africa between 60,000 to 75,000 years ago, crossing the Red Sea, then following the Indian Ocean coastline.