Anthropologists believe early humans evolved in Africa and then moved out from there in successive waves. However, what drove their migrations has been a matter of conjecture.
One new explanation is climate change.
Anthropologist Anders Erikkson of Cambridge University in England says the first few hardy humans who left Africa might've gone earlier but couldn't. Northeastern Africa — the only route to Asia and beyond — was literally a no man's land.
Believe it or not, there's a lot of food involved in wet-plate photography. Egg whites (albumen) are used to make the glass plates adhesive to the light-sensitive chemicals. And one way to keep the plates from drying out after processing is to coat them in honey. It's also physically demanding, so you get really hungry.
On this morning 150 years ago, Union and Confederate troops clashed at the crossroads town of Sharpsburg, Md. The Battle of Antietam remains the bloodiest single day in American history.
The battle left 23,000 men killed or wounded in the fields, woods and dirt roads, and it changed the course of the Civil War.
It is called simply the Cornfield, and it was here, in the first light of dawn that Union troops — more than 1,000 — crept toward the Confederate lines. The stalks were at head level and shielded their movements.