科学美国人60秒:Ancient Human Migration Route Marked by Snail Shell "Bread Crumbs"

Want to know the route humans took when they first migrated from Africa into Europe? Seems that they might have marked the path. Not like Hansel and Gretel, who consciously left bread crumbs. Ancient humans ate as they trekked. And they appear to have chucked aside the packaging for some of their slimy sustenance: snails.  

Conventional wisdom has been that humans initially traveled from Africa to the Near East, then up around the Mediterranean through Lebanon before heading into Europe some 40[,000] to 50,000 years ago. But recently, some scientists have theorized that humans made it to Europe first and then headed east.  

Now there’s more support for the old view that humans traveled through the Levant on the way to Europe–in the form of the shells of edible marine snails. The study is in the Proceedings of the National Academy of Sciences. [Marjolein D. Bosch et al, New chronology for Ksâr ‘Akil (Lebanon) supports Levantine route of modern human dispersal into Europe]

Researchers evaluated shells from an archaeological site dated to the Upper Paleolithic in Lebanon. The shells were mostly intact, except the tapered pointy tip had been removed—most likely for easier access to the meat inside.

The scientists calculated the age of the shells via a variety of methods. And they found that the snails dated back almost 46,000 years. The earliest evidence of modern human remains in Europe seem to be no more than 45,000 years old. The snail evidence thus adds weight to the hypothesis that ancient people passed through the Levant on their way to Europe. And not at a snail’s pace, either.

—Cynthia Graber