Michael Ferrara with his German shepherd, Lhotse, at the top of Colorado's Independence Pass Paolo Marchesi/Outside hide caption

itoggle caption Paolo Marchesi/Outside

Clay figurines discovered on the Mann Hopewell Site show faces with slanted eyes, which were not a Hopewell feature.  Some believe the figurines show a connection between Indiana and Central or South America. Indiana State Museum and Historic Sites hide caption

itoggle caption Indiana State Museum and Historic Sites

A Lens On History: Advances in DNA technology have given scientists a new tool with which to study ancient human origins. "I think ancient DNA becomes very powerful" now, says one researcher, "because it gives you a direct look into the past." Here, a photographer shoots a reconstruction of a Neanderthal man at a museum in Germany. Sebastian Willnow/AFP/Getty Images hide caption

itoggle caption Sebastian Willnow/AFP/Getty Images

The hallucinogenic mushroom Amanita muscaria. Harvard biologist Donald Pfister claims that both people and reindeer ate the mushrooms. "Reindeers flying -- are they flying, or are your senses telling you they're flying because you're hallucinating?" he says. John Tann/flickr hide caption

itoggle caption John Tann/flickr

This tooth, which was also found in Denisova Cave, has a DNA structure similar to that of a finger bone. Its shape and physical structure are, however, very different from that of Neanderthals and modern humans, leading researchers to believe that the Denisovans are a distinct group. David Reich, et al./Nature hide caption

itoggle caption David Reich, et al./Nature

Researchers have built a database of more than 500 billion words, culled from a collection of 5 million books. Parsing the words provides a unique insight into cultural changes, they say. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images