The ancestors of Native Americans came to the New World by walking over a land bridge across the Bering Strait. But there's a rather glaring 10,000 year gap in the story — one that could be explained by a migratory pause that lasted for millennia.
Genetic evidence proves that Asian populations made the trek across Beringia roughly 25,000 year ago (though some still hold out for the so-called the Solutrean hypothesis in which humans made the trek from southwest Europe). But a recent genetic analysis of mitochondrial DNA by University of Utah anthropologist Dennis O'Rourke and colleagues shows that these populations didn't actually make it to North America until about 15,000 years ago. Quite obviously, it shouldn't take a group of paleolithic-era humans 10,000 years to trek across a 51 mile (82 km) stretch. So what happened?