Inside a cave so deep and dark it's called Hoyo Negro, or Spanish for "black hole", divers are transporting a 12,000-year-old skull for 3D scanning. The skull belongs to one of the oldest and most complete skeletons ever found in the Americas. Lucky for us, the expedition was documented with an entire set of stunning photos.
The skeleton, belonging to a 15-year-old or 16-year-old girl whom scientists have named Naia, helps solve a long-running debate on what early Americans looked like. Naia's narrow face and prominent forehead look nothing like Native Americas, but her DNA markers prove their related ancestry.
At the time of her death at the end of the ice age, the caves on the Yucatan peninsula were likely dry. Since then, rising sea levels have flooded the caves. Divers first discovered Naia's bones, along with the bones of extinct animals like saber-toothed cats and giant ground sloths, in 2007. Her bones have since been moved after unauthorised divers entered the cave. And while we'll never visit the cave, we can look at these extraordinary photos documenting underwater anthropology. [Science, National Geographic]
Diver Susan Bird working at the bottom of Hoyo Negro, a large dome-shaped underwater cave on Mexico's Yucatán Peninsula. She carefully brushes the human skull found at the site while her team members take detailed photographs.
Divers Susan Bird and Alberto Nava search the walls of Hoyo Negro.
Alberto Nava at 145-ft depth in Hoyo Negro, inspecting a forelimb of an extinct Shasta ground sloth, one of two sloth species found in the cave. The Shasta ground sloth has not previously been found so far south in the Americas.
A broad view of Hoyo Negro, shot from the floor near the south edge, showing the immensity of the chamber and the complexity of the boulder-strewn bottom. One access tunnel can be seen near the ceiling at top left. This photo was taken by the "painting with light" method on a 30 second exposure.
Pictures: Paul Nicklen/National Geographic