Christopher JoyceChristopher Joyce is a correspondent on the science desk at NPR. His stories can be heard on all of NPR's news programs, including NPR's Morning Edition, All Things Considered, and Weekend Edition.
Displayed in the hand of University of Oregon archaeologist Dennis Jenkins are three bases for western stemmed projectiles from the Paisley Caves in Oregon. The bases date to some 13,000 years ago.
A water tank truck is seen on the main street in Waynesburg, Pa., on April 13. Scientists say naturally polluted water can rise to the surface of the Marcellus Shale; that finding suggests that frack water could seep out, too.
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The Panel of Hands in the Cave of El Castillo in Spain. New dating methods suggest the paintings could have been drawn by Neanderthals, not humans, as previously thought.
Pete Vavricka conducts an underground train from the entrance of Yucca Mountain in Nevada in 2006. President Obama canceled the planned nuclear waste repository there in 2009.
Demand for natural gas has created a hydraulic fracturing or fracking boom; since 2008 over 5,000 new wells have been drilled nationwide. Workers at Chesapeake Energy, one of the biggest gas companies conducting fracking, are seen on the job site near Towanda, PA.
Conservator Angelyn Bass cleans and stabilizes the surface of a wall of a Mayan house that dates to the ninth century. The figure of a man who may have been the town scribe appears on the wall to her left.
Tyrone Turner/Copyright 2012 National Geographic
Researchers say our brains are probably wired from an evolutionary sense to encourage running and high aerobic activities. Above, a man runs past the Sydney Harbour Bridge on April 22.
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