Ancient Fall: 5 Most Incredible Discoveries of the Week

An educated guess about one of our famous ancestors and a possible game-changer regarding the planet's first life make the list:

• Study: Lucy Fell to Her Death 3M Years Ago: The famous human ancestor known as Lucy walked the Earth some 3 million years ago, but it was her tree climbing that might have led to her demise, a new study suggests. An analysis of her partial skeleton reveals telltale bone breaks, including some that suggest a surprisingly specific chain of events.
• These Rocks May Hold Oldest Evidence of Life on Earth: Researchers say they've discovered evidence of life on Earth more than 200 million years before the oldest known fossils. A layer of permanent snow melted away last spring on Greenland's Isua supracrustal belt, revealing a series of wavy peaks called stromatolites in the 3.7 billion-year-old rock. Researchers say those peaks were created by bacterial colonies, though a skeptic has a different theory.

• Huge New Reef Discovered Behind Great Barrier Reef: So, do we have to call it the Even Greater Barrier Reef now? Researchers have announced the discovery of a massive 2,353-square-mile reef just north of Australia's Great Barrier Reef. How did it go undiscovered so long? Its precise locale helps explain that.
• Tasmanian Devils May Be Defeating Cancer: Scientists may not have figured out a cure for cancer, but the Tasmanian devil just might have. A new study finds that the marsupial is quickly evolving to fend off devil facial tumor disease, one of only three known infectious cancers. The disease was only discovered in 1996, but it's killed off 80% of wild Tasmanian devils since. The fix seems to take place in just six generations.
• Doling Out Fake Praise? Your Dog Knows: New research suggests dogs truly understand their owners—not just the words they speak, but also their tone of speaking. Researchers measured the brain activity of 13 pet dogs as a trainer repeated words of praise used by their owners, as well as other meaningless words, in both a neutral and happy tone. The dogs could tell the difference.

Click to read about more discoveries, including an "interesting" signal that may or may not be from the nether regions of space. (More discoveries stories.)