No one quite knows when humanity's direct ancestors — the Homo genus — first evolved, but a fossil discovered in Ethiopia in 2013 may provide clues. And according to new studies, those clues point back further into time than was previously thought.
Each year, a couple hundred billion dollars are wasted on scientific experiments that can't be reproduced. And if they can't be reproduced, it's almost as if they didn't happen. Scientist Moshe Pritsker has tried to figure out a way to reduce that failure rate.
The 195 nations that signed the Paris climate deal have pledged to keep the average global temperature from rising 2 degrees Celsius above pre-industrial levels. Here's one way to visualize how close we're already getting to those limits.