Asteroids are not the only threat to life from space

We think of outer space as distant and unreachable, but in fact events out in the cosmos may have helped and hindered the evolution of life on Earth. By Philip Ball.
Read more: http://www.bbc.com/earth/story/20161125-events-in-space-may-have-changed-the-course-of-evolution?ocid=fbert?source=Snapzu