Did Cosmic Ray Radiation Affect Evolution?

This seems to be a topic that has come up at various times over the last 50-100 years (the amount of time we've known about radiation and the fact that a lot of it comes from space). My impression is that the role of cosmic radiation in evolution and extinction over the history of the Earth is still under debate.

Some "astrobiologists" have recently argued that massive amounts of radiation from a relatively nearby exploding star (supernova) could have caused "extinction events," and there's lots of interesting discussion about how changes in cosmic ray radiation could affect the earth's climate.

Read about some of these ideas in this Space.com piece.