Neat coincidence to see this on the front page today. On the train this morning I was re-reading David Brin's "The Deadly Thing at 2.4 Kiloparsecs". His 1984 article examining Earth's fairly regular mass extinctions and what might be causing them.

As a new forward to the story, Brin mentions the OP-linked theory.

Imho, the article still holds up well and you can read it here: http://davidbrin.blogspot.jp/2015/07/the-deadly-thing-at-24-...