From Yahoo ESCONI Group – via Dave

A new study suggests that phosphorus, an element that is key to life as
we know it, was brought to Earth by a meteorite bombardment during the
Archean eon, 3.5 billion years ago.

Summary at: http://www.scienced aily.com/ releases/ 2013/06/13060415 3520.htm

Journal abstract at: http://www.pnas. org/content/ early/2013/ 05/30/1303904110