At http://lifeunbounded.blogspot.com/2010/08/panspermis-paradox.html is a post on panspermia, ‘The Panspermia Paradox’ (August 19th) … the notion of panspermia, the transfer of viable organisms between planets and even star systems is discussed from what appears to be a neutral position. Planetary surface material such as dust grains and rocks is continually being shipped around moons and rocky planets in the solar system or ejected by comets and asteroids. There is increased evidence that microbial organisms could also be carried on such rocks and debris surviving extremes of heat and cold as well as pressure as they penetrate atmospheres. Life may even infest or seed – but enthusiasts for panspermia go further and suggest a mechanism for galaxy wide dispersal of life. However, the author then adds the caveat, how might this effect natural selection? He goes on to say, if galactic panspermia is real then life should evolve everywhere. On the moon, on Mars, Europa, Ganymede, and so on. In every nook and cranny of the solar system, which we might suppose to be a veritable paradise for the tough little life forms (such as bacteria) that have hitched a ride. Life appears to be sparse within our solar system which argues strongly against galactic panspermia – or does it?
In the 2010 SIS Review Trevor Palmer looks at evolution rather closely and suggests that catastrophism is a factor often overlooked for the introduction of new life forms and novelties – in response to extinction events that left open wide gaps in the variety of fauna and flora that might fill niches etc.