The Instapundit is afraid of bacterial exchange between Earthlings and Martians.  Why is the prospect of life on Mars causing Mr. Reynolds such anxiety?

Of course, the discovery of life on Mars would be a stunning scientific advance, solving once and for all the question of whether life is unique to our planet. But the price we would pay for that discovery might well be the loss of an entire new world for humanity. Mars is Earth’s closest twin in the solar system, a planet that many scientists think could be modified to become a suitable second home for humankind.

Selfish humans want the land for themselves!  They have their own world, but they screwed that up, and so now they want ours.  I smell the very first inter-planetary war brewing.  I’ll keep you posted.