The odds are against our colonizing the Galaxy and surviving to the far future, not because these things are intrinsically beyond our capabilities, but because living things usually do not live up to their maximum potential. Intelligence is a capability which gives us in principle a vast potential if we could only use it to its maximum capacity, but […] to succeed the way we would like, we will have to do something truly remarkable (such as colonizing space), something which most intelligent species do not do.
Richard Gott, Implications of the Copernican Principle for Our Future Prospects, Nature, vol. 363, no. 6427 (May 27, 1993), p. 319