Great link! It is not the belief that we may be alone that is not scientific and humanocentric, but the belief that human level intelligence is some inevitable destiny of evolution. The Cheetah is the fastest land mammal yet is in endanger of extinction. The largest flier lived tens of millions of years ago. Whales were far smarter than our ancestors for 10s of millions of years. There is no evidence our intelligence is more important or more preordained than any other unique adaption in the fossil record.

The biggest indicator of chance is that our distant relatives the mammal like reptiles ruled the land prior to the permian mass enxtinction only to be given a second chance after the next great extinction event at the end of the Cretaceous. Another is the change in the apex predators in the ocean: molluscs, arthropods, and fish (with a recent unlikely challenge from their descendents - land dwelling mammals returning to the sea) have all dominated at different periods. Fish dominance even forshadows that of whales in that a period in fresh water lead to the skeletons that now dominate in the see. On a water world (likely condition for super Earth class terrestrial planets) skeletons may never have evolved and molluscs or arthropods might still dominate the seas.

Regards,
Mark