1). The primate line was successful, regardless of the catastrophes that decimated the dinosaur populations. Thus proving the lines high resiliency. 2). Kepler mission is current, and revealing much more detail and evidence--many more habitable zones then realized in 2001 database. 3). Sentient beings of low stress, non-combatant cultures (no cultural variances from continental/geographical isolation) wouldn't be driven culturally to advance technically to rocket construction/space travel. 4)Habitable, single continent planets would generate a passive sentient population. Habitable multi-continent, highly uplifted mountain-ranged planets would generate culturally isolated, sentient warrior cultures that would advance to rocketry, planetary orbital technologies, and space travel.