See MTV's interview of David Brin, recorded during the 2012 World Science Fiction Convention. The topic: why haven't more Earth species self-uplifted naturally to full sapeince? With dolphins and apes clustered at a similar level, and with crows, parrots, sea lions ... even prairie dogs ... not far behind, is there a sentience "glass ceiling" that stymies bright creatures, for some unknown reason? And, if so, why did we smash through so hard and far and fast?
Here's an even bigger question. Is it then our duty and obligation - now that we have the tools of science - to turn around and offer other "pre-sapient" species a helping hand? Or would that be horrible hubris?