quote adithya528:
Why did species other than humans fail to have a successful evolution?
I think this question comes from a misunderstanding of "success" in terms of evolution. Success may be measured as adaptation to one’s ecological niche. In such terms, every species is "a success." Dolphins are better swimmers than us, eagles are better fliers, etc. We could also look at the success of bacteria. They could be considered more successful than us based on: total biomass, number of individuals, number of species, number of ecolgical niches occupied, length of time on earth, etc. When it comes down to it, every species that is around today is a result of "successful" evolution.