Premise
Typically, we might view the evolution of the brain as a linear progression: with its primitive reptilian brain stem as the origin and the lofty neocortex as the pinnacle. However, I'm aiming to depict an exoplanet that whose formation and conditions spurred its inhabitants to develop abstract thought as one of their brains initial functions. That is to say the conventional progression from regulating the body to critical thinking would be broken: leaving scientists to conclude it's merely a result of Earthlings' primordial lineage.Initial thoughts
Initially, I dismissed my idea as being too absurd. Brains are expensive pieces of biology and require energy to fuel; evolving abstract thought for "fun" while competitors hone fight/flight could be your ticket to remove yourself from the gene pool. However, in an energy-rich world, or a world where reproduction hinges on the ability to solve abstract problems, perhaps such brains could be plausible. This is where I hit a dead-end, I could not think of any such situation.