Ffs, you were so quick with the snarky remark that you dont even understand that suceeding in life means a lot of different things to a lot of diferent People.
The definition you gave is your own and for me it reveals a skweded perspective of what means sucess, adaptation or intelligence.
That is pseudo science and a really stupid take. Our brain is expensive as fuck since the moment of conception, born realy early and mostly under developed because of Our fucking big head. The whole evolution says that we animals use it or loose it, let that be tails, guils or brain power.
If we didnt use the whole brain it would be cut off for efficiency.