Why brain surface has grooves and bumps ?

When you see a picture of the brain you probably think of a wrinkled gray blob. Well, the wrinkles are called cortex and it is where the majority of brain cells or neurons reside. This is wrinkled so as to increase the surface area within the limited space to accommodate more neurons, which is basically Charles Darwin theory, which is struggling to be the best, new generations with more talent stuff. Amazing isn't it?