Animals understand the seasons, and our evolution certainly took the basics to greater understandings, especially when it comes to migrating to areas because we followed creatures as well as were curious about what lay over the horizon. Just looking up at the stars would show what was where and when, but communication would have been the key to compiling knowledge about particular things, other than indicating simple things that impacted upon man's journeys.
An interesting posit is 'where does the sun and moon rise from?' which may have been quite the influence on the direction of travel our ancestors undertook. The ability to communicate greater amounts of information that included simple answers to ever increasingly harder questions would have given us knowledge to pass along, besides the basic knowledge necessary for survival and where certain places were and what they had in those places.
I guess they could develop memorable techniques for compiling quite a lot of knowledge when our brains developed and grew further in our evolution, which has both a good protein diet to start off with, but also the ability to query more about our surroundings, in order for brain development to occur. I don't think just thinking better is the key though...I think partaking of some of nature's mind altering substances is the key. We know animals and birds eat certain foods at certain times and they are affected in ways...over-ripe fruits make monkeys drunk; goats eating coffee-berries make them hyperactive...we learnt these behaviours from watching firstly, then trying ourselves, or we just accidentally tried something and discovered its effects.
But hmm...a whole lineage of a certain people being affected and altering their own brain structure to a certain extent where they don't need anything ingested anymore because it is in-built? Why not...