Perhaps the following may sound a bit simple minded, but I have this idea humans "allways" may have had some potential capability rational ways of thinking , reasoning, observing. The peoples with greater mobility may have had best chances to actually use such a potential, since they saw differences between different parts of the world, like greeks who were great seafarers, especially peoples like the ancient greeks (perhaps malayans and polynesians too. Without some good observational skills - and some use of what was inside their skulls it is hard to see they could have travelled as wide as they did). Observation and reasoning over those observations must have been essentials for good navigators , especially meteorology, astronomy and geography.