retarded question but please hear me out. suppose you're some prehistoric tribesman somewhere on the level of "not dumb as bricks" already, and capable of counting - how exactly would you conclude that a year has 365 days? if you don't have even rudimentary writing yet, as many cultures didn't, you won't have any longer-term day-by-day chronicles either - so you'll have to wing it somehow. or is there a clear yearly phenomenon to observe? (solstices are not a clear phenomenon, I can't imagine someone being able to tell "yup. this is the longest day". it too requires record keeping) or is the moon just enough here?