They knew what was relevant to them. More personal experience kind of knowledge than book larnin’. When your livelihood depends on finding edible plants and tracking animals to hunt you het pretty good at recognizing patterns in the weather and seasons. I might be able to say that there are just under 365.25 days in a solar year. A hunter gatherer will know that when the rains stop you have only a few days to move camp to where the herd likes to come through. But harvest as many of the funny blue berries as you can before you leave because they’ll be gone before you come back.