> I can imagine that to a paleolithic hunter/gatherer it would be beneficial to use an arrangement of stones to "capture" a particular date. Dates of interest might be 'migration', 'planting', or 'harvesting' dates.
This is almost always done by observing the behavior of local plants and animals. For example, you might say that spring starts after the cherry trees have bloomed -- an event which is obvious -- and start your planting then. The precise date will wander around the year, from an astronomical point of view, but it will generally be better chosen each year than any fixed astronomical date would be.
This is almost always done by observing the behavior of local plants and animals. For example, you might say that spring starts after the cherry trees have bloomed -- an event which is obvious -- and start your planting then. The precise date will wander around the year, from an astronomical point of view, but it will generally be better chosen each year than any fixed astronomical date would be.