Fair enough, thanks

Your original comment sounded like taking our current world (or even the world of the last 500 years) for granted. A world where enough people have the time to sit around and measure things like this and make accurate enough conclusions and then also be able to influence the hierarchy enough to make it into a "calendar".

Also they would have had to stay in one place rather than migrate long enough, again, we're talking this for granted. That's no small thing although I didn't consider organised religion who of course tick all of these boxes and have been around for thousands of years.

Anyway, your subsequent response clarified that you weren't thinking like this. Thanks