@freemo I am sure it does go back... but no record of it so far. Nature is a poor record keeper
@sgul @freemo Wikipedia says 7-day "weeks" go back to Babylonia, including one day a week for making offering to the gods and avoiding prohibited activities.
https://en.m.wikipedia.org/wiki/Babylonian_calendar
Of course, other systems since have used different approaches including the French Revolution attempting to create a decimal calendar of 10-weeks.
Most calendar systems are lunisolar with the sun's position determining year length and the moon's phase determining month length. Reckoning weeks was more or less optional and of little interest.
And since prehistory is, by definition, before anything was recorded we can only speculate from limited findings how, or even if, time was recorded. It seems likely that some tribal leader made scratches on something to tally lunar months and maybe solar years.
@lePetomaneAncien @freemo thanks for the share. Every interesting.
Im not so much curious how far back 7-day weeks go but how long the weekdays we know have been aligned. How long has Sunday fallen on Sundays.
My curiosity is about religious communities. They deem Sunday, or in some cases Saturday, as religious days.. but if you go back far enough did Sundays at one point in the past fall on what would have been a Tuesday?
I know we had a shift in dates and so when you hear an ancient date it sometimes isnt the correct date according to modern counting of dates (shifted by a few days)... I wonder if something similar happened with religious Sundays where in the past it may have been a different day shifted a bit.
@freemo @sgul Ah! Let me attempt to answer your actual question a bit more directly.
The Jewish people adopted the Babylonian calendar systems during the Babylonian Exile so for Western purposes we can mark the observance of the Sabbath and a 7-day cycle beginning sometime around 600 BCE. Of course every lunisolar calendar requires intercalary "leap" days to reconcile the lunar and solar cycles so "counting by Sundays" isn't easy over very long timeframes.
The last major revision to the Western calendar was, as others have noted, the switch from Julian to Gregorian, a process that took a couple centuries.
Would you say from a scientific perspective it is fair to say that which day of the week is Sunday, at this point, is arbitrary and doesn't really line up with any ancient idea of "Sunday" other than by name?
@freemo @sgul You probably could, as an exercise, extrapolate calendar systems forward and backward in time then attempt to align them. Any system that used a 7-day weekly cycle would allow aligning by weeks to "line up the Sundays." The hard part is that each system used a different approach to intercalary days to correct slippage.
@lePetomaneAncien @freemo seems like the result of some sort of a cyclical event.The Cannanite script and Babylonian obsession with measurement leading to the invention of the days of the week.
@lePetomaneAncien @sgul @freemo iirc (no I'm not really that old) the Babylonians also had multiples of 60 which still reflected a bit into some of our recent systems like seconds and minutes and degrees.
@sgul it would be curious if it goes back to pre-recorded history