Expert: Jayendra Upadhye - 5/6/2008

Question
how did people long ago develop calendars?

Answer
Hi,
Macy, It is all about events, and periodicity of events.
Calendars in a fashion are built into our very physical systems.
The diurnal cycle [ref:-http://en.wikipedia.org/wiki/Diurnal_animal] is a har-coded calendar that is of 24 hour length and has two "months" day, and night!

The menstrual cycle in humans is a calendar closely attuned to the moon! (implying may be humans may have been a nocturla species, mating on full moon nights?)

People observed that the moon waxed and waned (the sun came up and went down daily so it was too mundane to be noticed. The waxing/waning moon quickly became a focus of attention of the very early astronomers, and most likely the first "brick" or building block of the calendar, the month was thus born. Its very name "mon"th has moon in it.

The periodicity of the season became imperative when agriculture caught on, some 10000 bc! It is from there that a solar calendar with "lunations" or months came up, and it was by virtue of the constancy of the seasonal cycle, that it was "reasonably" accurate.

It became again more inaccurate when people started to have fixations with numbers! Until fractions were invented and understood, the 1/4 day part played accumulated havoc. Before then people just "forgot the extra days, or enjoyed them as holiday or "gave them up" and resynchronised!!

In India, everytime a war was won, a Calendar was started. Thus we have the Vikram & Shalivahan Calendars in India.

So Vikram 1 would be the year he won the war over another warlord!

In Egypt the prompt annual flooding of the Nile with the ascent of Orion in the sky had the egyptians in a tizzy and caused many cultural things to happen there, and of course resulted in a calendar! :)

Wonde why the war of the roses, or Napoleaonic wars or Waterloo in Europe's medeival ages did not trigger a calendar!

Hope that suffices.
Please do rate the answer if you find it helpful.
Jayen