"Differing from the cyclical cosmological-historical time concepts of [the Maya in America,] the early Greeks in Europe, and the Indians and others in Asia, the Judeo-Christian...concept is linear..." [and taints our sciences] - Dr. Cremo.
The pyramids themselves were calendars.
And these are literal cycles as described in the ancient Vedic accounting of time (inherited by Buddhism and later by Hinduism) in great aeons (maha kalpas), ordinary aeons (kalpas), and aeons of indeterminate length (asamkhya kalpas), epochs (manvantaras), and ages (yugas).
The boredom is so great with the slow moving gears of cosmic time that the world is distracted by the much more colorful and complicated Aztec Calendar, a later creation following the fall of the Mayan Empire. It is the universally recognized "Mayan Calendar," which it is not.
Neither calendar "ends" but only clicks away to the next age. The day after Dec. 21, 2012 will not be the end of the world so much as the end of an age. The day after the 13th ends is the day the 14th begins in sidereal time. And the baktuns roll on.
"Hindu historical literatures, particularly the Puranas and Itihasas, place human existence in the context of repeating time cycles called yugas and kalpas, lasting hundreds of millions of years. During this entire time, according to the Puranic accounts, humans coexisted with creatures in some ways resembling the earlier toolmaking hominids of modern evolutionary accounts" (mcremo.com).
The best explanation we have been presented with comes from Dr. Michael Cremo, America's "forbidden archeologist," in his A Vedic Conception of Time.
Mayan Calendar (erates.co.cc).
But this brahma is by no means the "creator" of either the universe or time -- even if It mistakenly concludes that that must be so.
But the first must be the Prime Mover, the Causeless Cause, we surmise; never mind that countless world periods have gone before and that impersonal karma is running the show since beginningless time.
This world is very old (16.4 billion years according to the Maya). "Modern" human beings have been around for many millions of years coexisting with other ("primitive") human species and varieties.
The scientific evidence tells us so, but the "knowledge filterers" prevent anyone from hearing the evidence. Our indoctrination into the now unquestionable Darwin-Wallace theory of evolution keeps us from even thinking in these terms.
We think we understand evolution. Creationism is certainly wrong. So everything that is not strictly in line with evolutionary theory must be creationism or intelligent design. Both are wrong, and both have something to say. The truth is far stranger, and the evidence for it comes from any fields beyond archeology.