If you do the math (tedious, but straightforward) converting a base 20 numbering system to base 10, then count backwards, interpolating different calendar systems (which have changed regularly over the centuries), you eventually arrive at August 11, 3114 BCE in the Gregorian calendar. Exactly 5,135 years ago today.
Technically that’s the “proleptic” Gregorian calendar, because it didn’t exist in 3114 BCE. It’s the calendar most people use today, but it wasn’t introduced until 1582. But that calendar in base 20 did, and it was used by several different civilizations — the best-known one is the Mayans. August 11, 3114 BCE is the day they started counting.
The way the Mayan calendar worked was by the same principle that computer-based dates are calculated; you pick a start date and count from there. The Mayans weren’t the only ones to use it, but since it’s unusual to hear anything about the Teotihuacans, the Tarascans, or the Purepecha, it’s best known as the Mayan calendar — or if you want to be nitpicky about it, it’s the Mesoamerican Long Count Calendar.
The “long count” part is because there were two other calendars in use at the same time: the Tzolk’in, which used a repeating cycle (think “year”) of 260 days and the Haab’, which had a 365-day cycle. It seems that the Mayans used the two cyclic calendars together to refer to a particular date. Put together, the calendars result in a cycle of 18,980 days (about 52 years). That is, they might say today is something like “Haab’ 187; Tzolk’in 44”.
Except it was even more complicated than that, because they were counting in base 20. Sort of. The Mayans, who were very, very good at math, but, well, different, used a version of base 20 that sometimes acts like base 18. It’s super interesting, but I’ll leave it to you to look it up if you want to.
For a while — well, not much of a while considering the scope of the Mesoamerican Long Count Calendar, but quite some time to our peripatetic present — a great deal was made of 2012 being the “end of the world” predicted by the Mayan calendar. That was complete nonsense, and a particular sort of nonsense. When somebody who understands a subject starts to explain it, it seems to be a common pattern that some people only listen to the first part, then get bored, wander off, and dream up what they think the rest of the explanation might be (refer to “peripatetic present” comment, above). Anyway, if you devote the considerable time and attention to actually learning to read what Mayan inscriptions say, 2012 wasn’t end of the world; it was a shift to a new “cycle” according to the combination of the two cyclic calendars, and would have occasioned a big celebration.
Speaking of spending the time and attention to understanding Mayan, the way dates in the long count calendar are correlated with dates in a calendar we’re familiar with is because of three scholars: Goodman, Martinez, and Thompson. The way to do it is to use the “GMT correlation constant” created by those guys. The Mayans left a lot of records behind, including notes about astronomical events that were remarked on in Europe at the same time. Or failing that, you can work them out astronomically. So we now know exactly what date in the proleptic Gregorian calendar corresponds to a given date in the Mesoamerican long count calendar. (Aren’t you glad you visited this site so you an read sentences like that?)
Studying the ancient American civilizations isn’t easy, though. For one thing, there were a lot more of them than you might think, and the tropical environment makes it harder to find anything they might have left behind. Much more difficult than it is to, for example, take a hike in England and say “look at those huge rocks set in a circle; let’s call it Stonehenge.” One of the things that makes it difficult is the weird proliferation of calendars in that part of the world. There were at least 60 of them.
That sounds like a lot, but also remember that the Gregorian calendar we’re familiar with is just the latest in a long line of other calendar systems used by European cultures. Not anywhere near 60, but there was the Julian calendar before the Gregorian, and before the Julian calendar (named after Julius Caesar), the Romans messed around with even more convoluted ways to figure out what day it was. The Romans weren’t even in the same ballpark as the Mayans when it came to math, either; the Mayans were adept at base 20 calculations while the Romans never even figured out the idea of a base.
Anyway, if you’d like to use the long count calendar for the day just to commemorate its beginning, today is 13.0.7.13.10. At least I’m pretty sure it is. You see, if you start at 1.0.0.0.0 in the long count, the Julian day would be 584,283, which corresponds to the proleptic Gregorian date of August 11, 3114 BCE (it was a Monday). Then you calculate forward from there. You can start back at 0.0.0.0.0 in the long count if you must, but there wouldn’t be any reason to. According to the Mayans, anything before 1.0.0.0.0 was a whole different world. Besides, if you go back to all zeroes it’s something like 8200 BCE Gregorian, and there really wasn’t much going on back that far. At least as far as anybody knows. Pretty much the only things that last that long are paintings made inside caves, and the Mayans were much too practical to worry about things like that. They probably even had some plans for that festival in 2012.
