Tzolk'in - Origins

Origins

The 260-day calendar spread throughout the Mesoamerican cultural region, and it is regarded as being the oldest and most important of the calendar systems attested in the region, with an origin pre-dating its first appearances in Maya inscriptions. It is uncertain which Mesoamerican culture first developed this calendar. Stelae with the earliest known Long Count dates come from this general area. Some of the oldest calendric inscriptions are from early strata of Zapotec in the Oaxacan highlands at sites such as Monte Albán, dating from mid-1st millennium BCE. A few earlier-dated inscriptions and artifacts have what appear to be calendric glyphs, such as at San José Mogote and in the Olmec Gulf Coast region. However, either the dating method or the calendric nature of the glyphs are disputed by scholars.

The original purpose of such a calendar, with no obvious relation to any astronomical or geophysical cycle, is not securely known, but there are several theories. One theory is that the calendar came from mathematical operations based on the numbers thirteen and twenty, which were important numbers to the Maya, (Thompson 1950: An Introduction to Maya Hieroglyphic Writing). The number twenty was the basis of the Maya counting system, taken from the total number of human digits. (See Maya numerals). Thirteen symbolized the number of levels in the Upperworld where the gods lived, and is also cited by modern daykeepers as the number of "joints" in the human body (ankles, knees, hips, shoulders, elbows, wrists, and neck). The numbers multiplied together equal 260.

Barbara Tedlock, studied this system in the contemporary K'iche Maya community of the municipality of Momostenango in highland Guatemala. She underwent a formal apprenticeship in calendar divination with a local adept, and was initiated as a diviner in 1976. She says: "The Momostecan calendar embraces both the 260-day cycle and the 365-day solar year, with the four Classic Maya Year-bearers, or Mam, systematically linking the two. The 260-day cycle is conceived as linked firmly to worldly or earthly affairs, mirroring no astronomical period but rather the period of human gestation. Past ethnographic accounts of this cycle contain various conflicting opinions as to what its first day is, but a comparison of the present results and those of previous studies indicates that there is no fixed first day."

Anthony Aveni asserts, "Once a Maya genius may have recognized that somewhere deep within the calendar system lay the miraculous union, the magical crossing point of a host of time cycles: 9 moons, 13 times 20, a birth cycle, a planting cycle, a Venus cycle, a sun cycle, an eclipse cycle. The number 260 was tailor made for the Maya". Others have observed that the "Venus Table" in the Dresden Codex, is an accurate ephemeris for predicting Venus positions. Others have also observed a basis for the 260 day cycle in the agricultural cycle of highland Guatemala, which is also about 260 days. There may also be a relation to the average length of time it takes between appearances of the planet Venus as morning or evening star, which is in round numbers 263 days. Aveni notes that "the average duration between successive halves of the eclipse season, at 173 ½ days, fits into the tzolkin in the ratio of 3 to 2." This may seem contrived, but the Maya did employ the tzolkin to predict positions of Venus and eclipses.

Another theory is that the 260-day period is the length of human pregnancy. This is close to the average number of days between the first missed menstrual period and birth, unlike Naegele's rule which is 40 weeks (280 days) between the last menstrual period and birth. It is postulated that midwives originally developed the calendar to predict babies' expected birth dates.

Vincent Malmström identifies a correlation between the 260-day cycle and the 260-day gap between zenith and transits of the sun. According to this hypothesis, the 260-day cycle originated in the narrow latitudinal band (14°42′N to 15°N) in which the sun is vertically overhead about 12–13 August and again 260 days later about 30 April-l May (Malmström identifies the proto-Classic Izapan culture as one suitable candidate at this latitude). This period may have been used for the planting schedule of maize. However, others object to this conception, noting that while the 260-day calendar runs continuously the interval between autumn-spring and spring-autumn positions alternates between 260 and 105 days, and that the earliest-known calendric inscriptions are from considerably further north of this zone. Consequently this theory is not widely supported.

It is of course also possible that the number 260 has multiple sources.