Assumption #1: You’ve got to have astronomy because you’ve got to have an accurate calendar (Mursi Astronomy)

The Mursi. Photo by CharlesFred.

I’ve been mean­ing to write this up for a while. I need it online as a ref­er­ence note because it tackles a com­mon prob­lem I have when talk­ing to some people about ancient astro­nomy. Sometimes the reason I dis­agree with an astro­nom­ical inter­pret­a­tion of a site, like Fiskerton, is that there’s an unchal­lenged assump­tion that ancient people were on a quest for accur­acy and pre­dic­tion like mod­ern sci­ent­ists. It seems a reas­on­able assump­tion for some soci­et­ies. Mayan cal­en­dars were more accur­ate than those of Europe in the same period. Sometimes though you find some­thing which blows all your pre­con­cep­tions out of the water. Astronomy, as prac­ticed by the Mursi, is one example.

The Mursi live in south­west­ern Ethiopia by the banks of the River Omo. They live on sorghum, which is planted to coin­cide with either the flood­ing of the Omo or the rains, and from their live­stock. Agriculture in Ethiopia can pre­cari­ous at the best of times, so these people really need to know what they’re doing. Miss the rains or the floods and your sorghum crop is lost. Similarly you want to make sure you’re up in the moun­tains when the pas­ture is there for the cows. This would sug­gest they have a use­ful cal­en­dar and they do. But it’s very odd.

Initially it doesn’t look odd. They count lun­ations. They use the word bergu, which is goat, to count the moon. Each lun­ation the bergu ages by one step. They then plan their cal­en­dar around this, so when the bergu is one the floods are at their highest. When the bergu is two they pre­pare plots to plant sorghum and when the bergu is three they plant it. Bergu 4 is spent weed­ing and in Bergu 5 the sorghum flowers which means that in Bergu 6 they can har­vest the crop. In Bergu 7 the women move from the river to the land for the rain watered crop of sorghum and they tend this in a sim­ilar fash­ion till Bergu 12 when they thresh the rain-fed crop and then begin the cycle over again. Like us then, the Mursi have twelve months.

Unlike us though their twelve months are lunar. There are twelve and a half lunar months in year, so they must surely insert extra months every couple of years to keep in step with the seasons.


In fact they find the idea odd. The Bergu goes from one to twelve and that’s that. There’s never a thir­teenth stage for the Bergu. Yet they insist the cal­en­dar always stays in step with the sea­sons. This puzzled David Turton, who was the anthro­po­lo­gists out there. Eventually he found out that, if you asked the right ques­tion, there was a thir­teenth period gamwe. Gamwe was the period between Bergu 12 and Bergu 1, a period when there wasn’t a bergu. So prob­lem solved. When you get a bit out of step with the sun you insert gamwe. Actually, no. The Mursi insisted there was always gamwe too. This left a prob­lem now there were thir­teen months in the year, so it was half a lunar month too long. Baffling.

Turton asked one of his inform­ants what the cur­rent age of the bergu was. “How should I know?” was the reply. “I don’t have any­thing to do with the bergu me. You want to Jeff in the next vil­lage. He knows about the bergu.” So off David Turton went to talk to someone who prob­ably wasn’t called Jeff, but I can’t remem­ber the names.

He asked Jeff how old the bergu was. “How should I know? I’ll tell you who does know, Wayne on the other side of the ter­rit­ory. Wayne’s a real expert on the bergu.”

Off the anthro­po­lo­gist went across thirty kilo­metres of Mursi ter­rit­ory to see Wayne. He arrived at Wayne’s hut and ask the man out­side how old the bergu was. “How should I know?”

Jeff said you were an expert on the bergu.”

I’m no expert, you’re think­ing of dad, I’m his son Melvin.”

Sorry, my mis­take. Can I ask your dad how hold the bergu is?”

Well you could ask him, but I don’t know if it’ll do much good. We bur­ied him two weeks ago.”

It turned out all experts on the bergu were either on the other side of the ter­rit­ory, dead or both. So David Turton observed a dis­cus­sion by the tribe who were decid­ing what to do for the next month. Someone must surely know how old the bergu was.

Without writ­ing, how would you know if it was June or January? It’s fairly obvi­ous there are vari­ous signs you can look for like the pres­ence of birds or snow­drifts. It’s obvi­ous roughly what time of year it is. But how would you decide if it’s June or July? The dif­fer­ences are more subtle.

This is the same prob­lem the Mursi had. Some might argue that it was bergu 4 and oth­ers bergu 5. The pro­ponents of bergu 5 would point to the arrival of African swal­lows car­ry­ing migrat­ing coconuts*. The people in favour of bergu 4 would say that the coconuts were arriv­ing early this year. This is the prob­lem with sea­sonal indic­at­ors. For instance snow stops in February in the UK, yet we had late snows in April. Seasonal indic­at­ors are not accur­ate but – because agri­cul­ture is a sea­sonal activ­ity rather than a clock­work activ­ity – it doesn’t mat­ter much. No-one pays too much atten­tion to what what decided before to shifts in opin­ion aren’t noted. This allows the Mursi cal­en­dar to per­form its func­tion des­pite being (or rather because it is) a year-round argu­ment. In fact the astro­nomy is there simple as a plat­form to argue from. People can argue whether the New Moon really has been seen set­ting in the west, or even what month it is because the cal­en­dar is accur­ate enough and doesn’t need to be any more accurate.

Or does it? More to fol­low.

You can read more about the Mursi cal­en­dar in the chapter “The Haphazard Astronomy of the Mursi” by Turton and Ruggles in Songs from the Sky: Indigenous Astronomical and Cosmological Traditions of the World.

If you have access to JSTOR you can also read “Agreeing to Disagree: The Measurement of Duration in a Southwestern Ethiopian Community” Current Anthropology, Vol. 19, No. 3 (Sep., 1978) , pp. 585–600 by the same authors.

*They grip them by the husk. In real­ity these people are going to have an intens­ive know­ledge of their land­scape and are prob­ably going to argue about all sorts of metero­lo­gical and eco­lo­gical indicators.


When he's not tired, fixing his car or caught in train delays, Alun Salt works part-time for the Annals of Botany weblog. His PhD was in ancient science at the University of Leicester, but he doesn't know Richard III.