[Thomas Heyd]

I have a quick question, which I hope one of the members may be able to answer. I am writing a paper on the first philosopher of European ancestry, Thales of Miletus (on the coast of Asia Minor, near Samos and Bodrum), who supposedly predicted a bumper olive crop based on his 'astronomical' observations.

Now, it seems farfetched to suppose that anyone could see the crop yield in the stars, but I wonder if weather patterns preceding various sizes of crops could have been observed. In other words, I wonder if something like a self-made almanac would have been instrumental in his achievement. 

Do you know of anyone who could help me resolve this puzzle? Or a relevant text to read? 

Many thanks in advance,
Thomas Heyd
PD Answers can also be posted privately to me via heydt@uvic.ca.

Dept of Philosophy
University of Victoria
Victoria, Canada

[JTh]

I don’t know much about this, but I know that both apple and olive crops vary considerably from one year to the next. Last year we had a bumper crop of olives in Halkidi, Greece, everything was right, and no olive fruit flies, but this year it will be easy to predict that I will get almost nothing, the trees that did well last year, had hardly any flowers this spring.

That is not very scientific, though. I have seen many references to harvest prediction based on weather forecast for many crops, however, but few for olives. There is one from California which also includes olives: Weather-based yield forecasts developed for 12 California crops (http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.v060n04p211&fulltext=yes).
And another one from Spain: Modeling Olive Crop Yield in Andalusia, Spain (https://www.agronomy.org/publications/aj/abstracts/100/1/98?access=0&view=pdf).

Good luck with your paper!

[John J]

I agree with the comments made by Jorun regarding the variation in olive tree yield. I have no scientific evidence just personal observation of our own trees (20). Individual trees have a tendency to crop in cycles, a high yield one year and low the next. The amount of winter rainfall they receive seems to have an influence too (none of our trees get summer irrigation). High winds and heavy rains during the period of flowering and fruit set may also have an effect. Crop yield varies from variety to variety also and many of the varieties currently grown may not have been around when Thales was making his predictions. Sorry I can't be more scientific but I endorse Jorun's comment about good luck with your paper.

[David Bracey]

Olives are famous biennial bearers but I,m not sure that this helps.  How far ahead was Mr Thales predicting a bumper crop? One year or even two may be possible but I doubt if longer predictions are going to be very accurate.

Predicting weather, even to-day with sophisticated computors is accurate for only a few days.

[David Bracey]

I did read this about Mr Thales "Reportedly he used his knowledge of astronomy to predict a bumper crop of olives and, understanding that this would create a demand for olive processing, he borrowed money enough to purchase the olive presses in his region. Consequently, when his olive harvest prediction came true, he owned the means of olive oil production which resulted in a huge profit.".  Perhaps he was just a modern day entrepreneur.

[David Bracey]

There are some references from Spain forecasting olive yields over 10 years using pollen counts but that would require a means to magnify which I doubt was available to Mr Thales even if he had the time.

[Alisdair]

As any asthma sufferer will know, numbers of sneezes is a pretty good proxy for pollen count at olive-flowering time!

[JTh]

Sorry Alisdair, but there are conflicting studies on pollen counts and olive pollen allergy. This article says there is a correlation: Olea europaea pollen counts and aeroallergen levels predict clinical symptoms in patients allergic to olive pollen (http://www.ncbi.nlm.nih.gov/pubmed/21277516), while this one says: Airborne olive pollen counts are not representative of exposure to the major olive allergen Ole e 1( http://www.ncbi.nlm.nih.gov/pubmed/23647633). Life is not easy.

[Alisdair]

Jorun, I've seen only the abstracts, but I think that second paper was more demonstrating that olive-producing localities varied in the degree to which the aerial pollen counts showed the amount of allergen present, rather than attempting the (difficult!) assertion that extra pollen in a particular locality wouldn't produce more sneezes!

[JTh]

I suppose it is more precise than astronomy.

[Thomas Heyd]

Hello everyone,

Thank you for your heroic efforts to help untangle this archaeo-gardening puzzle. Right, pollen count I discount as an option for Thales. Sneezes: depends on whether he was allergic.

I tend to think that the report re his astronomical observations would have some basis in fact, even if it is, of course, out of the question that he would have foreseen the bumper crop in the stars (not even an astrologer should claim this much : ). so, on the assumption that he observed something to do with skies, the passage of time, interactions between atmosphere and ground perhaps, what in that mix has a chance of an accurate prediction of a harvest? As the quote says, he reserved the oil mills, so this cost him some money. He would, reasonably, do this only if he had some inkling that this could pan out. What did he know?

I had thought that perhaps it is meteorological. As he watched the night sky he might have recorded the number of cloudy/rainy days and found a pattern related to the following year's crop. Is raininess a predictor?

Another possibility that just occurred to me now is that he might have done some careful time keeping (after all, he supposedly determined the dates for the solstices, formerly allegedly unknown with exactitude). This time keeping, combined with a rule, such as 40 weeks after flowering olives can be harvested, may perhaps have been his tool for predicting the dates of the harvest, and for reserving the olive presses for that precise window of opportunity.

What else might be relevant? I did see the article about Spain having a very bad harvest this year due to dryness. So, are there signs in the sky for a dry -- or alternatively a sufficiently wet -- year, so as to be able to predict the following crop size?

Any way, I appreciate all your help in thinking this through. Perhaps there are some learned articles out there on these things that I don't know about (after all, I am only a philosopher, not a polymath, as Thales obviously was). I will be happy to share the article with anyone interested, though it deals mostly with understanding his accomplishments and not with his gardening knowledge.

Thom

[JTh]

I would say that if the previous year's harvest wasn't great, the winter was good (sufficient precipitation, no frost), no rain during the flowering period (which could disturb pollination), then it may be a good idea to buy up the ollive mills in the area, if you have the means to do so and are willing to take the risk (I'm not a natural gambler).

[David Bracey]

One further thought. Since olives are biennial bearers Mr THales, had he been a betting man, could have invested during the odd year only to reap his reward during the following on-year..

[JTh]

I thought about that as well, but in my experience, they are not completely synchronized; not all olive trees in the region have their highs and lows at the same time.

[Thomas Heyd]

Good thoughts, David and JTh. Would looking up to the sky ever make a difference? I am beginning to think that the report is poorly informed, that is, that Thales' good bet had nothing much to do with him being astronomically (that is, sky-oriented) active. From what you write, it may be that he kept track of good and bad years and noticed that a majority of trees in a certain area were in sync. Then he just needed the favourable conditions that JTh mentions, and bingo, he would have a good chance of a bumper crop in the 'up' year. Well. If anything else occurs to you, do let me know. I am still curious.

Might there be some regularity in good-bad crop years associated to other patterns, such as North Atlantic Oscillation or ENSO-El Niño? A good track-keeper, such as he was if he was able to predict an eclipse and determine the exact day of the solstice, might have dabbled with keeping track of all sorts of patterns....