Rye

Hansjörg Küster. Cambridge World History of Food. Editor: Kenneth F Kiple & Kriemhild Conee Ornelas. Volume 1. Cambridge, UK: Cambridge University Press, 2000.

Rye as a Grass

Rye (Secale cereale L.) is closely related to the genus Triticum (which includes bread wheat, durum wheat, spelt, and the like) and has sometimes been included within that genus (Mansfeld 1986: 1447). In fact, it was possible to breed Triticale, a hybrid of Triticum and Secale, which is cultivated today (Mansfeld 1986: 1449).

Cultivated rye (Secale cereale) is also so closely related genetically to the wild rye (Secale montanum) that both species would appear to have had the same ancestors. Yet to say that the cultivated rye plant derived from the wild one is an oversimplification because both plants have been changing their genetic makeup since speciation between the wild and cultivated plants first occurred.

The cultigen Secale cereale was brought to many parts of the world, but wild rye still grows in the area where cultivated rye originated, which embraces the mountains of Turkey, northwestern Iran, Caucasia, and Transcaucasia (Zohary and Hopf 1988: 64-5; Behre 1992: 142).

The distribution area of wild rye is slightly different from the area of origin of other Near Eastern crops. Wild rye is indigenous to areas north of the range of the wild Triticum and Hordeum species; these areas have a more continental climate with dry summers and very cold, dry winters. The environmental requirements of cultivated rye reflect these conditions of coldness and dryness: It has a germination temperature of only 1 to 2 degrees Centigrade, which is lower than that of other crops. Indeed, low temperatures are necessary to trigger sprouting (Behre 1992: 145), and the plant grows even in winter if the temperature exceeds 0 degrees Centigrade, although rye can suffer from a long-lasting snow cover. In spring it grows quickly, so that the green plant with unripe grains reaches full height before the summer drought begins (Hegi 1935: 498-9). Obviously, these characteristics make rye a good winter crop. It is sown in autumn, grows in winter and spring, and ripens and is harvested in summer – a growth cycle that is well adapted to continental and even less favorable climatic conditions. There is also another cultigen of rye – summer rye – which is grown as a summer crop. But because of a low yield and unreliability, it is rather uncommon today (Hegi 1935: 497).

Clearly, then, the constitution of the wild grass ancestor of cultivated rye is reflected in the cultivated crop. Rye is predominantly grown as a winter crop, on less favorable soils, and under less favorable climatic conditions than wheat.

The Question of Early Cultivation

There is evidence for the ancient cultivation of rye in the Near East dating back to the Neolithic. Gordon Hillman (1975: 70-3; 1978: 157-74; see also Behre 1992: 142) found cultivated rye in aceramic early Neolithic layers of Tell Abu Hureyra in northern Syria and also at Can Hasan III in central Anatolia. Hillman reports that there were entire rachis internodes at these sites, proof that the selective pressures of cultivation were operating, because only a plant with a nonbrittle rachis can be harvested efficiently. It is not clear, however, if rye was actually cultivated at these Neolithic sites or whether the plant only underwent such morphological adaptations while being sown and harvested as a weedy contaminant of other crops.

To this day, rye remains a vigorous weed in Near Eastern wheat and barley fields, and its nonbrittle rachis internodes resemble a cultivated plant in spite of the fact that it is not intentionally sown. It is harvested together with the more desirable wheat and barley as a “maslin crop” (a crop mixture), and, in climatically unfavorable years, the rye yield is often better than the yield of barley or wheat in these fields. Even an examination of the harvested crop may give the false impression that the rye has been deliberately cultivated. It is interesting to note that such “volunteer” rye is called “wheat of Allah” by Anatolian peasants (Zohary and Hopf 1988: 64) because it is assumed that God “sent” a crop in spite of the bad weather conditions that were unfavorable to the sown wheat.

Possibly this process of unintentionally cultivating rye, while intentionally cultivating wheat and barley, also took place in the early Neolithic fields of Tell Abu Hureyra and Can Hasan III that Hillman investigated. So we do not know if rye was deliberately grown as a crop in its own right or if it was only “wheat of Allah.” It is the case that Hillman’s evidence for the early cultivation of rye in the Near East contradicts an earlier opinion by Hans Helbaek (1971: 265-78), who assumed that rye derived from central rather than western Asia.

Rye as a Weed

Rye reached Europe at the dawn of the region’s Neolithic Revolution, but probably as a weed. Angela M. Kreuz (1990: 64, 163) has discovered rye remains in Bruchenbrücken, near Frankfurt, in central Germany. This site is dated to the earliest phase of the Linearbandkeramik, which is the earliest phase of agriculture in central Europe. Similarly, Ulrike Piening (1982: 241-5) found single rye grains in a Linearbandkeramik settlement at Marbach, near Stuttgart, in southern Germany. But at both sites only single rye grains were found among great amounts of grains of other species. The same is the case with the few other early rye finds in Europe (Piening 1982: 242-4; Behre 1992: 142-3). Thus, the evidence appears to indicate that rye existed during the early phase of agricultural development in Europe as a weed, and an uncommon one at that.

In the Neolithic, however, most grain cultivation took place on fertile loess soils situated in regions where typical winter crop weeds were not present. Such conditions did not favor rye expansion and, consequently, there was little opportunity to compare the durability of rye to that of Triticum species, as was the case with the development of the “wheat of Allah” in the maslin crop fields in the Anatolian mountains.

The proportions of rye, however, were greater in some grain assemblages from Bronze Age sites. Many have assumed that rye was cultivated as a Bronze Age crop, especially in eastern central Europe (Körber-Grohne 1987: 44), but the evidence remains scarce and questionable (Behre 1992: 143).Yet spelt (Triticum spelta), a grain similar to rye, was commonly grown in this region during the Bronze Age (Körber-Grohne 1987: 74). Because spelt was normally cultivated as a winter crop, spelt grain assemblages from archaeological sites are contaminated with winter crop weed seeds (Küster 1995: 101). Thus, it could be that the beginning of winter crop cultivation favored the expansion of winter rye as a weed in spelt fields. This was probably the case especially in areas less favorable to agriculture that were being cultivated from the Bronze Age forward, as, for example, in some areas of the Carpathians and the Alps, where rye pollen grains have been recorded several times in layers dating to the Bronze Age (Küster 1988: 117). Definitive evidence of an early rye expansion to the Alps, however, awaits more extensive plant macrofossil examination in these marginal agricultural areas high up in the mountains.

Rye as a Secondary Cultivated Crop

Spelt cultivation, possibly as a winter crop, expanded during the Pre-Roman Iron Age to other parts of Europe (Körber-Grohne 1987: 74), as agriculture itself spread to areas with less fertile soils, such as those of sand and gravel in northern central Europe. These soils, as well as the local ecological conditions of humid climate and light snow cover, favor a winter crop plant that grows during mild winter days and in the spring but will not suffer from summer drought on sandy soils.

Pollen (Küster 1988: 117; Behre 1992: 148) and macrofossil evidence (Behre 1992: 143) show that rye became more common during the Pre-Roman Iron Age, perhaps in those winter crop fields on the less favorable soils just described. At this point, rye was still growing as a weed, but because it had the qualities of a cultivated plant under these ecological conditions, rye eventually predominated in fields planted with spelt. This success is typical of secondary plants that are cultivated by chance within stands of other crops.

Karl-Ernst Behre (1992: 143) has compiled a list of the most ancient finds of pure, or possibly pure, rye cultivated during the Iron Age in Europe. This shows concentrations in the eastern Alps, the countries around the Black Sea, and the western and northern marginal areas of Europe.

But rye became more common during the Roman Age, as populations grew, thus increasing the demand for food. During this time, ever greater amounts of lands with less fertile soils were brought under cultivation, and the expansion of winter crop cultivation provided more reliable and greater yields. Abundant Secale grains have been discovered on some Roman sites, giving the impression that rye was cultivated as a main crop (Behre 1992: 143-5). It is, however, unlikely that the Romans themselves propagated rye (with which they were unfamiliar) because climate militated against its growth in the Mediterranean region (Behre 1992: 145). Only a few Roman Age sites outside the Roman Imperium have been examined by archaeobotanists so far, but there is clear evidence that rye was grown outside the Empire as a main crop. A detailed study from an area in northern Germany has shown that the shift to rye cultivation took place during the second century A. D. (Behre 1992: 146).

A few hypotheses for the increased importance of rye have been put forward. For one, rye may have been imported from areas outside to sites inside the Imperium (Dickson and Dickson 1988: 121-6), which suggests increased demand, and, in what is not necessarily a contradiction, Behre (1992: 149-50) emphasizes that the expansion of rye during the Roman Age reflects the improvement of harvesting methods beyond the earlier technique of plucking the grain ear by ear. Because all cultivars depend on harvesting for seed dispersal, such a thorough method would not have favored the expansion of rye. But during the Iron Age and Roman times, harvesting methods grew more sophisticated, and the advent of new mowing equipment made rye’s dispersal more likely.

Another hypothesis involves climatic deterioration as an explanation for the expansion of rye. To date, however, there is no clear evidence for climatic change during the Roman Age. Most likely then, by way of summary, the major reasons for the increased importance of rye cultivation were the expansion of agriculture to more marginal fields, the growing importance of winter crops, and changing harvesting methods.

Medieval Rye Cultivation

During the Middle Ages, rye became a very important crop in many parts of Europe. As agriculture was introduced to marginal mountainous landscapes, the cultivation of rye was frequently the best alternative. More important, although the acid, sandy soils in northern and north-central Europe became exhausted from overcropping, the custom developed of enriching them with “plaggen,” which was heath, cut down and transported from the heathlands to the farmlands (Behre 1992: 152). Although this caused a further impoverishment of the already relatively infertile heathlands, such a practice made it possible to control the fertility of marginal fields and to grow crops near the settlements. On these soils “eternal rye cultivation” (Behre 1992: 152) became possible, allowing cropping every year.

In other regions where rye replaced spelt, as for example in southern Germany, such a replacement resulted from practical reasons (Rösch, Jacomet, and Karg 1992: 193-231). Because spelt is a hulled crop, the grains must be dehusked after threshing. This is not necessary with rye or wheat, but the latter is very sensitive to diseases caused by primitive storage conditions in damp environments. Thus, because it was easier to store rye than wheat, and easier to process rye than spelt, rye replaced spelt in many places during the period between the Roman Age and the Middle Ages (Rösch et al. 1992: 206-13). In other areas, of course, such as the mountains of the Ardennes in Belgium and northern France, and the area around Lake Constance, spelt has been grown until recent times and was never replaced by rye.

The relative importance of a grain crop in the various areas of Germany can be determined from the language of historical documents. This is because the term Korn (“corn”) signifies the most important crop over the ages. So it is interesting to find that in regions where rye cultivation predominated during the Middle Ages and early modern times, the term Korn is connected with rye, but in others it is associated with spelt or wheat.

Rye crossed the Atlantic to the New World with colonists heading to both the south and the north of North America. In the south, Alexander von Humboldt, who visited Mexico at the turn of the nineteenth century, discovered rye growing “at heights where the cultivation of maize would be attended with no success” (Humboldt 1972: 97). In addition, he reported that the plant was seldom attacked by a disease that in Mexico “frequently destroys the finest wheat harvests when the spring and the beginning of the summer have been very warm and when storms are frequent” (Humboldt 1972: 104).

In the north, where rye was also extensively cultivated in colonial New England, symptoms of ergotism (a disease caused by ingestion of the ergot fungus that infects many grains, but especially rye) are believed to have often been manifested by the population. Such symptoms (especially those of nervous dysfunction), are seen to have been present in the Salem witchcraft affair, in the “Great Awakening,” and in epidemics of “throat distemper” (Matossian 1989). Certainly ergotism had a long and deadly history in Europe, beginning before the early Middle Ages. Some 132 epidemics were counted between 591 and 1789, the last occurring in France during the time of the “Great Fear,” which just preceded the French Revolution and which some have seen as leading to it (Haller 1993).

In conclusion, although rye has been said to be our “oldest crop,” and baking company advertisements call rye bread the traditional bread, as we have seen, this is certainly not the case. Only gradually did this crop, which began as a weed among cultigens, grow to prominence. But it has also traveled as far from its origins as the United States and Canada (KörberGrohne 1987: 40), where the winters are cold enough to stimulate the germination of the grains – the same stimulus rye plants received in the mountains of the Near East before they spread out into eastern, central, northern, and western Europe.