Citrus diversity in Roman Naples: pollen evidence for tangerines

The early history of Citrus fruits in the Mediterranean has been an active area of discussion amongst archaeobotanists, historians and palynologists in recent years. It has been well-established that citrons (Citrus medica) and lemons (Citrus limon) were known. For one thing they appear distinctively in Roman art, and for another their seeds are well known from Pompeii (e.g. Celant and Fiorentino 2018). What has been less clear is whether anything that we would call an orange today was known. Despite plausible textual sources, it is always hard to translate ancient terms into botanical species, especially in Citrus fruits that are so variety-rich, prone to both hybridization and frequent somatic mutations. So I have tended to think that some of the few orange-like seeds from Pompeii and from Rome, might just be outliers in the range of variation of early lemons (which are likely to have some pomelo and orange related ancestry in their South Asian origins (see, e.g. Fuller et al 2018). But an important new morphometric investigation of pollen of several Citrus species and archaeological pollen from Oplontis (near Pompeii) seems to have cleared this up. 

Lumaga et al. (2020) in a recent Vegetation History and Archaeobotany article, demonstrate the clear distinction in exine form, especially the cell or lumen size, that differentiates oranges (C. reticulata- the more primitive species, or less hybridized, of mandarin oranges or tangerines and similar small, sweet fruits). Much larger lumens characterize lemons. So I stand corrected on the Citrus diversity of Roman Italy: at least citrons, lemons and mandarins were grown.

This raises interesting questions about how these got to Rome. While these oranges were certainly known in China prior to the Han Dynasty, I have previously deduced that early orange in India-- known from Prakrit and Pali sources of the First Millennium BC-- naranga-- were perhaps most likely bitter oranges (Citrus aurantium), with sweet fruits coming later. Long distance transport of fruits from China to Rome strikes me as unlikely, so perhaps then there was more fruit diversity in northern Indian after all included under the rubrice of naranga, or other less obvious terms. Early South Dravidian languages (precursor to Old Tamil and Kannada) do seem to have two different kinds of oranges. This highlights all the more need for archaeobotanical investigations of early citrus (hidden in flots as charred rind fragments) throughout South Asia and Middle East in the Iron Age period.

I was recently interviewed about the history of Citrus fruits, especially oranges, in Europe in relation to how we can understand their use and symbolism in the writings of William Shakespeare: find the podcast here: That Shakespeare Life.

Buckwheat origins remain elusive

Harriet Hunt and colleagues have provided a new critical assessment of data and potential data on origins of the buckwheats (Fagopyrum esculentum and F. tartaricum) in a Vegetation History and Archaeobotany article. Buckwheat is an important carbohydrate crop at high elevations in Asia, as well as parts of Japan and Europe, but it has remained quite elusive archaeobotanically.

It is absent from the many large charred seed assemblages in central China, or the charred and Fagopyrum identifications as distinct from many other Polygonaceae. Even if we accept all identifications of Fagopyrum, there are several wild taxa in this genus that will have nothing to do with the cultivtion of the crop. They consider how reliable stratigraphic dating controls are for many of pollen sequences, but even so, pollen never allows for the direct dating nor direct association with human activities that archaeobotany does.
waterlogged assemblages of the Lower Yangtze. In the Indian Himalayas where it is traditionally an important crop, finds have been few, restricted to later First Millennium BC and medieval finds in Nepal. The new review by Hunt et al has compiled evidence from archaeobotanical macro-remains, a few reported based on apparent archaeological starch remains, and the many more reports from pollen diagrams. They take a threshold of fairly high quantities in pollen diagrams, but less clear is whether one can always rely on

Distribution of wild Fagopyrum species (Campbell 1997, IPGRI)

One of their key conclusions is that the past distribution of wild Fagopyrum species, including the wild progenitor of F. esculentum, was more widespread. Extending further north, even to the north of Sichuan. This certainly seems plausible and could support a domestication in Sichuan north of where modern wild populations (in NW Yunnan) have tended to suggest domestication. They point to a few pollen cores from Shaanxi and Gansu apparently 5000 years old or more, as perhaps relating to early cultivation-- although the absence of grain finds in these regions which have had considerable archaeobotanical sampling in recent years surely calls into question the paper's tentative conclusion that cultivation had begun before 5000 BP.  Another problem with many of these pollen cores is the reliability of dating. For example, the pollen sequence at Xishanping, which was collected through an archaeological sequence, has a number of inverted radiocarbon dates, suggesting reworked residual materials, but the short (and old) chronology followed by Hunt et al. removes the out of sequence dates-- which would make sense if this were a lake core with constant sedimentation, rather than a sequence 5 varied archaeological layers. A safer, and archaeologically logical reading of the original stratigraphy (see raw data in Li et al 2007) date makes the buckwheat pollen occurrence only slightly older than 3000 BP. (The short chronology also implies that wheat was present at this Gansu site before 2600 BC, which does not fit with the accumulated evidence on wheat's arrival in Gansu (as noted already in a previous blog), especially AMS dates (see Stevens et al 2006).

A more critical reading of the dates in the sequence of the earlier pollen cores find little support for any substantial quantities of Fagopyrum pollen before around 4000 years ago, so I stand by previous inferences of domestication taking place around this period. Nevertheless from the Second Millennium BC onwards, some archaeological seeds of Fagopyrum, possible supported by starch finds points to cultivation of this crop, with a focus on west Central China and southwest China, consistent with early dispersal around the eastern front of the Tibetan plateau. Nevertheless with central and eastern China, the lower reaches of the Yellow and Yangtze basins buckwheat appears to have been absent, from macro-remains (and supported by early Chinese written sources). In this regard some of the apparent pollen reports from natural cores in the Lower Yangtze seem unlikely to represent cultivation. Despite being clearly present among the crops known in early Tibetan languages (and many related Burmic languages), and having likely been loaned from a Tibetan language into Chinese since the Han dynasty period (see Bradley 2011), buckwheat remains elusive in Asian archaeology.

This new paper by Hunt et al. provides a solid starting point for new research on buckwheat origins, with a thorough compilation of pollen and archaeobotanical evidence (in China)long with some critical thinking on the rather limited genetic data.

African archaeobotany watch: new data on the First Millennium BC 'crisis'

In the latest issue of Quaternary Research (May 2009), Ngomanda, Katarina Neumann and colleagues report new pollen data from Cameroun which address the nature of vegetation changes between the end of the Second Millennium BC and the end of the First Millennium BC, a period when archaeological settlements are thin on the ground in sub-Saharan West Africa. Elsewhere Neumann and others(Breunig) have written on the apparent crisis in which early agricultural settlements of the West African Neolithic (based on pearl millet agriculture) were abandoned and sedentary agricultural settlement (often with a different, broader agricultural package) re-emerged in the later First Millennium BC. In this paper they suggest some possible reasons. I have been struck by a somewhat parallel abandoment phase in peninsular (savanna) India between ca, 1200 and 600/400 BC, i.e. the Jorwe collapse in the North Deccan and the end of Southern Neolithic. Could there have been a parallel kind of ecological shift involved?