“Forgotten Books: The Application of Unseen Species Models to the Survival of Culture”, 2022-05-31 ():
[media] Ecological methods for cultural history: Much of the narrative literature from the European Middle Ages has been lost over the ages because of manuscript physical degradation and destruction, including library fires. et al 2022 show that established methods from ecology for estimating the numbers of unseen species can be applied to abundance data representing cultural artifacts to estimate the losses that ancient cultural domains have sustained over the centuries. The authors obtain estimates that not only corroborate existing hypotheses from book history, but also reveal unexpected geographic differences that have gone unnoticed so far. For example, insular literatures, such as those from Iceland and Ireland, combine a surprisingly strong cultural persistence with an elevated distributional evenness.
The study of ancient cultures is hindered by the incomplete survival of material artifacts, so we commonly underestimate the diversity of cultural production in historic societies.
To correct this survivorship bias, we applied unseen species models from ecology to gauge the loss of narratives from medieval Europe, such as the romances about King Arthur.
The estimates obtained are compatible with the scant historic evidence.
In addition to events such as library fires, we identified the original evenness of cultural populations as an overlooked factor in these assemblages’ stability in the face of immaterial loss. We link the elevated evenness in island literatures to analogous accounts of ecological and cultural diversity in insular communities.
These analyses call for a wider application of these methods across the heritage sciences.
…We build on the information-theoretic analogy that medieval works can be treated as distinct species in ecology, and that the number of extant documents for each work can be regarded as analogous to the number of sightings for an individual species in a sample. Thus, if we treat the available count information for medieval literature as “abundance data” (3), then one can apply unseen species models to estimate the number of lost works in a corpus or assemblage. We collected count data for surviving medieval heroic and chivalric fiction in 6 European vernaculars (21): 3 insular (Irish, Icelandic, and English) and 3 continental (Dutch, French, and German). For all works, we have listed the number of handwritten medieval documents in which they survive (Table 1).
…The results for the union of the corpora (Table 1 & Table S2) suggest an overall survival ratio with a 68.3% confidence interval (CI) of 63.2 to 73.5% for works and a 9.0% CI of 7.5 to 10.7% for documents. The species accumulation curve (Figure 3B) indicates at which rate we might still be discovering new works in the future by sighting more documents (3). Figure 3A shows the empirical and estimated Hill number profiles. At q = 0, the curves indicate the absolute size of our current underestimation of the original diversity in the combined assemblage of chivalric and heroic narratives from the medieval period. Of the original ~1,170 works that once would have existed, 799 would survive today. Likewise, the 3,648 documents that are still observable constitute a sample from a population that originally would have counted ~40,614 specimens (Figure 3C).
…We observed considerable intervernacular variation (Table 1), ranging from the relatively poorly surviving English works (38.6%) to the relatively intact German tradition (79.0%). Dutch and French have a substantially lower survival factor than German, whereas 2 of the insular assemblages, Icelandic and Irish, have sustained similar losses to German, with point estimates of 77.3 and 81.0% and 16.9 and 19.2% for the survival of works and documents, respectively (12). It is puzzling that Old and Middle English documents did not travel far during their post-medieval afterlives (Figure 4), yet other literatures survive in a wide manuscript diaspora.
…Regarding documents, our results confirm the severity of the losses, with survival ratio estimates ranging from 4.9% (English) to 19.2% (Irish). This corroborates previous estimates from book history, positing an overall survival factor of 7%, ie. slightly lower than our point estimate for the union (9.0% CI = 7.5 to 10.7%). Contrary to previous analyses (16, 17), these results are therefore compatible with evidence from book history.