The paper entitled “Investigating relationships between technological variability and ecology in the Middle Gravettian (ca. 32-28 ky cal. BP) in France” [1] submitted by A. Vignoles and colleagues offers a robust and interesting new analysis of the niche differences between the Rayssian and Noaillian facies of the Middle Gravettian in France.

Understanding technological variability in the Palaeolithic is a long-standing challenge. Previous debates have vacillated between strong, quasi-ethnic culture-historical interpretations rooted in the traditional European school and extreme functional stances that would see artefact forms and their frequencies with assemblages conditioned by site function. While both positions have their merits, many empirical and conceptual caveats haunt them equally [see 2]. In this new study Vignoles and colleagues, so-called eco-cultural niche modelling is applied in an attempt to explore whether, and if so, which environmental background factors may have conditioned the emergence and persistence of two sub-cultural categories (facies) within the Middle Gravettian: the Rayssian and the Noaillian. These are are defined through, respectively, a specific knapping method and the presence of a specific burin type, and the occurrence of these seems divided by the Garonne River. Eco-cultural niche modelling has emerged as an archaeological application of distribution models widely employed in ecology, including palaeoecology, to understand organismal niche envelopes [3]. They constitute powerful tools for using the spatial and chronological information inherent in the archaeological record to up-scale interpretations of human-environment relations beyond individual site stratigraphies or dating series. Another important feature of such models is that their performance can, as Vignoles et al. also show, be formally evaluated and replicated. Following on from earlier applications of such techniques [e.g. 4], the authors here present an interesting study that uses very specific archaeological indicators – namely the Raysse method and the Noaillian burin – as defining features for the units (communities, traditions) whose adaptations they investigate. While broad tool types have previously been used as cultural taxonomic indicators in niche modelling studies [5], the present study is ambitious in its attempt to understand variability at a relatively small spatial scale. This mirrors equally interesting attempts of doing so in later prehistoric contexts [6].

Applications of niche modelling that use analytical units defined through archaeological characteristics (technology, typology) are opening up exciting new opportunities for pinning down precisely which environmental or climatic features these cultural components reference, if any. The study by Vignoles et al. makes a good case. At the same time, this approach also acutely raises questions of cultural taxonomy, of how we define our units of analysis and what they might mean [7]. It remains unclear to whether we can define such units on the basis of very different technological traits if the aim is to then use them as taxonomically equivalent in subsequent analyses. There is also a risk that these facies become reified as traditions of sub-cultures – then often further equated with specific people – through an overly normative view of their constituent technological elements. In addition, studies of adaptation in principle need to be conscious of the so-called ‘Galton’s Problem’, where the historical relatedness of the analytical units in question need to be taken into account in seeking salient correlations between cultural and environmental features [8]. In pushing forward eco-cultural niche modelling, the study by Vignoles et al. thus takes us some way forward in understanding the potentially adaptive variability within the Gravettian; future work should consider more strongly the specific historical relatedness amongst the cultural taxa under study and follow more theory-driven definition thereof. Such definition would also allow the post-analysis interpretations of eco-cultural niche modelling to be more explicit. Without doubt, the Gravettian as a whole – including, for instance, phenomena such as the Maisierian [9] – would benefit from additional and extended applications of this method. Similarly, other periods of the Palaeolithic also characterized by such variability (e.g. the Magdalenian and Final Palaeolithic) offer additional cases moving forward.

Bibliography

[1] Vignoles, A. et al. (2020). Investigating relationships between technological variability and ecology in 1 the Middle Gravettian (ca. 32-28 ky cal. BP) in France. PCI Archaeology. 10.31219/osf.io/ud3hj

[2] Dibble, H.L., Holdaway, S.J., Lin, S.C., Braun, D.R., Douglass, M.J., Iovita, R., McPherron, S.P., Olszewski, D.I., Sandgathe, D., 2017. Major Fallacies Surrounding Stone Artifacts and Assemblages. Journal of Archaeological Method and Theory 24, 813–851. 10.1007/s10816-016-9297-8

[3] Svenning, J.-C., Fløjgaard, C., Marske, K.A., Nógues-Bravo, D., Normand, S., 2011. Applications of species distribution modeling to paleobiology. Quaternary Science Reviews 30, 2930–2947. 10.1016/j.quascirev.2011.06.012

[4] Banks, W.E., d’Errico, F., Dibble, H.L., Krishtalka, L., West, D., Olszewski, D.I., Townsend Petersen, A., Anderson, D.G., Gillam, J.C., Montet-White, A., Crucifix, M., Marean, C.W., Sánchez-Goñi, M.F., Wolfarth, B., Vanhaeren, M., 2006. Eco-Cultural Niche Modeling: New Tools for Reconstructing the Geography and Ecology of Past Human Populations. PaleoAnthropology 2006, 68–83.

[5] Banks, W.E., Zilhão, J., d’Errico, F., Kageyama, M., Sima, A., Ronchitelli, A., 2009. Investigating links between ecology and bifacial tool types in Western Europe during the Last Glacial Maximum. Journal of Archaeological Science 36, 2853–2867. 10.1016/j.jas.2009.09.014

[6] Whitford, B.R., 2019. Characterizing the cultural evolutionary process from eco-cultural niche models: niche construction during the Neolithic of the Struma River Valley (c. 6200–4900 BC). Archaeological and Anthropological Sciences 11, 2181–2200. 10.1007/s12520-018-0667-x

[7] Reynolds, N., Riede, F., 2019. House of cards: cultural taxonomy and the study of the European Upper Palaeolithic. Antiquity 93, 1350–1358. 10.15184/aqy.2019.49

[8] Mace, R., Pagel, M.D., 1994. The Comparative Method in Anthropology. Current Anthropology 35, 549–564. 10.1086/204317

[9] Pesesse, D., 2017. Is it still appropriate to talk about the Gravettian? Data from lithic industries in Western Europe. Quartär 64, 107–128. 10.7485/QU64_5

In a recent article, Fumihiro Sakahira and Hiro'omi Tsumura (2023) used social network analysis methods to analyze change in obsidian trade networks in Japan throughout the 13,000-year-long Jomon period. In the paper recommended here (Sakahira and Tsumura 2024), Social Network Analysis of Ancient Japanese Obsidian Artifacts Reflecting Sampling Bias Reduction they revisit that data and describe additional analyses that confirm the robustness of their social network analysis. The data, analysis methods, and substantive conclusions of the two papers overlap; what this new paper adds is a detailed examination of the data and methods, including use of bootstrap analysis to demonstrate the reasonableness of the methods they used to group sites into clusters.

Both papers begin with a large dataset of approximately 21,000 artifacts from more than 250 sites dating to various times throughout the Jomon period. The number of sites and artifacts, varying sample sizes from the sites, as well as the length of the Jomon period, make interpretation of the data challenging. To help make the data easier to interpret and reduce problems with small sample sizes from some sites, the authors assign each site to one of five sub-periods, then define spatial clusters of sites within each period using the DBSCAN algorithm. Sites with at least three other sites within 10 km are joined into clusters, while sites that lack enough close neighbors are left as isolates. Clusters or isolated sites with sample sizes smaller than 30 were dropped, and the remaining sites and clusters became the nodes in the networks formed for each period, using cosine similarities of obsidian assemblages to define the strength of ties between clusters and sites.

The main substantive result of Sakahira and Tsumura’s analysis is the demonstration that, during the Middle Jomon period (5500-4500 cal BP), clusters and isolated sites were much more connected than before or after that period. This is largely due to extensive distribution of obsidian from the Kozu-shima source, located on a small island off the Japanese mainland. Before the Middle Jomon period, Kozu-shima obsidian was mostly found at sites near the coast, but during the Middle Jomon, a trade network developed that took Kozu-shima obsidian far inland. This ended after the Middle Jomon period, and obsidian networks were less densely connected in the late and last Jomon periods.

The methods and conclusions are all previously published (Sakahira and Tsumura 2023). What Sakahira and Tsumura add in Social Network Analysis of Ancient Japanese Obsidian Artifacts Reflecting Sampling Bias Reduction are:

·       an examination of the distribution of cosine similarities between their clusters for each period

·       a similar evaluation of the cosine similarities within each cluster (and among the unclustered sites) for each period

·       bootstrap analyses of the mean cosine similarities and network densities for each time period

These additional analyses demonstrate that the methods used to cluster sites are reasonable, and that the use of spatially defined clusters as nodes (rather than the individual sites within the clusters) works well as a way of reducing bias from small, unrepresentative samples. An alternative way to reduce that bias would be to simply drop small assemblages, but that would mean ignoring data that could usefully contribute to the analysis.

The cosine similarities between clusters show patterns that make sense given the results of the network analysis. The Middle Jomon period has, on average, the highest cosine similarities between clusters, and most cluster pairs have high cosine similarities, consistent with the densely connected, spatially expansive network from that time period. A few cluster pairs in the Middle Jomon have low similarities, apparently representing comparisons including one of the few nodes on the margins on the network that had little or no obsidian from the Kozu-shima source. The other four time periods all show lower average inter-cluster similarities and many cluster pairs have either high or low similarities. This probably reflects the tendency for nearby clusters to have very similar obsidian assemblages to each other and for geographically distant clusters to have dissimilar obsidian assemblages. The pattern is consistent with the less densely connected networks and regionalization shown in the network graphs. Thinking about this pattern makes me want to see a plot of the geographic distances between the clusters against the cosine similarities. There must be a very strong correlation, but it would be interesting to know whether there are any cluster pairs with similarities that deviate markedly from what would be predicted by their geographic separation.

The similarities within clusters are also interesting. For each time period, almost every cluster has a higher average (mean and median) within-cluster similarity than the similarity for unclustered sites, with only two exceptions. This is partial validation of the method used for creating the spatial clusters; sites within the clusters are at least more similar to each other than unclustered sites are, suggesting that grouping them this way was reasonable.

Although Sakahira and Tsumura say little about it, most clusters show quite a wide range of similarities between the site pairs they contain; average within-cluster similarities are relatively high, but many pairs of sites in most clusters appear to have low similarities (the individual values are not reported, but the pattern is clear in boxplots for the first four periods). There may be value in further exploring the occurrence of low site-to-site similarities within clusters. How often are they caused by small sample sizes? Clusters are retained in the analysis if they have a total of at least 30 artifacts, but clusters may contain sites with even smaller sample sizes, and small samples likely account for many of the low similarity values between sites in the same cluster. But is distance between sites in a cluster also a factor? If the most distant sites within a spatially extensive cluster are dissimilar, subdividing the cluster would likely improve the results. Further exploration of these within-cluster site-to-site similarity values might be worth doing, perhaps by plotting the similarities against the size of the smallest sample included in the comparison, as well as by plotting the cosine similarity against the distance between sites. Any low similarity values not attributable to small sample sizes or geographic distance would surely be worth investigating further.

Sakahira and Tsumura also use a bootstrap analysis to simulate, for each time period, mean cosine similarities between clusters and between site pairs without clustering. They also simulate the network density for each time period before and after clustering. These analyses show that, almost always, mean simulated cosine similarities and mean simulated network density are higher after clustering than before. The simulated mean values also match the actual mean values better after clustering than before. This improved match to actual values when the sites are clustered for the bootstrap reinforces the argument that clustering the sites for the network analysis was a reasonable result.

The strength of this paper is that Sakahira and Tsumura return to reevaluate their previously published work, which demonstrated strong patterns through time in the nature and extent of Jomon obsidian trade networks. In the current paper they present further analyses demonstrating that several of their methodological decisions were reasonable and their results are robust. The specific clusters formed with the DBSCAN algorithm may or may not be optimal (which would be unreasonable to expect), but the authors present analyses showing that using spatial clusters does improve their network analysis. Clustering reduces problems with small sample sizes from individual sites and simplifies the network graphs by reducing the number of nodes, which makes the results easier to interpret.

Reference

Sakahira, F. and Tsumura, H. (2023). Tipping Points of Ancient Japanese Jomon Trade Networks from Social Network Analyses of Obsidian Artifacts. Frontiers in Physics 10:1015870. https://doi.org/10.3389/fphy.2022.1015870

Sakahira, F. and Tsumura, H. (2024). Social Network Analysis of Ancient Japanese Obsidian Artifacts Reflecting Sampling Bias Reduction, Zenodo, 10057602, ver. 7 peer-reviewed and recommended by Peer Community in Archaeology. https://doi.org/10.5281/zenodo.7969330

This article “Sorghum and finger millet cultivation during the Aksumite period: insights from ethnoarchaeological modelling and microbotanical analysis”, submitted by Ruiz-Giralt and colleagues (2023a), presents an innovative attempt to address the lack of palaeobotanical data concerning ancient agricultural strategies in the northern Horn of Africa. In lieu of well-preserved macrobotanical remains, an especial problem for C4 crop species, these authors leverage microbotanical remains (phytoliths), in combination with ethnoarchaeologically-informed agroecology models to investigate finger millet and sorghum cultivation during the period of the Aksumite Kingdom (c. 50 BCE – 800 CE).

Both finger millet and sorghum have played important roles in the subsistence of the Horn region, and throughout much of the rest of Africa and the world in the past. The importance of these drought-resistant and adaptable crops is likely to increase as we move into a warmer, drier world. Yet their histories of cultivation are still only approximately sketched due to a paucity of well-preserved remains from archaeological sites - for example, debate continues as to the precise centre of their domestication. Recent studies of phytoliths (by these and other authors) are demonstrating the likely continuous presence of these crops from the pre-Aksumite period. However, phytoliths are diagnostic only to broad taxonomic levels, and cannot be used to securely identify species. To supplement these observations, Ruiz-Giralt et al. deploy models (previously developed by this team: Ruiz-Giralt et al., 2023b) that incorporate environmental variables and ethnographic data on traditional agrosystems. They evaluate the feasibility of different agricultural regimes around the locations of numerous archaeological sites distributed across the highlands of northern Ethiopia and southern Eritrea.

Their results indicate the general viability of finger millet and sorghum cultivation around archaeological settlements in the past, with various regions displaying greater-or-lesser suitability at different distances from the site itself. The models also highlight the likelihood of farmers utilising extensive-rainfed regimes, given low water and soil nutrient requirements for these crops. The authors discuss the results with respect to data on phytolith assemblages, particularly at the site of Ona Adi. They conclude that Aksumite agriculture very likely included the cultivation of finger millet and sorghum, as part of a broader system of rainfed cereal cultivation.

Ruiz-Giralt et al. argue, and have demonstrated, that ethnoarchaeologically-informed models can be used to generate hypotheses to be evaluated against archaeological data. The integration of many diverse lines of information in this paper certainly enriches the discussion of agricultural possibilities in the past, and the use of a modelling framework helps to formalise the available hypotheses. However, they emphasise that modelling approaches cannot be pursued in lieu of rigorous archaeobotanical studies but only in tandem - a greater commitment to archaeobotanical sampling is required in the region if we are to fully detail the histories of these important crops.

References

Ruiz-Giralt, A., Beldados, A., Biagetti, S., D’Agostini, F., D’Andrea, A. C., Meresa, Y. and Lancelotti, C. (2023a). Sorghum and finger millet cultivation during the Aksumite period: insights from ethnoarchaeological modelling and microbotanical analysis. Zenodo, 7859673, ver. 3 peer-reviewed and recommended by Peer Community in Archaeology. https://doi.org/10.5281/zenodo.7859673

Ruiz-Giralt, A., Biagetti, S., Madella, M. and Lancelotti, C. (2023b). Small-scale farming in drylands: New models for resilient practices of millet and sorghum cultivation. PLoS ONE 18, e0268120. https://doi.org/10.1371/journal.pone.0268120

I wholeheartedly recommend the publication of "DateBack, an evolving open-access repository of Phoenix archaeobotanical data supporting new perspectives on the history of date palm cultivation" (Besseiche et al. 2025). This work emerges at a crucial moment in archaeobotanical research, responding to calls for more integrative, open-access data infrastructures (e.g. Lodwick 2019; Reiter et al. 2024) that enable comparative studies across time and space.

The authors address a key question in agricultural and environmental history: how, when, and where did humans shape the distribution and cultivation of Phoenix dactylifera? They hypothesize that only through standardized, large-scale archaeobotanical data, long-standing narratives of domestication and dispersal can be assessed. To test this, they introduce DateBack, a curated database that aggregates published and unpublished archaeobotanical evidence, including seed morphometrics, radiocarbon dates, and contextual metadata.

The methodology is rigorous and transparent, involving systematic data collection, harmonization, and open-source publication following FAIR principles. The database’s preliminary results already suggest regionally distinct cultivation trajectories and long-distance interactions shaping date palm history, particularly in North Africa and the Arabian Peninsula.

I recommend the paper because it sets a new standard for data sharing in archaeobotany, moving beyond isolated case studies toward reproducible, collaborative science. The project fills a critical infrastructure gap and will likely catalyze new cross-disciplinary research. Its relevance extends from archaeology and botany to digital humanities and heritage data management.

In sum, DateBack is a timely and necessary resource, and I wish its publication will have a lasting impact on the field.

References

Margot Besseiche, Elora Chambraud, Vladimir Dabrowski, Elisa Brandstatt, François Sabot, Charlène Bouchaud, Muriel Gros-Balthazard (2025). DateBack, an evolving open-access repository of Phoenix archaeobotanical data supporting new perspectives on the history of date palm cultivation. bioRxiv, ver.2 peer-reviewed and recommended by PCI Archaeology https://doi.org/10.1101/2025.02.21.639487

Lodwick, L. (2019). Sowing the Seeds of Future Research: Data Sharing, Citation and Reuse
in Archaeobotany. Open Quaternary, 5, 7. https://doi.org/10.5334/oq.62

Reiter, S. S., Staniuk, R., Kolář, J., Bulatović, J., Rose, H. A., Ryabogina, N. E., ... & Timpson, A. (2024). The BIAD Standards: Recommendations for Archaeological Data Publication and Insights From the Big Interdisciplinary Archaeological Database. Open Archaeology, 10(1), 20240015. https://doi.org/10.1515/opar-2024-0015

Tektites, a naturally occurring glass produced by major cosmic impacts and ejected at long distances, are known from five impacts worldwide [1]. The presence of this impact-generated glass, which can be dated in the same way as a volcanic rock, has been used to date archaeological sites in several regions of the world. This paper by Marwick and colleagues [2] reviews and adds new data on the use and misuse of this specific material as a chronological marker in Australia, East and Southeast Asia, where an impact dated to 0.78 Ma created and widely distributed tektites. This material, found in archaeological excavations in China, Laos, Thaïland, Australia, Borneo, and Vietnam, has been used to date layers containing lithic artifacts, sometimes creating a strong debate about the antiquity of the occupation and lithic production in certain regions.

The review of existing data shows that geomorphological data and stratigraphic integrity can be questioned at many sites that have yielded tektites. The new data provided by this paper for five archaeological sites located in Vietnam confirm that many deposits containing tektites are indeed lag deposits and that these artifacts, thus in secondary position, cannot be considered to date the layer. This study also emphasizes the general lack of other dating methods that would allow comparison with the tektite age. In the Vietnamese archaeological sites presented here, discrepancies between methods, and the presence of historical artifacts, confirm that the layers do not share similar age with the cosmic impact that created the tektites.

Based on this review and these new results, and following previous propositions [3], Marwick and colleagues conclude that, if tektites can be used as chronological markers, one has to prove that they are in situ. They propose that geomorphological assessment of the archaeological layer as primary deposit must first be attained, in addition to several parameters of the tektites themselves (shape, size distribution, chemical composition). Large error can be made by using only tektites to date an archaeological layer, and this material should not be used solely due to risks of high overestimation of the age of the archaeological production. 

[1] Rochette, P., Beck, P., Bizzarro, M., Braucher, R., Cornec, J., Debaille, V., Devouard, B., Gattacceca, J., Jourdan, F., Moustard, F., Moynier, F., Nomade, S., Reynard, B. (2021). Impact glasses from Belize represent tektites from the Pleistocene Pantasma impact crater in Nicaragua. Communications Earth & Environment, 2(1), 1–8, https://doi.org/10.1038/s43247-021-00155-1

[2] Marwick, B., Son, P. T., Brewer, R., Wang, L.-Y. (2022). Tektite geoarchaeology in mainland Southeast Asia. SocArXiv, 93fpa, ver. 6 peer-reviewed and recommended by PCI Archaeology, https://doi.org/10.31235/osf.io/93fpa.

[3] Tada, T., Tada, R., Chansom, P., Songtham, W., Carling, P. A., Tajika, E. (2020). In Situ Occurrence of Muong Nong-Type Australasian Tektite Fragments from the Quaternary Deposits near Huai Om, Northeastern Thailand. Progress in Earth and Planetary Science 7(1), 1–15, https://doi.org/10.1186/s40645-020-00378-4