PaleoMaps: representations of quaternary paleoenvironments, human–environment interaction and human dispersal

Research on our own specie’s history with the spread of humans across the globe, throughout variable landscapes which incorporate past human-environment interactions, is an in-depth interdisciplinary field of science. Here, maps provide the chance to act as a common language across the involved research disciplines for any spatial component or topic. The underpinning rationale of this special issue, titled PaleoMaps, concerns collecting, integrating and creating explicit geospatial representations of paleoenvironments (Willmes et al., 2020). Utilising data within a geographical information system (GIS), these maps can be re-used in spatial modelling applications beyond the map itself. These maps and data sets are needed to represent Quaternary environmental changes and paleolandscapes, where archaeological evidence is integrated or used as a baseline for the spatial modelling of human activity. Very few sources for cartographic paleoenvironmental reconstructions currently exist, yet there are abundant sources of data and information which can be integrated to create a PaleoMap. This enables the appreciation, reuse and downstream application of these maps (and data) (Willmes et al., 2017). The intention of this special issue is to help enable the expansion of data visualisation and availability that result from GIS-based analysis of paleoenvironments. As a result landscapes – and their impact on human behaviour at various temporal and spatial scales – are considered. This focus upon cartographic outputs results from a realisation that maps are often simplified in publications about this topic, yet they can provide a powerful statement and synthesis of results. Authors from the variable field of sciences in the study of past human-environments (e.g. geography, geoscience, archaeology, climatology) have produced a set of exemplary spatial data visualizations that integrate mapping.


Motivation
Research on our own specie's history with the spread of humans across the globe, throughout variable landscapes which incorporate past human-environment interactions, is an in-depth interdisciplinary field of science. Here, maps provide the chance to act as a common language across the involved research disciplines for any spatial component or topic. The underpinning rationale of this special issue, titled PaleoMaps, concerns collecting, integrating and creating explicit geospatial representations of paleoenvironments (Willmes et al., 2020). Utilising data within a geographical information system (GIS), these maps can be re-used in spatial modelling applications beyond the map itself. These maps and data sets are needed to represent Quaternary environmental changes and paleolandscapes, where archaeological evidence is integrated or used as a baseline for the spatial modelling of human activity. Very few sources for cartographic paleoenvironmental reconstructions currently exist, yet there are abundant sources of data and information which can be integrated to create a PaleoMap. This enables the appreciation, reuse and downstream application of these maps (and data) (Willmes et al., 2017).
The intention of this special issue is to help enable the expansion of data visualisation and availability that result from GIS-based analysis of paleoenvironments. As a result landscapesand their impact on human behaviour at various temporal and spatial scalesare considered. This focus upon cartographic outputs results from a realisation that maps are often simplified in publications about this topic, yet they can provide a powerful statement and synthesis of results. Authors from the variable field of sciences in the study of past human-environments (e.g. geography, geoscience, archaeology, climatology) have produced a set of exemplary spatial data visualizations that integrate mapping.

Topics
This special issue covers ten papers with different spatial and temporal focuses: from regional historic landscapes (Brandolini & Turner, 2022) to global scale of early human cultural networks (Sommer et al., 2022). All articles share a common thread, representing the core idea of PaleoMaps and topics as well as authorships that are interdisciplinary. Nevertheless, two different aspects can be observed: (1) Large-scale summary analysis of existing datasets/databases, e.g. the study of raw material procurement strategies in central Europe by Gehlen et al. (2022); the early human networks by Sommer et al. (2022); and the reconstruction of paleovegetation in Ethiopia by Von Reumont et al. (2022). (2) Regional case studies of individual landscapes in terms of their geomorphologic-natural units in relation to human activity and action, with historic landscapes of the northern Appenines at Vetto (Italy) by Brandolini and Turner (2022); spatial distribution of Bronze Age megalithic towers from Sardinia (Italy) by Mariani et al. (2022); the relationship of geomorphology, archaeology and history for the Prignitz region in northeastern Germany in context to the Late Bronze Age royal tomb of Seddin by Nykamp et al. (2022); and impacts of sea level changes for prehistoric communities during the Neolithic/Mesolithic in central Mediterranean Spain by Brisset and de Pablo (2022). Three papers are just at the interface between these two general scales with archaeological sites and paleoenvironments of Pleistocene West Africa by Cerasoni et al. (2022); site probability for the Upper Paleolithic in Lower Austria by Boemke et al. (2022); and paleoenvironments with landscape diversity in Egypt during the Last Interglacial by Henselowsky et al. (2022)

Short summaries
Short summaries of each presented map and paper are briefly presented in alphabetical order.
Boemke et al., 2022 use a predictive model to investigate the probability of upper Paleolithic sites in lower Austria. Ten environmental predictors serve as a baseline for settlement choice and preservation issues and are discussed for their plausibility. The results emphasize the varying probability for sites at a larger scale with varying landscapes, but also at a smaller scale for distinct topographic features on medium scale slopes and river junctions. Brandolini and Turner (2022) show how landscape archaeology and spatial statistics reveal the landscape heritage in the Northern Apennines and anthropogenic modifications through population changes in historic times. Historic maps/aerial photos and satellite images are used to map "Historic landscape character types". As a result, landscape components before the 1950s are well distinguished from later changes and results can be used for future landscape management, especially during the promotion of repopulation of these regions including the preservation of cultural identity.
Spatial analysis for Mesolithic-Neolithic in coastal environments of the Mediterranean coast by Brisset and de Pablo (2022) identifies land use and risk perception for humans in a highly variable environment. In particular, the computation of different digital elevation models for five different time slices highlights the temporal changes of the coastline, integrates a four-dimensional perspective and variable sitecatchments depending on the respective land area.
The less researched region for paleoanthropological studies of West Africa is explored by Cerasoni et al. (2022), to map Pleistocene archaeological sites in different ecoregions with varying elevations. The spatial analysis is further expanded with a climate model over the last 120 ka to integrate temporal changes for the ecoregions in the study area. Overall, the regional imbalance of archaeological sites with dense concentrations and regions with a lack of sites are explained as research bias, but also due to different environmental conditions due to site preservation and natural accessibility. Gehlen et al. (2022) map raw material catchments in central Europe based on the origin of raw material and archaeological site distributions. Thereby, timeframes of the final Paleolithic, Mesolithic and Neolithic are considered. The resulting maps show diachronic alternation of the areas, which are interpreted as culturally determined cycles of mobility and communication networks. Raw material catchment sizes increase strongly during the Neolithic.
The mapping of environmental parameters, topography and flint as raw material sources for paleolithic humans in Egypt during the Last Interglacial is given by Henselowsky et al. (2022). Regional differences between the Western and Eastern Desert of Egypt highlight varying favourable landscapes with regard and so of direct relevance to the dispersal of Homo sapiensto Northeast Africa. Mariani et al. (2022) investigate the landscape and geological setting of Bronze Age megalithic towers (Nuraghes) in Sardinia, Italy. The combination of the distributions of Nuraghes and landscape setting shows that the megalithic towers are mainly found near the plains and near rivers within a high landscape diversity. In combination with a geological mapping, the location of the features are also considered to be placed on stable and elevated geological positions within the landscape. Nykamp et al. (2022) reveal, that the location of the royal tomb of Seddin is well-chosen and fits to the spatial setting of additional archaeological sites, which results in a ritual landscape of the Prignitz region. This observation results from the geomorphological mapping of the region, including the evaluation of digital elevation models, geological//topographic and soil maps with field mapping. Altogether, including medieval, historic and modern agriculture, the landscape represents a palimpsest of human activity. Sommer et al. (2022) made use of their ROCEEH Out of Africa Database (ROAD, www.roceeh.net), where archaeological, paleoanthropological, paleontological and paleobotanical records dated between 3 million and 20,000 years ago are stored. The technological similarities of stone tool assemblages and spatial distribution of these records represent the input data for a spatial visualization and analysis of the geographical network graph of these assemblages. This radial flow map as cartographic visualisation and edge construction offers the opportunity to discuss spatial correlations across cultures and time, but also to identify under-represented regions and lack of research (Sommer et al., 2022).
The reconstruction of the paleovegetation in Ethiopia by Von Reumont et al. (2022) can be used to reveal human behaviour in the past, as the livelihoods of humans is strongly affected by the spread of vegetation and different paleoecological and paleogeographic regions. A fuzzy-based modelling for the spatial distribution of the potential vegetation in Ethiopia considering paleoclimate is computed based on the climatic boundary for the variable vegetation zones. The results show two divergent vegetation maps under colder/ drier climate, e.g. the Last Glacial Maximum, or warmer/wetter climate, e.g. the Last Interglacial, in contrast to today.

Concluding remarks
The general trend towards digital methods is strongly present in contemporary geoarchaeology (Siart et al., 2018). The examples presented here show that there is are a large variety of possible applications, where the cartographic summary forms an important synthesis of the respective research. They are an excellent step in the direction of compiling a common collection of best practices for geoarchaeological mapping. Furthermore, they can serve as prime examples for a technological framework to publish and share paleoenvironmental and archaeological geospatial data in the form of a map. All of them include geospatial modelling of paleoenvironments through time and space, advanced spatial analysis on larger amounts of spatio-temporal data or the development and validation of existing paleoenvironment models. Further applications can integrate in-depth agent-based modelling applications or machine learning approaches. Thus, the results provide the basis for a variety of subsequent research applications and directions.
It is important to emphasize that all studies rely on the use of open, freely available data that go beyond their own data collection. The positive trend that the scientific added value goes far beyond the actual (text) publications is visible. In the end, the general summaries of a study region or a scientific question are more than the sum of the individual findings and can be discussed further, e.g. by means of the maps presented.
The cartographic perspective has many advantages in summarizing complex spatial information, even though the result of a map may have a specific visual context while at the same time revealing deficiencies, e.g. in the coverage of research areas and research history. It is a significant opportunity for many participating disciplines -in addition to the contribution of the individual sub-aspects of interdisciplinary research -to find a common cartographic language, with all its advantages and disadvantages, so that this medium can be used positively as a method of knowledge transfer.