What is a good shape? Analysing variability in early Neolithic spherical vessels from Kuyavia (Poland) using geometric morphometrics

•Typological analysis of vessel types is ineffective for very uniform assemblages.•GMM and redundancy analyses help to differentiate vessel types and identify factors influencing the variability.•Central European Early Neolithic LBK in Kuyavia, Poland as a case study.•Chronological and regional differences are visible, indicating various networks of prehistoric communities. The pottery of the first Central European farmers associated with the LBK is remarkably homogeneous: most vessels belong to a typologically single form of the so-called spherical vessels. The paper presents the application of geometric morphometrics combined with further explanatory data analysis such as redundancy analysis to investigate the morphological differentiation within this group and the factors that influenced it. Kuyavia in the Polish lowlands was used as a case study and compared with the upland loess regions of Silesia and western Lesser Poland as potential areas of origin and contact of the Kuyavian LBK communities. The variation in the shapes of spherical vessels concerns mainly the proportion of height and width, as well as the degree of openness of the rim and the width of the vessel base. In the early phase, LBK vessels are homogeneous throughout the study area, their shape depends on the ware group, which may be related to different functions of the vessels. Over time, these differences blur, while regional variability becomes important. Within Kuyavia, two groups are visible: eastern and western. Regionalisation, visible in the shape of vessels, does not correlate with the pottery decoration, which is homogeneous for the whole of Kuyavia. The observed differences are probably an expression of various learning networks and therefore different groups, which, however, shared a common identity expressed in pottery decoration.