Evaluation of porcine decomposition and total body score (TBS) in a central European temperate forest.

The total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the porcine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one "substantial agreement" category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic casework in comparable contexts in Central Europe.

The genetic history of Scandinavia from the Roman Iron Age to the present.

We investigate a 2,000-year genetic transect through Scandinavia spanning the Iron Age to the present, based on 48 new and 249 published ancient genomes and genotypes from 16,638 modern individuals. We find regional variation in the timing and magnitude of gene flow from three sources: the eastern Baltic, the British-Irish Isles, and southern Europe. British-Irish ancestry was widespread in Scandinavia from the Viking period, whereas eastern Baltic ancestry is more localized to Gotland and central Sweden. In some regions, a drop in current levels of external ancestry suggests that ancient immigrants contributed proportionately less to the modern Scandinavian gene pool than indicated by the ancestry of genomes from the Viking and Medieval periods. Finally, we show that a north-south genetic cline that characterizes modern Scandinavians is mainly due to the differential levels of Uralic ancestry and that this cline existed in the Viking Age and possibly earlier.

Outdoor human decomposition in Sweden: A retrospective quantitative study of forensic-taphonomic changes and postmortem interval in terrestrial and aquatic settings.

This paper presents a quantitative retrospective study of gross human decomposition in central and southeastern Sweden. The applicability of methods developed abroad for postmortem interval (PMI) estimation from decomposition morphology and temperature are is evaluated. Ninety-four cases were analyzed (43 terrestrial and 51 aquatic) with a median PMI of 48 days. The results revealed differences in decomposition patterns between aquatic, surface, hanging, and buried remains. While partial saponification and desiccation occurred in cases of surface remains, complete skeletonization was observed in all cases with a PMI over two years. Aquatic skeletonization was slower due to extensive saponification in cases with PMI higher than one year. Formulae for assessing accumulated degree-days (ADD) from the original methods did not fit the study material. However, a regression analysis demonstrated that 80% of decomposition variance in surface remains could be explained by ADD, suggesting that a geographically adapted equation holds promise for assessing PMI. In contrast, the model fit was poor for aquatic cases (43%). While this may be explained by problems in obtaining reliant aquatic temperature data or an insufficient scoring system, aquatic decomposition may be highly dependent on factors other than ADD alone. This study evaluates the applicability of current PMI methods on an outdoor sample from a previously unpublished region, and represents the first scientific publication of human outdoor decomposition patterns in Sweden. Suggestions for future research are provided, including that scoring methods should incorporate saponification to fit forensic taphonomy in Swedish environments.