Impact of body size on decomposition rate in juvenile-sized remains: An experimental animal study

Juveniles and infants are often believed to decompose faster than adults due to smaller body masses, yet research on juvenile decomposition rates remains limited. Studies examining body size and decomposition yield contradictory results and typically rely on human analogues of adult-like proportions. Thus, whether smaller or larger cadavers decompose more rapidly remains unclear. Limited research exists on juvenile decomposition rates, despite their relevance to forensic investigations. In the UK, 46% of homicides involving victims under 16 remained unsolved in the year ending March 2022, compared to 30% across all homicides. Moreover, from 2012 to 2022, children under 1 year old had the highest homicide rate. Increased forensic understanding of juvenile decomposition could improve case resolution and investigative accuracy. This study investigated the relationship between cadaver size and decomposition rates using juvenile-sized domestic pigs in the UK. Over 18 weeks, total body score and percentage mass change were recorded. Given the subjective nature of visual scoring, three independent observers assessed the total body score to evaluate inter-rater reliability. Larger cadavers (12.3-16.1 kg) decomposed faster in early stages, while smaller cadavers (6.6-7.1 kg) showed an accelerated rate between weeks 4 and 12 based on total body score. Inter-rater analysis confirmed strong reliability in the scoring system. Both total body score and percentage mass change showed strong positive correlations with time, indicating that each measure reliably tracks the progression of decomposition.