The sample comprised 297 non-adults and 793 adults, including 258 males, 244 females and 291 individuals of undetermined sex. Sex was estimated from the morphology of the innominate bones, cranium and mandible using standard anthropological criteria, applied only to individuals older than 15 because secondary sexual characteristics develop after puberty. Age at death in adults was reconstructed through a battery of well-established skeletal indicators, including the pubic symphysis, auricular surface of the ilium, acetabulum, ectocranial suture closure, sternal rib ends, the sternal end of the clavicle and patterns of dental wear. For non-adults, the researchers relied on the formation and fusion of ossification centers, the diaphyseal lengths of long bones and tooth eruption sequences. Individuals with severe skeletal pathologies capable of distorting body proportions, such as rickets, were excluded from stature and body mass analyses, whereas those with milder conditions such as osteoarthritis were retained.

Life expectancy at birth was calculated using a stationary population life table based on Halley’s model, an approach the authors selected because the burial assemblages reflect attritional rather than catastrophic mortality and because the method permits direct comparison with a substantial body of published paleodemographic research from the Iberian and Italian peninsulas. Stature was estimated with Pearson’s regression equations, derived from the physiological lengths of the left femur and tibia, chosen because the French reference sample is biologically and geographically the closest match to Mediterranean populations and has been shown to perform well on Spanish and Italian skeletal series. Body mass was derived from the femoral head diameter using equations developed by Ruff and colleagues, a well-validated proxy because the femoral head remodels in response to weight-bearing loads. Body mass index was then computed as body mass divided by the square of stature, with individuals classified as underweight, normal weight, overweight or obese according to conventional BMI thresholds. Statistical comparisons between the sexes employed Student’s t-tests or Mann-Whitney U tests depending on the distribution of the data, while temporal trends were tested with one-way ANOVA followed by Tukey post-hoc comparisons, all conducted in SPSS at a significance threshold of p < 0.05.

The results reveal a striking asymmetry between the four biological indicators. Life expectancy at birth remained relatively stable across most periods, hovering between roughly 21 and 27 years, before showing a marked increase during the Modern period. The Prehistoric value of just over 12 years is exceptionally low, but the authors caution that the small Prehistoric sample of 45 individuals, shaped by funerary practices such as adult cremation in the Late Bronze and Iron Ages, likely depresses this figure far below any biological reality. The Roman period yielded a life expectancy of about 21.6 years, squarely within the range documented for ancient Mediterranean populations, where nearly half of all children may have died before age five. Life expectancy peaked at approximately 27.2 years in Late Antiquity, dipped to about 25 years during the turbulent Medieval centuries, and climbed again to 27.15 years in the Modern period.

Stature, by contrast, displayed no statistically significant variation across the seven millennia under study. Male averages ranged narrowly between 164 and 166 centimeters, and female averages between 151 and 154 centimeters, in every period analyzed. Males were significantly taller than females throughout, as expected from sexual dimorphism, but the constancy of absolute height across such dramatic cultural transformations, from Neolithic farming villages to the proto-industrial city, surprised the researchers. The finding parallels a comparable diachronic study of Milan, and the authors suggest that restricting the analysis to a single urban area minimizes the confounding effects of geography, microclimate, agricultural systems and economic activity that have produced the U-shaped stature trends reported in earlier studies that mixed rural and urban, and multi-regional, samples.

Body mass and body mass index told a very different story, showing statistically significant changes over time in both sexes. In the Prehistoric assemblage, virtually all individuals fell within the normal weight range, with only about 14 percent of males classified as overweight and no underweight or obese individuals at all. Overweight cases rose during the Roman period to roughly 30 percent of males and 29 percent of females. Obesity made its first appearance in the archaeological record of Barcelona during Late Antiquity, detected in about 1 percent of females, alongside the earliest underweight individuals. During the Medieval period, male body mass dropped to its lowest recorded average of 59 kilograms, and underweight classifications climbed to over 19 percent of males, a pattern the authors link to famines, warfare, sieges and epidemic disease that plagued the city between the ninth and fourteenth centuries.

The Modern period brought a decisive reversal. Body mass peaked in both sexes, and overweight prevalence surged to 47 percent of males and 40 percent of females, the highest levels in the entire sequence. The authors attribute this shift to profound dietary and lifestyle transformations accompanying the transition from the pre-industrial to the industrial era: the Columbian Exchange introduced American crops such as maize and potatoes into the diets of the poor, proto-industrialization and textile manufacturing spurred economic recovery by the eighteenth century, and Spain experienced declining mortality thanks to improved nutrition, hygiene and disease treatment. Notably, the estimated body masses of Modern-period Barcelonans, averaging 67.6 kilograms for males and 59.5 kilograms for females, closely match those of post-medieval Dutch urban populations from Arnhem and Zwolle, underscoring a shared European trajectory of increasing body size in urban settings.

The study’s demographic data also captured the scars of Barcelona’s most catastrophic episodes. The Medieval decline in life expectancy, body mass and BMI coincides with centuries of conflict along the Spanish March between Islamic and Christian forces, recurrent famines, the devastating sack of the city by Almanzor’s army in 985, in which much of the population was killed or enslaved, and repeated outbreaks of the Black Death in the fourteenth century that decimated the population by as much as 40 percent. The city required roughly two centuries to recover its pre-1348 population levels. Violence against marginalized communities, including the destruction of the Jewish neighborhood of El Call, further marked this grim chapter. These historical events, the authors argue, left measurable imprints on the biological record, demonstrating that social inequality, conflict and epidemics translate directly into skeletal evidence of stress and mortality.

A central conclusion of the work is that life expectancy, body mass and body mass index proved far more sensitive to sociocultural and environmental change than stature did. While the skeleton preserved height with remarkable stability, the other three parameters registered three major shifts: the transition from Prehistory to the Roman period, a pronounced downturn during the Medieval era, and a strong recovery between the Medieval and Modern periods. Because the necropolises sampled predominantly contain individuals of lower socioeconomic status, buried in simple earth-cut graves rather than costly chapel tombs, the dataset offers a consistent window into the living conditions of ordinary working Barcelonans, from skilled tradesmen such as carpenters and weavers to unskilled laborers, across nearly seven millennia.

The authors acknowledge the inherent limitations of paleodemographic reconstruction, including the “osteological paradox,” the chronological gap between the Neolithic and Bronze Age assemblages, and the scarcity of comparable body mass data from other historical Spanish populations. Nevertheless, the study establishes a foundational reference framework for future diachronic bioarchaeological research in the Iberian Peninsula and contributes to a broader scientific conversation about how human biology, environment and history intertwine. It also carries a contemporary resonance: obesity, once entirely absent from the city’s dead, now ranks among its most pressing public health challenges, and the skeletal record makes clear that this epidemic is a product of the modern era’s abundance and sedentary living, not a feature of the human condition.