A Tale of Two Necropolises: Contrasting Patterns of Diet and Mobility in Late Medieval/Early Modern Lisbon Through Multi- Isotope Analysis

In the quiet corners of archaeology, where history is often written in silence, scientists have developed a way to listen to the bones. By analyzing the chemical fingerprints left behind in human teeth and bones, researchers can reconstruct the diet and travel history of people who lived centuries ago. This technique relies on the fact that the food we eat and the water we drink leave a unique signature in our bodies. Plants that grow in different climates and under different soils absorb distinct chemical elements from their environment. When humans consume these plants, or eat animals that have eaten them, those chemical signatures become locked into our growing tissues. Teeth, which form during childhood and do not change, preserve a record of where a person spent their early years. Bones, which constantly renew themselves throughout life, tell a different story: where a person lived and what they ate as an adult. By comparing these chemical records against known maps of local geology and climate, scientists can determine if someone grew up in the place where they were buried or if they had traveled from far away. This method offers a rare glimpse into the lives of ordinary people whose names and stories were lost to time, especially in eras where written records are scarce or were destroyed.

In the heart of Lisbon, Portugal, a rescue excavation at a site called Rua dos Lagares #74 uncovered a complex history buried beneath the modern city. The ground held two distinct layers of graves, separated by centuries of urban change, each telling a different story about the people who lived and died there. The first layer, known as Necropolis I, was a cemetery used from the 12th century until the late 15th century. Historical clues and the style of the burials suggest this was a Jewish cemetery, abandoned around the time the Jewish population was forcibly expelled from Portugal in 1496. The second layer, Necropolis II, was established shortly after, likely in the mid-15th century, and continued into the early 16th century. This later cemetery appears to have been a mixed burial ground for a diverse community, including Muslims and possibly people of African descent who had arrived in Lisbon through the expanding Portuguese trade networks. Because the 1755 Lisbon earthquake destroyed many historical records, the lives of these specific communities remain largely a mystery. To fill these gaps, a team of researchers analyzed the bones and teeth of 53 adults buried in these two cemeteries, using chemical analysis to reconstruct their life stories.

The results revealed two populations with strikingly different lives. The people in the first cemetery, the Jewish community, lived remarkably similar lives. Their teeth and bones showed that they ate a very consistent diet throughout their childhoods and into adulthood, relying on the same local foods as other residents of medieval Lisbon. Most of them had grown up in the Lisbon area or in places with very similar climate and geology. However, a small group of five men stood out. Their chemical signatures indicated they had spent their childhoods in different regions, likely in the mountainous or wetter areas of neighboring Spain, before moving to Lisbon later in life. This suggests that while the community was largely local, there was movement of men, perhaps for trade or to escape persecution, within the Jewish networks of the time.

In stark contrast, the people buried in the second cemetery, Necropolis II, lived vastly different lives from one another. The chemical analysis showed an extraordinary diversity in their childhood diets and places of origin. While the first group ate a uniform diet, the second group ate everything from foods grown in wet, humid regions to those from dry, arid landscapes. Some individuals had grown up eating a diet based on rice and other local plants, while others had consumed foods typical of the African savanna, such as millet and sorghum. The chemical data also pointed to a wide range of childhood homes. Most of these individuals were not from Lisbon. Their teeth carried the chemical signatures of places far beyond the city, with some hailing from the humid coasts of West Africa, others from the dry interiors of the Sahara, and some from the mountainous regions of North Africa.

The researchers found that many of the individuals in the second cemetery had physical traits and dental modifications that anthropologists had previously identified as possibly indicating African ancestry. The chemical evidence supported this, showing that these individuals had indeed spent their childhoods in diverse regions of West and North Africa. Some had grown up in the coastal areas of Senegal and Gambia, where rice was a staple, while others came from the arid Saharan coast or the highlands of Mali. The variety in their diets and origins suggests that this was not a single, homogenous group, but a collection of people from many different places who had been brought together in Lisbon. Some may have been enslaved, others freed, and some laborers, all arriving through the Portuguese trade routes that were expanding along the African coast at the time.

The study also highlighted the harsh realities these people faced. Many of the individuals in the second cemetery showed signs of severe physical stress and malnutrition in their bones, a pattern consistent with the hardships of enslavement and forced labor. Their chemical signatures also hinted at the difficult conditions they endured, with some showing signs of water stress, suggesting they had lived in very dry environments before arriving in the city. The presence of specific grave goods, such as blue glass beads known to have been traded in West Africa, further connected these individuals to their homelands.

Ultimately, the chemical analysis of these bones has brought a forgotten population into focus. While the first cemetery tells the story of a local Jewish community with a few outsiders, the second cemetery reveals a chaotic and diverse mix of people from across the globe, brought together by the forces of empire and trade. The data confirms that Lisbon in the 15th and 16th centuries was a place where people from vastly different worlds met, lived, and died. For a population that left few written records, these chemical stories provide a powerful voice, revealing the origins, diets, and struggles of individuals who were once just names on a list of the lost. The findings do not pinpoint exact birthplaces for everyone, as the chemical landscapes of different regions can overlap, but they clearly demonstrate that the people of Necropolis II came from a wide array of geological and climatic zones, making their presence in Lisbon a testament to the complex and often brutal history of the early modern world.