Tuberculosis (TB), a bacterial infection that kills more than a million people each year and sickens many more, has a short but complicated natural history involving humans, migration around the world, and animals that also carry the disease. Current strains of the bacterium that cause the disease in the Americas are closely related to European varieties, suggesting that TB, like other diseases, spread around the world as European powers took to the seas in the fifteenth and sixteenth centuries. What this does not explain, however, is archaeological evidence, such as lesions on ancient skeletons, that strongly indicates that TB was present in the Americas well before European contact. Researchers from Arizona State University and the University of Tübingen in Germany analyzed 68 skeletal samples in the Americas with TB-associated lesions and found three—from the Chiribaya culture in Peru, dating to around 1,000 years ago—that provided TB DNA that could be analyzed and compared to modern and ancient strains. They found that the ancient Peruvian TB bacterium was most akin not to any human strain, but to strains that infect pinnipeds—seals and sea lions. “The fact that the three ancient TB genomes were most closely related to pinniped strains was a huge surprise,” says Anne C. Stone of Arizona State University. Marine mammals, which ancient South Americans hunted for meat and fur, provide a plausible explanation for how the bacterium crossed the Atlantic before ships did. When the ships did arrive, the strains they carried swept through the Americas, replacing the seal-borne variety.

A metal detectorist near Dumfries in southwest Scotland has discovered what authorities are hailing as the largest and most significant Viking hoard found in the country in more than 120 years. Among the 100 artifacts, dating from the ninth and tenth centuries, are high-quality gold and silver objects including bracelets, brooches, pins, and armbands, as well as two exceptional items—a silver cross with unique enamel decorations and a rare silver cup. The engraved cup, which was made in the Holy Roman Empire during the time of Charlemagne or his successors, is one of only three Carolingian cups ever found in Britain. After archaeologists unearthed the vessel, wrapped in textiles and with its lid still intact, they discovered that it had also been filled with other valuable objects, including glass beads.

The hoard is especially significant due to its unusually broad range of material, with objects originating in Ireland, Britain, Scandinavia, and continental Europe. “It’s clear that these artifacts are of great value in themselves,” says Fiona Hyslop, Scotland’s cabinet secretary for culture and external affairs, “but their greatest value will be in what they can contribute to our understanding of life in early medieval Scotland, and what they tell us about the interaction between the different peoples in these islands at that time.”

Generations of archaeologists have studied ancient Egyptian tomb paintings and funerary objects for their religious, cultural, and historical significance. Now, a team of ecologists has scrutinized the same resources for evidence of which types of wildlife lived in Egypt at various points in its history—and concluded that the number of large mammal species has declined precipitously over the past 6,000 years, from 37 to just eight. The fossil record in Egypt is too sparse to provide this sort of information, explains Justin Yeakel, a quantitative ecologist at the Santa Fe Institute, so the rich record of artistic depictions is an invaluable resource. “Thanks to the careful observations of Egyptian artisans,” he says, “we have one of the few really high-resolution examinations of how animal communities change over time.”

Yeakel and his colleagues noted five dramatic shifts in the ratio of predators to prey, one of which occurred in the nineteenth century, along with modern population growth and industrialization. Three of the others coincided with well-known dry periods in the Nile River basin, which have also been associated with turning points in Egyptian history: the beginning of the Dynastic period, around 3000 B.C., and the collapses of the Old Kingdom (ca. 2170 B.C.) and the New Kingdom (ca. 1000 B.C.).