Archaeologists have wondered for decades how the ancient Maya, who maintained large cities in hilly territory covered with rain forest and thin soil, were able to produce enough food to support their numbers. “That’s the Maya mystery,” says Richard Terry, a Brigham Young University soil scientist whose work explores the agricultural methods of the civilization. In an excavation at Tikal, Guatemala, once a Maya settlement of some 60,000 people, Terry’s interdisciplinary team is constructing a map of where and when the 115-square-mile site was planted with corn, one of the Maya’s staple crops. Corn leaves distinctive traces in the soil, which the team revealed using mass spectrometry. Understanding how the Maya made use of the land could reveal how they fed their large populations and whether agricultural shortfalls hastened the decline of the civilization.

The findings, published in the Soil Science Society of America Journal, show evidence that the Maya planted corn in lowland areas where there was more soil, and that agriculture gradually spread up-slope to thinner soils, where erosion eventually undermined productivity. The next question, says Terry, is whether the Maya developed the capability to cultivate corn in the low-lying wetlands, or bajos, that ring the site. If the Maya did possess a “lost technology” for growing corn in swampy conditions, the Maya crop mystery could constitute a new puzzle, as well as, perhaps, prove useful to modern agriculture.

A team of archaeologists from Mexico’s National Institute of Anthropology and History has entered a brilliantly painted Maya tomb inside Palenque’s Temple 20, 13 years after it was first discovered, following consultation with dozens of specialists on how best to conserve the find. The tomb is believed to hold the remains of K’uk Bahlam I, the founder of the city’s ruling dynasty, who came to the throne in A.D. 431. In 2011, a camera was lowered through a small hole in the tomb’s ceiling, providing a tantalizing glimpse of the murals (see “A Peek Inside Two Secret Chambers,” September/October 2011). The paintings, which may depict the nine lords of the Maya underworld, will be stabilized and conserved before the tomb is further excavated.

Each of us is home to a vibrant community of gut microbes, the bacteria that live in our digestive systems. Because these bacteria often reflect the diets of their hosts, scientists are examining coprolites—fossilized feces—to learn more about the microbiomes, and lives, of ancient humans.

For instance, the abundance of the bacteria Bifidobacterium breve—commonly found in the stool of recently breastfed children—in a 1,400-year-old sample taken from La Cueva de los Chiquitos Muertos (“The Cave of Dead Children”) in northern Mexico suggests the coprolite had come from a young child. The sample also contained a large quantity of a bacteria called Prevotella, which indicates a diet heavy in carbohydrates but relatively low in proteins.

Cecil M. Lewis, Jr., a molecular anthropologist at the University of Oklahoma, and his team also found Treponema in both ancient samples and modern rural populations. He thinks this implies that both groups have diets heavy in raw, fibrous foods. The microbe, however, does not appear in the stool of urban or Western populations, which might be attributable to more sanitary living conditions. “As we learn more about how well these microbiome profiles predict aspects of the human condition,” says Lewis, “we can use the information to better understand the past.”