Imprimir

FIELD WORK

Scenes from an archeological site

Meticulous system enables researchers to compile data on life and death 10,000 years ago in a cave in Lagoa Santa

Can I pull out this little bone?” Lisiane Müller, a biologist from the city of Petrópolis, points to a fragment held up by toothpicks on a still-buried skeleton. Bending over the excavation site for hours on end, she separates grains of sediment with a brush and pushes them into a plastic bottle cut open like a scoop. Brazilian archeologist André Strauss, a visiting professor at the University of Tübingen, Germany, confirms that it won’t be possible to continue the exhumation without removing the bone. Strauss is one of the leaders of a team averaging 25 volunteers from a range of specialty areas—and accents. Nothing happens at the archeological site without authorization from Strauss or his colleague, Rodrigo Elias de Oliveira, a dentist and bioanthropologist from the Laboratory for Human Evolutionary and Ecological Studies (LEEEH) at the University of São Paulo (USP). The setting is Lapa do Santo, a cave in the Lagoa Santa region in the state of Minas Gerais, which in recent years has proven to be an important center for mortuary rituals performed between 10,000 and 8,000 years ago, as described in a paper published in the journal Antiquity in December 2016 (see Pesquisa FAPESP Issue nº 247).

Before they are removed, all the finds must be positioned in space with the help of a topography instrument known as a total station, which provides coordinates along three axes. Every day, and before modifications are made in any part of the excavation, the team also makes a detailed photographic record of the progress achieved in exposing each group of bones. The photos are printed on-site and annotated with the observations made by the person in charge of each exhumation. Small red plastic squares positioned at several points at the burial site are also located, or plotted, and included in the photograph. This procedure subsequently helps the researchers to build a three-dimensional model of each skeleton.

The work is carried out with enormous care, and even solemnity, since any slip can represent thousands of years lost. To prevent damage to the bones, the researchers can walk around the excavation site only in stocking feet. But the more striking presence is that of the ancient inhabitants who were buried by their companions, such as the child who died at approximately eight years of age and was laid on its side, with legs folded and arms positioned between them. Seeing this skeleton up close, buried so carefully that it has remained in the same position for some 10,000 years, is an emotional experience. It is even more moving to observe that same level of care being exercised by a group so removed in time and provenance. In addition to the multi-accented Brazilians on-site, in 2016 the team also included two students from the University of Tübingen, María López Sosa from Mexico and Franziska Mandt from Germany.

The sensation of the expedition was the skeleton of a woman accompanied by tiny bones which, once exposed, proved to be from the skeleton of a fetus or a newborn. Oliveira was there for practically the entire day, removing sediment one grain at a time while he kept an eye on the other exhumations in progress. He notes that the woman was placed on her knees in the pit, with her body bent over her legs in the fetal position, probably with the trunk twisted so that, if she were still pregnant, her belly would lay sideways and not beneath her ribs. This, plus the stone that served as a grave marker, likely explains why the tiny skeleton was some distance away from the bones of the presumed mother.

Exhaustive precision
“I won’t find out whether it was a baby or a fetus until we examine this tooth in the lab,” the dentist explained when he found a fragment recovered thanks to the team’s exhaustive investigative practices. The sediment is removed with the help of a brush or a rubber bulb used for blowing, and then put through small kitchen strainers—the kind you hold over a cup to separate cream from boiling milk—with the help of a watering can, to separate out the smaller fragments. When a small container called a petisqueira, thought to contain nothing important, was brought back to the dentist, he plucked out the tooth with tweezers. But the analyses conducted back in São Paulo yielded an inconclusive result. “It’s quite typical of that era in regard to birth, with some margin of error, so it could be nearly end-of-term, or it could have been born,” he explains. The milk teeth begin to form between the second and third month of pregnancy.

In addition to strainers for the delicate material, much of the sediment removed from the excavation is filtered through a large screen hanging from a tripod, to separate out fragments that escaped screening by the brush. That job, which requires constant attention and a strong tolerance of the dust that fills the air, was often handled by Gabriel Francisco Pereira, a volunteer who lives in Lagoa Santa and “knows everything about the region,” according to Strauss, and Nina Hochreiter, who, soon after completing 50 years as a veterinarian, retired and began to devote herself to her passion for archeology. This was her fourth stint as a volunteer at Lapa do Santo.

While the team functions like an ant colony, with everyone handling a certain job and working collaboratively, Strauss takes notes on much of what happens, using a computer labeled “journal.” Its keyboard is covered in plastic film to help withstand the fine dust that is impossible to escape. There he reports everything that is done, as a public record. “It’s a guide to help us think about what to do next, and especially for when we’re back in São Paulo,” he explains. Another important reference is the video journal, made at the end of each day, when hundreds of parrots return squawking to their nests in the rock wall above the shelter. “There’s an impressive level of site control,” observes Rita Scheel-Ybert, an archeobotanist from Brazil’s National Museum at the Federal University of Rio de Janeiro (MN-UFRJ), during a visit. She says that the set of meticulous procedures at the site is a hallmark of the work being done there. “It’s because we’re lazy,” Strauss quips. In truth, the work flow, which includes a computerized management system he developed, enables the team to finish the field work with much of the material already curated, and the information computerized and easily recoverable from a database.

Click on the photos to see the captions

Diversified collaboration
And there are many details. Miniscule fragments can help the researchers reconstruct the way of life and identity of the people who lived and died in the area. “I need to plot a charcoal!” Oft-heard shouts of this kind are requests for the person operating the total station to aim a laser beam at a specific point and then shout back the coordinates to whoever is operating the computer that contains the database Strauss developed to organize all the data. The abundant charcoal fragments are evidence of a time when so many bonfires burned continuously that much of the floor in the shelter consisted of ashes, as described in a paper published in July 2016 in the Journal of Archaeological Science by Uruguayan archeologist Ximena Villagran of the USP Museum of Archeology and Ethnology (MAE), who also collaborated on the project. Detailed analyses of charcoals can reveal what type of material was burned, and when. Patrícia de Sousa, a biologist from Minas Gerais State who volunteers at the site, is interested in beginning master’s studies in which she plans to investigate which plant species were used as fuel.

Other noteworthy fragments include the bones of small animals—generally rodents that roamed the area and may have served as food—and what are known as lithic tools, or simply “lithics.” Arrowheads and axe heads have previously been found, but the dominant material comes in the form of fragments of quartz—a mineral commonly found in the area. The fragments are just a few centimeters long, like sharp-edged glass shards, and could have had a wide range of uses. In her master’s research under Villagran, Daniela Ortega, an archeologist from the state of Goiás, is examining microscopic plant debris removed from lithics to infer which plants were processed with these tools and were probably part of the inhabitants’ diet.

Also working in the realm of the invisible, archeologist Andersen Lyrio da Silva of MN-UFRJ, who is from Rio de Janeiro, is looking for any parasites that might be found in the intestines of Lapa do Santo’s inhabitants—a possible indicator of diet or disease. To do this, he needs to work late in the day, after the excavations have been closed up. Using disposable surgical instruments to avoid contamination, he collects sediment near the bones in the space around each bone group and stores the samples in tubes wrapped in aluminum foil to protect them from the light, to be brought to the laboratory of parasitologist Alena Iñiguez of the Oswaldo Cruz Foundation (Fiocruz), who will analyze them. Although he has been trying since 2012, so far he has found nothing. But rather than give up, he is looking for ways to improve procedures so as to ensure that the absence of findings is not due to improper collection.

Most of the action occurs outside, in a rock-covered shelter. Inside the cave, Strauss jokes that he expects to find a saber-toothed tiger. A team headed by Elver Mayer, a doctoral candidate in biology at the Federal University of Rio Grande do Sul, focuses on deepening a 1-meter-by-1-meter area to search for bones of megafauna, which are larger animals. Despite the profusion of charcoals and lithics, there has been no loss of enthusiasm, and the discovery of a bone from something resembling a deer precipitated a celebration.

Subtitles in English are avaiable

Tasks
Although the most concentrated activity occurs inside the cave, there are team members working in other locations. One such place is the home of João Bárbara Filho, a key stopover for many archeologists traveling through the area. He was a driver at the Federal University of Minas Gerais in the 1970s when the expeditions to Lagoa Santa first started to search for human remains. In addition to driving, at that time he was also helping the members of the Franco-Brazilian expedition—who spoke only broken Portuguese—to communicate with the ranch owners to ask them about rock paintings. He also repaired camp tents, built whatever was needed and made tools. Now retired and living in Matozinhos, the municipality in which Lapa do Santo is located, he still stores, repairs and builds equipment, and makes room on his land for the flotation apparatus, a system he assembled that uses water to recover the organic matter that floats in sediment. “I make sure that all the charcoal is collected,” Strauss notes.

In addition, there are always four people at the base, the house made available by Sumidouro State Park where the team lives during this period. There, they can finish curating the material that was initially cleaned and organized the previous day, and stored in small bags with barcoded labels generated automatically by the database. Only the human bones, the more delicate and valuable material, are brought back intact for more careful analysis at USP.

The volume of data unearthed in a month of field work is so large that it is not possible to go to Lapa do Santo more often than every two years—the amount of time needed to process the findings. Back at LEEEH, the skeletons that seemed almost alive because they were so well-positioned turn into a profusion of bones, many of them broken into countless fragments. Some members of the field team—archeologist Renato Panunzio, biologist Paulo Lanznaster and journalist and history student Luisa Bittencourt—continue the work under Oliveira’s direction, reconstructing shattered skulls and assembling the skeleton like a jigsaw puzzle. The documented and cleaned material is ultimately stored in the collection at the laboratory headed by bioanthropologist Walter Neves. “We take great pains to go back into the field only when we sort out the material in the lab,” Oliveira comments.

Even so, planning for the next expedition has already begun.

See video interviews (in Portuguese)

* Maria Guimarães and Léo Ramos Chaves visited Lapa do Santo in September 2016 to produce a report, a video and photos.

Scientific articles
STRAUSS, A. et al. Early Holocene funerary complexity in South America: The archaeological record of Lapa do Santo (east-central Brazil). Antiquity. V. 90, No.. 354, p. 1454-73. December 2016.
VILLAGRAN, X. S. et al. Buried in ashes: Site formation processes at Lapa do Santo rockshelter, east-central Brazil. Journal of Archaeological Science. Online. July 26, 2016.

Republish