Homo sapiens in the middle of South America

Site near Cuiabá indicates that humans were present in Mato Grosso 27,000 years ago

Leo Ramos ChavesSituated about 80 kilometers (km) northwest of the city of Cuiabá, the Mato Grosso municipality of Jangada lies at the geographic center of South America. Whatever direction you take in your wanderings, you will not catch a view of the ocean, either the Pacific or the Atlantic, until you have traveled at least 1,500 km. In this part of the Cerrado savannah the vegetation is denser and the Araras ridge, with altitudes varying from 500 meters (m) to 800 m, punctuate the landscape. In a shelter beneath the rocks, very difficult to access and situated in a valley in the southeastern part of the mountain chain, two thick limestone walls protect a little-known piece of the prehistory of Brazil and the Americas. Between 1984 and 2004, archeologists Denis Vialou and his wife Águeda Vilhena Vialou from the National Museum of Natural History in France, coordinated excavations in two contiguous 80-square meter areas of that rocky shelter and found indications that modern man had twice inhabited the region: first at around 27,000 years ago and then between 12,000 and 2,000 years ago. However, there are no Homo sapiens skeletons at the site, only indirect vestiges of their presence. How the human species would have established itself at a point so far from the coast, so far back in time is, however, is still an unanswered question.

A summary of the findings from two decades and from subsequent studies conducted using material obtained at the Santa Elina shelter, which takes its name from the paleoarcheological site, reached the pages of the August edition of the scientific journal Antiquity. Data from the article had already been presented in other documents and even in books written in Portuguese or French, but not in English and in an influential international archaeological journal. In their paper, the Brazilian Águeda and her French husband Denis, with the aid of collaborators, summed up the three kinds of vestiges of human presence found in the region and the dating associated with them.

The first vestige consists of fragments of stone that exhibit marks such as serrations, finishing touches, and scratches that could only have been produced artificially by the hand of man with the aid of some stone tool. The second consists of bones from two specimens of giant sloths of the genus Glossotherium, discovered in geological strata along with a large quantity of stone artefacts worked by the inhabitants of the shelter. “We found two ornaments with holes on the ends, made from sloth osteoderms,” says Águeda. Osteoderms are bony plates, like scales, found on the backs of certain animals. The third type of vestige consists of residues of fire pits, of anthropic origin, that were found along the length of the rock strata associated with the human occupation.

Materials obtained at Santa Elina are preserved at the Museum of Archaeology and Ethnology of the University of São Paulo (MAE-USP) where the archaeologists give classes as guest lecturers for two months every year. Some of their Brazilian collaborators, like archaeologists Levy Figuti and Veronica Wesolowski de Aguiar e Santos, are also researchers at the São Paulo institution. The collection from the rocky shelter features 4,000 pieces of stone fabrication, as well as 200 bones from giant sloths. “The site also exhibits about 1,000 paintings on the rocks,” Denis points out. On the thick walls that protect the shelter, the drawings, usually of human figures, animals, or deformed beings, exhibit yellowish tones resulting from the use of hematite, the principal form of iron ore. Hematite was carried into the site’s interior and rubbed against the blocks of stone that formed a kind of interior paving. That is how prehistoric man obtained the pigment for his drawings. Those blocks, some of them preserved at the MAE-USP, even today exhibit flecks of color from the iron ore.

Different samples taken from Santa Elina, where excavations went as deep as 4 meters at some points, were subjected to three methods of dating, with convergent results. More than 50 samples of coal, residues of fire pits used by humans and found in the rock strata closest to the surface, have been dated using the carbon 14 method. Most samples were classified as between 2,000 and 12,000 years old; six of them were said to be between 10,000 and 20,000 years old. Shards of wood and tiny pieces of coal obtained from the deeper excavations have also been dated by that classic method, and classified as about 27,000 years old. Two bones from megafauna, one taken from a more superficial stratum and another from deeper sediments, were subjected to the so-called uranium-thorium method of dating. The first was gauged at 13,000 years and the second at 27,000 years. Three samples of sediments containing quartz from different strata (2.30 m, 3 m, and 3.85 m deep) were dated by optical thermoluminescence. Their ages were pegged, respectively as 18,000, 25,000, and 27,000 years.

Indian writings
The French-Brazilian couple learned of the existence of the Santa Elina shelter early in the 1980s. During the months that they customarily spend in Brazil, Águeda and Denis were invited by acquaintances in Cuiabá to visit their ranch in Mato Grosso where there were some “Indian writings” at isolated points of the Araras ridge. The trip proved to be useful and yielded the discovery of the shelter that was filled with paintings and rich paleoarcheological materials. While the excavations at Santa Elina were underway, the couple, always accompanied by colleagues and students from Brazilian and French universities, also began field work in another part of Mato Grosso. Near Rondonópolis, about 300 km south of the municipality of Jangada, there is a group of more than 170 Paleolithic sites known as Cidade de Pedra. In addition to paintings, findings in that area include ceramics, ornaments made with pieces of hematite, and an abundance of residues of anthropic fire pits from prehistory. “We have dated the coal from those fire pits and the results indicate a human presence at Cidade de Pedra between 6,000 and 2,000 years ago,” Águeda explains.

Reproduction from the book PRÉ – HISTÓRIA DE MATO GROSSO, Vol. 1 – SANTA ELINA | Léo Ramos Chaves Ornament dating back 25,000 years, made of sloth bone on top; a lithic artefact modified by manReproduction from the book PRÉ – HISTÓRIA DE MATO GROSSO, Vol. 1 – SANTA ELINA | Léo Ramos Chaves

The chronology proposed by the Vialous for the Mato Grosso sites, especially the Santa Elina shelter, suggest that Homo sapiens may have become established in the center of South America much earlier than was thought. In Brazil, only the region of the Serra da Capivara National Park, in São Raimundo Nonato, state of Piauí, exhibits indications of human presence as old or older than those at Santa Elina. Since the 1980s, Brazilian archaeologist Niède Guidon has maintained that this region of Brazil’s Northeast, where there are 1,350 known archaeological sites, has been inhabited by man for tens of thousands of years, or perhaps even since 100,000 years ago.

For a long time, the oldest datings adopted by Guidon, which were based on analyses of fire pit residues and later of lithic materials worked by man, were the target of major controversy. New studies conducted in recent years suggest that the human presence in Piauí does indeed seem to have occurred in excess of 20,000 years ago. “There is nothing wrong about claiming to have found very old datings at various points of the Americas, as in the case of Santa Elina,” Guidon observes. She is director-president of the Museum of the American Man Foundation (FUMDHAM), which administers the Serra da Capivara National Park in cooperation with the Chico Mendes Institute for Biodiversity Conservation (ICMBio) and the National Institute for Historic and Artistic Heritage (Iphan).

A paradigm shift
The chronology of the arrival of Homo sapiens in the Americas, the last continent to be conquered by modern man, has undergone major revisions in the past 15 years. “There has been a paradigm shift,” explains archaeologist Adriana Schmidt Dias, from the Federal University of Rio Grande do Sul (UFRGS). “The idea advanced by U.S. colleagues that the so-called Clovis culture was the first in the Americas is now shown to have been overtaken by the discovery of older sites on several parts of the continent. Scientific journals now are more open to publishing papers that reinforce that line of thought.” Known primarily because of the distinctive stone spear points gathered at localities in the state of New Mexico, Clovis sites have been dated as no older than 13,000 years. Their supposed primacy in terms of antiquity fit in well with the hypothesis of the arrival of Homo sapiens more or less at the same time via Beríngia, an ancient portion of dry land that connected Siberia with Alaska, and their later dispersion through the Americas via internal routes.

Reproductions from the book PRÉ – HISTÓRIA DE MATO GROSSO, Vol. 2 – CIDADE DE PEDRA Painting on stone, found at one of the 170 prehistoric sites at Cidade de Pedra, near RondonópolisReproductions from the book PRÉ – HISTÓRIA DE MATO GROSSO, Vol. 2 – CIDADE DE PEDRA

While that approach predominated, archaeological sites that were claimed to be older than Clovis or that did not reinforce the view that modern man entered the Americas through Alaska were viewed with extreme mistrust. For example, the Monte Verde site in Chile has been the topic of heated discussions among archaeologists since the 1970s, when the first data came out that insinuated the presence of man in the south of the continent 14,500 years ago. The most recent revision of the status of Monte Verde took place in November 2015, when a study in the journal PLOS ONE dated stone artefacts modified by humans at 18,500 years old.

The Vialou couple avoids discussing how humans might have arrived in Santa Elina, in the heart of South America, more than 25,000 years ago. Owing to its location, the shelter serves as a natural refuge in the midst of the elevations of the mountain range. It is likely that the region has been accessible by river navigation since ancient times, since the Araras ridge is 30 km from the Cuiabá river, an important tributary of the Paraná-Paraguay basin. “We do not have enough archaeological sites in the Americas that are 25,000 years old to enable us to trace a probable route,” says Denis. “What we know for sure is that man was already present throughout the continent 10,000 years ago.”

A survey published in 2013 in the scientific journal Quaternary International indicates that between 13,000 and 8,000 years ago man had become established in all major regions and biomes of Brazil. The survey compiled data from 90 sites and 277 datings. “Man probably entered the Americas at least 18,000 years ago,” suggests Adriana Dias, author of the study alongside archaeologists Lucas Bueno, from the Federal University of Santa Catarina (UFSC) and James Steele, from University College London, in the United Kingdom. “But effective occupation of the entire continent took place about 12,000 years ago. Santa Elina is a tiny light blinking on the colonization circuit board that attests to the possibility of there having been an ancient settlement in the center of South America.”

Scientific article
VIALOU, D. et al. Peopling South America’s center: The late Pleistocene site of Santa Elina. Antiquity. Vol. 91, No. 358, pp. 865-84.