Recently Found Brazilian Rock Art Oldest in Americas
Archaeologists unearthed a 10,000 year-old male figure on the walls of a Brazilian rock shelter, according to a report published in late February in PLoS One. Excavators found the stick figure-like man in their last few days of digging the site, and radiocarbon and optically-stimulated luminescence (OSL) dating revealed it to be the oldest reliably dated piece of rock art found thus far in the Americas.
The Lapa do Santo rock shelter is a sizable piece of real estate – about 14,000 ft2. 12,000 years ago, the floor of the rock shelter (which differ from caves because light reaches the back wall) was 12 feet lower in some places. Towards the bottom, submerged beneath thousands of years of piled up layers of cooking fires, is a small figure chipped into the stone. In the report, investigators describe him as an “anthropomorphic filiform petroglyph with tri-digits, a c-like head, and an oversized phallus.” WA Neves, the lead author, told the media that his nickname was “the little horny man.”
The people who made the figure hunted small game and foraged for the South American fruits and nuts now coveted by smoothie-drinkers. The aroused figure, at 30 cm long and 20 cm wide, is about the size of a laptop. Quoted in LiveScience, Neves said “there is another site in the same region where you find paintings with men with oversized phalluses, and also pregnant women, and even a [childbirth] scene.”
But differences between the ancient depictions outweigh their similarities at this point. The article cites Cueva de las Manos and Cueva Epullán Grande in Argentina as examples of South American caves with rock art from the same time period. Rock art in those caves consist of handprints and geometric figures, respectively. So many different themes, styles, and subjects across the Americas at this early time means two things: people arrived early enough to develop diverse art traditions, and more than one group was present at the same time.
Dating rock art is difficult; in the case of the little horny man, who was chipped into the limestone, two options are available. Archaeologists can use radiocarbon dating to find the age of the layers that buried the figure from top to bottom, or they can use OSL to date quartz grains from nearer the rock art itself.
Radiocarbon dating is more common, and is fairly reliable because of all the research out there on it. Despite its widespread use, there are pitfalls in using its data: it only tests organic (containing carbon) samples, it can only reliably date samples back to about 45,000 years, and it has standard deviations of hundreds of years. The date from the layer right above where the little horny man was found came back 9,470 RCYBP (Radiocarbon Years Before Present) plus or minus 50 RCYBP.
OSL dating is fairly cool but less widely used. It dates the last time a sample (a quartz or feldspar grain) saw sunlight. While the grain waits in darkness, radiation from cosmic rays and radioactive elements in the soil (uranium, potassium, etc.) traps electrons in the grains. When certain light – shot from this setup – shines on the grain, it releases the electrons as photons that are then measured by the same, really cool gun. The age is then calculated from the amount of light the sample re-emits. A neat way to shed some light on this not-so-little dude, huh?
Special thanks to Danilo Vicensotto Bernardo and the Laboratory for Human Evolutionary Studies at the University of Sao Paulo for sending me the excavation pictures. Muito obrigado!