Aging Rockers

Recently Found Brazilian Rock Art Oldest in Americas

External view of limestone formation where Lapa do Santo rock shelter is located. Fazenda Cauaia, Matozinhos, MG. July/2009. Photo by Mariana Inglez/ photo collection of Laboratory for Human Evolutionary Studies - University of São Paulo.

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.

Thanks to DVB for this great shot of discovery in action. Last stage of excavation of unit FG of Lapa do Santo. A complete surprise to archaeologists, a pecked petroglyph was found during excavations. Lapa do Santo Rock Shelter, Fazenda Cauaia, Matozinhos, MG. July/2009. Source: photo collection of Laboratory for Human Evolutionary Studies - University of São Paulo.

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.”

Petroglyph found at bottom of unit FG-12/13 of Lapa do Santo. The figure is 30 cm long and represents a small anthropomorphic filiform with tri-digits, a c-like head and an oversized phallus. Lapa do Santo Rock Shelter, Fazenda Cauaia, Matozinhos, MG. July/2009. Source: photo collection of Laboratory for Human Evolutionary Studies - University of São Paulo. The head is at the top and the phallus is circled at the bottom. (LiveScience did the measurements and found the phallus was only slightly shorter than the arm above it.)

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.

This kind of rock art differs from Lapa do Santo's because it uses pigments. (Wikimedia Commons)

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!

An ‘Invisibility Cloak’ Outside of the Harry Potter World?

Harry Potter and earthquakes. Do you see any links between the two? Scientists believe they have discovered the reason why Harry treasured his cloak so much as they attempt to create an ‘invisibility cloak’ for buildings, not for people. Mathematicians at the University of Manchester have a theory that we will soon be able to ‘cloak’ buildings in order to protect them from natural disasters, such as earthquakes. These researchers are trying to prove that ‘invisibility cloaks’ are not only an element of fantasy, but may become an important part in the protection of structures when a natural disaster strikes.

Lead scientist, Dr. William Parnell, describes that the ‘cloaking’ of the buildings will not use a luxurious fabric that Harry uses while traveling through Hogwarts School of Witchcraft and Wizardry, but a special rubber. This pressurized rubber material will divert the vibrations, for example, of an earthquake and shield the structures using it. Hopefully, the rubber, or the cloak, will disguise buildings and allow the vibrations to pass around these structures. Such structures that may be inclined to use this rubber cushion are government buildings since they hold valuable information or nuclear energy plants which could cause great harm if damaged.

Although the rubber shielding will most obviously be used to protect from vibrations, it will also be helpful towards sound, light, and elastic waves. This research on light waves is less advanced than vibration waves most likely because it is more difficult to find a ‘cloak’ for these waves. Researchers will continue to make advancements in this area.

Despite the fact that the rubber cushion is not yet verified, there is the potential for it to be highly beneficial when dangerous earthquakes rumble through cities. It is possible that this cushion system can be used for larger scale structures. With continued research, this ‘invisibility cloak’ may be more like that of Harry Potter than we thought possible.

Manchester University (2012, February 14). ‘Invisibility’ cloak could protect buildings from earthquakes. ScienceDaily. Retrieved February 16, 2012, from­ /releases/2012/02/120214100817.htm

W. J. Parnell. Nonlinear pre-stress for cloaking from antiplane elastic waves. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2011; 468 (2138): 563 DOI: 10.1098/rspa.2011.0477