Anthropologists' research unveils early stone plaza in the Andes

Two University of Wyoming anthropology professors have discovered one of the earliest circular plazas in Andean South America, showcasing monumental megalithic architecture, which refers to construction that uses large stones placed upright with no mortar.

Located at the Callacpuma archaeological site in the Cajamarca Basin of northern Peru, the plaza is built with large, vertically placed megalithic stones -- a construction method previously unseen in the Andes.

Associate Professor Jason Toohey, project lead, and Professor Melissa Murphy have been researching this topic since the project's inception in 2015.

Excavations took place in the plaza starting in 2018.

Their paper, which reports new data on this earliest known megalithic circular plaza in the northern Andes, is titled "A Monumental Stone Plaza at 4750 BP in the Cajamarca Valley of Peru" and has been published today (Feb.

14) in the peer-reviewed journal Science Advances.

Radiocarbon dating places its initial construction around 4,750 years ago during the Late Preceramic Period, making it one of the earliest instances of such architecture in the Americas.

To better understand this timeline, the team carefully excavated within the plaza, uncovering artifacts related to life in the past and collecting charcoal samples for dating.

All material remains then were cleaned, processed and analyzed in the laboratory.

"This structure was built approximately 100 years before the Great Pyramids of Egypt and around the same time as Stonehenge," Toohey says.

These dates signify that the circular plaza at Callacpuma is the earliest known example of monumental and megalithic architecture in the Cajamarca Valley -- and one of the earliest examples in ancient Peru.

"It was probably a gathering place and ceremonial location for some of the earliest people living in this part of the Cajamarca Valley," Toohey adds.

"These people were living a primarily hunting-and-gathering lifestyle and probably had only recently begun growing crops and domesticating animals."

The plaza is formed by two concentric walls and measures about 60 feet in diameter.

The project is led by Toohey and Patricia Chirinos Ogata from the University of California-Santa Barbara.

The team also includes Murphy, as well as undergraduate and graduate students from Peru and the U.S.

Toohey is an anthropological archaeologist who is dedicated to taking a holistic and multidisciplinary approach to the field.

He has conducted fieldwork in the Peruvian Andes since 2003.

The department head for anthropology at UW, Murphy is a biological anthropologist specializing in bioarchaeology and committed to multidisciplinary approaches within anthropology.

Read more at Science Daily

Oldest architectural plans detail mysterious desert mega structures

An international team of researchers including the University of Freiburg identifies engravings in Jordan and Saudi Arabia as the oldest known scaled building plans in human history.

Although human constructions have modified natural spaces for millennia, few plans or maps predate the period of the literate civilizations of Mesopotamia and Ancient Egypt. Researchers from the French research organisation "Centre national de la recherche scientifique" (CNRS), together with Prof. Dr. Frank Preusser from the University of Freiburg, have now been able to identify engravings in Jordan and Saudi Arabia as the oldest known true-to-scale construction plans in human history. The 8,000 to 9,000-year-old engravings depict so-called desert dragons -- kilometre long prehistoric megastructures used to trap animals. "Conclusions can be drawn from the findings about the people of the time. The ability to transfer a large space to a small, two-dimensional plan represents a milestone in intelligent behaviour," explains Preusser. The results, which were published in mid-May in the scientific journal PLOS ONE, should help to understand how desert dragons were conceived and built.

Scale plans of desert dragons discovered in Jordan and Saudi Arabia

Both finds are representations of nearby desert dragons engraved with stone tools. First sighted from aircrafts in the 1920s, desert dragons, up to five kilometres long, consist of stone walls that converge in a complex bounded by pits. As archaeologists have been able to determine in recent years, they were used for large-scale trapping of wild animals. In Jordan, there are eight desert dragons in the area of Jibal al-Khasabiyeh. There, the researchers found a depiction engraved in stone that measures 80 by 32 cm, its age is about 9,000 years. At Jebel az-Zilliyat in Saudi Arabia, two visible pairs of dragons are found three and a half kilometres apart. Here, too, a scaled engraving dating back about 8,000 years was discovered with a total length of 382 cm and a width of 235 cm.

Read more at Science Daily

Acoustic illusions

When listening to music, we don't just hear the notes produced by the instruments, we are also immersed in its echoes from our surroundings. Sound waves bounce back off the walls and objects around us, forming a characteristic sound effect -- a specific acoustic field. This explains why the same piece of music sounds very different when played in an old church or a modern concrete building.

Architects have long been capitalising on this fact when building, say, concert halls. However, the principle can also be transferred to other applications: objects hidden underground can be visualised by measuring how sound waves from a known source are reflected.

Active and passive manipulation

Some scientists want to go one step further and systematically manipulate the acoustic field to achieve an effect that shouldn't exist per se, given the real-life situation. For instance, they are attempting to create an illusory audio experience that tricks the listener into believing they are in a concrete building or an old church. Alternatively, objects can be made invisible by manipulating the acoustic field in such a way that the listener no longer perceives them.

Usually, the desired illusion relies on using passive methods that involve structuring the surfaces with the help of what are known as metamaterials. One way of hiding an object acoustically is to coat its surface and stop it from reflecting any sound waves. However, this approach is inflexible and usually works only within a limited frequency range, making it unsuitable for many applications.

Active methods seek to achieve the illusion by superimposing another layer of sound waves. In other words, by adding a second signal to the initial acoustic field. However, until now the scope for using this approach has also been limited, as it works only if the initial field can be predicted with some certainty.

Real-time illusion

Now the group headed by Johan Robertsson, Professor of Applied Geophysics at ETH Zurich, has worked with scientists from the University of Edinburgh to develop a new concept that significantly improves the active illusion. Led by Theodor Becker, a postdoc in Robertsson's group, and Dirk-Jan van Manen, the senior scientist who was instrumental in designing the experiments, the researchers have managed to augment the initial field in real time, as they report in the latest issue of the journal Science Advances. As a result, they can make objects disappear and they can mimic non-existent ones.

To achieve the special acoustic effects, the researchers installed a large test facility for the project in the Centre for Immersive Wave Experimentation at the Switzerland Innovation Park Zurich in Dübendorf. Specifically, this facility allows them to mask the existence of an object measuring roughly 12 centimetres or simulate an imaginary object of equal size.

The target object is enclosed in an outer ring of microphones as control sensors and an inner ring of loudspeakers as control sources. The control sensors register which external acoustic signals reach the object from the initial field. Based on these measurements, a computer then calculates which secondary sounds the control sources must produce to achieve the desired augmentation of the initial field.

Sophisticated technology

To mask the object, the control sources emit a signal that completely obliterates the sound waves reflected off the object. By contrast, to simulate an object (also known as holography), the control sources augment the initial acoustic field as if sound waves were bouncing off an object at the centre of the two rings.

For this augmentation to work, the data measured by the control sensors must be transformed instantaneously into instructions for the control sources. To control the system, the researchers therefore use field-programmable gate arrays (FPGAs) with an extremely short response time.

"Our facility allows us to manipulate the acoustic field over a frequency range of more than three and a half octaves," Robertsson says. The maximum frequency for cloaking is 8,700 Hz and 5,900 Hz for simulating. To date, the researchers have been able to manipulate the acoustic field on a surface in two dimensions. As a next step, they want to increase the process to three dimensions and extend its functional range. The system currently augments airborne sound waves. However, Robertsson explains, the new process could also produce acoustic illusions under water. He envisages a vast array of potential uses in different fields, such as sensor technology, architecture and communications, as well as in the education sector.

Read more at Science Daily