The Rome of America: What Lies Under Teotihuacan? – The Real City of the Gods

It was one of the first large cities in the Western Hemisphere, the Huge. And its origins are a mystery.  About a thousand years before the gradual arrival in central Mexico of the Nahuatl-speaking Aztec, it was built by hand. But it was the Aztec, descending on the abandoned site, no doubt falling awestruck by what they saw, who gave its current name: Teotihuacan.

According to George Cowgill, an archaeologist at Arizona State University and a National Geographic Society grantee—Teotihuacan, a famous archaeological site less than 30 miles (50 kilometres) from Mexico City, Teotihuacan reached its zenith about 100 B.C. And A.D. 650.

It covered 8 square miles (21 square kilometres) and supported a population of a hundred thousand.

“It was the largest city anywhere in the Western Hemisphere before the 1400s,” Cowgill says. “It had thousands of residential compounds and scores of pyramid-temples … comparable to the largest pyramids of Egypt.”

Oddly, Teotihuacan, which contains a massive central road (the Street of the Dead) and buildings including the Temple of the Sun and the Temple of the Moon, has no military structures—though experts say the military and cultural wake of Teotihuacan was heavily felt throughout the region.

Who Built It?

Cowgill says the site’s visible surface remains have all been mapped in detail. But only some portions have been excavated.

Scholars once pointed to the Toltec culture. Others note that the Toltec peaked far later than Teotihuacan’s zenith, undermining that theory. Some scholars say the Totonac culture was responsible.

No matter its principal builders, evidence shows that Teotihuacan hosted a patchwork of cultures including the Maya, Mixtec, and Zapotec.

One theory says an erupting volcano forced a wave of immigrants into the Teotihuacan valley and that those refugees either built or bolstered the city.

The main excavations, performed by Professors Saburo Sugiyama of Aichi Prefectural University in Japan and Rubén Cabrera, a Mexican archaeologist, have been at the Pyramid of the Moon.

It was there, beneath layers of dirt and stone, that researchers realized the awe-inspiring craftsmanship of Teotihuacan’s architects was matched by a cultural penchant for brutality and human and animal sacrifice.

Inside the temple, researchers found buried animals and bodies, with heads that had been lobbed off, all thought to be offerings to gods or sanctification for successive layers of the pyramid as it was built.

Since 2003, archaeologist Sergio Gomez has been working to access new parts of the complex and has only recently reached the end of a tunnel that could hold a king’s tomb.

It’s unclear why Teotihuacan collapsed; one theory is that poorer classes carried out an internal uprising against the elite.

For Cowgill, who says more studies are needed to understand the lives of the poorer classes that inhabited Teotihuacan, the mystery lies not as much in who built the city or in why it fell.

“Rather than asking why Teotihuacan collapsed, it is more interesting to ask why it lasted so long,” he says. “What were the social, political, and religious practices that provided such stability?”

Golden Eagle Sculpture Unearthed in Aztec Temple

According to a statement released by Mexico’s National Institute of Anthropology and History (INAH), archaeologists led by Rodolfo Aguilar Tapia have uncovered a bas-relief sculpture of a golden eagle in the floor of the Aztec chapel dedicated to Huitzilopochtli at the Templo Mayor.

The well-preserved floor surface was covered during an expansion of the temple before the arrival of the Spanish in Tenochtitlan in the sixteenth century, Tapia explained.

“From what we have seen through photographs, it is a very beautiful piece that shows the great secrets that the Templo Mayor of Mexico Tenochtitlan has yet to reveal to us. I want to extend my appreciation to the INAH archaeologists who collaborate in this space, since, thanks to their effort and dedication, we can continue to recover our history and our memory.

Due to the health contingency, the fieldwork has had to be postponed, however, it is clear that there is also an important work of research and academic reflection that has not stopped “, said the Secretary of Culture, Alejandra Frausto Guerrero, about this notable finding.

Although it was in February 2020 when a multidisciplinary team concluded the release and cleaning of this itzcuauhtli , a Nahua voice that means “obsidian eagle”, and with which the Mexica referred to the golden eagle ( Aquila chrysaetos canadensis ), it is now, when his investigation in the cabinet has been deepened, the finding is made known.

Carved on red tezontle and with dimensions of 1.06 meters long by 70 centimetres wide, this bas-relief is the largest in a set of 67 similar elements found so far in the Templo Mayor.

According to specialists, the relevance of the sculpture is denoted not only by its size and finish but also by its location, at the foot of the most important building for the Mexica and in the central axis that crosses the ‘chapel’ of Huitzilopochtli and the monumental sculpture of the goddess Coyolxauhqui. It is also close to Cuauhxicalco, a circular building whose name translates as “place of the eagle’s gourd”, where, according to 16th-century documents, the ritual cremations of the Tenochca rulers were carried out.

Regarding the discovery of the bas-relief, the archaeologist assigned to the PTM, Rodolfo Aguilar Tapia, who investigated the piece together with the interns in archaeology Mary Laidy Hernández Ramírez and Karina López Hernández; and in physical anthropology, Jacqueline Castro Irineo, from the National School of Anthropology and History, reported that it was verified during the ninth field season of the PTM.

This season, directed by the head of the Project, the archaeologist Leonardo López Luján, has focused on exploring under the ‘liga bridge’ that connects the streets of Guatemala and Argentina, wherein pre-Hispanic times the west plaza of the Sacred Precinct was located of Mexico-Tenochtitlan. The sculptural carving was part of a floor of that space, which would have been in use during the government of Motecuhzoma Ilhuicamina, between the years 1440 and 1469 of our era.

“This floor is unique in the entire Templo Mayor as it contains bas-reliefs that allude to the dual conception of the building. On the south side, where we are exploring, there are elements like this eagle, linked to the mythical cycle of the birth of Huitzilopochtli; while to the north, the bas-reliefs located earlier —the first in 1900 by Leopoldo Batres, and the later by the PTM and the Urban Archeology Program (PAU) – contain representations associated with Tláloc, the water cycle and the regeneration of corn “.

Aguilar Tapia specifies that thanks to the work carried out by archaeologists Eduardo Matos Moctezuma and Leonardo López Luján, today there is a defined stratigraphic correspondence, which allows researchers to know in which construction stage of the Templo Mayor the findings are located, and at what time belong the same.

Thus, he exemplifies, when the exploration at the aforementioned intersection began, the floor that the archaeologists saw was from Stage VI of the Templo Mayor, corresponding to the government of Ahuítzotl between 1486 and 1502, while now, after meticulous excavations, specialists have managed to reach Stage IV-a, that is, they have gone back in time to the 1440s and to the period of government of Motecuhzoma I.

The aforementioned plaza floor was covered since pre-Hispanic times during the expansion of the Templo Mayor. “That is why it has a good state of conservation,” says the researcher, noting that “it is an element that was never seen by the Spanish.”

The symbolism of the golden eagle

The pause in the fieldwork that the COVID-19 pandemic brought with it, allowed the PTM researchers to carry out the investigation of various elements, including the bas-relief. Among other aspects, the iconographic representations that exist of the golden eagle in historical sources such as the codices were studied, in order to correlate them with the sculpture discovered at the foot of the Templo Mayor.

One of those representations, Aguilar Tapia points out, is in Plate 50 of the Codex Borgia, where a golden eagle is shown posing on top of a mesquite tree, a tree that rises from a stark deity. “The interesting thing is that this image is iconographically very similar to the bas-relief that we find in the field, in both representations the feathers end in the shape of sacrificial knives, which allude to the Nahua name of the bird: obsidian eagle.”

For the Mexica, this bird of prey was closely related to war and sacrifice, while it was considered a nahual of the sun and, therefore, also of its tutelary god, Huitzilopochtli.

In the incoming seasons of the PTM field, the researcher concludes, the actions will focus on completing the exploration of the floor where the bas-relief is located to look for more others and then, with extreme care, temporarily remove them and be able to investigate under them in search of offerings or other architectural elements. “After all this exploratory process, with the support of restoration specialists, we will place each bas-relief in its precise place”, he concludes.

Similar elements could also be found when the excavations around Cuauhxicalco are resumed. The intention of the PTM is that, after its investigation, the bas-reliefs can be shown to the public in their original position: at the west foot of the Templo Mayor.

Experts find 2,000 ruin sites near the Maya train route project in Mexico

Archaeologists in Mexico have provided a study from specialists that cites have more than 2,000 pre-Hispanic ruins or clusters of artifacts along the planned path of the president’s controversial “Maya Train” project on the Yucatan peninsula.

The discovery of sites using LiDAR elevation mapping technology could slow down the already disputed project, which opponents contend also threatens indigenous communities and water supplies.

The laser elevation data showed a total of 2,187 “archaeological monuments” along 277 miles (366 kilometers) of the proposed route, about one-quarter of the total planned track. Experts already knew about the existence of some of the sites, but some are new.

The term “monuments” can mean many things, ranging from the remains of a pre-Hispanic Maya home, or carved stones, all the way up to remains of temple platforms.

It was not clear how many of each type of artifact was detected, but Mexico’s National Institute of Anthropology and History said at least 91 were large-scale structures like plazas, pyramid or temple platforms.

Mayan houses were generally relatively insubstantial, with stone bases topped by thatch and wooden structures of which little remains.

The institute said in a statement that the builders of the train would have to take “specific measures” to avoid damaging the artifacts, but did not say whether that meant parts would have to be re-routed.

In July, President Andres Manuel Lopez Obrador inaugurated the start of construction on the “Maya Train,” a pet project of his that would run some 950 miles (about 1,500 kilometers) in a rough loop around Yucatan.

The train is intended to connect Caribbean beach resorts to the peninsula’s interior, with largely indigenous populations and ruin sites, in a bid to stimulate economic development around its 15 stations. The government says it will cost as much as $6.8 billion, but others say it will be much more.

Critics say Lopez Obrador rammed through the project without adequate study of its effects on the environment, underground sinkhole caves known as cenotes, and ruin sites.

Some stretches of the route already have tracks, and the institute said some artifacts had already been disturbed by railway construction decades ago.

But other stretches are to push through sensitive jungle terrain, though they will parallel existing roads or transmission lines. Even where an old railway line exists, the project would imply updating tracks and building new stations.

Some Mayan communities have filed court challenges against the project, arguing that it will cause environmental damage. They also say they were not adequately consulted about it or they will not share in its benefits.

LiDAR, which stands for Light Detection and Ranging, involves shooting a pulsed laser at the ground to get a high-resolution, detailed image of the surface, even through dense vegetation.

The Mayas formed a sprawling empire of city-states across the Yucatan and Central America between 2,000 B.C. and A.D. 900, and their descendants still live on the peninsula.

Aztec skull tower: Archaeologists unearth new sections in Mexico City

More sections of an extraordinary Aztec tower of human skulls have been excavated by archaeologists in the centre of Mexico City. The National Institute of Anthropology and History (INAH) of Mexico said a further 119 skulls had been uncovered.

While restoring a building in the Mexican capital, the tower was discovered in 2015. It is thought to be part of the temple’s skull rack for the Aztec god of the sun, war, and human sacrifice.

Known as the Huey Tzompantli, the skull rack stood on the corner of the chapel of Huitzilopochtli, the patron of the Aztec capital Tenochtitlan.

The Aztecs were a group of Nahuatl-speaking peoples that dominated large parts of central Mexico from the 14th to the 16th centuries.

Their empire was overthrown by invaders led by the Spanish conquistador Hernán Cortés, who captured Tenochtitlan in 1521.

A similar structure to the Huey Tzompantli struck fear in the soldiers accompanying the Spanish conqueror when they invaded the city.

The cylindrical structure is near the huge Metropolitan Cathedral built over the Templo Mayor, one of the main temples of Tenochtitlan, now modern-day Mexico City.

“The Templo Mayor continues to surprise us, and the Huey Tzompantli is without doubt one of the most impressive archaeological finds of recent years in our country,” Mexican Culture Minister Alejandra Frausto said.

Archaeologists have identified three construction phases of the tower, which dates back to between 1486 and 1502.

The tower’s original discovery surprised anthropologists, who had been expecting to find the skulls of young male warriors but also unearthed the crania of women and children, raising questions about human sacrifice in the Aztec Empire.

“Although we can’t say how many of these individuals were warriors, perhaps some were captives destined for sacrificial ceremonies,” said archaeologist Raul Barrera.

“We do know that they were all made sacred,” he added. “Turned into gifts for the gods or even personifications of deities themselves.”

OU archaeologists uncover buried building in the ancient Mexican city

University of Oklahoma researchers have made a finding that they believe could change the world’s view of an ancient capital.

The location of a buried building under the surface of the Main Plaza at Monte Alban, one of the first towns to establish in all of pre-Hispanic Mexico, was recently found by archaeologists from the University of Oklahoma.

The team used ground-penetrating radar, electrical resistance, and gradiometry to locate the structure.

“This discovery changes our understanding of the history of the Main Plaza and how it was organized and used,” said Marc Levine, assistant curator of archaeology at the Sam Noble Oklahoma Museum of Natural History and assistant professor in the Department of Anthropology, College of Arts and Sciences. “Everything is deeply symbolic here.”

The building appears to resemble stone temples that were excavated by Mexican archaeologists in the 1930s.

Evidence from those temples indicates they were used for religious practices like burning incense, making offerings and ritual bloodletting.

Monte Albán was established in 500 BCE and eventually grew to become a powerful regional capital with impressive buildings featuring carved stone monuments with a highly developed artistic style and written language.

The Main Plaza was built, expanded and remodelled over 1,000 years before the site’s collapse around 850 CE.

Archaeologists have investigated many of the buildings erected around the Main Plaza, but have never focused research on the plaza itself to better examine its role in society.

OU researchers hope to develop a clearer picture of what the Main Plaza looked like during its early history and better appreciate the amount of work that went into its construction.

“If you think of the National Mall in Washington, D.C., every monument and every building that goes on that mall has a significance and was thought over, carefully planned and oriented in a certain way,” Levine said. “The same goes for Monte Albán.”

Levine stresses the importance of the site, saying the Main Plaza is even featured on the country’s 20 peso note.

The OU team also used a drone to create a digital map of the Main Plaza and its associated structures. With the help of a supercomputer, the team is creating 3-D images of all the buildings to measure their volume.

This will provide a better understanding of the effort required to move all the dirt and construct the buildings. Levine estimates the team will spend about two years analyzing all of their data to complete their study of the plaza.

“We may find some other things that are important that we haven’t had a chance to process yet,” he added.

The giant pyramid is hidden inside a mountain

Although the Great Pyramid of Giza in Egypt is by far the most talked-about pyramid in the world, it is not by a long shot the tallest. The title goes to the Great Pyramid of Cholula, an ancient temple of the Aztecs in Puebla, Mexico, with a base four times the size of Giza, and about twice the volume.

Why is the world’s biggest pyramid so often overlooked? It could be because that gigantic structure is actually hidden beneath layers of dirt, making it look more like a natural mountain than a place of worship.

In fact, it looks so much like a mountain, that famed Spanish explorer Hernán Cortés completely missed it, and unwittingly built a church right on top of it, as you can see in the image above.

To understand how awesome the Great Pyramid of Cholula is, we must jump back to well before Cortés and his army planted a symbol of Christianity on its peak.

Known as Tlachihualtepetl (meaning “man-made mountain”), the origins of the pyramid are a little sketchy, though the general consensus is that it was built in around 300 BC by many different communities to honour the ancient god Quetzalcoatl.

As Zaria Gorvett reports for the BBC, the pyramid was likely constructed with adobe – a type of brick made of out of baked mud – and features six layers built on top of each over many generations. Each time a layer was completed, construction was picked back up by a new group of workers.

This incremental growth is what allowed the Great Pyramid of Cholula to get so big. With a base of 450 by 450 metres (1,480 by 1,480 feet), it’s four times the size of the Great Pyramid of Giza.

In fact, at roughly 66 metres (217 feet) tall, the pyramid’s total volume is about 4.45 million cubic metres (157 million cubic feet), while the Great Pyramid of Giza’s volume is just 2.5 million cubic metres (88.2 million cubic feet).

The Great Pyramid of Giza is taller, though, at 146 metres (481 feet) high. The ancient Aztecs most likely used the Great Pyramid of Cholula as a place of worship for around 1,000 years before moving to a new, smaller location nearby.

Before it was replaced by newer structures, it was painstakingly decorated in red, black, and yellow insects. But without maintenance, the mud bricks were left to do what mud does in humid climates – provide nutrients to all kinds of tropical greenery.

“It was abandoned sometime in the 7th or 8th Century CE,” archaeologist David Carballo from Boston University told Gorvett at the BBC. “The Choluteca had a newer pyramid-temple located nearby, which the Spaniards destroyed.”

When Cortés and his men arrived in Cholula in October 1519, some 1,800 years after the pyramid was constructed, they massacred around  3,000 people in a single hour – 10 per cent of entire city’s population – and levelled many of their religious structures.

But they never touched the pyramid, because they never found it. 

In 1594, after settling in the city and claiming it for their own, they built a church – La Iglesia de Nuestra Señora de Los Remedios (Our Lady of Remedies Church), on top of the hidden pyramid mountain. 

It’s unclear if the Aztecs knew the mud bricks would encourage things to grow all over it and eventually bury the entire structure, but the fact that it looks more like a hill than a pyramid is probably the only reason it still survives today.

And just as well, because according to the BBC, not only is it the world’s largest pyramid, it retains the title of the largest monument ever constructed anywhere on Earth, by any civilisation, to this day.

The pyramid wasn’t discovered until the early 1900s when locals started to build a psychiatric ward nearby. By the 1930s, archaeologists started to uncover it, creating a series of tunnels stretching 8 kilometres (5 miles) in length to give them access.

Now, over 2,300 years after its initial construction, the site has become a tourist destination.

Hopefully, as our ability to study important sites using non-invasive tools continues to improve, archaeologists will gain a better understanding of how the structure was built, by whom, and how it came to look so much like a mountain.  

Long-lost Maya capital discovered in a backyard in Mexico

Archaeologists claim that they discovered the long-lost capital of an ancient Maya kingdom on the Mexico-Guatemalan border.

In what is now Chiapas, Mexico, the Sak Tz’i Kingdom has 5,000-10,000 inhabitants from around 750 BCE by 900 AD, an associate professor of anthropology at Brandeis University, Charles Golden, said to LiveScience.

Golden said the empire was not particularly powerful and was surrounded by some of the superpowers of the day. He said that in inscriptions found in other cities, the Sak Tz’i’ kingdom was frequently mentioned.

“The reason we know about the kingdom from the inscriptions is that they get beat up by all these superpowers, their rulers are taken captive, they’re fighting wars, but they’re also negotiating alliances with those superpowers at the same time,” he said.

The downtown area was about a third of a mile long and a quarter-mile wide (600 meters by 400 meters) and had pyramids, a royal palace, a ball court and a number of houses.

“These are not big empires. They’re small city-states trying to carve out their little, little territories,” Golden said.

Golden and Brown University bioarchaeologist Andrew Scherer is leading the team that has been excavating the site since 2018. They published their findings in the Journal of Field Archaeology.

Golden said they found out about the site after graduate student Whittaker Schroder got a tip from a street food vendor, who introduced him to the rancher who owned the property.

The rancher had a stone tablet that had an inscription and a drawing of a Sak Tz’i’ king dressed as the Maya storm god.

Golden said the site had been raided by looters in 1960s and many of its monuments were stolen. The owner found the stone tablet in some rubble while working to protect what is left of the site.

“He found it by accident. There’s a lucky, lucky rescued object the looters had missed,” Golden said.

Golden said the looters used saws and other heavy equipment to cut the off faces of the monuments. The pieces wound up in museums and private collections around the world.

“When you go to the museum and see these objects, you’re seeing something that’s been really butchered from its original piece of stone, so we would try to reconnect it to the original piece of stone that may still be on on-site,” he said.

He said it’s taken years to build trust in the community and get permission to dig at the site.

“We are both excavating to find out how people lived and more about how they built these places, but we also have to conserve these buildings,” Golden said. “They were damaged by looters and we’ll be working with the landowner to stabilize and keep these buildings from further deterioration.”

He said he hopes the discovery will help them learn how these smaller kingdoms and their citizens lived their lives and negotiated to live between their powerful, feuding neighbours.

Found: The Oldest and Largest Maya Structure in Mexico

The oldest and largest Maya monumental structure on record has just been discovered after scientists shot millions of lasers from a plane to map an area in southern Mexico.

At the newfound site, called Aguada Fénix, researchers found an artificial plateau measuring about 0.9 miles (1.4 kilometers) long, 0.2 miles (399 meters) wide, and between 33 and 50 feet (10 and 15 m) high. And it likely served as a communal gathering place for the Maya. 

The discovery pushes back when archaeologists thought this civilization built large structures, especially because there weren’t yet any dynasties to organize such an endeavor.

“It forced us to change our understanding of the development of Maya civilization and the development of human society in general,” said Takeshi Inomata, a professor of anthropology at the University of Arizona, who led a new study on the finding.

Archaeologists have traditionally thought that the Maya civilization developed gradually. From 1200 B.C. to 1000 B.C., the people in the Maya lowlands were thought to have moved about, with a combination of hunting, gathering, and some farming, including growing maize.

It wasn’t until the Middle Preclassic period (1000-350 B.C.), the thinking went, that small village began to emerge, along with the creation of ceramics and a transition to sedentism — staying in one place for a long time.

According to this theory, the Maya didn’t begin building ceremonial centers with large pyramids until much later, sometime between 350 B.C. and 250 B.C. However, this idea is now under fire. Radiocarbon dating of 69 samples from Aguada Fénix shows that it was used between 1000 B.C. and 800 B.C. After it was largely abandoned by 750 B.C., small groups returned to use the structure.

Aguada Fénix isn’t the only site overturning the traditional interpretation. For instance, a ceremonial complex and artificial plateau built at Ceibal in 950 B.C. (until now, considered the oldest Maya ceremonial center), indicates that the early Maya built large structures even before the civilization became organized under dynasties with centralized government, the researchers said.

Not ‘deep in the jungle’

Aguada Fénix wasn’t hidden deep in the jungle, but rather on a cattle ranch in Tabasco, Mexico, near the northwestern Guatemalan border. Nobody knew about this site because it’s so big, that if you walk on the site it just looks like a natural landscape, Inomata told Live Science. 

After finding the site in 2017, Inomata and his colleagues did a lidar (light detection and ranging) survey at Tabasco. With lidar, a plane flies over an area while equipment on board shoots millions of lasers that can pass through vegetation and generate 3D maps depicting the shape of the Earth and the structures on it.

The lidar survey revealed the artificial plateau and nine causeways radiating from it. The main plateau is up to 151 million cubic feet (4.3 million cubic meters) in volume. The next largest Maya structure, the La Danta complex at El Mirador in Guatemala, is 98 million cubic feet (2.8 million cubic meters).

“In other words, the main plateau of Aguada Fénix is the largest construction in the pre-Hispanic Maya area,” the researchers wrote in the study. After the lidar survey, the researchers excavated the plateau to learn more about its construction. During that time, the team found jade and stone artifacts that were likely used in rituals at Aguada Fénix. 

Power to the people

Aguada Fénix bears some similarities to San Lorenzo, an even larger artificial plateau built by the Olmec, who thrived there from 1400 B.C. to 1150 B.C. in what is now the Mexican state of Veracruz. San Lorenzo also has colossal sculptures of stone heads and thrones, a clue that the Olmec society already had a hierarchy because it was honoring certain elites. 

There is a debate on whether the Olmec civilization led to the Maya, or whether the Maya developed independently, Inomata noted. 

That said, unlike San Lorenzo, Aguada Fénix had far less evidence of social inequality, the researchers found. “Unlike those Olmec centers, Aguada Fénix does not exhibit clear indicators of marked social inequality, such as sculptures representing high-status individuals,” the researchers wrote in the study. “The only stone sculpture found so far at Aguada Fénix depicts an animal” — a peccary, or wild pig.

Aguada Fénix differs in other ways from San Lorenzo; it incorporates distinctly Maya features, including raised causeways and reservoir systems, said Lisa Lucero, a professor of anthropology at the University of Illinois at Urbana-Champaign, who was not involved with the study.

While later Maya pyramids were built for the elite, Aguada Fénix was built by the people, for the people. “This big plateau is basically for everybody,” Inomata said. “It’s a place where people [could] gather.”

It’s no surprise that the Maya built a place to congregate, Lucero said. Other monumental structures, including Stonehenge in Great Britain and Göbekli Tepe in Turkey, show “when people lived dispersed and/or a more nomadic lifestyle, that they created a community to build such places,” and they didn’t need elite political leaders to organize it, she said. 

At Aguada Fénix, Maya who was dispersed due to agricultural demands could come together to work, celebrate, share knowledge, exchange goods, meet potential mates, worship, and so on, Lucero told Live Science. 

“Based on the different soils, it is likely that people from many different communities built Aguada Fénix, even bringing soils from their homes,” she added. The study was published online June 3 in the journal Nature.