Category Archives: JAPAN

Remains of a 3000-year-old shark attack victim discovered in Japan

Remains of a 3000-year-old shark attack victim discovered in Japan

Newspapers regularly carry stories of terrifying shark attacks, but in a paper published today, Oxford-led researchers reveal their discovery of a 3,000-year-old victim – attacked by a shark in the Seto Inland Sea of the Japanese archipelago.

The research in the Journal of Archaeological Science: Reports, shows that this body is the earliest direct evidence for a shark attack on a human and an international research team has carefully recreated what happened – using a combination of archaeological science and forensic techniques.

The grim discovery of the victim was made by Oxford researchers, J. Alyssa White and Professor Rick Schulting, while investigating the evidence for violent trauma on the skeletal remains of prehistoric hunter-gatherers at Kyoto University.

They came upon No24, from the previously excavated site of Tsukumo, an adult male riddled with traumatic injuries.

‘We were initially flummoxed by what could have caused at least 790 deep, serrated injuries to this man,’ say the Oxford pair. ‘There were so many injuries and yet he was buried in the community burial ground, the Tsukumo Shell-mound cemetery site.’

They continue, ‘The injuries were mainly confined to the arms, legs, and front of the chest and abdomen. Through a process of elimination, we ruled out human conflict and more commonly-reported animal predators or scavengers.’

Since archaeological cases of shark reports are extremely rare, they turned to forensic shark attack cases for clues and worked with expert George Burgess, Director Emeritus of the Florida Program for Shark Research. And reconstruction of the attack was put together by the international team.

The team concluded that the individual died more than 3,000 years ago, between 1370 to 1010 BC. The distribution of wounds strongly suggest the victim was alive at the time of the attack; his left hand was sheared off, possibly a defence wound.

Individual No 24’s body had been recovered soon after the attack and buried with his people at the cemetery. Excavation records showed he was also missing his right leg and his left leg was placed on top of his body in an inverted position.

According to the pair, ‘Given the injuries, he was clearly the victim of a shark attack.

Remains of a 3000-year-old shark attack victim discovered in Japan

The man may well have been fishing with companions at the time, since he was recovered quickly. And, based on the character and distribution of the tooth marks, the most likely species responsible was either a tiger or white shark.’

Co-author Dr Mark Hudson, a researcher with the Max Planck Institute, says, ‘The Neolithic people of Jomon Japan exploited a range of marine resources…

It’s not clear if Tsukumo 24 was deliberately targeting sharks or if the shark was attracted by blood or bait from other fish. Either way, this find not only provides a new perspective on ancient Japan but is also a rare example of archaeologists being able to reconstruct a dramatic episode in the life of a prehistoric community.’

Original 15th-Century Castle Wall Found in Tokyo

Original 15th-Century Castle Wall Found in Tokyo

The Mainichi reports that a 400-year-old stone wall standing about 13 feet tall has been uncovered at Edo Castle, which was constructed in the mid-fifteenth century A.D. by Ōta Dōkan, a samurai warrior-poet who eventually became a Buddhist monk.

The historic remnants were excavated at the spot where Sannomaru Shozokan (Museum of the Imperial Collections) is undergoing renovation work, in the East Garden of the Imperial Palace, in Tokyo’s Chiyoda Ward.

The stone walls are not thought to have been repaired since they were first built at the beginning of the Edo period (1603-1867). An official at the Chiyoda Ward Government said the finding “allows us to examine stone wall construction techniques at the time.”

Original 15th-Century Castle Wall Found in Tokyo
Stone walls from the Edo Castle, thought to be about 400-years-old, are seen at a construction site in the Imperial Palace in Tokyo’s Chiyoda Ward

According to the ward government, the stone walls were found near the Imperial Palace’s Otemon Gate.

They run about 16 meters north to south and measure about 4 meters high — or about seven steps. It seems they were part of the stone wall for the water-filled moat, and a band-shaped white line for indicating the water flow at the time remains on its surface. It is believed water went up to the stone walls’ fourth to fifth steps.

Researchers assume the whole stone walls were buried by the mid-1600s, based on the loss of its top, the condition of soil on the structure, and drawings from the time.

The field excavation survey was conducted from November to December 2020. Researchers are examining and analyzing the excavated relics and soil and will summarize the results in the future. The stone walls will be covered with soil again afterwards.

Stone walls from the Edo Castle, thought to be about 400-years-old, are seen at a construction site in the Imperial Palace in Tokyo’s Chiyoda Ward

Sannomaru Shozokan is set to greatly expand its storage and exhibition areas and had aimed to open fully to the public in 2025, but the effects of the excavation survey mean a year’s delay is now expected.

Japan’s Ancient Underwater “Pyramid” Mystifies Scholars

Japan’s Ancient Underwater “Pyramid” Mystifies Scholars

Submerged stone structures lying just below the waters off Yonaguni Jima are actually the ruins of a Japanese Atlantis—an ancient city sunk by an earthquake about 2,000 years ago. That’s the belief of Masaaki Kimura, a marine geologist at the University of the Ryukyus in Japan who has been diving at the site to measure and map its formations for more than 15 years. Each time he returns to the dive boat, Kimura said, he is more convinced than ever that below him rest the remains of a 5,000-year-old city.

“The largest structure looks like a complicated, monolithic, stepped pyramid that rises from a depth of 25 meters [82 feet],” said Kimura, who presented his latest theories about the site at a scientific conference in June. But like other stories of sunken cities, Kimura’s claims have attracted controversy.

“I’m not convinced that any of the major features or structures are manmade steps or terraces, but that they’re all-natural,” said Robert Schoch, a professor of science and mathematics at Boston University who has dived at the site.

These 10,000-Year-Old Sunken Ancient Ruins in Japan Remain a Huge Mystery

“It’s basic geology and classic stratigraphy for sandstones, which tend to break along planes and give you these very straight edges, particularly in an area with lots of faults and tectonic activity.”

And neither the Japanese government’s Agency for Cultural Affairs nor the government of Okinawa Prefecture recognize the remains off Yonaguni as important cultural property, said agency spokesperson Emiko Ishida. Neither of the government groups has carried out research or preservation work on the sites, she added, instead of leaving any such efforts to professors and other interested individuals.

Ruins Point

Yonaguni Jima is an island that lies near the southern tip of Japan’s Ryukyu archipelago, about 75 miles (120 kilometres) off the eastern coast of Taiwan (see map). A local diver first noticed the Yonaguni formations in 1986, after which a promontory on the island was unofficially renamed Iseki Hanto or Ruins Point.

The district of Yonaguni officially owns the formations, and tourists and researchers can freely dive at the site. Some experts believe that the structures could be all that’s left of Mu, a fabled Pacific civilization rumoured to have vanished beneath the waves. On hearing about the find, Kimura said, his initial impression was that the formations could be natural. But he changed his mind after his first dive.

“I think it’s very difficult to explain away their origin as being purely natural, because of the vast amount of evidence of man’s influence on the structures,” he said.

As teams of expert divers fanned out from the south coast of Okinawa using grid-search patterns, they found five sub surface archaeological sites near three offshore islands. The locations vary at depths from 100 to only 20 feet.

For example, Kimura said, he has identified quarry marks in the stone, rudimentary characters etched onto carved faces, and rocks sculpted into the likenesses of animals.

“The characters and animal monuments in the water, which I have been able to partially recover in my laboratory, suggest the culture comes from the Asian continent,” he said.

“One example I have described as an underwater sphinx resembles a Chinese or ancient Okinawan king.” Whoever created the city, most of it apparently sank in one of the huge seismic events that this part of the Pacific Rim is famous for, Kimura said.

The world’s largest recorded tsunami struck Yonaguni Jima in April 1771 with an estimated height of more than 131 feet (40 meters), he noted, so such a fate might also have befallen the ancient civilization. Kimura said he has identified ten structures off Yonaguni and a further five related structures off the main island of Okinawa. In total, the ruins cover an area spanning 984 feet by 492 feet (300 meters by 150 meters).

The structures include the ruins of a castle, a triumphal arch, five temples, and at least one large stadium, all of which are connected by roads and water channels and are partly shielded by what could be huge retaining walls. Kimura believes the ruins date back to at least 5,000 years, based on the dates of stalactites found inside underwater caves that he says sank with the city.

And structures similar to the ruins sitting on the nearby coast have yielded charcoal dated to 1,600 years ago—a possible indication of ancient human inhabitants, Kimura added. But more direct evidence of human involvement with the site has been harder to come by.

“Pottery and wood do not last on the bottom of the ocean, but we are interested in further research on a relief at the site that is apparently painted and resembles a cow,” Kimura said.

“We want to determine the makeup of the paint. I would also like to carry out subsurface research.”

Natural Forces

Toru Ouchi, an associate professor of seismology at Kobe University, supports Kimura’s hypothesis. Ouchi said that he has never seen tectonic activity having such an effect on a landscape either above or below the water.

“I’ve dived there as well and touched the pyramid,” he said. “What Professor Kimura says is not exaggerated at all. It’s easy to tell that those relics were not caused by earthquakes.”

Boston University‘s Schoch, meanwhile, is just as certain that the Yonaguni formations are natural. He suggests that holes in the rock, which Kimura believes were used to support posts, were merely created by underwater eddies scouring at depressions. Lines of smaller holes were formed by marine creatures exploiting a seam in the rock, he said.

“The first time I dived there, I knew it was not artificial,” Schoch said. “It’s not as regular as many people claim, and the right angles and symmetry don’t add up in many places.”

He emphasizes that he is not accusing anyone of deliberately falsifying evidence. But many of the photos tend to give a perfect view of the site, making the lines look as regular as possible, he said.

Natural Formations

Schoch also says he has seen what Kimura believes to be renderings of animals and human faces at the site. “Professor Kimura says he has seen some kind of writing or images, but they are just scratched on a rock that is natural,” he said.

“He interprets them as being manmade, but I don’t know where he’s coming from.”

But Kimura is undeterred by critics, adding that the new governor of Okinawa Prefecture and officials from the United Nations Educational, Scientific, and Cultural Organization have recently expressed interest in verifying the site.

“The best way to get a definitive answer about their origins is to keep going back and collecting more evidence,” he continued.

“If I’d not had a chance to see these structures for myself, I might be skeptical as well.”

Was this Massive Sword from the 15th Century used by a Giant Samurai?

Was this Massive Sword from the 15th Century used by a Giant Samurai?

The Norimitsu Odachi is displayed in its full glory at the Kibitsu Shrine in the Okayama Prefecture. The giant sword has captivated Japan and its foreign visitors with its size and grandeur.

The Norimitsu is so large, legends have stated that the weapon was once forged and wielded by a giant warrior. Other than its measurements, 12.37 feet in length and 31.97 lbs in weight, the exact origins of the Norimitsu Odachi continues to be shrouded in mystery.

A Look into the Mysterious Norimitsu Odachi

Samurais have been a part of Japanese culture since the start of the tenth century. They were fierce warriors who swore oaths to protect their respective clans. One of the things they were most renowned for was their primary weapon of choice: the sword.

The giant sword is 12½ feet long (3.8m), the body being 7 ½ feet (2.3m) and the nakago 5 feet (150m). It weighs about 31lb 15.47249oz pounds (14.5 kg). 1)

There are a wide variety of blades produced by the skilled swordsmiths of Japan. The katana is without a doubt the most popular one due to its connection to the samurai.

A lesser-known traditional Japanese sword is the odachi, which literally translates to “large/great sword.” In order to be classified as an odachi, the weapon must have a blade length of 3 shaku (35.79 inches or 90.91 cm), though there have been some records of blades reaching around 6.56 feet in length.

What was the purpose of the odachi?

The odachi functioned either as ceremonial objects or infantry swords. As an offering to a shrine’s patron gods. Some odachi was actually used as an offering to the gods to protect warriors in battle. Others were displayed in temples as mythological symbols.

As a ceremonial object.  Production of the odachi was at an all-time high during the Edo period where it was used in various ceremonies. Researchers have also stated that the odachi had a more “ritualistic” role when it came to war, similar to that of flags during a battle.

The odachi was also said to be a weapon of choice during the fourteenth century, specifically the Nanboku-chō period. This claim is backed up by literary works such as the Heike Monogatari and the Taiheiki

As a weapon for war, the odachi’s large size proved to be a problem. It was believed that samurai would carry it on their back or by hand.

During the Muromachi era, samurais would have their assistants carry the massive sword to help draw it during battle. Foot soldiers were more likely to carry the sword slung across their backs as opposed to katanas, which were typically carried on the side.

Fumon Tanaka, a traditional Japanese martial arts practitioner, uses a special drawing technique for a “shorter” odachi. It involves pulling out the sheath rather than drawing the actual blade. Swordsmanship schools around the country have adopted this method, as well as the Shin musō Hayashizaki-ryū and Iaidō.

Production and decline

Forging the odachi proved to be no easy feat. Their length made heat treatment more complicated due to its expense and technique. Polishing was quite the challenge too.

Because of their size, the odachi needed to be hung from the ceiling or carefully placed in a stationary position to be polished as opposed to normal swords that are merely moved over polishing stones.

The odachi’s reverence dwindled down after the 1615 Siege of Osaka (Osaka Natsu no Jin), in which the Tokugawa Shogunate annihilated the Toyotomi clan. The loss was said to be due to the Shogunal government prohibiting swords above a set length. Odachi swordsmiths were forced to cut down the length to meet the standards.

So what is the truth behind the Norimitsu Odachi?

Everyone agrees that if the sword truly had an owner who took it out to battle, they would have been a giant of unproportionate measures.

However, if one were to disregard mythology and folklore, it looks like the Norimitsu odachi was nothing more than a ceremonial sword created by a skillful craftsman. Whoever was behind the forging of this beautiful weapon certainly wanted to showcase their skills—or wealth, for that matter.

Yonaguni Monument: Man-made structure or natural geological formation

Yonaguni Monument: Man-made structure or natural geological formation

THE YONAGUNI-JIMA KAITEI CHIKEI, LITERALLY translated as “Yonaguni Island Submarine Topography,” is an underwater mystery off the coast of the Ryukyu Islands, Japan. 

The massive underwater rock formation is speculated to have existed for more than 10,000 years, but whether the formation is completely man-made, entirely natural, or has been altered by human hands is still up for debate.

The monument was first discovered in 1986 by a diver searching for a good spot to observe hammerhead sharks. After its discovery, Masaaki Kimura, a marine geologist at the University of the Ryukyu, explored the monument for nearly two decades.

Yonaguni Monument: Man-made structure or natural geological formation

Kimura remains convinced that the site was carved thousands of years ago when the landmass was above water.

According to Kimura the Yonaguni’s numerous right angles, strategically placed holes and aesthetic triangles are signs of human alteration. He also claims that carvings exist on the monuments, resembling Kaida script.

He believes that a pyramid, castles, roads, monuments and a stadium can be identified within the structure – which for him is evidence that the monument is what remains of the Lost Continent of Mu, the Japanese equivalent to Atlantis.

As with most theories of lost civilizations, Kimura has met with controversy about his beliefs. Robert Schoch, a professor at Boston University, has dived at the site and explains that the formation is “basic geology and classic stratigraphy for sandstones, which tend to break along planes and give you these very straight edges, particularly in an area with lots of faults and tectonic activity.”

Sandstone structures typically erode into rigid formations, and it is unlikely that the structure was entirely man-made, if man-made at all, because the visible structure is connected to a hidden rock mass.

Geology and strong currents may explain the peculiar shape of the rock, but they cannot account for the pottery, stone tools and fireplaces found there, possibly dating back to 2500 BCE.

However, the items merely show that the area was once inhabited and do not indicate that the monument is anything other than a natural geological formation.

Yonaguni is composed of sandstone and mudstone that dates back 20 million years. If the monument was carved by human hands, it was during the last ice age (about 10,000 years ago) when Yonaguni was part of a land bridge that connected the site to Taiwan.

Both the Japanese Government’s Agency for Cultural Affairs and the Government of Okinawa Prefecture deny Yonaguni as a historical-cultural site.

Emergency food from 1965 Japan expedition found in Antarctica

Emergency food from 1965 Japan expedition found in Antarctica

The Asahi Shimbun reports that Japanese researchers have found fragments of a cardboard box and a cache of emergency food dated to 1965 about five miles from Japan’s Syowa Station in Antarctica. The ration included a can of Coca-Cola, chewing gum, and a can of stewed beef and vegetables. 

A can of the first generation of Coca-Cola, which went on sale in Japan for the first time in 1965

On 3 September, the unopened objects were found at the Mukai Rocks location about eight kilometers from the Syowa station in Japan. The location had been used to land in Antarctica after a voyage through the sea ice through the 10th Japanese Antarctic expedition.

Four members of the current 61st Japanese research expedition team visited Mukai Rocks for observation. There were pieces of cardboard around the food, suggesting they arrived in a box.

The National Institute of Polar Research, which dispatches Japanese expeditions, said no records have been left about the food. Apart from the Coca-Cola and the chewing gum, a can of stewed beef and vegetables, made in February 1965, was found with a label that denoted it as an emergency ration of the Maritime Self-Defense Force.

It was the year when Japan’s Antarctic research resumed with the dispatch of the 7th team. Syowa Station was closed temporarily after Japan’s first ice breaker, the Soya was decommissioned. The Fuji, which succeeded Soya in 1965, was operated by the MSDF.

Susumu Kokubun, 85, a former member of the 7th expedition, recalled that Masayoshi Murayama, who headed his team, went to a location near Mukai Rocks in January 1966 on a helicopter that was loaded on the Fuji.

“He may have left the food on that occasion,” Kokubun said.

The can of Coca-Cola came with a label written in katakana and no stay-on tab opening mechanism. 

According to Coca-Cola (Japan) Co., it is the design of the company’s first canned Coca-Cola introduced into the Japanese market in 1965. A drinker opens it by making a hole with an opener on top of the can. 

The product was available in the market for only one to two years, a company official said, adding that no stock of that particular product is left at the beverage maker.

“It is greatly encouraging to imagine that expedition members had Coca-Cola in the harsh environment,” the official said.

The chewing gum, Cool Mint from Lotte Co., comes in a package featuring a penguin, an iconic creature symbolizing Antarctica. Lotte said it is the design of Cool Mint when it was first released in 1960. But it is not just ordinary, everyday chewing gum.

Records by the company and former members of the Japanese expedition teams show that Eizaburo Nishibori, head of the first wintering party, requested in 1956 the confectionery maker develop a special gum for the country’s first expedition team prior to its departure for Antarctica.

Lotte presented them with a gum mixed with vitamins and minerals that can be preserved for a year and five months without deteriorating despite traveling through the equator or areas where the temperature drops 50 degrees below zero.

Nishibori’s request led Lotte to give birth to Cool Mint in 1960, with its catch phrase “Fresh like in Antarctica.” It was a hit and a long seller. The company said only one Cool Mint sample from those days is left at Lotte.

“It was a pleasant surprise to know that the chewing gum remained after the passage of many decades,” said a public relations official with the company.

Noriaki Obara, one of the four members of the current expedition who discovered the food, said he was stunned to stumble into the long-forgotten cache.

“I initially suspected that they were things just scattered about,” said Obara, 55. “I feel a special connection with the discovery because I was born in 1965.”

1.4-Million-Year-Old Bone Hand Ax Identified

1.4-Million-Year-Old Bone Hand Ax Identified

According to a BBC report, paleoanthropologists Katsuhiro Sano of Tohoku University and Gen Suwa of the University of Tokyo have identified a 1.4-million-year-old hand ax made from a hippo’s leg bone at Ethiopia’s Konso-Gardula site. Tools at the site are thought to have been crafted by the human ancestor Homo erectus. 

A 1.4-million-year-old bone hand ax found in East Africa (shown from both sides) expands the known toolmaking repertoire of Homo erectus, scientists say. Hardened sediment attached to the artifact is lighter colored than the tool.

Approximately 1.4 million years ago, researchers claim, Homo erectus, a likely direct ancestor of people today, crafted an unexpectedly cutting – edge tool from a hippo’s leg bone.

This find is a rare example of an ancient type of hand ax made out of bone rather than stone, reports a team led by paleoanthropologists Katsuhiro Sano of Tohoku University in Sendai, Japan, and Gen Suwa of the University of Tokyo.

The tool was discovered at Ethiopia’s Konso-Gardula site, which has produced stone tools and fossils attributed to H. Erectus.

Along with a variety of stone tools now recognized at several East African sites (SN: 3/4/20), the bone hand ax “suggests that Homo erectus technology was more sophisticated and versatile than we had thought,” Suwa says.

Taken together, these finds show that, perhaps several hundred thousand years earlier than previously known, the H. Erectus toolkit consisted of items requiring a series of precise operations to manufacture, such as stone and bone hand axes, as well as simpler tools that could be made relatively quickly.

H. Erectus at Konso-Gardula modified a chunk of a hippo’s leg bone so that a roughly 13-centimeter-long oval piece with a sharp edge near the tip could be struck off in one blow from a stone or bone hammer, the researchers conclude July 13 in the Proceedings of the National Academy of Sciences.

One or more toolmakers then chipped off the bone from the artifact to render its final shape. Signs of wear indicate that the hand ax was used in cutting or sawing activities.

Only one other bone hand ax of comparable age has been found. That roughly 1.3- to 1.6-million-year-old implement, from Tanzania’s Olduvai Gorge, contains fewer signs of chipping and shaping than the Konso-Gardula hand ax does, the scientists say.

Dental Tartar Yields Food Data from Japan’s Edo Period

Dental Tartar Yields Food Data from Japan’s Edo Period

Rikai Sawafuji of the University of the Ryukyus, Shintaroh Ueda of the University of Tokyo, and their colleagues analyzed samples of tartar from the teeth of 13 people who were buried in what is now eastern Tokyo in the latter half of the Edo Period, from A.D. 1603 to 1867. DNA from the rice was identified in the tartar of eight of the individuals. The DNA of other foods, including daikon radish, the minty herb “shiso” perilla, green onion, Japanese chestnut, carrot, and the pumpkin was also identified. 

A tartar formation found on teeth (Provided by Rikai Sawafuji)

However, the scientists from the University of the Ryukyus, the University of Tokyo, and elsewhere identified even the families and genera of plants eaten at the time by surveying calculus on the teeth of human remains.

The findings, expected to shed light on the dietary and other habits of people of the time, were published in the academic journal Plos One. The team of scientists sampled the DNA from teeth on the bones of 13 people unearthed in Tokyo’s Koto Ward that date to the latter half of the Edo Period.

The researchers studied what plant the samples are from, as recent research has revealed tartar contains the DNA of what was consumed by the individuals. According to the team’s findings, rice-derived DNA was detected from calculus specimens of eight people, while DNA highly likely connected to such plants as the daikon radish, “shiso” perilla, Welsh onion, Japanese chestnut, carrot and pumpkin from nine genera in seven families were also discovered.

Those plants are, according to the scientists, described as foods in records from the period. Meanwhile, DNA from the tobacco genus was identified as well, reinforcing the theory that smoking had already become a popular practice by that time.

A Dipterocarpaceae-linked DNA sample, which is typically found in the tropics, indicates that the resin of the plant was used as an ingredient for tooth powder in the Edo Period, the scientists said.

Team members included Rikai Sawafuji from the University of the Ryukyus, a research fellow affiliated with the Japan Society for the Promotion of Science who now belongs to the Graduate University for Advanced Studies; and Shintaro Ueda, a professor emeritus of bioscience at the University of Tokyo. 

Sawafuji expressed high expectations for the possibility of the DNA analysis allowing researchers in the future to determine even people’s personal favorites based on the remnants left behind on their teeth.

“The technique will make it possible to survey what each individual ate,” said Sawafuji.

Another anticipated benefit of the method is that how plants were used, including the staple foods of each era, which can be determined, because “plants detected from the teeth of many people’s remains were likely widely consumed.”

Tartar as Research Specimen

In the past, calculus formations remaining in human skulls were often simply removed, since their presence made it difficult to examine the shapes of teeth and other factors.

But DNA, starch particles, proteins, and other substances contained in tartar can currently be surveyed in detail, adding to calculus’ significance for research purposes.

Among other ways to take advantage of tartar, the DNA analysis was introduced 10 or so years ago, although more than 99 percent of DNA detected from the object come from bacilli and the method was first adopted to research changing bacterial floras in the oral cavity.

In the early stage of the development, a study was carried out in 2014 to collect DNA from pork and wheat ingested by Germans in the medieval period.

In 2017, the results of the analysis of calculus from Neanderthal men dating to 50,000 years ago were released, showing they ate different foodstuffs in different regions because DNA from mutton and other kinds of meat, as well as moss and mushrooms, were found.

As the poplar-derived DNA was also discovered, speculation swirled that the plant, currently used for making aspirin, “could be used to ease the pain.”

Hiroki Ota, a bioscience professor at the University of Tokyo, noted, however, that the DNA-based method should be combined with various other techniques for improved research.

“Tartar DNA no doubt reflects what the person ate, so use of the substance will spread further,” said Ota. “But calculus could be formed differently in differing dietary cultures. So the research accuracy needs to be improved by conducting a variety of methods using coprolites (fossilized feces) and other objects to uncover all details.”