Some of these eruptions produce solar proton events (SPEs), during which charged particles race toward Earth at speeds reaching 90% of the speed of light. In 1972, several SPEs erupted between the Apollo 16 and Apollo 17 Moon missions. If astronauts had been exposed during a lunar mission, they could have faced lethal radiation levels. As space agencies prepare for future Moon exploration, scientists are working to better understand these unpredictable solar events.

Researchers at the Okinawa Institute of Science and Technology (OIST) have now developed a new way to uncover evidence of past SPEs. The team combined medieval historical records with ultra precise carbon 14 measurements taken from buried asunaro trees in northern Japan. Using this method, they identified a solar proton event that likely occurred sometime between the winter of 1200 CE and the spring of 1201 CE, a period marked by unusually intense solar activity. The findings were published in the Proceedings of the Japan Academy, Series B.

Professor Hiroko Miyahara from the OIST Solar-Terrestrial Environment and Climate Unit explained: “Previous studies on historical SPEs have focused on rare, extremely powerful events. Our paper provides a basis for detecting sub-extreme SPEs — events that occur more frequently and are around 10-30% of the size of the most extreme cases, but still hazardous. Sub-extreme SPEs are more challenging to detect, but our method now allows us to efficiently identify them and better understand the conditions under which they are more likely to occur.”

Ancient Trees Preserve Clues About Solar Storms

Earth’s magnetic field blocks most high energy particles released during SPEs. Near the poles, however, magnetic field lines open into space, allowing some particles to enter the atmosphere. During especially powerful events, these particles collide with atmospheric gases and create carbon 14 compounds that spread around the globe and become trapped inside living organisms.

By analyzing carbon 14 levels in preserved organic material such as ancient buried trees, scientists can track changes in solar activity stretching back thousands of years. The OIST team used an ultra precise measurement technique they spent more than a decade refining. This method can detect much smaller carbon 14 fluctuations than conventional techniques, making it possible to identify weaker “sub-extreme” solar proton events that were previously invisible.

Because the carbon 14 analysis is extremely time intensive, the researchers first needed clues about when unusual solar activity may have occurred.

Medieval Japanese Diary Revealed “Red Lights” in the Sky

One of the key clues came from Meigetsuki, the diary of the Japanese poet and courtier Fujiwara no Teika (1162-1241). In February 1204 CE, he described seeing “red lights in the northern sky over Kyoto.”

Solar proton events do not directly create auroras, but they are often linked with the same kinds of solar disturbances that do. That historical observation gave researchers a timeframe to investigate more closely.

The scientists then measured carbon 14 levels in buried asunaro wood recovered from Aomori Prefecture in northern Japan. They discovered spikes in carbon 14 that pointed to a sub-extreme solar proton event. By combining those measurements with dendroclimatic studies — that is, a dating method based on comparing patterns of tree-ring growth associated with regional climate — the researchers determined that the event likely occurred sometime between the winter of 1200 CE and the spring of 1201 CE. Historical records from China also described a red aurora visible at unusually low latitudes during that same period.

Evidence of an Exceptionally Active Sun

“The high-precision data not only allowed us to accurately date sub-extreme solar proton events, but it also lets us clearly reconstruct the solar cycles of the period,” said Miyahara. “Today, the Sun’s activity fluctuates over eleven-year-long cycles, but we’ve found that the cycle was just seven to eight years long back then, indicating a very active Sun. The SPE we have dated occurred at the peak of one of these cycles.”

The research helps fill important gaps in the history of solar activity and improves scientists’ understanding of dangerous space weather events. According to Miyahara, carbon 14 analysis alone is not enough. Historical records and other scientific methods are also essential for reconstructing past solar behavior.

“Historical literature provides a candidate time window, and dendroclimatology enables direct intercomparison between detected SPE and reports of sunspots and auroras recorded in literature. Integrated approaches like these are necessary to accurately reconstruct past solar activity, helping us better understand the characteristics of extreme space weather,” concluded Miyahara. “For example, while the SPE we found occurred near the peak of the solar cycle, some of the prolonged low-latitude aurora recorded in the literature seems to fall near the minimum of our reconstructed solar cycle. This is unexpected, and we’re excited to look further into what solar conditions could cause this.”

But a major genetic analysis from researchers at RIKEN’s Center for Integrative Medical Sciences suggests the picture is far more complicated.

Using whole-genome sequencing on more than 3,200 people from across Japan, the team found evidence supporting a third ancestral group tied to northeastern Asia and possibly linked to the ancient Emishi people. The findings, published in Science Advances, add powerful support to the increasingly discussed “tripartite origins” theory of Japanese ancestry.

The results also revealed something else surprising: Japan’s population is genetically more diverse than many researchers once assumed.

“The Japanese population isn’t as genetically homogenous as everyone thinks,” said Chikashi Terao, who led the study at RIKEN. “Our analysis revealed Japan’s subpopulation structure on a fine scale, which is very beautifully classified according to geographical locations in the country.”

A Massive DNA Map of Japan

To investigate Japan’s deep genetic history, researchers analyzed DNA samples collected from seven regions stretching from Hokkaido in the north to Okinawa in the south. The project became one of the largest whole-genome studies ever conducted on a non-European population.

Instead of relying on older DNA microarray methods, the team used whole-genome sequencing, which reads nearly all three billion DNA base pairs in a person’s genome. According to the researchers, this provides roughly 3,000 times more information than traditional techniques.

“Whole-genome sequencing gives us the chance to look at more data, which helps us find more interesting things,” Terao explained.

The scientists then combined the genetic information with medical histories, disease diagnoses, family histories, and clinical test results to build a large database known as the Japanese Encyclopedia of Whole-Genome/Exome Sequencing Library (JEWEL).

One especially important focus involved rare genetic variants. These uncommon DNA changes can sometimes preserve clues about ancient migration patterns and long-lost ancestral populations.

“We reasoned that rare variants can sometimes be traced back to specific ancestral populations, and could be informative in revealing fine-scale migration patterns within Japan,” Terao said.

The Hidden Third Ancestor

The analysis uncovered striking regional differences across Japan.

Jomon ancestry appeared strongest in Okinawa, where it was found in 28.5% of samples, while western Japan showed much lower levels at 13.4%. Researchers found that people in western Japan had stronger genetic connections to Han Chinese populations, likely reflecting major migration waves from continental East Asia between 250 and 794 CE. Those migrations also coincided with the spread of Chinese-style government systems, writing, and education throughout Japan.

The newly identified Emishi-related ancestry was concentrated in northeastern Japan and became less common farther west.

The findings build on earlier ancient DNA studies published in 2021 that first proposed the idea that modern Japanese people descend from three major ancestral sources instead of two. Those studies suggested that a third migration connected to the Kofun period played a major role in shaping modern Japan.

Recent follow-up studies have continued strengthening that idea. Researchers analyzing ancient genomes and skeletal remains have found increasing evidence that multiple migration waves entered Japan over centuries, creating a much more layered population history than previously believed.

Ancient Neanderthal and Denisovan DNA Still Affects People Today

The study also explored genetic material inherited from Neanderthals and Denisovans, two ancient human groups that interbred with Homo sapiens tens of thousands of years ago.

Scientists have become increasingly interested in why some of these ancient DNA fragments survived in modern humans while others disappeared. In many cases, the inherited genes appear linked to health, adaptation, or disease risk.

For example, earlier studies showed that Tibetans inherited a Denisovan-related version of the EPAS1 gene that may have helped humans survive in high-altitude environments. Researchers also previously identified Neanderthal-derived DNA associated with severe Covid-19 complications in some populations.

The Japanese genome study identified 44 archaic DNA regions still present in modern Japanese populations, many of them unique to East Asians. One Denisovan-derived region inside the NKX6-1 gene was associated with type 2 diabetes and may influence how some patients respond to semaglutide treatments.

Researchers also found 11 Neanderthal-derived genetic segments connected to conditions including coronary artery disease, prostate cancer, and rheumatoid arthritis.

Toward Personalized Medicine

Beyond tracing ancestry, the researchers believe the work could eventually improve healthcare.

The team identified potentially harmful variants in the PTPRD gene that may be linked to hypertension, kidney failure, and myocardial infarction. They also found common loss-of-function variants in the GJB2 and ABCC2 genes, which are associated with hearing loss and chronic liver disease.

“What we’ve tried to do is to find and catalog loss-of-function gene variants that are very specific to Japanese people, and to understand why they are more likely to have some specific traits and diseases,” Terao said. “We’d like to connect population differences with differences in genetics.”

The study reflects a broader shift happening in genetics research. For years, most large genomic databases heavily focused on people of European ancestry, limiting scientists’ understanding of disease risk in other populations.

Terao hopes expanding JEWEL with more Asian genomic data will help change that.

“It’s quite important to expand this to the Asian population so that in the long run, the results can benefit us too,” he said.

Mitraphylline belongs to a unique class of plant chemicals known as spirooxindole alkaloids. These molecules are recognized for their unusual twisted ring structures and their powerful biological effects, including anti inflammatory and anti tumor activity.

Even though scientists have studied these compounds for years, the exact molecular steps plants use to produce them had remained unknown.

Breakthrough Discovery in Plant Chemistry

That mystery began to unravel in 2023 when Dr. Thu-Thuy Dang’s team in UBC Okanagan’s Irving K. Barber Faculty of Science identified the first known plant enzyme capable of twisting a molecule into the distinctive spiro shape.

Building on that earlier finding, doctoral student Tuan-Anh Nguyen led new research that uncovered two critical enzymes involved in the production of mitraphylline. One enzyme organizes the molecule into the correct three dimensional structure, while the second transforms it into mitraphylline itself.

“This is similar to finding the missing links in an assembly line,” says Dr. Dang, UBC Okanagan Principal’s Research Chair in Natural Products Biotechnology. “It answers a long-standing question about how nature builds these complex molecules and gives us a new way to replicate that process.”

Why Mitraphylline Is So Valuable

Many promising natural compounds are found only in tiny amounts inside plants, making them difficult and expensive to recreate in laboratories. Mitraphylline is one of those rare substances. It exists only in trace quantities in tropical trees such as Mitragyna (kratom) and Uncaria (cat’s claw), both members of the coffee family.

Now that researchers have identified the enzymes responsible for shaping and assembling mitraphylline, they have a clearer path toward producing the compound and related molecules in more sustainable ways.

“With this discovery, we have a green chemistry approach to accessing compounds with enormous pharmaceutical value,” says Nguyen. “This is a result of UBC Okanagan’s research environment, where students and faculty work closely to solve problems with global reach.”

Nguyen also reflected on the experience of contributing to the breakthrough.

“Being part of the team that uncovered the enzymes behind spirooxindole compounds has been amazing,” Nguyen adds. “UBC Okanagan’s mentorship and support made this possible, and I’m excited to keep growing as a researcher here in Canada.”

International Collaboration Fuels the Research

The project brought together Dr. Dang’s laboratory at UBC Okanagan and Dr. Satya Nadakuduti’s research group at the University of Florida.

Funding for the work came from Canada’s Natural Sciences and Engineering Research Council’s Alliance International Collaboration program, the Canada Foundation for Innovation, and the Michael Smith Health Research BC Scholar Program. Additional support was provided by the United States Department of Agriculture’s National Institute of Food and Agriculture.

“We are proud of this discovery coming from UBC Okanagan. Plants are fantastic natural chemists,” Dr. Dang says. “Our next steps will focus on adapting their molecular tools to create a wider range of therapeutic compounds.”