Some people from Oceania harbor thousands of genetic variants inherited from the Denisovans ‪—‬ a mysterious group of extinct humans ‪—‬ that are still active in their immune systems today, a new study finds.

The findings, published June 11 in the journal Science, come from the largest-ever map of Denisovan-inherited DNA ever created. The discovery shows that Denisovan DNA "is not just a remnant of ancient liaisons; it continues to influence our biology today," study co-author Serena Tucci, an assistant professor of anthropology and head of the Human Evolutionary Genomics Laboratory at Yale University, said in a statement.

Experiments revealed 3,127 variants inherited from Denisovans that still function in the immune systems of modern-day people; some of these variants switch genes that turn the immune response on or off, according to the new research.

However, because many of the immune system genes identified also affect other bodily functions, it is unclear exactly how these genes benefited survival, study first author Patrick Reilly, an evolutionary genomics researcher at Yale, told Live Science.

Denisovan DNA is active in humans today

Previous research has already found that some modern-day people in Oceania ‪—‬ a region that includes New Guinea, the Solomon Islands and Fiji ‪—‬ have some Denisovan DNA. For example, people from Papua New Guinea are known to carry up to 5% Denisovan DNA in their genomes thanks to prehistoric trysts with the enigmatic group of humans who lived in Asia and disappeared around 30,000 years ago. This is among the highest proportion in the world, with modern-day East Asians typically carrying only around 0.1% Denisovan DNA.

Previous research has also shown that modern-day Tibetans carry a Denisovan version of the EPAS1 gene that supports their adaptation to living at high altitudes. People living in the highlands and lowlands of Papua New Guinea have different Denisovan gene variants depending on their local environments.

Yet Oceanians are vastly underrepresented in genomic databases. Sequencing the genomes of Oceanians can give a glimpse into the lives of the Denisovans and is essential for closing gaps in health disparities in Pacific Islanders as a whole, Reilly said.

To fill this gap, Tucci and her team sequenced the genomes of 177 Oceanians from 12 populations and compared them to 1,284 previously published genomes from populations worldwide. Then, they compared these segments to the known Denisovan genome and three Neanderthal genomes.

Combined, the team built a catalog containing three times more Denisovan genetic sequences inherited from Denisovans than were previously identified, over 70% of which were unique to Oceanians.

Natural selection increased the frequency of some of these variants in people from Near Oceania, which includes New Guinea, the Bismarck Archipelago and the Solomon Islands in the Pacific Ocean, including genes linked to bone development, metabolism and fertility.

The team also ran experiments to assess whether any of the Densiovan DNA was changing how genes behaved in these populations, Reilly said.

This revealed that Denisovan genetic variants can switch various immune system genes on or off, although the exact immune functions that were targeted varied among the Oceanic populations studied.

Early migrants to Oceania at least 42,000 years ago benefited from Denisovan genes when they entered their new environment and encountered new disease-causing pathogens, Reilly said.

"This is consistent with multiple independent instances of local adaptation in response to novel immune environments and pathogens during human dispersal into the Pacific," the authors wrote in the study.

Although the researchers don't know exactly why natural selection acted on these genes, the findings highlight the major role pathogens played in shaping the way humans and our extinct relatives evolved, Reilly said.

The research is an "outstanding effort to try to understand the biological implications" of the enduring Denisovan genetic variants, Mathilde André, an evolutionary geneticist at the Pasteur Institute in France who was not involved in the study, told Live Science in an email.

The tripling of known Denisovan-inherited genetic sequences, most of which are unique to Oceanians, highlights the need to sequence the genomes from previously unrepresented populations to capture the diversity of Denisovan DNA, André said.

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Evidence of two ancient wooden posts aligned with the summer and winter solstices has been discovered near Stonehenge in southwest England. The posts have rotted away, and only traces of the postholes survive. But archaeologists say the structure predated Stonehenge, and they think it was a temporary religious monument until a permanent one was built. They even suggest it may have been a Stonehenge prototype.

Analysis suggests that ancient people used the posts to mark the summer and winter solstices, Phil Harding, an archaeologist at Wessex Archaeology who's leading the project, noted at a news conference on Wednesday (June 17).

"These people were capable of establishing the points on the horizon where the sun rises in the midsummer and sets in midwinter," he said. "This was a pioneering achievement." (The 2026 summer solstice will be celebrated at Stonehenge on June 21.)

Harding's team at Wessex Archaeology, a private firm that often works for the government and local authorities, publicly announced the finds June 18 in the U.K., and a report on their research will be peer-reviewed and published. The ancient monument consisted of the two large, wooden posts, about 400 feet (120 meters) apart, on land near the village of Bulford, a few miles east of Stonehenge.

The land is now controlled by the U.K. Ministry of Defence, but archaeologists have been allowed to excavate there since 2015. They previously found traces of two "henges" ‪—‬ rings of ditches and banks made from earth ‪—‬ and dozens of Neolithic pits from about 5,000 years ago, centuries before Stonehenge was completed. The pits were filled with animal bones, pottery, flints and charcoal, and the researchers think they date to the time that the first phase of Stonehenge was being built.

Solstice alignment

The posts were aligned to point along an axis that marked the direction of sunrise on the summer solstice, or "midsummer's day," and the setting of the sun exactly six months later, at the winter solstice, or "midwinter's day," according to a statement from Wessex Archaeology. The same astronomical alignments are seen at Stonehenge.

The animal bones and other signs of feasting in the pits at Bulford are evidence of large numbers of people gathering for religious festivals. (Signs of ancient feasting have also been found at Stonehenge.)

"When we talk about the solstice, we're talking about religion," Matt Leivers, an archaeologist at Wessex Archaeology and one of the researchers, said in the statement. "What we see at Bulford, and later at Stonehenge, is a way of celebrating and marking the passage of time, but it's also about making sure the world keeps working as it should."

The site predates the largest circles of stones at Stonehenge, which have the same alignments. "What we've discovered at Bulford is 500 years earlier than the famous stones we know so well," Harding said. The researchers even suggest that the Bulford monument may have been a sort of prototype for Stonehenge itself.

Ancient stones

Stonehenge is the world's most famous Neolithic monument, but its original purpose was long a mystery. Archaeological investigations have established that the first earthwork henge was started there about 5,000 years ago, and the famous central stones were added about 500 years later.

Recent discoveries at Stonehenge include evidence of ancient cremations, and many archaeologists now think the monument was originally a burial site. If that's the case, the alignment with sunset on the winter solstice might have represented "new life," as the days then became longer and warmer after the depths of winter. However, no human remains have been found at the Bulford site.

Susan Greaney, an archaeologist at the University of Exeter who was not involved in the research, said the new finds show the importance of the region to prehistoric people. "It is intriguing to think that simple posts were erected here to align with the solstices around 500 years before Stonehenge was built," she told Live Science.

The Bulford monument may have been a temporary "model" for Stonehenge itself, Amanda Chadburn, an independent archaeologist who wasn't involved in the research, told Live Science "If you were designing a very complicated piece of engineering like Stonehenge," she said, "you would have had to understand how to make it before starting."

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