ANCIENT DNA SHOWS HOW PASIFIKA CARRIED PIGS ACROSS THE OCEAN

“A major genetic study has revealed how Pacific people helped move pigs across the ocean for thousands of years, shaping island life, culture, and ecosystems from Southeast Asia to Polynesia.

The study, published in the journal Science, looked at the DNA of more than 700 pigs, including living animals and archaeological remains.

By comparing their genomes, researchers were able to track where pigs came from, when they arrived on different islands, and how they mixed with local pig species.

The research was led by Professor Laurent Frantz from Queen Mary University of London and Ludwig Maximilians University of Munich, Dr David Stanton from Cardiff University, and Professor Greger Larson from the University of Oxford.

Scientists from Indonesia, the Philippines, and Vanuatu were also part of the team.

For a long time, scientists believed many animals could not cross a major natural divide known as the Wallace Line, which separates Asian wildlife from Australasian species.

While animals such as monkeys and leopards remained on the Asian side, pigs were found on both sides of the boundary.

The new study shows this did not happen naturally. Instead, people carried pigs with them as they travelled and settled across islands.

Early Pacific journeys

The earliest movements may have happened as far back as 50,000 years ago when people living in Sulawesi, known for some of the world's oldest cave art, moved warty pigs to nearby islands such as Timor.

The pigs may have been taken along to provide food for future hunting. Around 4000 years ago, pig movements increased quickly as early farming communities expanded into the Pacific.

From a Polynesian archaeology perspective, the findings support long-held knowledge that Pacific voyagers travelled with food systems, not just people, and that pigs reflect careful planning and adaptation as communities settled new islands.

Researchers say these journeys started from Taiwan, moved through the Philippines and eastern Indonesia, and continued into Papua New Guinea, Vanuatu, and remote Polynesia.

Researchers at the Vanuatu Cultural Centre say pigs hold deep cultural value there and were intentionally brought by ancestors than arriving by chance as invasive animals.

Stanton, the lead author, says the research shows how human movement across the Pacific reshaped animal populations over time.

"This research reveals what happens when people transport animals enormous distances, across one of the world's most fundamental natural boundaries," he says. "These movements led to pigs with a melting pot of ancestries."

Mixing with local species

The study also found that many pigs escaped or were released and became wild.

In some places like the Komodo Islands, pigs introduced in different periods interbred. These hybrid pigs are now an important food source for the endangered Komodo dragon.

European pigs were also introduced during the colonial period, adding another layer to the region's complex history.

Larson says pigs were ready to spread once people helped them reach new islands. "When people have lent a hand, pigs were all too willing to spread out on newly colonised islands in South East Asia and into the Pacific," he says.

"By sequencing the genomes of ancient and more recent populations, we've been able to link those movements to specific human populations in both space and time."

Big questions for Pacific conservation

The findings raise difficult questions for conservation. Today, pigs are seen very differently across the Pacific.

In some places, they are sacred, spiritually important or central to culture. In others, they are pests, while in some islands, pigs have been present for so long that they are treated almost as native species.

Pacific scholars say the findings question Western ideas of what is considered "native", showing that animals present for thousands of years are now part of Pacific landscapes and history.

Frantz says the research helps uncover layers of human activity across the region and challenges simple conservation labels.

"It is very exciting that we can use ancient DNA from pigs to peel back layers of human activity across this megabiodiverse region," he says.

"The big question now is, at what point do we consider something native? What if people introduced species tens of thousands of years ago? Are these worth conservation efforts?"

Pacific conservation practitioners say pigs highlight ongoing challenges in the region, where their cultural importance must be balanced against real environmental damage.

The researchers say future conservation efforts in the Pacific will need to respect culture, history, and community knowledge instead of relying only on traditional definitions of "native and invasive species.”

SOURCE: RNZ STATIONS

 IMAGE: RNZ STATIONS; Kavaforums

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Their DNA survives in diverse populations across the world – but who were the Denisovans

It started with a finger bone found in a cave in the Altai mountains in Siberia in the late 2000s. Thanks to advances in DNA analysis, this was all that was required for scientists to be able to identify an entirely new group of hominins, meaning upright primates on the same evolutionary branch as humans.

Now known as the Denisovans (De-NEES-ovans), after the Denisova cave in which the finger bone was found, the past few years have seen numerous other discoveries about these people. I’ve recently co-published a paper collating everything we know so far.

So who were the Denisovans, where did they live, and why are they important to the story of humanity?

Around 600,000 years ago, early humans in Africa diverged into groups. Some migrated out of Africa, becoming Neanderthals in eastern and western Eurasia and Denisovans in eastern Eurasia.

Modern humans later evolved in Africa, spread across the globe, and encountered Neanderthals, Denisovans and possibly other unknown archaic human groups. Yet by 40,000 years ago, only modern humans remained on the archaeological record.

The genetic legacy

Unlike Neanderthals, whose fossils are relatively abundant, Denisovan remains continue to be very scarce. Apart from that Siberian finger bone, the main other discovery was a jawbone found in China, in a limestone cave located on the northeastern edge of the Tibetan Plateau. It had been believed that the Denisovans had been confined to Siberia, but this jawbone demonstrated that they had lived much further afield.

Their DNA has enabled scientists to build on this insight, since it survives in contemporary populations, particularly in Oceania, parts of Asia, and even Indigenous American populations. This shows that the Denisovans were widely distributed across these areas.

Strikingly, recent studies reveal that Denisovans interbred with modern humans multiple times. For instance, east Asians harbour ancestry from at least two distinct Denisovan populations. Also, the people of Papua New Guinea, which retain up to 5% Denisovan ancestry, a much higher proportion than other groups, interbred with at least two Denisovan groups at different times.

Additionally, research has shown that some populations from the Philippines carry a distinct Denisovan ancestry compared to their neighbouring groups. These various genetic differences highlight that the interbreeding between modern humans and Denisovans has a complex history.

Adaptations

While much about the Denisovans’ lifestyle, appearance and culture remains unknown, the discovery of the Tibetan jawbone showed that these people lived in diverse environments, and that they must have been very adaptable. Sure enough, we now know that Denisovan ancestry in modern humans has contributed to adaptive traits, particularly in challenging environments.

A notable example is the EPAS1 gene. Inherited from Denisovans, it helps regulate the body’s response to low oxygen levels, giving Tibetans a physiological advantage in the high altitudes of the Tibetan plateau.

Other human adaptations possibly derived from Denisovan interbreeding relate to being able to tolerate cold weather, and being able to metabolise lipids, which include fats and oils. These may have been beneficial for populations in northern regions, such as the Arctic. For example, Inuit populations carry Denisovan genes that help to regulate body fat and maintain warmth.

Some genes that aid in fighting infections also appear to have Denisovan origins. These immune-related genes might have played crucial roles in protecting ancient and modern humans from south and east Asia, the Americas and Papua New Guinea against specific pathogens, illustrating how Denisovan heritage continues to affect human health today.

Unanswered questions

Many questions about the Denisovans remain unanswered. For instance, how genetically distinct were these populations, and how many distinct groups existed? We know that at least four distinct Denisovan populations interbred with modern humans. However, with further analyses, this number might increase, revealing an even more complex story.

We’re also looking for a better understanding of the biological impact of Denisovan DNA in modern humans. While many beneficial traits have been identified as derived from Neanderthals, only a few have been found for Denisovans so far. Many other potential contributions remain to be explored.

This will be possible only if additional Denisovan remains are discovered and DNA is extracted and sequenced. We need more data, especially from diverse geographical regions and time periods, to provide new insights into these people’s adaptations, interactions with other hominins, and lasting legacy in human evolution.

To address these questions, our research capabilities will need to improve. For example, we need new tools to more accurately distinguish Denisovan genetic material from Neanderthal and modern human DNA.

Additionally, studying Denisovan ancestry in populations beyond east Asia and Oceania, such as Indigenous Americans, could shed light on exactly which Denisovan sources have contributed to modern humans genomes.

The discoveries to date highlight the power of genetic studies in uncovering hidden chapters of our past. Each discovery brings us closer to understanding who the Denisovans were and how their lives and adaptations continue to affect humans today