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Hunter-gatherers introduced fish to a mountain lake 7000 years ago

The exposed bed of Lake Tesse in Norway, where archaeologists found ancient fish traps
Magne Samdal, Museum of Cultural History, University of Oslo

Hunter-gatherers transported brown trout into the mountains of Norway at least 7000 years ago so they could be harvested during summer foraging trips into the highlands.

That is the only possible explanation for how fish could have populated isolated mountain lakes that had been covered by a kilometres-thick ice sheet for tens of thousands of years, says Axel Mjærum at the University of Oslo, Norway.

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“This is the oldest documented example of human-mediated translocation of fish in the world,” says Mjærum.

Until around 8400 years ago, Lake Tesse, at an elevation of around 850 metres, was covered by the Fennoscandian ice sheet, leaving an ecological blank canvas once it retreated.

Yet before it was transformed for hydropower storage in the 1940s, Lake Tesse was regarded as one of the richest brown trout waterways in Norway, yielding 9 tonnes of the fish annually.

While it has long been suspected that humans had a hand in establishing the brown trout population in Lake Tesse, we had no idea how long ago this happened.

Alternative ideas have included transportation by birds or natural migration of fish and eggs upstream. But most Norwegian mountain lakes, including Lake Tesse, only had brown trout, and geographical features such as large waterfalls make natural dispersal upstream impossible.

Mjærum and his colleagues studied the partially buried remains of elaborate fish traps, discovered in 2022 when the lake level was lowered.

Radiocarbon dating showed that the oldest trap dated from around 4950 BC. By correlating the recovered wood with the pine tree ring chronology available for the central Scandinavian mountains, the team was also able to precisely date some of the younger posts.

One was felled between spring 2669 BC and winter 2669-2668 BC, and another 12 years later during the winter of 2657-2656 BC, demonstrating that the traps must have been maintained to keep them in good working order.

“Therefore, it is possible that this form of trap fishing was ongoing in Tesse during much of the period between 5000 and 2650 BC,” says Mjærum.

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The transport of fish into the lakes is an early example of people managing the environment to provide food, centuries before the advent of farming in Scandinavia. There is evidence that fish farming began even earlier in other parts of the world, including channels and traps for catching eels built in Australia 8600 years ago.

How people transported the fish is unknown, but they may have used waterskins. People probably stayed in the mountains for part of the summer season, hunting reindeer and fishing, but spent the winters in the valleys or along the coast where the climate was milder, says Mjærum.

“A good and predictable food supply also made longer stays possible, not only for hunters aiming for big game, but for whole family groups,” he says.

Journal reference:

Antiquity DOI: 10.15184/aqy.2026.10392

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Congolese monkey with mask-like face and strong BO is new to science

The newly recognised monkey species Colobus congoensis
Daniel Rosengren

A monkey with a distinctive mask-like face, found in a remote part of the Democratic Republic of the Congo, has been declared a new species – only the fifth new species of monkey documented from Africa in the past 75 years.

The monkey is known as likweli to local people who hunt it for bushmeat, and it has been given the scientific name Colobus congoensis. It lives in one of the most inaccessible parts of Africa, without paved roads or infrastructure.

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“A typical expedition involves multiple modes of transportation: a flight, followed by a motorcycle ride, two days of hiking on foot and finally travel by dugout canoe to reach the monkey’s range,” says Kate Detwiler at Florida Atlantic University.

One of the most intriguing features of likweli is its facial appearance, says Detwiler. The light-coloured skin around the mouth and beneath the nose is unlike that of any other African colobus species, but resembles the facial pattern seen in some Asian colobine monkeys.

Detwiler and her colleagues believe the species’ mask-like face may represent ancestral traits that were present before the African and Asian colobine lineages diverged over 8 million years ago. “If so, likweli may have retained characteristics that were subsequently modified or lost in the other African colobus species,” says Detwiler.

Like other colobus monkeys, likweli also has a distinctive body odour that defies description, she says.

Scientists first became aware of the species in 2008 when a team surveying on the banks of the Lomami river, in what is now Lomami National Park, took a photo that showed only a part of a monkey that had not been seen before, high in the canopy.

Then, in November 2018, another group again spotted the monkey, which is about 1.3 metres long and weighs around 7 kilograms. Between 2018 and 2022, there were 114 recorded observations of the new species, 25 of which were from vocalisations.

In 2021, several monkeys that had been killed by hunters for bushmeat were confiscated and handed over to researchers. Detailed morphological and genetic analysis confirmed they were indeed a wholly separate species. Genetic tests and recordings of their vocalisations also added to the evidence of their uniqueness.

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“The genetic analyses revealed that likweli is a deeply divergent lineage that split from its closest known relative, Colobus satanas, approximately 4 to 5 million years ago,” says Detwiler. “That was much older than we expected and provided strong evidence that likweli represents a distinct species.”

Likweli is isolated from C. satanas by more than 1200 kilometres and several major river barriers. Unlike most other members of the genus, which have habitats exceeding 60,000 square kilometres, likweli is only known to exist in 1700 square kilometres of rainforest.

“Hunting is one of the primary threats facing likweli, particularly because the species has such a small known range and appears to occur at low densities,” says Detwiler.

Because of the risk of poaching and the monkey’s small population and home range, the team is proposing that the species should be listed as endangered. “Now that likweli has been recognised as a distinct species, another important step would be to grant it protected status under national law,” says Detwiler. “This would make it illegal to hunt the species, including in the buffer zone surrounding the park.”

Journal Reference:

PLOS One: DOI: 10.1371/journal.pone.0349857

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Maya mathematician’s name decoded alongside astronomical formula

The Maya solar calendar is made up of 19 months
zimmytws/Getty Images

An ancient Maya astronomer-mathematician has been identified for the first time along with his complex calculations made around 1200 years ago, predicting the orbital cycles of Mars and Venus.

“This is the first direct mention of an ancestral Maya astronomer-mathematician by personal name,” says Franco Rossi at the Massachusetts Institute of Technology.

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It is also the oldest recorded name of an astronomer-mathematician ever known from anywhere in the Americas, he says.

The Maya civilisation flourished in Central America between roughly 2000 BC and AD 1697. They had advanced knowledge of mathematics and astronomy, but much of it was lost after the mass burning of their books by Spanish missionaries.

Since 2010, excavations at the site of Xultun, Guatemala, have revealed astronomical and mathematical inscriptions inside a small masonry building.

On the east and north-east wall of the building are around 50 texts that scientists believe are “rough drafts” made by Maya mathematicians as they charted and predicted the cycles of celestial objects relative to Earth and to one another.

Rossi and his colleagues have painstakingly deciphered one of these murals, named Text 19. At the bottom of the mural is the name of Sak Tahn Waax, which translates to White-chested Fox, who is believed the be the author of the formula.

The mathematical formula inscribed on a wall at the Maya site of Xultun, Guatemala
F.D. Rossi; H. Hurst

Text 19 consists of 11 hieroglyphs, which had to be scanned, photographed and magnified under different illumination angles, and compared to other, later, astronomical-mathematical writings, before their meaning could be deduced.

While similar mathematical and astronomical expertise is found across Maya cities, the mention of Sak Tahn Waax, who the researchers believe was probably male, is unique.

“Whether this is an instance of the scribe himself signing his own calculation or attributing the intellectual work to another, we have a formula and the name of its creator, which serves to demonstrate the importance of this kind of intellectual contribution for Classic Maya people,” says Rossi.

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The calendar system on display in Text 19 uses maths in relation to time periods, he says. These time periods were drawn from a 260-day calendar, a 365-day solar calendar, a 584-day approximation of Venus’s synodic cycle (when the planet returns to the same position relative to both Earth and the sun) and a 780-day approximation of Mars’s synodic cycle. The total length of the formula is five Venus synodic cycles or 2920 days, and the date that Text 19 most likely refers to is 7 November of AD 781 in the Julian calendar.

Exactly how this formula would have been applied is unknown, says Rossi, as it “isn’t incorporated into any larger body of work”.

“We think it is meant to concisely and meaningfully show the relationship between these two planets and human counts of time in ways that could then be applied to political ceremony, predictive astronomy and understandings of seasonality,” he says.

Such meticulous mathematical legwork would have been critical to structuring life in a world before computers, smartphones and weather apps, says Rossi.

Journal Reference:

Antiquity DOI: 10.15184/aqy.2026.10378