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Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

Who were the Anglo Saxons? 

Debate has long raged over the ancestry of Anglo-Saxons in Great Britain – did they replace the Celtic inhabitants as a marauding new group, or did they develop relationships over time with indigenous Brits?

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Replica of a decorated gold and silver Anglo Saxon helmet found at the Sutton Hoo archeological site in East Anglia, UK. Image credit: lightphoto/Getty Images.

In a new study, researchers compared Anglo-Saxon skulls dated from 1600 to 2800 years ago across England and Denmark to establish the ancestry of each individual. The team looked at the three-dimensional shape of the base of the skull – an indicator of relationships between human populations.

The earliest Anglo-Saxons, they found, were majority European (around two-thirds or three-quarters), while the remainder were of local ancestry. But later, in the Middle Anglo-Saxon period, they found 50 to 70 per cent of individuals were of local ancestry. The results suggest Anglo-Saxon Britain was a cultural and ethnic melting pot.

Co-author Keith Dobney at the University of Sydney says the team’s results indicate that “the Anglo-Saxon kingdoms of early medieval Britain were strikingly similar to contemporary Britain – full of people of different ancestries sharing a common language and culture”.

“These findings tell us that being Anglo-Saxon was more likely a matter of language and culture, not genetics,” says co-author Mark Collard, of Simon Fraser University, Vancouver.

Ancient bones provide clues about Kangaroo Island’s past

Kangaroo Island may be a world-renowned biodiversity hotspot, but it has been haemorrhaging local species since Europeans arrived on the island 200 years ago, according to researchers at Curtin University’s School of Molecular and Life Sciences.

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Kangaroo Island is a biodiversity hotspot, but it used to be home to many more species than it is today, according to new research out of Curtin University. Image credit: Megan Spooner/Getty Images.

Led by Curtin’s Fredrik Seersholm, the team analysed 2000 bone fragments to determine which species once thrived on the island – knowledge that the researchers say is key to ensuring biodiversity in the future.

“We identified 33 species, 10 of which are extinct on the island today,” says Dr Seersholm. We also found DNA traces from both the eastern and the western grey kangaroos, which is interesting given it was previously thought that only the western used to roam the Island.”

Seersholm says the work is particularly important in the wake of the 2019/20 bushfires that devastated the island.

“We hope our work in accurately identifying species can aid conservation and restoration efforts and help to restore the biodiversity on Kangaroo Island,” says Dr Seersholm.

“While more research is needed in this area, our study has confirmed that Kangaroo Island could be a potential haven for the reintroduction of some species.”

New Zealand’s Lake Taupō sits on a giant pocket of ‘magma mush’

In 2019, New Zealand’s Lake Taupō underwent a string of earthquakes and seismic activity. Seeking to understand more about the planet’s most active supervolcano system, researchers from Victoria University of Wellington, New Zealand, investigated.

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View Of Mount Tauhara And Lake Taupo, New Zealand. Image credit: Salvatore Alleruzzo/EyeEm/Getty Images.

As detailed in a new study in the journal Geochemistry, Geophysics, Geosystems, the team used the locations and patterns of these earthquakes and deformations to predict that an active magma reservoir, at least 250 cubic kilometres in size, is lurking beneath the country’s largest lake.

The research suggests that as new magma feeds into the reservoir, it triggers earthquakes along regional fault lines in the brittle surrounding crust.

Beyond shining a light on the complexity of volcanic activity underneath the volatile North Island, the results may inform future monitoring for earthquakes and volcanic eruptions.

Goal-oriented marmosets 

Marmosets, like humans, are goal-oriented creatures. They also share key similarities in brain structure, making the charismatic, furry little monkeys particularly useful for scientists looking to understand aspects of human action and response.

As described in a new study published in the journal Neuron, researchers set out to investigate which brain region is involved in linking actions and outcome. To do this, they taught the marmosets a goal-oriented behaviour: tap a coloured cross on a touchscreen, and they were rewarded with their favourite juice drink.

This connection between action and reward was occasionally uncoupled, with the marmosets receiving the juice without having to respond to the image. The clever creatures quickly noticed the change and stopped tapping the cross, having figured out that they could get the drink with minimal effort.

Then, using drugs, the researchers temporarily switched off the anterior cingulate cortex, including its connection with another brain region called the caudate nucleus. Repeating the experiment, they found that when the connection between the cross and the juice was disconnected, the marmosets kept on tapping – suggesting they had lost the ability to connect an action to an outcome.

“We think this is the first study to have established the specific brain circuitry that controls goal-directed behaviour in primates, whose brains are very similar to human brains,” says Angela Roberts in the University of Cambridge’s Department of Physiology, Development and Neuroscience, joint senior author of the report.

The find is important because it may inform future therapies for mental health disorders such as obsessive compulsive disorder (OCD), which involves a cognitive disconnect between action and outcome.

Did the ancient Maya have parks?

The ancient Maya city of Tikal, in modern-day Guatemala, was a busy metropolis, home to tens of thousands of people and complex architecture, including roads, paved plazas, pyramids, temples and palaces.

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A pyramid at Tikal rises from the rainforest in Guatemala. Image credit: David Lentz.

Now, researchers from the University of Cincinnati (UC) say Tikal’s reservoirs – the sources of the city’s drinking water – were lined with trees and wild vegetation.

According to a new study in the journal Scientific Reports, the researchers developed a novel system to analyse plant DNA in the sediment of the city’s temple and reservoirs, using it to identify more than 30 species of trees, grasses, vines and flowering plants that grew along its banks more than 1000 years ago.

“Almost all of the city centre was paved,” says paleoethnobotanist David Lentz, a professor of biology in UC’s College of Arts and Sciences and lead author of the study. “That would get pretty hot during the dry season.”

“So it would make sense that they would have places that were nice and cool right along the reservoir. It must have been beautiful to look at with the water and trees and a welcome place for the kings and their families to go.”

Researchers found little evidence to support the idea that the Maya cultivated these gardens as they cultivated their fields elsewhere. Instead, the prevalence and variety of native species suggest the embankments were left as wild forests.

“I think they were [parks],” Lentz says. “I don’t know how public they would have been. This was a sacred area of the city surrounded by temples and palaces. I don’t know if the commoners would have been that welcome.

“Given that the Maya were a forest culture whose cosmology included many forest elements – for example, certain sacred trees that held up the sky – having a sacred grove adjacent to the sacred spring and pool at the heart of the city was an extremely potent symbol, kind of like parts of the cosmos in miniature,” says co-author Nicholas Dunning, a professor of geography at UC. 

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