Advanced civilizations could be using Dyson spheres to collect energy from black holes

by Andy Tomaswick, Universe Today

Example of a partial Dyson sphere around a star. Credit: Kevin Gill

Black holes are more than just massive objects that swallow everything around them—they're also one of the universe's biggest and most stable energy sources. That would make them invaluable to the type of civilization that needs huge amounts of power, such as a Type II Kardashev civilization. But to harness all of that power, the civilization would have to encircle the entire black hole with something that could capture the power it is emitting.

One potential solution would be a Dyson sphere—a type of stellar mega-engineering project that encapsulates an entire star (or, in this case, a black hole) in an artificial sheath that captures all of the energy the object at its center emits. But even if it was able to capture all of the energy the black hole emits, the sphere itself would still suffer from heat loss. And that heat loss would make it visible to us, according to new research published by an international team led by researchers at the National Tsing Hua University in Taiwan.

Obviously, no such structure has yet been detected. Still, the paper proves that it is possible to do so, despite no visible light making it past the sphere's surface and a black hole's reputation for being light sinks rather than light sources. To understand how we would detect such a system, first, it would be helpful to understand what that system would be designed to do.

The authors study six different energy sources that a potential Dyson sphere could collect around a black hole. They are the omnipresent cosmic microwave background radiation (which would be washing over the sphere no matter where it was placed), the black hole's Hawking radiation, its accretion disk, its Bondi accretion, its corona, and its relativistic jets.

Credit: Universe Today

Some of these energy sources are much more high-powered than others, with the energy from the black hole's accretion disk leading the pack in terms of potential energy captures. Other types of energy would require completely different engineering challenges, such as capturing the kinetic energy of the relativistic jets that shoot out from the black hole's poles. Size obviously plays a large factor in how much energy these black holes emit. The authors primarily focus on stellar-mass black holes as a good point of comparison against other potential energy sources. At that size, the accretion disk alone would provide hundreds of times the energy output of a main-sequence star.

It would be impossible to build a Dyson sphere around any object that size with current known materials. But the type of civilization that would be interested in taking on such an engineering challenge would most likely have much stronger materials than we do today. Alternatively, they could work with known materials to create a Dyson swarm or Dyson bubble, which doesn't require as much material strength but does lose some of the energy that a complete sphere would capture, and adds multiple layers of complexity when coordinating orbital paths and other factors. Any such structure would have to be outside the accretion disk to get the full benefit from the energy the black hole emits.

Composite image of Centaurus A, our galaxy’s central supermassive black hole, showing the jets emerging together with the associated gamma radiation. Credit: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray), H.E.S.S. collaboration (Gamma)

Even a single sphere around a single stellar-mass black hole would be enough to push any civilization that created it into Type II territory, giving it a level of power output unimaginable with current technology. But even such a potent civilization most likely won't be able to bend the laws of physics. No matter the power level, some of it will be lost to heat.

Credit: Universe Today

To astronomers, heat is simply another form of light—infrared, to be exact. And according to the researchers, the heat emitted by a Dyson sphere around a black hole should be detectable by our current crop of telescopes, such as the Wide Field Infrared Survey Explorer and the Sloan Digital Sky Survey, to a distance of about 10kpc at least. That's about 1/3 of the distance across the entire Milky Way. No matter how close they were, they wouldn't appear like traditional stars but could be detectable using the radial velocity method commonly used to find exoplanets.

While this is useful theoretical work, there certainly hasn't been any evidence of any such structure existing yet—Fermi's Paradox still holds. But given all the data that we're already collecting these telescopes, it might be interesting to scan through them one more time to check if there happens to be heat emanating from a place where it wouldn't be expected. It would be worth the time to at least look for what could be such a fundamentally ground-breaking discovery.

Astronomers see first hint of the silhouette of a spaghettified star

More information: Tiger Yu-Yang Hsiao et al, A Dyson sphere around a black hole, Monthly Notices of the Royal Astronomical Society (2021). DOI: 10.1093/mnras/stab1832

Journal information: Monthly Notices of the Royal Astronomical Society 

Provided by Universe Today 

 

Unraveling the mystery of brown dwarfs

by University of Geneva

This artist’s illustration represents the five brown dwarfs discovered with the satellite

 TESS. These objects are all in close orbits of 5-27 days (at least 3 times closer than

 Mercury is to the sun) around their much larger host stars. 

Credit: CC BY-NC-SA 4.0 - Thibaut Roger - UNIGE

Brown dwarfs are astronomical objects with masses between those of planets and stars. The question of where exactly the limits of their mass lie remains a matter of debate, especially since their constitution is very similar to that of low-mass stars. So how do we know whether we are dealing with a brown dwarf or a very low mass star? An international team, led by scientists from the University of Geneva (UNIGE) and the Swiss National Centre of Competence in Research (NCCR) PlanetS, in collaboration with the University of Bern, has identified five objects that have masses near the border separating stars and brown dwarfs that could help scientists understand the nature of these mysterious objects. The results can be found in the journal Astronomy & Astrophysics.

Like Jupiter and other giant gas planets, stars are mainly made of hydrogen and helium. But unlike gas planets, stars are so massive and their gravitational force so powerful that hydrogen atoms fuse to produce helium, releasing huge amounts of energy and light.

'Failed stars'

Brown dwarfs, on the other hand, are not massive enough to fuse hydrogen and therefore cannot produce the enormous amount of light and heat of stars. Instead, they fuse relatively small stores of a heavier atomic version of hydrogen: Deuterium. This process is less efficient and the light from brown dwarfs is much weaker than that from stars. This is why scientists often refer to them as "failed stars."

"However, we still do not know exactly where the mass limits of brown dwarfs lie, limits that allow them to be distinguished from low-mass stars that can burn hydrogen for many billions of years, whereas a brown dwarf will have a short burning stage and then a colder life," points out Nolan Grieves, a researcher in the Department of Astronomy at the UNIGE's Faculty of Science, a member of the NCCR PlanetS and the study's first author. "These limits vary depending on the chemical composition of the brown dwarf, for example, or the way it formed, as well as its initial radius," he explains.

To get a better idea of what these mysterious objects are, we need to study examples in detail. But it turns out that they are rather rare. "So far, we have only accurately characterized about 30 brown dwarfs," says the Geneva-based researcher. Compared to the hundreds of planets that astronomers know in detail, this is very few. All the more so if one considers that their larger size makes brown dwarfs easier to detect than planets.

New pieces of the puzzle

Today, the international team characterized five companions that were originally identified with the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOI) - TOI-148, TOI-587, TOI-681, TOI-746 and TOI-1213. These are called "companions" because they orbit their respective host stars. They do so with periods of 5 to 27 days, have radii between 0.81 and 1.66 times that of Jupiter, and are between 77 and 98 times more massive. This places them on the borderline between brown dwarfs and stars.

These five new objects therefore contain valuable information. "Each new discovery reveals additional clues about the nature of brown dwarfs and gives us a better understanding of how they form and why they are so rare," says Monika Lendl, a researcher in the Department of Astronomy at the UNIGE and a member of the NCCR PlanetS.

One of the clues the scientists found to show these objects are brown dwarfs is the relationship between their size and age, as explained by François Bouchy, professor at UNIGE and member of the NCCR PlanetS: "Brown dwarfs are supposed to shrink over time as they burn up their deuterium reserves and cool down. Here we found that the two oldest objects, TOI 148 and 746, have a smaller radius, while the two younger companions have larger radii."

Yet these objects are so close to the limit that they could just as easily be very low-mass stars, and astronomers are still unsure whether they are brown dwarfs. "Even with these additional objects, we still lack the numbers to draw definitive conclusions about the differences between brown dwarfs and low-mass stars. Further studies are needed to find out more," concludes Grieves.

Observations detect a brown dwarf orbiting the star TOI–1278

More information: Nolan Grieves et al, Populating the brown dwarf and stellar boundary: Five stars with transiting companions near the hydrogen-burning mass limit, Astronomy & Astrophysics (2021). DOI: 10.1051/0004-6361/202141145

Journal information: Astronomy & Astrophysics 

Provided by University of Geneva 

Oort Cloud News: How Many Comets From Elsewhere?

Posted by
Kelly Kizer Whitt
August 26, 2021

Comet Borisov, spotted in 2019, was a visitor from another solar system. It’s the 2nd known interstellar object, and 1st known interstellar comet. But could there be billions more interstellar comets in the Oort Cloud?

 Image via NASA/ ESA/ D. Jewitt (UCLA).

Oort Cloud news

Astronomers picture the Oort Cloud as a cloud of comets on the farthest outskirts of our solar system. Dutch astronomer Jan Oort theorized its existence in 1950. He said long-period comets are sometimes knocked from their distant orbits in the Oort Cloud (perhaps by passing stars). That’s how they end up in orbits that bring them near our sun. If it exists, Oort thought, this comet cloud is made of material left over from our solar system’s formation 4.5 billion years ago. But is it? Scientists now generally agree that billions of comets must reside in the Oort Cloud. But what fraction of these comets might have originated in other star systems? This week (August 22, 2021), two scientists said the answer might be … most of them.

The two scientists are Amir Siraj and Avi Loeb, both of Harvard. Loeb is also author of Extraterrestrial, the First Sign of Intelligent Life Beyond Earth, which proposes that the first known interstellar visitor (1I/ ‘Oumuamua), might have been an artificial object, made by an advanced extraterrestrial civilization. The peer-reviewed journal Monthly Notices of the Royal Astronomical Society published these scientists’ new study about the Oort Cloud on August 23, 2021.

The study focuses on a realm of space that lies between 1,000 and 100,000 times Earth’s distance from our sun. In fact, some astronomers estimate the Oort Cloud may extend out nearly as far as a light-year from our sun. By contrast, the nearest star to our sun is about 4 light-years away.

The Oort Cloud is so far out from the sun that its existence is still hypothetical 

(though it’s logical  PROBABLE to believe it does exist). The cloud is visualized as stretching from 1,000 times the Earth-sun distance to about 100,000 times that distance. Image via NASA.

Comet Borisov, the first interstellar comet

Astronomers spotted the first known interstellar object, ‘Oumuamua, in 2017. In 2019, they spotted a second object from interstellar space. This one looked more distinctly comet-like. Astronomers call it 2I/ Borisov, or sometimes just Comet Borisov. Traveling at 110,000 miles per hour (177,000 kph), Comet Borisov passed closest to the sun and Earth in December 2019, displaying a tail 14 times the size of Earth. Then it headed back toward interstellar space.

It’s the information drawn from Comet Borisov that enabled Siraj and Loeb to speculate that the Oort Cloud consists mostly of interstellar visitors. The scientists admit the information on Comet Borisov still holds a degree of uncertainty. But, even with these uncertainties, the scientists said their calculations show that interstellar objects are more numerous than solar system objects in the Oort Cloud. Siraj commented in a statement:

Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system. But theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents. Now we’re finding that there could be substantially more visitors.

Interstellar objects are dark and distant

If the Oort Cloud contains perhaps billions of interstellar objects, why haven’t we seen more of them? Siraj said it’s because we don’t yet have the technology to see them. Consider first how far away the Oort Cloud is. The Earth-sun distance (93 million miles, or 150 million km) is called an astronomical unit (AU) from the sun. Tiny Pluto is about 40 AU from the sun. The even-smaller comets in the Oort Cloud are some 1,000 to 100,000 AU away. But remember that the comets don’t shine by their own light. They only reflect our sun’s light. So a comet in the Oort Cloud, interstellar or otherwise, is simply too far from the sun, too dim and too small for us to see directly. Thus we see comets – and speculate about an Oort Cloud – only thanks to those comets that are dislodged from the Oort Cloud and come hurtling in to our part of the solar system.
Could there be interstellar objects closer to Earth?

Matthew Holman, former director of the Center for Astrophysics Minor Planet Center, who did not participate in the research, wondered if the abundance of interstellar visitors in the farthest regions of the solar system could translate to some interstellar visitors closer to the sun. He said:

These results suggest that the abundances of interstellar and Oort cloud objects are comparable closer to the sun than Saturn. This can be tested with current and future solar system surveys. When looking at the asteroid data in that region, the question is: Are there asteroids that really are interstellar that we just didn’t recognize before?

There are asteroids that scientists have detected but not tracked over the years. Holman mused:
We think they are asteroids, then we lose them without doing a detailed look.

Co-author Loeb added:
Interstellar objects in the planetary region of the solar system would be rare, but our results clearly show they are more common than solar system material in the dark reaches of the Oort cloud.

Future searches

The Vera C. Rubin Observatory, currently under contruction in Chile, should help astronomers find more visitors from outside our solar system. Siraj commented that the new observatory will:

… blow previous searches for interstellar objects out of the water.

First light for the Vera Rubin’s engineering camera is expected in October 2022 – and full survey operations expected perhaps a year later.

Also slated for 2022, the Transneptunian Automated Occultation Survey will operate three medium-sized telescopes at the Observatorio Astronomico Nacional at San Pedro Mártir, a mountain range in Baja California, México. This system is specifically designed to find small bodies on the outer edges of our solar system. Perhaps it will unlock the door to more interstellar objects. 

Siraj said:

Our findings show that interstellar objects can place interesting constraints on planetary system formation processes. [A large number of interstellar objects in the Oort Cloud] requires a significant mass of material to be ejected [from our solar system] in the form of planetesimals. Together with observational studies of protoplanetary disks [disks around newly forming stars] and computational approaches to planet formation, the study of interstellar objects could help us unlock the secrets of how our planetary system – and others – formed.

Bottom line: Scientists’ calculations show that the majority of comets in the Oort Cloud may be interstellar objects, or visitors from beyond our solar system.

Source: Interstellar objects outnumber Solar system objects in the Oort cloud

Preprint at arXiv: Interstellar Objects Outnumber Solar System Objects in the Oort Cloud

Via Harvard and Smithsonian Center for Astrophysics

Interstellar comets visit our solar system more frequently than thought

By Tereza Pultarova about 13 hours ago

Just because we don't see them doesn't mean they're not here.

The outer solar system might be full of comets from other stars. 

(Image credit: NOIRLab/NSF/AURA/J. da Silva)

Comets from other star systems, such as 2019 Borisov, visit the sun's neighborhood more frequently than scientists had thought, a new study suggests.

The study, based on data gathered as Borisov zipped by Earth at a distance of about 185 million miles (300 million kilometers) in late 2019, suggests that the comet repository in the far outer solar system known as the Oort Cloud might be full of objects that were born around other stars. In fact, the authors of the study suggest that the Oort Cloud might contain more interstellar material than domestic stuff. 

Named after famous Dutch astronomer Jan Oort, who first proved its existence in the 1950s, the Oort Cloud is a spherical shell of small objects — asteroids, comets and fragments — far beyond the orbit of Neptune. The cloud's inner edge is thought to begin about 2,000 astronomical units (AU) from the sun, and its outer edge lies about 200,000 AU away. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.)

No spacecraft has ever visited the Oort Cloud, and it will take 300 years for NASA's farflung Voyager 1 probe to even glimpse the cloud's closest portion. 

Related: Interstellar Comet Borisov Shines in New Photo

Astronomers have very limited tools to study this intriguing world, as objects in the Oort Cloud don't produce their own light. At the same time, these objects are too far away to reflect much of the sun's light. 

So how exactly did the scientists figure out that there must be so many interstellar objects in the Oort Cloud, and what did Borisov have to do with it?

Amir Siraj, a graduate student at Harvard University's Department of Astronomy and lead author of the study, told Space.com in an email that he could calculate the probability of foreign comets visiting the solar system simply based on the fact that the Borisov comet had been discovered. 

"Based on the distance that Borisov was detected at, we estimated the implied local abundance of interstellar comets, just like the abundance of 'Oumuamua-like objects was calibrated by the detection of 'Oumuamua," Siraj said. 

The mysterious 'Oumuamua, first spotted by astronomers in Hawaii in October 2017, was the first interstellar body ever detected within our own solar system. The object passed Earth at a distance of 15 million miles (24 million km), about one-sixth of the distance between our planet and the sun. An intense debate about 'Oumuamua's nature ensued, as it wasn't clear at first whether the object was a comet or an asteroid.

Even the detection of a single object can be used for statistical analysis, Siraj said. The so-called Poisson method, which the astronomers used, calculates the probability of an event happening in a fixed interval of time and space since the last event. 

Taking into consideration the gravitational force of the sun, Siraj and co-author Avi Loeb, an astronomer at Harvard, were able to estimate the probability of an interstellar comet making its way to Earth's vicinity. They found that the number of interstellar comets passing through the solar system increases with the distance from the sun. 

"We concluded that, in the outer reaches of the solar system, and even considering the large uncertainties associated with the abundance of Borisov-like objects, transitory interstellar comets should outnumber Oort Cloud objects (comets from our own solar system)," Siraj added.

So why have astronomers seen just one interstellar comet so far? The answer is technology. Telescopes have only recently gotten powerful enough to be able to spot those small but extremely fast-travelling bodies, let alone study them in detail. 

"Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in our solar system," said Siraj. "Theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents. Now we're finding that there could be substantially more visitors."

The astronomers hope that with the arrival of next-generation telescopes, such as the Vera C. Rubin Observatory, currently under construction in Chile, the study of extrasolar comets and asteroids will truly take off. 

The new study was published in the journal Monthly Notices of the Royal Astronomical Society on Monday (Aug 24).

Secrets of Earth’s largest carbon sink revealed by synchrotron research


A team of scientists has discovered microscopic dissolution seams that dissolve about 10 percent of the carbon in ancient deep-sea limestones where most of the world’s carbon is stored.

Ancient deep-sea limestones’ role in carbon cycle probed

Sophisticated synchrotron X-ray microscopy showed thousands of micro-dissolution seams in limestone layers

Micro-dissolution seams dissolve about 10 per cent of the total carbon of the limestones studied

The research team, led by Dr Christoph Schrank from QUT’s School of Earth and Atmospheric Sciences, Dr Michael Jones from QUT’s Central Analytical Research Facility, and Australian Nuclear Science and Technology Organisation (ANSTO) synchrotron scientist Dr Cameron Kewish, published their findings in the Nature journal Communications Earth and Environment.

Dr Schrank said deep-sea limestones had been the Earth’s largest carbon sink for the past 180 million years because they trapped most of the planet’s carbon.

“However, their contribution to the long-term carbon cycle is poorly quantified,” he said.

“Measuring the amount of carbon captured in deep-sea limestones is fundamental to understanding the long-term carbon cycle – how carbon is exchanged between the atmosphere, the oceans, the biosphere, and the rocky bones of the Earth itself over thousands to millions of years.

“Scientists try to unravel the carbon cycle in order to understand important processes such as climate change. To do that, we need to estimate how much carbon the limestones can really trap.”

Dr Christoph Schrank, front, with a deep sea limestone sample and co-researchers l/r- Dr Luke Nothdurft, Dr Craig Sloss, Dr Michael Jones

Dr Schrank said they used high-resolution chemical and structural maps to work out that these micro-dissolution seams were ultrathin layers along which large amounts of calcium carbonate had dissolved away.

“While individual micro-dissolution seams are much thinner than a human hair, their spacing is incredibly dense – the average distance between two seams is about a hair’s breadth,” Dr Schrank said.

“We put this geometric information and mass-balance estimates together to work out that the micro-dissolution seams dissolved about 10 per cent of the total carbon of the limestones in our study.

“Published mathematical models of limestone dissolution and geological evidence suggest that this dissolution process occurred within 10 cm to 10 m below the sediment over 50 to 5000 years.”

Where the dissolved carbon goes is not yet known for sure. Dr Schrank said the limestones they studied were formed near an extremely tectonically active region off the North Island’s east coast

.

Limestone rocks on east coast of North Island of New Zealand

“For the past 25 million years, and even today, this region is regularly shaken up by earthquakes, which are known to stir up sediments at the ocean floor.

“We suggest that the dissolved carbon could be returned to the ocean when the seafloor is disturbed by earthquakes or underwater landslides.”

The research team from QUT, ANSTO, University of Queensland, University of New South Wales, and La Trobe University discovered the micro-seams using the extremely powerful X-rays of the ANSTO Australian Synchrotron.


“The team at ANSTO, QUT, and La Trobe University developed cutting-edge X-ray microscopy techniques at the Australian Synchrotron over the past decade to probe the chemical composition and structure of materials down to tens of nanometres,” Dr Kewish said.

“The synchrotron produces light more than a million times brighter than the sun, and X-ray microscopy allows us to see features that have previously remained invisible.”

Australian Synchrotron THERE IS ONE IN SASKATCHEWAN,CANADA

Dr Jones said: “Applying these novel techniques to sections of 55-million-year-old limestones from the east coast of the North Island of New Zealand enabled us to see, for the first time, that layers of limestone contain thousands of tiny micro-dissolution seams that are practically invisible to other microscopic techniques.”

Dr Schrank said the team planned to examine other limestone deposits around the world with high-resolution synchrotron techniques to better understand how micro-dissolution contributes to carbon exchange between the sediment and the ocean.

Micro-scale dissolution seams mobilise carbon in deep-sea limestones was published in the Nature journal Communications Earth and Environment.

TOLEAN BESSIE UPDATE

First ancient human DNA from islands between Asia and Australia

Credit: University of Hasanuddin


A research team co-led by Griffith University archaeologists has discovered DNA in the remains of a hunter-gatherer woman who died 7200 years ago on the Indonesian island of Sulawesi. Nicknamed Bessé’, she is the first known skeleton from an early foraging culture called the Toaleans.

Genomic analysis shows that this ancient individual was a distant relative of Aboriginal Australians and Papuans. But it also revealed that Bessé’ is a rare ‘genetic fossil’, in the sense that she belonged to a group with an ancestral history that was unlike that of any previously known human population.

 

Excavations at Leang Panninge cave. Credit: Leang Panninge Research Project.

This surprising find, published in the journal Nature, is the first time ancient human DNA has been reported from ‘Wallacea’, the vast group of islands between Borneo and New Guinea and the gateway to the continent of Australia. 

The Sulawesi remains were excavated in 2015 from a cave called Leang Panninge (‘Bat Cave’). They belong to a young female hunter-gatherer who was about 17-18 years old at time of death. She was buried in a foetal position and partially covered by rocks. Stone tools and red ochre (iron-rich rock used to make pigment) were found in her grave, along with bones of hunted wild animals. 

The University of Hasanuddin archaeologists who discovered the woman affectionately dubbed her Bessé’, following a custom among Bugis royal families of bestowing this nickname on newly born princesses before they were formally named.


This is the first relatively complete skeleton to be found alongside securely dated artefacts of the Toalean culture, according to study co-leader Professor Adam Brumm from Griffith’s Australian Research Centre for Human Evolution.

“The Toaleans were early hunter-gatherers who lived a secluded existence in the forests of South Sulawesi from around 8,000 years ago until 1,500 years ago, hunting wild pigs and collecting edible shellfish from rivers,” Professor Brumm said.  

Professor Brumm’s team re-excavated Leang Panninge in 2019 to clarify the context of the burial and collect more samples for dating. Through radiocarbon dating the team was able to constrain the age of Bessé’ to between about 7300 to 7200 years old.

Toalean artefacts have only been found in one small part of Sulawesi, encompassing about 6% of the total land area of the island, the world’s eleventh largest.

“This suggests that this past culture had limited contact with other early Sulawesi communities or people in nearby islands, existing for thousands of years in isolation,” said study co-author Adhi Agus Oktaviana, a researcher in Indonesia’s national archaeological research institute (Pusat Penelitian Arkeologi Nasional) and a doctoral candidate in the Griffith Centre for Social and Cultural Research.


Archaeologists have long debated the origins of the Toaleans. But now analyses of ancient DNA from the inner ear bone of Bessé’ partly confirm existing assertions that Toalean foragers were related to the first modern humans to enter Wallacea some 65,000 years ago, the ancestors of Aboriginal Australians and Papuans. 

“These seafaring hunter-gatherers were the earliest inhabitants of Sahul, the supercontinent that emerged during the Pleistocene (Ice Age) when global sea levels fell, exposing a land bridge between Australia and New Guinea,” Professor Brumm said.

Professor Adam Brumm.

“To reach Sahul, these pioneering humans made ocean crossings through Wallacea, but little about their journeys is known.”

The genomic analyses were led by Selina Carlhoff from the Max Planck Institute for the Science of Human History at Jena, Germany, under the supervision of Professor Cosimo Posth (University of Tübingen) and Professor Johannes Krause (Max Planck Institute for Evolutionary Anthropology, Leipzig).

The results show that Bessé’ shares about half of her genetic makeup with present-day Indigenous Australians and people in New Guinea and the Western Pacific islands. This includes DNA inherited from the now-extinct Denisovans, distant cousins of Neanderthals whose fossils have only been found in Siberia and Tibet. 


“In fact, the proportion of Denisovan DNA in Bessé’ relative to other ancient as well as present-day groups in the region may indicate that the crucial meeting point between our species and Denisovans was in Sulawesi or another Wallacean island,” Professor Posth said.

The research could suggest that ancestors of Bessé’ were among the first modern humans to reach Wallacea, but instead of island hopping eastward to Sahul they remained in Sulawesi.

If so, it may have been the forebears of Bessé’ who created the very old cave paintings found in South Sulawesi. As recently shown by Griffith University researchers, this rock art dates to at least 45,500 years ago and includes what may be the earliest known human representations of animals.  

But analyses also revealed something unexpected in the genome of Bessé’: a deep ancestral signature from an early modern human population of Asian origin. This group did not intermix with the predecessors of Aboriginal Australians and Papuans, suggesting it may have entered the region after the initial peopling of Sahul. 

“It is unlikely we will know much about the identity of these early ancestors of the Toaleans until more ancient human DNA samples are available from Wallacea,” said Indonesian senior author Professor Akin Duli from the University of Hasanuddin.


“But it would now appear that the population history and genetic diversity of early humans in the region were more complex than previously supposed.”

The researchers could detect no ancestry resembling that of Bessé’ in the DNA of people who live in Sulawesi today, who seem to largely descend from Neolithic farmers (‘Austronesians’) who arrived in the region from Taiwan some 3,500 years ago.

This is not unexpected, given that the last traces of Toalean culture vanished from the archaeological record by the fifth century AD. The scientists do note, however, that more extensive genomic sampling of Sulawesi’s diverse population could reveal evidence for the genetic legacy of Toaleans.

“The discovery of Bessé’ and the implications of her genetic ancestry show just how little we understand about the early human story in our region, and how much more there is left to uncover,” Professor Brumm said.

Who were the Toaleans? Ancient woman’s DNA provides first evidence for the origin of a mysterious lost culture

Stone arrowheads (Maros points) and other flaked stone implements from the Toalean culture of South Sulawesi. 

Shahna Britton/Andrew Thomson, Author provided

August 25, 2021 

In 2015, archaeologists from the University of Hasanuddin in Makassar, on the Indonesian island of Sulawesi, uncovered the skeleton of a woman buried in a limestone cave. Studies revealed the person from Leang Panninge, or “Bat Cave”, was 17 or 18 years old when she died some 7,200 years ago.

Her discoverers dubbed her Bessé’ (pronounced bur-sek¹) — a nickname bestowed on newborn princesses among the Bugis people who now live in southern Sulawesi. The name denotes the great esteem local archaeologists have for this ancient woman.

She represents the only known skeleton of one of the Toalean people. These enigmatic hunter-gatherers inhabited the island before Neolithic farmers from mainland Asia (“Austronesians”) spread into Indonesia around 3,500 years ago.

Burial of a Toalean hunter-gatherer woman dated to 7,200 years ago. Bessé’ was 17-18 years old at time of death. She was buried in a flexed position and several large cobbles were placed on and around her body. Although the skeleton is fragmented, ancient DNA was found preserved in the dense inner ear bone (petrous). University of Hasanuddin

Our team found ancient DNA that survived inside the inner ear bone of Bessé’, furnishing us with the first direct genetic evidence of the Toaleans. This is also the first time ancient human DNA has been reported from Wallacea, the vast group of islands between Borneo and New Guinea, of which Sulawesi is the largest.

Genomic analysis shows Bessé’ belonged to a population with a previously unknown ancestral composition. She shares about half of her genetic makeup with present-day Indigenous Australians and people in New Guinea and the Western Pacific. This includes DNA inherited from the now-extinct Denisovans, who were distant cousins of Neanderthals.

In fact, relative to other ancient and present-day groups in the region, the proportion of Denisovan DNA in Bessé’ could indicate the main meeting point between our species and Denisovans was in Sulawesi itself (or perhaps a nearby Wallacean island).

Read more: Evolutionary study suggests prehistoric human fossils 'hiding in plain sight' in Southeast Asia

The ancestry of this pre-Neolithic woman provides fascinating insight into the little-known population history and genetic diversity of early modern humans in the Wallacean islands — the gateway to the continent of Australia.

Sulawesi is the largest island in Wallacea, the zone of oceanic islands between the continental regions of Asia and Australia. White shaded areas represent landmasses exposed during periods of lower sea level in the Late Pleistocene. The Wallace Line is a major biogeographical boundary that marks the eastern extent of the distinctive plant and animal worlds of Asia. The Toalean cave site Leang Panninge (where Bessé’ was found) is located in Sulawesi’s southwestern peninsula (see inset panel). Toalean archaeological sites have only been found in a roughly 10,000 km² area of this peninsula, south of Lake Tempe. Kim Newman

Toalean culture

The archaeological story of the Toaleans began more than a century ago. In 1902, the Swiss naturalists Paul and Fritz Sarasin excavated several caves in the highlands of southern Sulawesi.

Their digs unearthed small, finely crafted stone arrowheads known as Maros points. They also found other distinctive stone implements and tools fashioned from bone, which they attributed to the original inhabitants of Sulawesi — the prehistoric “Toalien” people (now spelled Toalean)

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A Toalean stone arrowhead, known as a Maros point. Classic Maros points are small (roughly 2.5cm in maxiumum dimension) and were fashioned with rows of fine tooth-like serrations along the sides and tip, and wing-like projections at the base. Although this particular stone technology seems to have been unique to the Toalean culture, similar projectile points were produced in northern Australia, Java and Japan.                Shahna Britton/Andrew Thomson.

Some Toalean cave sites have since been excavated to a higher scientific standard, yet our understanding of this culture is at an early stage. The oldest known Maros points and other Toalean artefacts date to about 8,000 years ago.

Excavated findings from caves suggest the Toaleans were hunter-gatherers who preyed heavily on wild endemic warty pigs and harvested edible shellfish from creeks and estuaries. So far, evidence for the group has only been found in one part of southern Sulawesi.

Toalean artefacts disappear from the archaeological record by the fifth century AD — a few thousand years after the first Neolithic settlements emerged on the island.

Prehistorians have long sought to determine who the Toaleans were, but efforts have been impeded by a lack of securely-dated human remains. This all changed with the discovery of Bessé’ and the ancient DNA in her bones.

Toalean stone arrowheads (Maros points), backed microliths (small stone implements that may have been hafted as barbs) and bone projectile points. These artefacts are from Indonesian collections curated in Makassar and mostly comprise undated specimens collected from the ground surface at archaeological sites. Basran Burhan

The ancestral story of Bessé’

Our results mean we can now confirm existing presumptions the Toaleans were related to the first modern humans to enter Wallacea some 65,000 years ago or more. These seafaring hunter-gatherers were the ancestors of Aboriginal Australians and Papuans.

They were also the earliest inhabitants of Sahul, the supercontinent that emerged during the Pleistocene (ice age) when global sea levels fell, exposing a land bridge between Australia and New Guinea. To reach Sahul, these pioneering humans made ocean crossings through Wallacea, but little about their journeys is known.

Read more: Island-hopping study shows the most likely route the first people took to Australia

It is conceivable the ancestors of Bessé’ were among the first people to reach Wallacea. Instead of island-hopping to Sahul, however, they remained in Sulawesi.

But our analyses also revealed a deep ancestral signature from an early modern human population that originated somewhere in continental Asia. These ancestors of Bessé’ did not intermix with the forebears of Aboriginal Australians and Papuans, suggesting they may have entered the region after the initial peopling of Sahul — but long before the Austronesian expansion.

Who were these people? When did they arrive in the region and how widespread were they? It’s unlikely we will have answers to these questions until we have more ancient human DNA samples and pre-Neolithic fossils from Wallacea. This unexpected finding shows us how little we know about the early human story in our region.
A new look at the Toaleans

With funds awarded by the Australian Research Council’s Discovery program we are initiating a new project that will explore the Toalean world in greater detail. Through archaeological excavations at Leang Panninge we hope to learn more about the development of this unique hunter-gatherer culture.

Excavations at Leang Panninge cave, Mallawa, South Sulawesi.

 Leang Panninge Research Team.

We also wish to address longstanding questions about Toalean social organisation and ways of life. For example, some scholars have inferred the Toaleans became so populous that these hitherto small and scattered groups of foragers began to settle down in large sedentary communities, and possibly even domesticated wild pigs.

It has also recently been speculated Toaleans were the mysterious Asian seafarers who visited Australia in ancient times, introducing the dingo (or more accurately, the domesticated ancestor of this now-wild canid). There is clearly much left to uncover about the long island story of Bessé’ and her kin.

¹The “bur” syllable is pronounced as in the English word “bursary”. The “k” is essentially a strangulated stop in the throat, akin to the “t” in the Cockney “bo'ol”, for bottle. (With thanks to Professor Campbell Macknight).