75,000-year-old female Neanderthal from cave where species buried their dead

A new documentary has recreated the face of a 75,000-year-old female Neanderthal whose flattened skull was discovered and rebuilt from hundreds of bone fragments by a team of archaeologists and conservators led by the University of Cambridge.

The team excavated the female Neanderthal in 2018 from inside a cave in Iraqi Kurdistan where the species had repeatedly returned to lay their dead to rest. The cave was made famous by work in the late 1950s that unearthed several Neanderthals which appeared to have been buried in succession.

'Secrets of the Neanderthals', produced by BBC Studios Science Unit, is released on Netflix worldwide. The documentary follows the team led by the universities of Cambridge and Liverpool John Moores as they return to Shanidar Cave to continue excavations.

"The skulls of Neanderthals and humans look very different," said Dr Emma Pomeroy, a palaeo-anthropologist from Cambridge's Department of Archaeology, who features in the new film.

"Neanderthal skulls have huge brow ridges and lack chins, with a projecting midface that results in more prominent noses. But the recreated face suggests those differences were not so stark in life.

"It's perhaps easier to see how interbreeding occurred between our species, to the extent that almost everyone alive today still has Neanderthal DNA."

Neanderthals are thought to have died out around 40,000 years ago, and the discoveries of new remains are few and far between. The Neanderthal featured in the documentary is the first from the cave for over fifty years, and perhaps the best preserved individual to be found this century.

While earlier finds were numbered, this one is called Shanidar Z, although researchers think it may be the top half of an individual excavated in 1960.

The head had been crushed, possibly by rockfall, relatively soon after death -- after the brain decomposed but before the cranium filled with dirt -- and then compacted further by tens of thousands of years of sediment.

When archaeologists found it, the skull was flattened to around two centimetres thick.

The team carefully exposed the remains, including an articulated skeleton almost to the waist, and used a glue-like consolidant to strengthen the bones and surrounding sediment. They removed Shanidar Z in dozens of small foil-wrapped blocks from under seven and a half metres of soil and rock within the heart of the cave.

In the Cambridge lab, researchers took micro-CT scans of each block before gradually diluting the glue and using the scans to guide extraction of bone fragments. Lead conservator Dr Lucía López-Polín pieced over 200 bits of skull together freehand to return it to its original shape, including upper and lower jaws.

"Each skull fragment is gently cleaned while glue and consolidant are re-added to stabilise the bone, which can be very soft, similar in consistency to a biscuit dunked in tea," said Pomeroy. "It's like a high stakes 3D jigsaw puzzle. A single block can take over a fortnight to process."

The team even referred to forensic science -- studies on how bones shift after blunt force trauma and during decomposition -- to help them understand if remains had been buried, and the ways in which teeth had pinged from jawbones.

The rebuilt skull was surface scanned and 3D-printed, forming the basis of a reconstructed head created by world-leading palaeoartists and identical twins Adrie and Alfons Kennis, who built up layers of fabricated muscle and skin to reveal a face.

New analysis strongly suggests that Shanidar Z was an older female, perhaps in her mid-forties according to researchers -- a significant age to reach so deep in prehistory.

Without pelvic bones, the team relied on sequencing tooth enamel proteins to determine her sex. Teeth were also used to gauge her age through levels of wear and tear -- with some front teeth worn down to the root. At around five feet tall, and with some of the smallest adult arm bones in the Neanderthal fossil record, her physique also implies a female.

While remnants of at least ten separate Neanderthals have now come from the cave, Shanidar Z is the fifth to be found in a cluster of bodies buried at a similar time in the same location: right behind a huge vertical rock, over two metres tall at the time, which sits in the centre of the cave.

The rock had come down from the ceiling long before the bodies were interred. Researchers say it may have served as a landmark for Neanderthals to identify a particular site for repeated burials.

"Neanderthals have had a bad press ever since the first ones were found over 150 years ago," said Professor Graeme Barker from Cambridge's McDonald Institute for Archaeological Research, who leads the excavations at the cave.

"Our discoveries show that the Shanidar Neanderthals may have been thinking about death and its aftermath in ways not so very different from their closest evolutionary cousins -- ourselves."

The other four bodies in the cluster were discovered by archaeologist Ralph Solecki in 1960. One was surrounded by clumps of ancient pollen. Solecki and pollen specialist Arlette Leroi-Gourhan argued the finds were evidence of funerary rituals where the deceased was laid to rest on a bed of flowers.

This archaeological work was among the first to suggest Neanderthals were far more sophisticated than the primitive creatures many had assumed, based on their stocky frames and ape-like brows.

Decades later, the Cambridge-led team retraced Solecki's dig, aiming to use the latest techniques to retrieve more evidence for his contentious claims, as well as the environment and activities of the Neanderthals and later modern humans who lived there, when they uncovered Shanidar Z.

"Shanidar Cave was used first by Neanderthals and then by our own species, so it provides an ideal laboratory to tackle one of the biggest questions of human evolution," said Barker.

"Why did Neanderthals disappear from the stage around the same time as Homo sapiens spread over regions where Neanderthals had lived successfully for almost half a million years?"

A study led by Professor Chris Hunt of Liverpool John Moores University now suggests the pollen was left by bees burrowing into the cave floor. However, remains from Shanidar Cave still show signs of an empathetic species. For example, one male had a paralysed arm, deafness and head trauma that likely rendered him partially blind, yet had lived a long time, so must have been cared for.

Site analysis suggests that Shanidar Z was laid to rest in a gully formed by running water that had been further hollowed out by hand to accommodate the body. Posture indicates she had been leant against the side, with her left hand curled under her head, and a rock behind the head like a small cushion, which may have been placed there.

While Shanidar Z was buried within a similar timeframe as other bodies in the cluster, researchers cannot say how contemporaneous they are, only that they all date to around 75,000 years ago.

In fact, while filming onsite for the new documentary in 2022, the team found remains of yet another individual in the same burial cluster, uncovering the left shoulder blade, some ribs and a fairly complete right hand.

In the sediments several feet above, another three Neanderthals dating to around 50,000 years had been found by Solecki, more of which have been recovered by the current team.

Further research since Shanidar Z was found has detected microscopic traces of charred food in the soil around the older body cluster. These carbonised bits of wild seeds, nuts and grasses, suggest not only that Neanderthals prepared food -- soaking and pounding pulses -- and then cooked it, but did so in the presence of their dead.

"The body of Shanidar Z was within arm's reach of living individuals cooking with fire and eating," said Pomeroy. "For these Neanderthals, there does not appear to be that clear separation between life and death."

"We can see that Neanderthals are coming back to one particular spot to bury their dead. This could be decades or even thousands of years apart. Is it just a coincidence, or is it intentional, and if so what brings them back?"

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Archaeologists unearth one of earliest known frame saddles

In April 2015, looters sacked an ancient cave burial at a site called Urd Ulaan Uneet high within the Altai Mountains of western Mongolia. When police apprehended the criminals, they uncovered, among other artifacts, an elegantly carved saddle made from several pieces of birch wood.

Now, in a new study, researchers from Mongolia collaborating with University of Colorado Boulder archaeologist William Taylor have described the find. The team's radiocarbon dating pins the artifact to roughly the 4th Century C.E., making it one of the earliest known frame saddles in the world.

"It was a watershed moment in the technological history of people and horses," said Taylor, corresponding author of the new study and curator of archaeology at the CU Museum of Natural History.

He and his colleagues, including scientists from 10 countries, published their findings Dec. 12 in the journal Antiquity.

The research reveals the underappreciated role that ancient Mongolians played in the spread of horse riding technology and culture around the globe. Those advances ushered in a new and sometimes brutal era of mounted warfare around the same time as the fall of the Roman Empire.

The discovery also highlights the deep relationships between human and animals in Mongolia. For millennia, pastoral peoples have traveled between the vast grasslands of the Mongolian Steppe with their horses -- which, in the region, tend to be short but sturdy, capable of surviving winter temperatures that can plummet far below freezing. Airag, a lightly alcoholic beverage made from fermented horse milk, remains a popular libation in Mongolia.

"Ultimately, technology emerging from Mongolia has, through a domino effect, ended up shaping the horse culture that we have in America today, especially our traditions of saddlery and stirrups," Taylor said.

But these insights also come at a time when Mongolia's horse culture is beginning to disappear, said study lead author Jamsranjav Bayarsaikhan.

"Horses have not only influenced the history of the region but also left a deep mark on the art and worldview of the Nomadic Mongols," said Bayarsaikhan, an archaeologist at the Max Planck Institute for the Science of Human History in Germany. "However, the age of technology is slowly erasing the culture and use of horses. Instead of herders riding horses, more and more people are riding motorcycles in the plains of Mongolia."

Mounted combat

Bayarsaikhan was working as a curator at the National Museum of Mongolia when he and his colleagues got the call from police in Hovd Province. The team later excavated the Urd Ulaan Uneet cave and unearthed the mummified remains of a horse, which the group partially described in a 2018 paper.

The saddle itself was made from about six pieces of birch wood held together with wooden nails. It bears traces of red paint with black trim and includes two leather straps that likely once supported stirrups. (The researchers also reported an iron stirrup recently discovered from around the same time period in eastern Mongolia).

The group couldn't definitively trace back where those materials came from. Birch trees, however, grow commonly in the Mongolian Altai, suggesting that locals had crafted the saddle themselves, not traded for it.

Taylor explained that humans had used pads, a form of proto-saddle, to keep their rear ends comfortable on horseback since the earliest days of mounted riding. Rigid wooden saddles, which were much sturdier, paired with stirrups opened a new range of things that people could do with horses.

"One thing they very gave rise to was heavy cavalry and high-impact combat on horseback," Taylor said. "Think of jousting in Medieval Europe."

Traveling west

In the centuries after the Mongolian saddle was crafted, these types of tools spread rapidly west across Asia and into the early Islamic world. There, cavalry forces became key to conquest and trade across large portions of the Mediterranean region and northern Africa.

Where it all began, however, is less clear. Archaeologists have typically considered modern-day China the birthplace of the first frame saddles and stirrups -- with some finds dating back to the 5th to 6th Century C.E. or even earlier.

The new study, however, complicates that picture, Taylor said.

"It's not the only piece of information suggesting that Mongolia might have been either among the very first adopters of these new technologies -- or could, in fact, be the place where they were first innovated," he said.

He suspects that Mongolia's place in that history may have gone underappreciated for so long in part because of the region's geography. The population density in the country's mountainous expanses is low, among the lowest on Earth, making it difficult to encounter and analyze important archaeological finds.

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South Africa's desert-like interior may have been more inviting to our human ancestors

Lining the Cape of South Africa and its southern coast are long chains of caves that nearly 200,000 years ago were surrounded by a lush landscape and plentiful food.

During a glacial phase that lasted between 195,000 to 123,000 years ago, these caves served as refuge to a group of humans that some researchers think were the only people to survive this ice age, called Marine Isotope Stage Six, or MIS6. And in this coastal region, a lot of archaeological research has taken place. Of less interest to archaeologists has been the interior of South Africa, which was thought to be an uninhabited, inhospitable place during at least two waves of ice ages, MIS3 and 2.

Now, a study has shown that the region might have been more fertile and temperate during these two glacial periods than previously thought, and that the region likely played host to human populations living around a series of paleolakes. The study, led by University of Michigan archaeologist Brian Stewart, provides a more comprehensive timeline of the age and stages of these lakes, and shows human fingerprints across the region. The research, funded by the National Geographic Society, is published in the journal PNAS.

"There's this perennial assumption that human population centers were always along the coast and that the interior, especially the southern interior of the Karoo Desert, were largely depopulated for long stretches of time," Stewart said. "The funny thing is that one just has to go into the interior and walk around and notice that there's archaeology everywhere."

But to flag the region as worthy of archaeological attention, the researchers needed to show that humans could have actually lived there. The research team, an international group including researchers from South Africa, the United Kingdom and France, examined a series of super flat areas of land ringed by higher ground. They showed that these regions, called "pans" in Afrikaans, are ancient lake beds, while the areas of higher elevation that encircle them are erosional landforms and sedimentary deposits left over from their ancient shorelines.

This suggests that these time periods were not as dry in this region as previously thought: there would have needed to have been sustained rainfall and humidity to keep these lakes full. The more temperate climate required to sustain lakes also meant the landscape was also able to sustain both vegetation and animals required to support human populations.

Reconstructing the paleolakes

The researchers used a variety of technologies to date and reconstruct these ancient lakes, shorelines and lake bottom deposits, and to recreate the landscape of the region.

These include radiocarbon dating and a technique called luminescence, which measures the radioactivity of tiny crystals of quartz or feldspar that haven't seen the light of day since they were covered by sediment tens of thousands of years earlier. While buried, electrons from radioactive elements common to all sediments get trapped in these crystal matrices at a constant rate. By measuring how many electrons accumulated in the sample and comparing that to the degree of background radioactivity, the researchers can predict its age.

The researchers used these techniques to date columns of sedimentary lakeshore and lake bottom deposits, called lacustrine deposits, found surrounding and within a series of three pans dotted across a region some 100,000 square miles, about the size of Texas. They also aged the shells of freshwater mollusks found scattered throughout the region and embedded within the sedimentary lake deposits.

An aquatic gastropod, Tomichia ventricosa, found at a pan called Swartkolkvloer, was embedded in a column of lacustrine deposits. Together, the deposits and shells were radiocarbon dated to two time periods: approximately 39-55 thousand years before present, and approximately 31-34 thousand years before present.

At another pan called Grootvloer, the researchers found a freshwater mollusk called Unio caffer, which required "perennial freshwater" and the presence of fish to reproduce. These shells and lacustrine deposits in this pan were dated to between approximately 20-22 thousand years before present.

The researchers were also able to predict the area of land the lakes encompassed, as well as how deep they were, based on the height of the lacustrine deposits ringing their shorelines. For example, they determined that the paleolake at Swartkolkvloer was about 83 miles square and 59 feet deep, while the paleolake at Grootvloer was likely about 17 miles square and 62 feet deep. Another pan called Alexanderfontein, some 300 miles northeast near the town of Kimberley, held a lake about 13.5 miles square and 48 feet deep.

Based on these parameters, the researchers knew the lakes would have required a climate drastically different from the one that exists in South Africa's interior today. Using a hydrological model, they determined that evaporation rates within the region were between 20% and 25% lower than what they are today, while precipitation would have been more than 200% higher at Swartkolkvloer and 88% higher at Alexanderfontein.

"In various parts of the interior, between about 60 to about 12,000 years ago, we can see that there were enduring phases of pretty large bodies of water kicking around what used to be thought of as an arid and inhospitable environment," Stewart said. "This was a period that used to be thought of as notoriously dry and freezing cold in the winter. But we've got this evidence for these large lakes existing during this time period."

The researchers say current day regions that have similar climates and rates of precipitation and evaporation are likely northern Botswana, Zambia and Zimbabwe. Based on this estimation and data found from a contemporaneous site called Equus Cave, the researchers think large grazing and browsing mammals would have thrived in this region.

A complex, prehistoric people

Scattered alongside the lakes are human artifacts such as triangular points, bladelets, weathered ostrich shells and other assemblages. Much of these are from the Middle Stone Age, which ranged from about 280,000 years ago to about 25,000 years ago, and the Later Stone Age, which lasted from 25,000 years ago right up to European contact in the 15th century.

"There's Middle Stone Age archaeology just everywhere," Stewart said. "You can't drive anywhere and open the car door and not step on it. It's astounding how much there is."

Stewart says their findings could also expand the region where archaeologists think humans became more behaviorally complex. Over the past decades, researchers have found evidence that humans living in coastal South Africa started making the leap into complex thought, showing some of the earliest signs of behavioral complexity. It was thought that both climate and nutrient stability -- including the rich omega fatty acids gleaned from seafood -- allowed humans here to become behaviorally modern.

The group's work may challenge this idea by suggesting that favorable conditions for hunter-gatherers were not confined to the coastline but probably characterized many regions as climates changed, including the interior, current-day desert.

"Ours is a basin-wide study with much more macro scale implications. It also involves some of these areas that are just inland of this coastal and mountain belt that's dominated the archaeological narratives for so long," Stewart said. "Just inland of this area is a region that has been, for a long time, portrayed as hostile, and it just simply appears not to have been the case for big chunks of time -- with the caveat that we need information on temperature depressions to understand how humans dealt with that."

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Searching for ancient bears in an Alaskan cave led to an important human discovery

The first people to live in the Americas migrated from Siberia across the Bering land bridge more than 20,000 years ago. Some made their way as far south as Tierra del Fuego, at the tip of South America. Others settled in areas much closer to their place of origin where their descendants still thrive today.

In "A paleogenome from a Holocene individual supports genetic continuity in Southeast Alaska," published Friday in the journal iScience, University at Buffalo evolutionary biologist Charlotte Lindqvist and collaborators show, using ancient genetic data analyses, that some modern Alaska Natives still live almost exactly where their ancestors did some 3,000 years ago.

Lindqvist, PhD, associate professor of biological sciences in the UB College of Arts and Sciences, is senior author of the paper. In the course of her extensive studies in Alaska, she explored mammal remains that had been found in a cave in the state's southeast coast. One bone was initially identified as coming from a bear. However, genetic analysis showed it to be the remains of a human female.

"We realized that modern Indigenous peoples in Alaska, should they have remained in the region since the earliest migrations, could be related to this prehistoric individual," says Alber Aqil, a UB PhD student in biological sciences and the first author of the paper. This discovery led to efforts to solve this mystery, which DNA analyses are well suited to address when archeological remains are as sparse as these were.

Learning from an ancestor

The earliest peoples had already started moving south along the Pacific Northwest Coast before an inland route between ice sheets became viable. Some, including the female individual from the cave, made their home in the area that surrounds the Gulf of Alaska. That area is now home to the Tlingit Nation and three other groups: Haida, Tsimshian, and Nisga'a.

As Aqil and colleagues analyzed the genome from this 3,000-year-old individual -- "research that was not possible just 20 years ago," Lindqvist noted -- they determined that she is most closely related to Alaska Natives living in the area today. This fact showed it was necessary to carefully document as clearly as possible any genetic connections of the ancient female to present-day Native Americans.

In such endeavors, it is important to collaborate closely with people living in lands where archeological remains are found. Therefore, cooperation between Alaska Native peoples and the scientific community has been a significant component of the cave explorations that have taken place in the region. The Wrangell Cooperative Association named the ancient individual analyzed in this study as "Tatóok yík yées sháawat" (Young lady in cave).

Genetic continuity in Southeast Alaska persists for thousands of years

Indeed, Aqil and Lindqvist's research demonstrated that Tatóok yík yées sháawat is in fact closest related to present-day Tlingit peoples and those of nearby tribes along the coast. Their research therefore strengthens the idea that genetic continuity in Southeast Alaska has continued for thousands of years.

Human migration into North America, although it began some 24,000 years ago, came in waves -- one of which, about 6,000 years ago -- included the Paleo-Inuit, formerly known as Paleo-Eskimos. Importantly for understanding Indigenous peoples' migrations from Asia, Tatóok yík yées sháawat'sDNA did not reveal ancestry from the second wave of settlers, the Paleo-Inuit. Indeed, the analyses performed by Aqil and Lindqvist helped shed light on the continuing discussion of migration routes, mixtures among people from these different waves, as well as modern territorial patterns of inland and coastal people of the Pacific Northwest in the pre-colonial era.

Oral history links an ancient woman to people living in Southeast Alaska today

The oral origin narratives of the Tlingit people include the story of the most recent eruption of Mount Edgecumbe, which would place them exactly in the region by 4,500 years ago. Tatóok yík yées sháawat, their relative, therefore informs not just modern-day anthropological researchers but also the Tlingit people themselves.

Out of respect for the right of the Tlingit people to control and protect their cultural heritage and their genetic resources, data from the study of Tatóok yík yées sháawat will be available only after review of its use by the Wrangell Cooperative Association Tribal Council.

"It's very exciting to contribute to our knowledge of the prehistory of Southeast Alaska," said Aqil.

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Hansel and Gretel's breadcrumb trick inspires robotic exploration of caves on Mars and beyond

House hunting on Mars could soon become a thing, and researchers at the University of Arizona are already in the business of scouting real estate that future astronauts could use as habitats. Researchers in the UArizona College of Engineering have developed technology that would allow a flock of robots to explore subsurface environments on other worlds.

"Lava tubes and caves would make perfect habitats for astronauts because you don't have to build a structure; you are shielded from harmful cosmic radiation, so all you need to do is make it pretty and cozy," said Wolfgang Fink, an associate professor of electrical and computer engineering at UArizona.

Fink is lead author of a new paper in Advances in Space Research that details a communication network that would link rovers, lake landers and even submersible vehicles through a so-called mesh topology network, allowing the machines to work together as a team, independently from human input. According to Fink and his co-authors, the approach could help address one of NASA's Space Technology Grand Challenges by helping overcome the limited ability of current technology to safely traverse environments on comets, asteroids, moons and planetary bodies. In a nod to the fairy tale "Hansel and Gretel," the researchers named their patent-pending concept the "Breadcrumb-Style Dynamically Deployed Communication Network" paradigm, or DDCN.

A fairy tale inspires the future

"If you remember the book, you know how Hansel and Gretel dropped breadcrumbs to make sure they'd find their way back," said Fink, founder and director of the Visual and Autonomous Exploration Systems Research Laboratory at Caltech and UArizona. "In our scenario, the 'breadcrumbs' are miniaturized sensors that piggyback on the rovers, which deploy the sensors as they traverse a cave or other subsurface environment."

Continuously monitoring their environment and maintaining awareness of where they are in space, the rovers proceed on their own, connected to each other via a wireless data connection, deploying communication nodes along the way. Once a rover senses the signal is fading but still within range, it drops a communication node, regardless of how much distance has actually passed since it placed the last node.

"One of the new aspects is what we call opportunistic deployment -- the idea that you deploy the 'breadcrumbs' when you have to and not according to a previously planned schedule," Fink said.

All the while, there is no need for input from the mother rover; each subordinate rover will make that determination on its own, Fink added. The system can work in one of two ways, Fink explained. In one, the mother rover acts as a passive recipient, collecting data transmitted by the rovers doing the exploration. In the other, the mother rover acts as the orchestrator, controlling the rovers' moves like a puppet master.

Machines take over

The new concept dovetails with the tier-scalable reconnaissance paradigm devised by Fink and colleagues in the early 2000s. This idea envisions a team of robots operating at different command levels -- for example, an orbiter controlling a blimp, which in turn controls one or more landers or rovers on the ground. Already, space missions have embraced this concept, several with participation by UArizona researchers. For example, on Mars, the Perseverance rover is commanding Ingenuity, a robotic helicopter. A concept for another mission, which ultimately was not selected for funding, proposed sending an orbiter carrying a balloon and a lake lander to study one of the hydrocarbon seas on Saturn's moon Titan. The breadcrumb approach takes the idea one step further by providing a robust platform allowing robotic explorers to operate underground or even submerged in liquid environments. Such swarms of individual, autonomous robots could also aid in search and rescue efforts in the wake of natural disasters on Earth, Fink said.

Fink said the biggest challenge, apart from getting the rovers inside the subsurface environment in the first place, is to retrieve the data they record underground and bring it back to the surface. The DDCN concept allows a team of rovers to navigate even convoluted underground environments without ever losing contact to their "mother rover" on the surface. Outfitted with a light detection and ranging system, or lidar, they could even map out cave passages in all three dimensions, not unlike the drones that can be seen exploring an alien spacecraft in the movie "Prometheus."

"Once deployed, our sensors automatically establish a nondirected mesh network, which means each node updates itself about each node around it," said Fink, who first detailed the DDCN concept in a proposal to NASA in 2019.

"They can switch between each other and compensate for dead spots and signal blackouts," added Mark Tarbell, paper co-author and senior research scientist in Fink's laboratory. "If some of them die, there still is connectivity through the remaining nodes, so the mother rover never loses connection to the farthest node in the network."

Mission of no return

The robust network of communication nodes ensures all the data collected by the robotic explorers make it back to the mother rover on the surface. Therefore, there is no need to retrieve the robots once they have done their job, said Fink, who published the idea of using groups of expendable mobile robotic surface probes as early as 2014.

"They're designed to be expendable," he said. "Instead of wasting resources to get them into the cave and back out, it makes more sense to have them go as far as they possibly can and leave them behind once they have fulfilled their mission, run out of power or succumbed to a hostile environment."

"The communication network approach introduced in this new paper has the potential to herald a new age of planetary and astrobiological discoveries," said Dirk Schulze-Makuch, president of the German Astrobiological Society and author of many publications on extraterrestrial life. "It finally allows us to explore Martian lava tube caves and the subsurface oceans of the icy moons -- places where extraterrestrial life might be present."

The proposed concept "holds magic," according to Victor Baker, a UArizona Regents Professor of Hydrology and Atmospheric Sciences, Geosciences and Planetary Sciences."The most amazing discoveries in science come about when advances in technology provide both first-time access to a thing or place and the means of communicating what is thereby discovered to creative minds that are seeking understanding," Baker said.

Exploring hidden ocean worlds

In places that call for submersible robots, the system could consist of a lander -- either floating on a lake, as might be the case on Titan, or sitting on the ice atop a subsurface ocean like on Europa -- that is connected to the submarine, for example through a long cable. Here the communication nodes would act as repeaters, boosting the signal in regular intervals to prevent it from degrading. Importantly, Fink pointed out, the nodes have the capabilities to gather data themselves -- for example measuring pressure, salinity, temperature and other chemical and physical parameters -- and to ingest the data into the cable connecting back to the lander.

"Imagine you make it all the way to Europa, you melt your way through miles of ice, make it down to the subsurface ocean, where you find yourself surrounded by alien life, but you have no way of getting data back to the surface," he said. "That's the scenario we need to avoid."

Read more at Science Daily

Exploring the possibility of extraterrestrial life living in caves

Is there life in Martian caves?

It's a good question, but it's not the right question -- yet. An international collaboration of scientists led by NAU researcher Jut Wynne has dozens of questions we need asked and answered. Once we figure out how to study caves on the Moon, Mars and other planetary bodies, then we can return to that question.

Wynne, an assistant research professor of cave ecology, is the lead author of two related studies, both published in a special collection of papers on planetary caves by the Journal of Geophysical Research Planets. The first, "Fundamental Science and Engineering Questions in Planetary Cave Research," was done by an interdisciplinary team of 31 scientists, engineers and astronauts who produced a list of 198 questions that they, working with another 82 space and cave scientists and engineers, narrowed down to the 53 most important. Harnessing the knowledge of a considerable swath of the space science community, this work is the first study designed to identify the research and engineering priorities to advance the study of planetary caves. The team hopes their work will inform what will ultimately be needed to support robotic and human missions to a planetary cave -- namely on the Moon and/or Mars.

The second, "Planetary Caves: A Solar System View of Products and Processes," was born from the first study. Wynne realized there had been no effort to catalog planetary caves across the solar system, which is another important piece of the big-picture puzzle. He assembled another team of planetary scientists to tackle that question.

"With the necessary financial investment and institutional support, the research and technological development required to achieve these necessary advancements over the next decade are attainable," Wynne said. "We now have what I hope will become two foundational papers that will help propel planetary cave research from an armchair contemplative exercise to robots probing planetary subsurfaces."

What we know about extraterrestrial caves

There are a lot of them. Scientists have identified at least 3,545 potential caves on 11 different moons and planets throughout the solar system, including the Moon, Mars and moons of Jupiter and Saturn. Cave formation processes have even been identified on comets and asteroids. If the surrounding environment allows for access into the subsurface, that presents an opportunity for scientific discovery that's never been available before.

The discoveries in these caves could be massive. Caves may one day allow scientists to "peer into the depths" of these rocky and icy bodies, which will provide insights into how they were formed (but also can provide further insights into how Earth was formed). They could also, of course, hold secrets of life.

"Caves on many planetary surfaces represent one of the best environments to search for evidence of extinct or perhaps extant lifeforms," Wynne said. "For example, as Martian caves are sheltered from deadly surface radiation and violent windstorms, they are more likely to exhibit a more constant temperature regime compared to the surface, and some may even contain water ice. This makes caves on Mars one of the most important exploration targets in the search for life."

And it's not just finding life -- these same factors make caves good locations for astronaut shelters on Mars and the Moon when crewed missions are able to explore.

"Radiation shielding will be essential for human exploration of the Moon and Mars," said Leroy Chiao, a retired astronaut, former commander of the International Space Station and co-author of the first paper. "One possible solution is to utilize caves for this purpose. The requirements for astronaut habitats, EVA suits and equipment should take cave exploration and development into consideration, for protection from both solar and galactic cosmic radiation."

What Earth can tell us about other planets

Wynne, whose primary research is in terrestrial caves, said planetary cave research has long been a parallel research question to the earthly variety for nearly two decades. Caves support unique ecosystems that are sometimes quite divorced from the surface ecosystem in the same area. Who's to say a cave on the Moon or Mars would not be similar? So, many questions he's investigated about caves on Earth, he's wondered how it could apply on other planets.

He's not the only one making the connection. Wynne has done multiple research projects with NASA to help advance detection technologies, and his modeling of cave habitats does not much care if a cave is terrestrial or extraterrestrial. There are enough similarities in the cave environment to make reasonable predictions that will factor prominently into the selection of cave targets for exploration.

"Tellurian caves at depth are often characterized by complete darkness, a stable temperature approximating the average annual surface temperature, low to no air flow and a near-water-saturated atmosphere," he said. "The caves of other planetary bodies likely exhibit similar environmental conditions, but these will also be influenced by the surface conditions of the planetary body and the internal structure of the cave."

Keith Cowing, editor of SpaceRef.com and NASAWatch.com, said using the existing infrastructure of a planet's surface and subsurface may help humans get to other planets sooner than if we had to bring everything needed to survive with us.

"Humans have been living in caves for hundreds of thousands of years. Then they built their own when none were available," he said. "As such, it is only natural to assume that caves will offer similar utility as humanity expands to other worlds. While planet-wide terraforming may be an end goal, the use of large, pre-existing structures such as caves and lava tubes may be a more practical way to bootstrap the technology to the maturity needed to tackle the surface of an entire planet."

Where are we now?

While much of this research is forward-looking, there's also a need to consider what resources, research and support currently exist. Numerous robotic platforms and instrumentation suites are being tested, but the roadblock comes where it so often does -- the lack of funding. With sufficient support, a robotic exploration mission to a lunar or Martian cave could be possible in the next five to 10 years.

This research builds on past work to form a road map of sorts to move forward; Wynne sees it as a to-do list for that same process. The questions the scientists and engineers answered identify the tasks needed to prepare for that robotic exploration; it also looks even further ahead to the advancements needed in spacesuit technology, habitation modules and hardware that will enable humans to live and work safely underground on the Moon and Mars.

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Hidden in caves: Mineral overgrowths reveal 'unprecedented' sea level rise

The early 1900s were an exciting time across the world, with rapid advances in the steel, electric and automobile industries. The industrial changes also mark an inflection point in our climate. According to an international team of researchers led by the University of South Florida (USF), the sea level has risen 18 centimeters since the start of the 20th century.

The study, featured on the cover of the July 1 issue of Science Advances, works to identify preindustrial sea levels and examines the impact of modern greenhouse warming on sea-level rise.

The team, which includes USF graduate students, traveled to Mallorca, Spain -- home to more than 1,000 cave systems, some of which have deposits that formed millions of years ago. For this study, they focused on analyzing deposits from 4,000 years ago to present day.

The team found evidence of a previously unknown 20 centimeter sea-level rise that occurred nearly 3,200 years ago when ice caps melted naturally over the course of 400 years at a rate of 0.5 millimeters per year. Otherwise, despite major climatic events like Medieval Warm Period and the Little Ice Age, the sea level remained exceptionally stable until 1900.

"The results reported in our study are alarming," said lead author Bogdan P. Onac, geology professor at USF. "The sea-level rise since the 1900s is unprecedented when compared to the natural change in ice volumes over the last 4,000 years. This implies that if global temperatures continue to rise, sea levels could eventually reach higher levels than scientists previously estimated."

To create the timeline, the team gathered 13 samples from eight caves along the coastline of the Mediterranean Sea. The deposits are rare -- only forming near the coastline in cave passages that were repeatedly flooded by sea water, making them accurate markers of sea-level changes overtime. Each deposit holds valuable insight into both the past and future, helping researchers determine how quickly the sea level will rise in the coming decades and centuries.

The samples were taken to the University of New Mexico and University of Bern in Switzerland, where special instruments were used to determine their age by uranium-series method. Over time, uranium decays into other elements such as thorium and lead, allowing researchers to create a timeline of the sea level documented in each deposit.

A complex software at Harvard University helped generate predictions using various ice models and Earth's parameters to showcase an accurate history of the sea level. These predictions are essential because they allow researchers to estimate past global mean sea level, which is key in addressing future sea-level rise.

"If humans continue to be the main driver and the temperature increases 1.5 degrees in the near future, there will be irreversible damage," Onac said. "There will be no turning back from that point on."

Based on ice mass loss from the Antarctic and Greenland, the average sea-level rise since 2008 is 1.43 millimeters per year.

Permanent flooding from the rising sea level won't happen overnight, but Onac says it will be seen more and more during storm surges and hurricanes. With nearly 40 percent of the world's population living within 62 miles of a coast, the rising sea level could be catastrophic with substantial societal and economic impacts.

"Even if we stop right now, sea level will continue to rise for at least a couple of decades, if not centuries, simply because the system is warmed up."

In June, Onac received a new research grant from the National Science Foundation to continue his research to predict future sea-level rise due to global warming. The grant will allow Onac to expand the research further into history by 130,000 years and create a better understanding of sea level globally. Starting in September, Onac and his team will begin analyzing cave deposits from around the globe, including Italy, Greece, Mexico and Cuba.

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Early humans placed the hearth at the optimal location in their cave -- for maximum benefit and minimum smoke exposure

A groundbreaking study in prehistoric archaeology at Tel Aviv University provides evidence for high cognitive abilities in early humans who lived 170,000 years ago. In a first-of-its kind study, the researchers developed a software-based smoke dispersal simulation model and applied it to a known prehistoric site. They discovered that the early humans who occupied the cave had placed their hearth at the optimal location -- enabling maximum utilization of the fire for their activities and needs while exposing them to a minimal amount of smoke.

The study was led by PhD student Yafit Kedar, and Prof. Ran Barkai from the Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures at TAU, together with Dr. Gil Kedar. The paper was published in Scientific Reports.

Yafit Kedar explains that the use of fire by early humans has been widely debated by researchers for many years, regarding questions such as: At what point in their evolution did humans learn how to control fire and ignite it at will? When did they begin to use it on a daily basis? Did they use the inner space of the cave efficiently in relation to the fire? While all researchers agree that modern humans were capable of all these things, the dispute continues about the skills and abilities of earlier types of humans.

Yafit Kedar: "One focal issue in the debate is the location of hearths in caves occupied by early humans for long periods of time. Multilayered hearths have been found in many caves, indicating that fires had been lit at the same spot over many years. In previous studies, using a software-based model of air circulation in caves, along with a simulator of smoke dispersal in a closed space, we found that the optimal location for minimal smoke exposure in the winter was at the back of the cave. The least favorable location was the cave's entrance."

In the current study the researchers applied their smoke dispersal model to an extensively studied prehistoric site -- the Lazaret Cave in southeastern France, inhabited by early humans around 170,000 to 150,000 years ago. Yafit Kedar: "According to our model, based on previous studies, placing the hearth at the back of the cave would have reduced smoke density to a minimum, allowing the smoke to circulate out of the cave right next to the ceiling. But in the archaeological layers we examined, the hearth was located at the center of the cave. We tried to understand why the occupants had chosen this spot, and whether smoke dispersal had been a significant consideration in the cave's spatial division into activity areas."

To answer these questions, the researchers performed a range of smoke dispersal simulations for 16 hypothetical hearth locations inside the 290sqm cave. For each hypothetical hearth they analyzed smoke density throughout the cave using thousands of simulated sensors placed 50cm apart from the floor to the height of 1.5m.

To understand the health implications of smoke exposure, measurements were compared with the average smoke exposure recommendations of the World Health Organization. In this way four activity zones were mapped in the cave for each hearth: a red zone which is essentially out of bounds due to high smoke density; a yellow area suitable for short-term occupation of several minutes; a green area suitable for long-term occupation of several hours or days; and a blue area which is essentially smoke-free.

Yafit and Gil Kedar: "We found that the average smoke density, based on measuring the number of particles per spatial unit, is in fact minimal when the hearth is located at the back of the cave -- just as our model had predicted. But we also discovered that in this situation, the area with low smoke density, most suitable for prolonged activity, is relatively distant from the hearth itself.

Early humans needed a balance -- a hearth close to which they could work, cook, eat, sleep, get together, warm themselves, etc. while exposed to a minimum amount of smoke. Ultimately, when all needs are taken into consideration -- daily activities vs. the damages of smoke exposure -- the occupants placed their hearth at the optimal spot in the cave."

The study identified a 25m2 area in the cave which would be optimal for locating the hearth in order to enjoy its benefits while avoiding too much exposure to smoke. Astonishingly, in the several layers examined by in this study, the early humans actually did place their hearth within this area.

Prof. Barkai concludes: "Our study shows that early humans were able, with no sensors or simulators, to choose the perfect location for their hearth and manage the cave's space as early as 170,000 years ago -- long before the advent of modern humans in Europe. This ability reflects ingenuity, experience, and planned action, as well as awareness of the health damage caused by smoke exposure. In addition, the simulation model we developed can assist archaeologists excavating new sites, enabling them to look for hearths and activity areas at their optimal locations."

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