Sunday, May 10, 2026

Ice Age butcher’s tools are a sign of ancient humans’ creativity during hard times

Crystals inside a prehistoric bone rewrote scientists’ estimates of the age of the archaeological site, suggesting that the stone tools were made during a harsh ice age

Field Museum

Crystals in bone — image:
*Crystals growing inside a bone found at the Lingjing archaeological site; these crystals were used to date the site, and the tools found there, to an ice age 146,000 years ago. Photo by Zhanyang Li.*
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Credit: Zhanyang Li.

In central China, scientists have spent over a decade excavating and studying an archaeological site where ancient humans butchered animals. Amidst bones, archaeologists found complex stone tools that would have required a level of intelligence and creativity to make. A new analysis, based on the crystals growing inside one of the bones, showed scientists the site dated back to an ice age 146,00 years ago— challenging long-held ideas about early humanity at this site becoming creative thanks to warmer times of plenty.

“People often imagine creativity as something that flourishes in good times,” says Yuchao Zhao, the assistant curator of East Asian archaeology at the Field Museum in Chicago and the lead author of a paper describing the findings in the Journal of Human Evolution. “Finding out that these stone tools were made during a harsh ice age tells a different story. Hard times can force us to adapt.”

Zhao and his colleagues, led by senior author Zhangyang Li, a professor at Shandong University in China, have been examining stone tools found at the Lingjing archaeological site in central China. Lingjing was occupied by early humans called Homo juluensis. They were cousins of modern humans (Homo sapiens), and our ancestors may have interacted with them. Homo juluensis show a striking mosaic of features, including very large brain size and traits seen in both eastern Asian archaic humans and Neanderthals in Europe.

Until recently, archaeologists had thought that the ancient humans in East Asia during the late Middle Pleistocene (300,000-120,000 years ago) hadn’t made many significant technological advances, in comparison to the early humans living in Europe and Africa. But the stone tools found at Lingjing tell a different story.

The disc-shaped stone cores at Lingjing might not look especially fancy at first glance, but Zhao and his colleagues’ analysis of them revealed that they were part of a painstaking and carefully organized tool-making process. The Homo juluensis people crafted them by hitting small stones against larger stone cores.

Some of the cores were worked fairly evenly on both sides. Others were more carefully structured: one side served mainly as the surface to strike from, while the other side was shaped to produce sharp flakes. These asymmetrical cores are especially important because they show that ancient humans were not just knocking pieces off a stone at random. They were managing the core as a three-dimensional object, giving different surfaces different roles and maintaining the right angles to keep producing useful flakes.

“This was not casual flake production, but a technology that required planning, precision, and a deep understanding of stone properties and fracture mechanics,” says Zhao. “The underlying logic of this system— and the cognitive abilities it reflects— shows important similarities to Middle Paleolithic technologies often associated with Neanderthals in Europe and with human ancestors in Africa, suggesting that advanced technological thinking was not limited to western Eurasia.”

So, the stone artifacts left behind by the Homo juluensis at Lingjing suggest that the people there were capable of complex thought and creativity. But the story is further complicated by recent studies that have adjusted scientists’ estimates of how long ago these tools were made.

Lingjing was a site where Homo juluensis came to butcher animals like deer, and these animals’ bones are found alongside the stone tools. One of these bones, a rib from a deer-like animal, contained glittering calcite crystals. Calcite crystals contain trace amounts of uranium, which slowly degrades into another element called thorium. By measuring the ratio of uranium to thorium present in a calcite crystal, scientists can tell how old the crystal is.

“The calcite crystals inside the bone acted like a natural clock, allowing us to refine the age of the site,” says Zhao.

Previously, researchers thought that the tools found in Lingjing were about 126,000 years old at most, but based on the presence of the crystals, they're about 20,000 years older— a small, but important difference.

“Even though these tools are just a little bit older than we’d previously thought, the entire story is changed,” says Zhao. “During the Pleistocene, Earth repeatedly shifted between colder ice-age periods and warmer intervals between them. We used to think these tools were made 126,000 years ago, during a warm interglacial period, but based on the new dates suggested by the crystals, some of these tools were actually produced 146,000 years ago, during a harsh, cold glacial period.”

The new age assigned to these stone artifacts calls into question the idea that creativity is a luxury for good times; instead, in this case, it seems to be an adaption for surviving hard times. “Altogether, this research reveals a much richer story of innovation, intelligence, and human evolution in East Asia,” says Zhao.

One of the 146,000-year-old stone cores used to make butcher's tools, found in Lingjing, China. Photo by Yuchao Zhao.

Credit

Yuchao Zhao

Journal

Journal of Human Evolution

Article Title

Earliest centripetal flaking system in eastern Eurasia reveals human behavioral complexity in late Middle Pleistocene China

Article Publication Date

7-May-2026

Biggest black holes built up in busy star clusters after series of violent merging events, research finds

Team identifies two distinct black hole populations in version 4.0 of the Gravitational-Wave Transient Catalog

Cardiff University

The globular cluster M80 — image:
Caption: About 28,000 light-years away, the globular cluster M80 is home to hundreds of thousands of stars bound together by gravity. Crowded environments like this can help drive the growth of black holes through consecutive mergers. Credit: NASA, ESA, STScI, and A. Sarajedini (University of Florida).
Alt text: Yellow and white objects of different shapes and sizes are shown against a black background, representing hundreds of thousands of stars bound together in a crowded environment in space.
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Credit: Credit: NASA, ESA, STScI, and A. Sarajedini (University of Florida).

Biggest black holes built up in busy star clusters after series of violent merging events, research finds

Team identifies two distinct black hole populations in version 4.0 of the Gravitational-Wave Transient Catalog

The most massive black holes in the Universe detected by the ripples they make in space time were not born directly from collapsing stars, according to a new study.

These cosmic giants instead build up through a series of repeated and extremely violent collision events in very densely populated star clusters, an international team of researchers argue.

Their study, led by Cardiff University, analysed version 4.0 of LIGO–Virgo–KAGRA’s Gravitational-Wave Transient Catalog (GWTC4), containing 153 sufficiently confident black hole merger detections.

The team wanted to test the idea that the heaviest black holes in GWTC-4 are second-generation objects, formed when earlier black holes merged and then merged again in the dense cores of star clusters, where stars can be packed up to a million times more tightly than in the Sun’s neighbourhood.

Their findings, published in Nature Astronomy, probe the origins of the heaviest black holes detected by their gravitational waves, revealing two distinct populations.

“Gravitational-wave astronomy is now doing more than counting black hole mergers,” explains lead author Dr Fabio Antonini from Cardiff University’s School of Physics and Astronomy.

“It is starting to reveal how black holes grow, where they grow, and what that tells us about the lives and deaths of massive stars. This is exciting because we can use the information to test our understanding of how stars and clusters evolve in the Universe.”

In the gravitational-wave data, the team identified:

a lower-mass population consistent with ordinary stellar collapse
a higher-mass population whose spins appear exactly like those expected from hierarchical mergers in dense star clusters

“What surprised us most was how clearly the high-mass black holes stand out as a separate population,” recalls co-author Dr Isobel Romero-Shaw, Ernest Rutherford Fellow at Cardiff University.

“Unlike the lower-mass systems we analysed, which were generally slowly-spinning, the higher-mass systems are consistent with having more rapid spins, oriented in seemingly random directions. This is the exact signature you would expect if black holes were repeatedly merging in dense star clusters.

“That makes the cluster origin much more compelling than it was with earlier catalogues.”

The study also provides the strongest evidence yet for a “mass gap”, where extremely massive stars explode catastrophically rather than collapsing into black holes.

The long-predicted theory describes a forbidden mass range for black holes made directly from stars, where very massive stars are expected to be disrupted before they can form black holes.

The team pinpoints this range in a population of stellar-origin black holes 45 times the mass of the Sun and above.

Dr Antonini said: “In our study we find evidence for the long-predicted pair-instability mass gap — a range of masses where stars are not expected to leave behind black holes at all. Gravitational-wave detectors have successfully found black holes that appear to sit in or near that gap, which we identify at around 45 solar masses.

“So, the key question now is are these black holes telling us that our models of stellar evolution are wrong, or are they being made in another way?

“The biggest black holes in the current sample seem to be telling us about cluster dynamics, not just stellar evolution.

“Above about 45 solar masses the spin distribution changes in a way that is hard to explain with normal stellar binaries alone but is naturally explained if these black holes have already been through earlier mergers in dense clusters.”

The team also used this transition to shed light on an important nuclear reaction involved in helium burning inside massive stars.

“In the future, gravitational-wave data may help scientists study nuclear physics, because the mass limit set by pair instability depends on the nuclear reactions taking place in the cores of massive stars,” added co-author Dr Fani Dosopoulou, a research associate at Cardiff University.

ENDS

Journal

Nature Astronomy

DOI

10.1038/s41550-026-02847-0

Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

Gravitational-wave constraints on the pair-instability mass gap and nuclear burning in massive stars

Article Publication Date

7-May-2026

Rapidly melting Antarctic ice shelves may cause global sea levels to rise far faster than expected – new study

Global sea levels may rise faster than previously expected, a new study suggests. The reason is that warming oceans appear to be melting Antarctic ice shelves from below much more rapidly than expected

iC3 Polar Research Hub

image:
Front of Antarctic ice shelf
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Credit: Julius Lauber NPI

Ice shelves, which are extensions of gigantic glaciers that float on the water surface, act like buttresses that slow the flow of gigatons of ice into the sea. Now, researchers in Norway have discovered that long, channel-like grooves on the underside of these ice shelves can trap relatively warm ocean water. This sharply increases local melting.

The study has global implications. If Antarctic ice shelves thin and weaken, the downhill journey of the ice behind them can accelerate, fast-forwarding the process in which huge amounts of ice cascade into the ocean, causing sea levels worldwide to rise far faster than currently projected.

This dynamic has already been observed elsewhere in Antarctica. The Intergovernmental Panel on Climate Change (IPCC) has flagged polar ice shelf instability as a major but poorly understood risk factor that could lead to sea level rise that is far more rapid and severe than most current models predict.

What the team found

Using Fimbulisen Ice Shelf in East Antarctica as a case study, the team found that the shape of the ice shelf base can strongly alter how ocean water moves beneath it. Where the underside is channelled, the circulation can create small overturning cells that hold warmer water in place beneath the ice instead of letting it pass through quickly.

In those channels, melt rates can rise by about an order of magnitude locally. In simple terms, the geometry of the ice shelf helps decide where ocean heat goes, and how destructive that heat becomes.

“We found that the shape of the ice shelf underside is not just a passive feature. It can actively trap ocean heat in exactly the places where extra melting matters most,” lead author Tore Hattermann from the iC3 Polar Reseach Hub in Tromsø, Norway explains.

Fimbulisen Ice Shelf is located in East Antarctica, a region that is colder and therefore usually seen as less immediately threatened than the rest of the continent.

“We observed beneath the Fimbulisen Ice Shelf that even small amounts of warmer water can substantially increase melting within the channels,” Tore Hatterman says. “As a result, the channels can grow and, in the worst case, weaken the stability of the entire ice shelf.”

Qin Zhou, who co-led the study, adds that “What is striking is that even modest inflows of warmer deep water can have a large effect when the ice shelf base is channelled. That means some ice shelves that scientists usually think of as cold may be more fragile than expected.”

How the team worked

To reach these conclusions, the researchers combined a detailed map of the ice shelf underside with a high-resolution model of the ocean cavity beneath Fimbulisen.

They compared cases with a smoother ice base and a more realistic channelled one, under both cooler and slightly warmer ocean conditions. This allowed them to isolate the effect of the channels on water flow, mixing and melt.

The study also drew on earlier field observations from the region, showing the value of combining long-term measurements with modelling that can resolve small features beneath the ice. Tore Hattermann himself has spent hundreds of days camped out on Antarctic ice shelves.

Why this matters

The wider implications are serious. Faster melting inside channels can make those channels grow deeper and wider, causing uneven thinning in the deeper part of the ice shelf. That can reduce the shelf’s structural strength and weaken its ability to hold back the glaciers feeding it.

“Current climate models do not capture this effect,” Tore Hattermann warns. “This means that they risk underestimating the sensitivity the ‘cold’ ice shelves along East Antarctica’s coastline to small changes or warming in coastal waters. Such changes have already been observed, and are projected to increase in the future.”

That is important for science, because ice sheet and climate models need to capture these small-scale features more realistically. It is important for policy too, because decisions about coastal planning and adaptation depend on credible sea level projections. And it is important ecologically, because changes in the delivery of meltwater can influence ocean circulation and marine ecosystems around Antarctica.

Find out more

The study “Channelized topography amplifies melt-sensitivity of 1

cold Antarctic ice shelves” is published in the journal Nature Communications.

The study was led by Tore Hattermann from the iC3 Polar Research Hub and Qin Zhou from Akvaplan-niva (joint first authors). Both are based in Tromsø, the capital of Arctic Norway. Tore is an assistant lead of the iC3 research group that develops and applies novel technologies for cryospheric science

Note for editors

For a backgrounder on the links between Antarctic ice shelves and global sea level rise, see this Carbon Brief post, also by Tore Hattermann. More research on the Fimbulisen Ice Shelf by Tore Hattermann can be found here.

Lead researcher Tore Hattermann works at the Norwegian Polar Institute, which has an extensive library of photos of Antarctic ice shelves. Please contact him for photos, additional quotes and interviews: Tore.Hattermann@npolar.no copying in NPI comms officer Stig.Mathisen@npolar.no

Co-lead researcher Qin Zhou works at Akvaplan-niva. Please contact her for additional quotes and interviews: qin@akvaplan.niva.no

Antarctica ice shelf