An international research team led by Griffith University, Indonesia’s national research and innovation agency (BRIN), and Southern Cross University determined that these paintings on the island of Sulawesi were created at least 67,800 years ago.

Researchers say this breakthrough helps clarify when and how humans first reached Australia. The people who made the Sulawesi art were likely closely related to the ancestors of Indigenous Australians.

Ancient Handprint and Advanced Dating Techniques

The artwork was preserved in limestone caves in southeastern Sulawesi, on the nearby island of Muna. Scientists identified a partial hand stencil surrounded by much younger paintings.

To determine its age, the team used uranium-series dating, examining tiny mineral layers that had formed over and sometimes beneath the artwork in Liang Metanduno cave. This allowed them to establish when the paintings were created.

The hand stencil dates back at least 67,800 years, making it the oldest reliably dated cave art ever found. It is significantly older than another Sulawesi painting identified by the same team in 2024.

The findings also show that people continued creating art in this cave for a remarkably long time. Artistic activity spanned at least 35,000 years, lasting until around 20,000 years ago.

“It is now evident from our new phase of research that Sulawesi was home to one of the world’s richest and most longstanding artistic cultures, one with origins in the earliest history of human occupation of the island at least 67,800 years ago,” said Professor Maxime Aubert, an archaeologist and geochemist from the Griffith Centre for Social and Cultural Research (GCSCR), who co-led the study.

A Unique Claw-Like Handprint

The team noted that this hand stencil stands out as a unique variation of a common motif.

After it was first created, the image appears to have been intentionally modified. The outlines of the fingers were narrowed, giving the hand a claw-like appearance.

Professor Adam Brumm of Griffith University’s Australian Research Centre for Human Evolution (ARCHE), a co-leader of the study, said the meaning behind this alteration remains uncertain.

“This art could symbolize the idea that humans and animals were closely connected, something we already seem to see in the very early painted art of Sulawesi, with at least one instance of a scene portraying figures that we interpret as representations of part-human, part-animal beings,” Professor Brumm said.

Clues to Early Human Migration to Australia

Dr. Adhi Agus Oktaviana, a rock art specialist at BRIN and a team leader whose doctoral research at Griffith University contributed to the study, said the discovery has major implications for understanding the deep history of Australian Aboriginal culture.

“It is very likely that the people who made these paintings in Sulawesi were part of the broader population that would later spread through the region and ultimately reach Australia,” Dr. Oktaviana said.

For years, archaeologists have debated when humans first arrived on the ancient landmass known as Sahul, which once connected present-day Australia, Tasmania and New Guinea.

Some researchers support a short chronology, suggesting humans arrived around 50,000 years ago. Others favor a long chronology, placing their arrival at least 65,000 years ago.

“This discovery strongly supports the idea that the ancestors of the First Australians were in Sahul by 65,000 years ago,” Dr. Oktaviana said.

Migration Routes and Ongoing Research

Scientists have proposed two main pathways into Sahul. One is a northern route through Sulawesi and the ‘Spice Islands’ toward New Guinea. The other is a southern route that carried early seafarers more directly to Australia via Timor or nearby islands.

Professor Renaud Joannes-Boyau of the Geoarchaeology and Archaeometry Research Group (GARG) at Southern Cross University said the new evidence strengthens the case for the northern route.

“With the dating of this extremely ancient rock art in Sulawesi, we now have the oldest direct evidence for the presence of modern humans along this northern migration corridor into Sahul,” Professor Joannes-Boyau said.

“These discoveries underscore the archaeological importance of the many other Indonesian islands between Sulawesi and westernmost New Guinea,” said Professor Aubert, who continues working with colleagues to uncover more evidence of early human activity along this route with support from the Australian Research Council (ARC).

The ARC funding is part of a broader effort to study human origins. This includes the ARC Centre of Excellence for Transforming Human Origins Research, led by Griffith University, and the ARC Training Centre for Advancing Archaeology in the Resources Sector at Southern Cross University. These initiatives aim to expand knowledge of human evolution and help protect cultural heritage.

Additional support for the research came from Google Arts & Culture and the National Geographic Society.

The Sulawesi discoveries have also been featured in a documentary, ‘Sulawesi l’île des premières images,’ produced by ARTE and released in Europe.

The study, titled ‘Rock art from at least 67,800 years ago in Sulawesi,’ was published in Nature.

A study published in JASA, on behalf of the Acoustical Society of America by AIP Publishing, set out to test whether closing the eyes truly improves hearing under noisy conditions. Researchers from Shanghai Jiao Tong University examined how visual input affects the ability to detect sounds.

Experiment Testing Hearing in Noise

Participants in the study listened to a range of sounds through headphones while background noise played at the same time. Their task was to adjust the volume until each sound was just barely audible over the noise.

The experiment included several visual conditions. First, participants completed the task with their eyes closed. They then repeated it with their eyes open while looking at a blank screen, followed by viewing a still image related to the sound, and finally watching a video that matched what they were hearing.

Closing Eyes vs Visual Cues

The results went against a widely held assumption. “We found that, contrary to popular belief, closing one’s eyes actually impairs the ability to detect these sounds,” said author Yu Huang. “Conversely, seeing a dynamic video corresponding to the sound significantly improves hearing sensitivity.”

Rather than helping, closing the eyes made it harder to pick out faint sounds in noisy settings, while relevant visual input provided a clear advantage.

Brain Activity and Over-Filtering

To understand why this happens, the researchers used electroencephalography (EEG) to track brain activity during the tests. They found that closing the eyes shifts the brain into a state known as neural criticality, which increases how strongly it filters incoming information.

This heightened filtering does not just reduce background noise. It can also suppress the target sounds participants are trying to hear.

“In a noisy soundscape, the brain needs to actively separate the signal from the background,” said Huang. “We found that the internal focus promoted by eye closure actually works against you in this context, leading to over-filtering, whereas visual engagement helps anchor the auditory system to the external world.”

When Closing Your Eyes Still Helps

The researchers noted that the effect appears specific to noisy environments. In quieter conditions, closing the eyes may still improve the ability to detect subtle sounds.

However, since everyday life often involves significant background noise, keeping your eyes open may be the more effective strategy in many situations.

Future Research on Vision and Hearing

The team plans to continue studying how sight and sound interact. One key question is whether the benefit comes simply from having visual input or from seeing something that matches the sound.

“Specifically, we want to test incongruent pairings — for example, what happens if you hear a drum but see a bird?” said Huang. “Does the visual boost come from simply having the eyes open and processing more visual information, or does the brain require the visual and audio information to match perfectly? Understanding this distinction will help us separate the general effects of attention from the specific benefits of multisensory integration.”

New findings suggest a far more down to earth explanation. The platinum spike may have come from a volcanic fissure eruption in Iceland rather than an object from space.

The Younger Dryas and a Sudden Climate Shift

The timing of this signal is critical. It appears close to the start of the Younger Dryas Event, a dramatic cold period that lasted from roughly 12,870 to 11,700 years ago. During this time, temperatures across the northern hemisphere dropped sharply.

This cooling came just as the planet was emerging from the last ice age and beginning to warm. Identifying what caused this sudden reversal could offer valuable insight into how Earth’s climate system behaves under stress.

Researchers now suggest that this cold phase may have been triggered by a major volcanic eruption in Germany or possibly an eruption from an as yet unidentified volcano.

Competing Theories Behind the Climate Mystery

Ice core records show just how extreme the Younger Dryas was. In Greenland, temperatures fell to more than 15°C colder than today. Across Europe, forests gave way to tundra, and rainfall patterns in lower latitudes shifted southward.

The leading explanation has long been a massive influx of freshwater from melting North American ice sheets. This surge is thought to have disrupted ocean circulation and cooled the climate. However, another theory proposed that a comet or asteroid impact over North America triggered the event.

Platinum Spike Raises New Questions

In 2013, scientists studying ice cores from the Greenland Ice Sheet Project (GISP2) found unusually high platinum concentrations. The ratio of platinum to iridium was especially puzzling. Space rocks typically contain high levels of iridium, but this signal did not. The chemical signature also did not match known meteorites or volcanic materials.

Some researchers suggested the spike could be evidence of an unusual iron rich asteroid. Others proposed it might be linked to the Laacher See volcanic eruption in Germany, which occurred around the same time and has a distinctive chemical profile.

To investigate, researchers analyzed 17 samples of volcanic pumice from Laacher See deposits. They measured platinum, iridium, and other trace elements to build a chemical fingerprint.

The results were decisive. The pumice samples contained almost no platinum, with levels at or below detection limits. This ruled out the Laacher See eruption as the source of the Greenland platinum spike.

Timing and Duration Tell a Different Story

A closer look at the timeline provided another important clue. Updated ice core dating shows the platinum spike occurred about 45 years after the Younger Dryas began, making it too late to have caused the initial cooling.

This finding aligns with earlier studies. In addition, the elevated platinum levels persisted for about 14 years, indicating a sustained process rather than a sudden event like a meteorite or comet impact.

When scientists compared the ice core chemistry with other geological samples, the closest match came from volcanic gas condensates (the products formed when gases released from a volcano cool from a gas to a liquid or solid state), especially those linked to underwater volcanic activity.

Icelandic Volcanoes as a Likely Source

Volcanoes in Iceland are capable of producing fissure eruptions that last for years or even decades, consistent with the 14 year platinum signal. During the period leading up to the Younger Dryas, increased melting of ice sheets reduced pressure on the Earth’s crust, likely boosting volcanic activity in the region.

Submarine and subglacial eruptions interact with water in ways that can produce unusual chemical signatures. Seawater can remove sulfur compounds while concentrating metals such as platinum in volcanic gases. These gases can travel through the atmosphere and settle onto distant ice sheets, including Greenland.

Evidence from more recent Icelandic eruptions supports this idea. The 8th century Katla eruption created a 12-year spike in metals like bismuth and thallium in Greenland ice cores. The 10th century Eldgjá eruption left behind a cadmium signal. Although platinum was not measured in those cases, they show that Icelandic volcanoes can transport heavy metals over long distances.

Did Volcanoes Trigger the Younger Dryas

Because the platinum spike occurred after the cooling began, it was not the trigger for the Younger Dryas. However, other ice core records reveal a large volcanic sulfate spike that lines up precisely with the onset of cooling around 12,870 years ago.

This eruption, whether from Laacher See or another volcano, released enough sulfur into the atmosphere to rival the most powerful eruptions in recorded history. Sulfur in the stratosphere can reflect sunlight and cool the planet, potentially setting off feedback effects such as expanding sea ice, shifting winds, and disrupted ocean circulation.

At a time when Earth’s climate was already in a delicate transition between glacial and interglacial (the periods between cold snaps) conditions, this volcanic activity may have pushed the system back into a cold state.

What This Means for Future Climate Risks

This research focused specifically on the platinum signal and did not evaluate other proposed impact evidence such as spherules (spherical fragments of melted rock) and black mats (mysterious dark layers in soil). Even so, the simplest explanation based on current evidence points to a large volcanic eruption in the northern hemisphere as the main driver of the Younger Dryas.

Understanding how past events triggered abrupt climate shifts is essential for anticipating future risks. While large meteorite impacts and major volcanic eruptions are rare in any given year, they are inevitable over long timescales. Learning how Earth responded in the past helps scientists better prepare for the consequences of future global disruptions.