Category: 7. Science

Sharks rely on their razor-sharp teeth – replaced every few days to ensure maximum killing power – to survive. But this weapon is under threat, which could spell disaster for one of the ocean’s top predators.

The more carbon dioxide humans release into the atmosphere, the more the ocean absorbs. With increased absorption of carbon dioxide, the ocean becomes more acidic, and by 2300 the sea is projected to be ten times more acidic than it currently is. This is likely to be catastrophic for animals such as corals and shellfish, but how this acidification might affect top predators isn’t well understood.

A new study, published in Frontiers in Marine Science, explores the impact ocean acidification will have on sharks by focussing in on one of their most important survival tools: their teeth.

The researchers collected newly shed teeth from captive blacktip reef sharks. Blacktip reef sharks must swim with their mouths open – and their teeth exposed – in order to breathe, and their teeth are therefore extremely vulnerable to the effects of ocean acidification. By placing the collected teeth in acidified seawater, the scientists could observe what might happen to shark teeth in the near future.

The results are not good news for sharks. In more acidic seawater, shark teeth begin to crumble. They develop cracks and holes, and the roots corrode. But what does this mean for the ocean’s top predators?

“Damaged teeth may reduce feeding efficiency,” Maximilian Baum, lead author of the study, tells BBC Wildlife. “Over time, this could affect their hunting success, fitness and ecological role.”

There is a possibility that sharks might be able to repair their teeth by remineralising them. While costly, this would increase the sharks’ chances of surviving ocean acidification.

Unfortunately, it is not only acidification that sharks have to contend with.

“Acidification adds to many other human-driven stressors like overfishing, pollution and habitat loss,” Maximilian says. “The speed and scale of change may outpace their ability to adapt.”

Discover more amazing wildlife stories from around the world

Top image: a great white shark. Credit: Getty

Scientists in China have unveiled a supercomputer built on brain-like architecture — specifically, that of a monkey.

Called Darwin Monkey or “Wukong”, the system features over 2 billion artificial neurons and more than 100 billion synapses, putting it roughly on par with the neural structure of a macaque.

The likelihood of such downpours would increase by up to 40% if the world warms by more than two degrees above pre-industrial levels, scientists said.

Extreme rain conditions similar to those linked to a fatal train derailment five years ago will become more common due to climate change, according to a new study.

Researchers found that intense deluges like one that preceded a derailment at Carmont near Stonehaven, Aberdeenshire, which claimed three lives in August 2020 are between 15% and 20% more likely in future due to the warming environment.

Experts said that should the world warm by more than two degrees above pre-industrial levels, the likelihood of such downpours would increase by 30 to 40%.

Train driver Brett McCullough, 45, conductor Donald Dinnie, 58, and passenger Christopher Stuchbury, 62, died following the derailment on August 12 2020 while six people were injured.

A criminal prosecution saw Network Rail fined £6.7 million in 2023 after it admitted health and safety failings over the crash, which happened on a day of torrential rainfall.

Climate scientists from the University of Edinburgh’s school of geosciences and school of physics and astronomy and the Met Office examined data from weather radars and climate models to calculate the extent to which global warming changed the intensity, frequency and distribution of rainfall at and near Carmont.

The team discovered that on the morning of August 12 2020, a huge burst of rainfall lasting for around four hours landed close to the crash site, followed by another severe downpour just one hour prior to the derailment on the Aberdeen to Glasgow line.

A Rail Accident Investigation Branch (RAIB) report published in March 2022 found errors in the construction of a drainage system installed by Carillion meant it was unable to cope with heavy rain which fell in the area on the morning of the crash.

Carillion went into compulsory liquidation in January 2018.

Professor Simon Tett, chairman in earth system dynamics, school of geosciences, University of Edinburgh, said: “Climate change is not only increasing the risk of heatwaves but also extreme rainfall.

“Scotland would be wise to prepare for heavier summer deluges as the climate continues to warm.”

The researchers found more frequent extreme rainfalls will increase the risk of flash floods in urban areas and cause more damage to infrastructure.

Previous research has shown the earth’s atmosphere and oceans are currently 1 to 1.5 degrees warmer compared to conditions in the late nineteenth century.

Scientists said a warmer atmosphere holds more water and extreme rain happens when all the water in the atmosphere falls out.

The paper, published in the journal Environmental Research Climate, was funded by the University of Edinburgh and the Met Office Hadley centre climate programme, funded by the UK Department of Science, Innovation and Technology (DSIT).

A fatal accident inquiry is to be held into the train derailment.

Network Rail previously said it is determined to build on the “significant changes” it has made since the incident, which have “helped us to manage the risk of severe weather to the network”, and it has invested millions to improve the resilience of the railway.

Cosmic dust particles that give birth to planets around young stars have for the first time been found forming — the James Webb Space Telescope has witnessed the creation of these tiny planetary building blocks around a dead star.

“This discovery is a big step forward in understanding how the basic materials of planets come together,” Mikako Matsuura of Cardiff University, who led the new James Webb Space Telescope (JWST) observations, said in a statement.

Discovery reveals a previously undocumented 30-million-year gap in dragonfly evolution.

For the first time in Canadian paleontology, a fossilized dragonfly wing from the Cretaceous period has been identified as a new species. Found in Alberta’s Dinosaur Provincial Park, it represents the earliest dragonfly fossil ever recovered from Canada’s dinosaur-era rock layers. The discovery, made by a McGill University research team, helps bridge a 30-million-year gap in the evolutionary record of dragonflies.

The specimen was unearthed in 2023 by a McGill undergraduate student during a vertebrate paleontology field course directed by Prof. Hans Larsson.

A surprising fossil discovery

“We were excavating an area where many leaf fossils had been found by cracking rocks,” said André Mueller, lead author of the study and a Master’s student in Larsson’s lab in McGill’s Department of Biology. “When the partial wing was uncovered, we were taken by surprise as we were not expecting to find any insects there.”

The team named the new species Cordualadensa acorni. Because of its remarkable distinction and unique anatomy, they even created a new family – Cordualadensidae – to classify it. They chose “acorni” for the species name to honor of University of Alberta lecturer John Acorn, entomologist and science communicator at the University of Alberta who has promoted the natural history of Alberta for decades, including with the TV show “Acorn, the Nature Nut.”

Adding to Alberta’s fossil record

“This is the first ever dinosaur-aged dragonfly found in Canada,” said Mueller. “Its wingspan was about the width of a human hand, and while small, it would have been an important part of the Cretaceous ecosystem—a tasty raptor snack, no doubt.”

The fossil was uncovered in the 75-million-year-old Dinosaur Park Formation, a site internationally recognized for its exceptional abundance of dinosaur remains. Until this discovery, however, evidence of insects in the formation was almost entirely absent. The only insect previously reported was a tiny aphid preserved in amber.

“This discovery not only doubles our knowledge of insects from the park, but also represents a completely unknown preservation method, impression fossils, for insect fossils in the area,” said Alexandre Demers-Potvin, a former Larsson PhD student and now a postdoctoral fellow in McGill’s Department of Biomedical Engineering. “We’ve now started finding more insect fossils by expanding where and how we search. The diversity of insect life during this time was likely much greater than we thought.”

The new fossil helps fill a major 30-million-year-old evolutionary gap. It’s the first known North American member of a large group of dragonflies called Cavilabiata. “The wing anatomy tells us this species was adapted for gliding; a trait associated with migratory dragonflies today and possibly a key to their success,” said Larsson. “This specimen also provides insight into what life was like in Canada 75 million years ago, adding an important new missing piece of the ecological puzzle of one of the most diverse dinosaur-bearing sites in the world.”

Reference: “New family of fossil dragonfly (Odonata, Cavilabiata) from the late Cretaceous (Campanian) Dinosaur Park Formation, Alberta, Canada” by André S. Mueller, Alexandre V. Demers-Potvin and Hans C.E. Larsson, 1 August 2025, Canadian Journal of Earth Sciences.
DOI: 10.1139/cjes-2024-0162

Funding for fieldwork was supported by an NSERC Discovery Grant (RGPIN/04370-2022) awarded to HCEL. This research was performed using the infrastructure of the Adaptable Earth Observation System, funded by the Quebec government, McGill University, and the Canadian Foundation of Innovation project 36146.

Never miss a breakthrough: Join the SciTechDaily newsletter.

Fossils reveal extreme sexual dimorphism in early hominins. The findings reshape views of their social behavior.

A recent study has revealed that males of some of humanity’s earliest ancestors were much larger than their female counterparts. This marked difference in body size, found in both Australopithecus afarensis (the East African species that includes the well-known fossil “Lucy”) and A. africanus (a closely related species from southern Africa), indicates that these early hominins may have lived in societies where strong competition among males contributed to the pronounced size gap between the sexes.

The research, led by Adam D. Gordon, an anthropologist at the University at Albany, was published in the July issue of the American Journal of Biological Anthropology. By applying a new method that addresses the challenges posed by incomplete fossil evidence, the study demonstrates that both A. afarensis and A. africanus showed greater sexual dimorphism than modern humans — and in some cases, even exceeded the differences seen in gorillas.

“These weren’t modest differences,” said Gordon, an associate professor in the College of Arts and Sciences. “In the case of A. afarensis, males were dramatically larger than females — possibly more so than in any living great ape. And although both of these extinct hominin species exhibited greater sex-specific size differences than modern humans do, they were also more different from each other in this respect than living ape species are, suggesting a greater diversity of evolutionary pressures acting on these closely-related species than we had previously appreciated.”

Interpreting fossils with new methods

The findings provide fresh insight into how the fossil record is interpreted. Previous research had produced conflicting views on dimorphism in A. afarensis, with some studies arguing it was comparable to the relatively modest differences seen in modern humans. Until now, however, scientists had not been able to directly compare fossil species, since earlier analyses were restricted by fragmentary skeletal remains and lacked the statistical strength needed to identify meaningful distinctions.

“This analysis overcomes these issues by using an iterative resampling method that mimics the missing data structure in both fossil species when sampling from skeletal material of living species, allowing the inclusion of multiple fossil individuals even when those individual specimens are fragmentary,” said Gordon. “This study provides strong evidence that sex-specific evolutionary pressures — likely involving both male competition for mates and resource stress acting more intensely on female size due to the metabolic constraints of pregnancy and lactation — played a larger role in early hominin evolution than previously believed.”

Why Sexual Size Dimorphism Matters

Sexual size dimorphism (SSD) is more than a simple physical difference between males and females — it also reflects patterns of behavior and evolutionary strategy. According to sexual selection theory, high SSD in living primates is usually linked to intense competition between males and social systems where a small number of large males control reproductive access to multiple females. By contrast, low SSD can occur across many species but is most often associated with pair-bonded social systems and reduced competition for mates. In modern human populations, SSD is generally low to moderate: men are slightly larger on average, though there is substantial overlap in body size between the sexes.

Gordon’s earlier research also indicates that high SSD can emerge under conditions of severe resource stress. When food is scarce, smaller but healthy females are often able to meet their nutritional needs and store enough energy for reproduction more effectively than larger females. This can result in greater reproductive success for smaller-bodied females and, over time, a widening size difference between males and females.

The pronounced SSD found in both Australopithecus species suggests strong male competition, much like what is observed in chimpanzees or gorillas. However, the differences in dimorphism between the two species may reflect variations in the intensity of sexual selection pressures or in the degree of environmental stress (for example, differences in the length of dry seasons and their impact on female body size).

Ultimately, the high SSD observed in these fossil hominins stands in contrast to the more balanced size patterns of modern humans. It points to a different model of early hominin life — one in which large body size may have given males a competitive advantage in reproduction, while smaller size in females may have been favored for its energetic efficiency.

How the Research Was Conducted

Fossil data are often fragmentary, and determining the sex of ancient individuals is nearly impossible. To work around this, Gordon used a geometric mean method that allows for size estimation from multiple skeletal elements — including the humerus, femur, tibia, and others. He then applied resampling techniques to simulate thousands of comparisons between fossil hominins and modern primates, ensuring that the statistical models mirrored the incomplete and uneven nature of real fossil samples.

Data from modern gorillas, chimpanzees, and humans with known sex and complete skeletons were used to build a comparative framework.

Unlike past studies, which sometimes interpreted weak or inconclusive statistical results as evidence of similarity, Gordon’s methods revealed clear and significant differences even when using relatively small fossil samples.

To rule out the possibility that body size changes in A. afarensis reflected evolutionary trends rather than sex differences, Gordon also tested for chronological trends across a 300,000-year span of fossils from the Hadar Formation in Ethiopia.

His analysis found no significant size increase or decrease over time, indicating that the observed variation is best explained by differences between males and females — not by evolutionary drift or long-term increases in average size.

Rewriting History

The implications of Gordon’s findings are wide-ranging. Australopithecus afarensis, which lived between 3.9 and 2.9 million years ago, is widely regarded as either a direct ancestor of modern humans or a species very closely-related to a direct ancestor.

Yet, its high degree of sexual dimorphism suggests that early hominins may have lived in social systems that were far more hierarchical and competitive than once thought.

Meanwhile, the less dimorphic A. africanus — which overlapped in time with A. afarensis but first shows up and last appears in the fossil record slightly later, between roughly 3.3 and 2.1 million years ago — may represent a different evolutionary branch on the hominin tree, or perhaps a transitional stage in the development of more human-like social behavior.

“We typically place these early hominins together in a single group called the gracile australopiths, a group of species that are thought to have interacted with their physical and social environments in very similar ways,” Gordon said. “And while that’s true to a certain extent — the evidence suggests that both these species may have had social organizations more like gorillas than modern people — the significant difference in the amount of dimorphism in these two extinct species suggests that these closely-related hominin species were subject to selection pressures more distinct than the selection pressures applied to any pair of similarly closely-related living ape species, highlighting the diversity of ways that our extinct ancestors and close relatives interacted with the world.”

Reference: “Sexual Size Dimorphism in Australopithecus: Postcranial Dimorphism Differs Significantly Among Australopithecus afarensis, A. africanus, and Modern Humans Despite Low-Power Resampling Analyses” by Adam D. Gordon, 11 July 2025, American Journal of Biological Anthropology.
DOI: 10.1002/ajpa.70093

Never miss a breakthrough: Join the SciTechDaily newsletter.