A new face for 'Little Foot,' the most complete Australopithecus skeleton to date

 What did the face of our ancestors look like three million years ago? Our international team has answered this question by virtually reconstructing the facial fragments of Little Foot, the most complete Australopithecus skeleton yet discovered. This reconstruction sheds light on the influence of the environment on how our face evolved. Our findings have just been published in the Comptes Rendus Palevol journal, and the new 3D face of Little Foot can be explored online on the MorphoSource platform.

The search for human origins has never been more fruitful, with fossil discoveries pushing back the appearance of the earliest humans (members of the genus Homo) to 2.8 million years ago, and the development of cutting-edge methods for analyzing these remains, such as recovering genetic information from fossils over two million years old.

Yet, while our knowledge of extinct human species grows with each discovery, the story of our ancestors before the first humans appeared remains blurry. It is during this pivotal period that the traits defining our humanity emerged, enabling our genus' evolutionary success.

Although the identity of our direct pre-Homo ancestor is far from resolved, one fossil group plays a central role in this search: Australopithecus. This genus, to which the famous "Lucy" belongs (discovered 50 years ago in Ethiopia), inhabited much of Africa and survived for over two million years. Australopithecus is known from many fossil remains, but often these are highly fragmentary, isolated, and have sometimes been distorted over the millions of years they have been buried. Notably, only a handful of skulls preserve nearly the entire face, a part of our anatomy that has profoundly shaped who we are today.

Through digestive, visual, respiratory, olfactory and non-verbal communication systems, the face is at the heart of interactions between individuals and their physical and social environments.

Significant changes occurred in the facial region throughout human evolution, with most structures generally becoming less robust. However, the factors driving these changes remain unclear. Were they caused by shifts in diet, social behavior, or both? Only the discovery of more complete skulls can clarify this debate, and this is why the skull of Little Foot is crucial.

The 'Cradle of Humankind'

South Africa has been and remains a crucial region for research into human origins. A century ago, the iconic "Taung Child" was published in Nature as a representative of a new African branch of humanity, Australopithecus. While scientific attention had previously focused on Eurasia, this discovery inspired decades of exploration and major finds across Africa.

In particular, South Africa saw a proliferation of paleontological sites in a region now UNESCO-listed and known as the "Cradle of Humankind." Among these, Sterkfontein has proven exceptionally rich in fossils, many attributed to the hominin genus Australopithecus, and including numerous remarkably preserved specimens.

But it was in 1994 and 1997 that Sterkfontein yielded its most spectacular find: the skeleton of Little Foot, over 90% complete, and the oldest human ancestor found in southern Africa. To date, it is the most complete Australopithecus skeleton ever discovered, far surpassing Lucy, of which only 40% of the anatomy is preserved.

Our team has been studying this skeleton since its complete excavation concluded in 2017. The skull, in particular, has been the focus of our attention, as it is relatively complete, preserving all parts of the head—the cranium and mandible. However, 3.7 million years of burial underground have fragmented and displaced parts of its fossilized face. This process is especially visible in the forehead and eye sockets (orbits), making it impossible to quantitatively analyze these informative areas. Given the exceptional and unique nature of this fossil, we decided to harness the most recent technological advances in imaging to restore the face of Little Foot.

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How an underground fungal map of the world's oldest, slowest-growing rainforest trees can boost Earth's resilience

The temperate rainforests of the Chilean Coast Range are home to a spectacular array of life: iridescent blue lizards, tiny wild cats called kodkods, and curly vines of waxy red bellflowers. Towering over this biodiversity are endangered ancient conifers, called alerce (Fitzroya cupressoides), whose trunks can get as wide as shipping containers. These alerce forests show exceptionally low mortality and grow slowly—one tree lived more than 3,600 years.

Ancient giants and hidden fungal worlds

New research published today in the journal Biodiversity and Conservation makes clear that these massive trees also shelter an enormous assortment of organisms belowground that have helped the forest, a massive carbon sink, survive and adapt over millennia.

One large individual—estimated to be over 2,400 years old—hosts more than twice the underground fungal diversity of smaller, younger trees of the same species. The bigger the alerce, the greater the variety of fungi that scientists found hidden in the soil, including hundreds of species that are likely new to science.

The discovery is important because these soil fungi, known as mycorrhizal fungi, help forests function. They funnel water and nutrients to trees through their root systems and assist plants in fighting stressors like drought and pathogens. The fungi also work as conduits for drawing carbon into soil. Globally, arbuscular mycorrhizal fungal communities—the type associated with alerce trees—move roughly one billion tons of carbon per year into Earth's soils.

The scientists determined that protecting and conserving old trees will protect hundreds, if not thousands, of mycorrhizal and other fungal species that inhabit soils around these giants, each of which play a role we might not fully understand in keeping these forests healthy and resilient.

"Not all trees are the same and if you remove a millennial tree, the impact on all the other species is going to be bigger than if you remove a smaller one," said the study's co-lead author Dr. Camille Truong, a research scientist with the Royal Botanic Gardens Victoria and the University of Melbourne in Australia, and a mycorrhizal ecologist at the Society for the Protection of Underground Networks (SPUN).

Taking out one huge tree, in other words, can destroy an entire underground community of forest helpers that took thousands of years to assemble.

And "all that diversity means resilience," said Truong's co-lead author Dr. Adriana Corrales, Field Science Lead at SPUN.

The study grew out of an expedition to Alerce Costero National Park in Chile in 2022 by scientists with Universidad Santo Tomás, Universidad Austral de Chile, Universidad de La Frontera (Chile), Fungi Foundation and SPUN, a non-profit dedicated to mapping and conserving mycorrhizal fungal networks across the planet. SPUN was co-founded by evolutionary biologist Dr. Toby Kiers. Kiers was recently awarded the Tyler Prize (often called the "Nobel for the Environment") for her work detailing the importance of underground fungal networks in unique ecosystems all over the world.

Alerce, sometimes called Patagonian cypress trees or lawal in Mapudungun, the language of the local Indigenous Mapuche people, are the second-longest-lived tree species on Earth after bristlecone pines. They are cousins to North America's redwoods but live even longer. Alerce forests are found along the coasts of southern Chile and in the foothills of the Andes, but their range shrunk roughly in half over centuries as trees were cut for their durable light-weight wood or burned to make way for pasture. In fact, the oldest known individual, which lived 3,622 years, was regrettably felled in 1976.

And the trees are still threatened by land-use shifts, climate change, and major infrastructure projects. One proposed road would run just a few hundred meters from alerce forests, increasing the threat of fires, tourist pressure, and invasive species.

So, wanting to understand what was at risk and how best to protect remaining stands, Kiers and other researchers took soil samples from below 31 individual trees, ranging from saplings to the "Alerce Abuelo," which is at least 2,400 years old, with a trunk that stretches more than 4.5 meters in diameter. They measured the size and biomass of each tree, later extracted DNA from the samples, and used genetic markers to identify fungi.

Truong then analyzed the soil data alongside the tree measurements and found that the fungal diversity in ground below the largest, oldest specimen was more than 2.25 times higher than in any other sample. Those soil samples also included more than 300 species of fungi unique to this tree.

This matters because losing soil fungal diversity "can trigger cascading, negative effects on multiple ecosystem functions," the researchers wrote in their paper. These huge millennial trees serve as an "umbrella" that protects soil fungal diversity. Protecting that diversity can help keep other plants in the forest healthy.

Their paper is titled "Large-diameter trees disproportionately contribute to soil fungal diversity in a coniferous forest with one of oldest living trees on Earth."

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Large land predators were hunting big plant-eaters more than 280 million years ago, study finds

 A study examining fossil evidence shows that large land predators were already hunting big plant-eating animals more than 280 million years ago. University of Toronto Mississauga researchers Jordan M. Young, Tea Maho, and Robert Reisz studied bite marks on the skeletons of three young herbivores from the early Permian of Texas, revealing feeding patterns from multiple predators and a glimpse into how animals hunted and interacted with each other.

"This discovery shows predator-prey hierarchies were formed earlier than previously expected," said Professor Reisz, co-author of the work titled "Earliest direct evidence of trophic interactions between terrestrial apex predators and large herbivores."

"While these interactions are well known in the 'Age of Reptiles,' there has been little information available in the Paleozoic Era, when terrestrial vertebrates first evolved into large apex predators and herbivores," added Reisz.

Master's student Young, lead author of the study published in the journal Scientific Reports, highlights how the size, shape, and texturing of the tooth markings reveals who the potential predators are during this time period.

"The puncturing, pitting, scoring and furrowing marks on the skeletons of these three young plant-eating animals are indicative of large predators found on this site and in nearby areas, including varanopid (Varanops) and sphenacodontid (Dimetrodon) synapsids," said Young.

He added that scavengers and small arthropods also joined in on the Paleozoic feast. The skeletons showed arthropod borings on areas where cartilaginous bone ends would be on the carcass.

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Cellular switch casts light on why humans are active in the day

 Early mammalian ancestors were nocturnal, sleeping during the day while the dinosaurs dominated the land. However, some mammalian lineages, including human ancestors, independently transitioned to diurnality (active during the day). Scientists have now discovered why humans are not nocturnal. A new study published in Science reveals that the answer is in the genes.

How the transition happened has been a long-standing puzzle because the brain's master circadian clock works similarly in both nocturnal and diurnal species.

Cells, signals and daily rhythms

The new research shows that the crucial difference lies not in the brain's wiring but in how individual cells respond to signals in their microenvironment. Over each 24-hour cycle, small shifts in the body's internal conditions like temperature or fluid balance subtly influence the chemical reactions inside cells.

These physical cues adjust basic cell processes, such as how proteins are made and modified, core processes that help determine when a cell "expects" day or night.

The team, led by Andrew Beale and John O'Neill at the Medical Research Council (MRC) Laboratory of Molecular Biology, studied cells from both diurnal mammals (including humans) and nocturnal mammals (such as mice). When exposed to daily temperature cycles, diurnal mammal cells and nocturnal mammal cells shifted their internal circadian clocks in opposite directions.

Key pathways and evolutionary changes

These opposite responses echo the animals' natural activity patterns. The researchers found that these contrasting reactions involve two major cellular signaling pathways:

• mechanistic target of rapamycin (mTOR)
• with-no-lysine (WNK)

These pathways help cells detect nutrients and regulate fundamental biochemical reactions.

Temperature changes caused human and mouse cells to alter protein synthesis and activities in different, and sometimes opposite, ways. This points to differences in how sensitive their mTOR and WNK pathways are.

Aided by Matthew Christmas, based at the Science for Life Laboratory at Uppsala University, Sweden, the group looked to contextualize this finding against the backdrop of mammalian evolution.

After analyzing genetic data across several species, Christmas found that genes within the mTOR and WNK networks have evolved unusually quickly in diurnal mammals. This suggests that the shift from nighttime to daytime activity required evolutionary tuning of basic cellular function at the genetic level.

Switching mice and broader implications

This discovery suggested that modification of their activity could enable nocturnal mammals to switch to more diurnal activity.

To explore this, the group gently altered mTOR activity in nocturnal mice using diet-based treatments. Once mTOR function was reduced, the mice began behaving more like diurnal animals, shifting their active hours into the daytime.

This underlined that changes in cellular pathways can influence when an animal is active, functioning like a day or night switch.

O'Neill explained, "Understanding why humans are diurnal while many other mammals are not shines new light on our circadian rhythm, part of our biology that is important for long-term health. Our research leverages an evolutionary approach to reveal the fine details of how fundamental cellular pathways sense and respond to daily environmental rhythms. These differ between species in ways we simply hadn't appreciated before."

The findings also highlight how climate change could impact mammal behavior as they adapt to transforming conditions.

Beale added, "As the atmosphere warms up, the current relationship between the external environment and food availability is rapidly changing. As a result, many mammals may shift the time of day they are active. This could have wide-ranging and detrimental effects on whole ecosystems."

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Fossil amber reveals the secret lives of Cretaceous ants

Tiny insects trapped in amber could tell us a great deal about their roles in past ecosystems: pollinators, parasites, predators, and prey. But how many of the insects preserved alongside each other reflect interactions during life, and how many are just unlucky coincidences?

Scientists in Spain scrutinized six key samples which preserve now-extinct insects unusually well, to try to learn more about the ants that lived at the same time as the dinosaurs.

"Amber inclusions are representative of possible interactions between different organisms shaping the environment," explained Dr. Jose de la Fuente of the Institute for Game and Wildlife Research, Spain, lead author of the article in Frontiers in Ecology and Evolution.

"The identification and morphological characterization of fossil ants in amber with other inclusions of insects provides a snapshot of life on Earth millions of years ago."

Snapshots of the past

The scientists looked at six different pieces of amber which include multiple different organisms of different species, a rare phenomenon called syninclusion. They chose these pieces of amber because they include ants, which are considered particularly important to ecosystems.

The earliest ants, which were first found in the Upper Cretaceous, are known as Stem ants and didn't leave modern descendants; all ants alive today evolved from Crown ants. Both species are found in the six pieces of amber studied by the scientists, as well as Hell ants, which evolved from Stem ants.

The study sample included four pieces of Cretaceous amber (around 99 million years old), one piece of Eocene amber (from approximately 56–34 million years ago), and one piece of Oligocene amber (from approximately 34–23 million years ago). The scientists used powerful microscopes to examine the amber, identify the different species found inside, and measure the distance between ants and other species.

In three of the six pieces of amber, the scientists found ants in close proximity to mites. In the first piece of amber, Case 1, the scientists found a Crown ant, wasp, and two mites so close to the ant that they may have been traveling on it. Similarly, Case 4 contained a Stem ant and a mite, about four millimeters apart. Case 5 also contained three different species of ant close to a mite and some termites, as well as poorly-preserved mosquitoes and a winged insect.

In Case 6 the scientists found a Stem ant alongside a probable parasitic wasp and a spider. The ant seems to have been feeding on something. It is resting against another insect inclusion, which could be a worm or a larva, but as there's no indication that the two were interacting, the scientists think this was a coincidence.

Finally, Case 2 contained a Stem ant and a spider, while Case 3 contained a Hell ant, a snail, a millipede, and some unidentifiable insects.

"The closest ant syninclusions are more likely to reflect behavior and interactions between these organisms," said de la Fuente. "The proposed ant-mite interactions in Case 4 may reflect two possible scenarios. First, a commensal specialized temporal relationship where mites attach to ants for free ride dispersal to new habitats. Second, a parasitism when mites feed on the ant host during transport."

Although pieces of amber that contain ants are rare, and pieces of amber that contain multiple species are rarer, there is some published evidence that points to interactions between mites and ants, sometimes mutually beneficial.

Future research could help clarify this by using micro-CT scanning to look for attachment structures on mites which would have allowed them to clamber onboard ants for travel purposes. Similarly, the spider in Case 6 is a species which could camouflage itself as an ant and might have benefited from proximity to real ants.

The scientists say that smaller distances between insects in amber are more likely to reflect interactions during life, such as those between ants and mites. But they call for caution around inferred interactions: insects that aren't in contact could just be insects that got stuck in the same resin.

"To improve the analysis of interactions between different organisms in fossil amber inclusions, future research should use advanced imaging techniques," said de la Fuente. "Nevertheless, these results provide evidence of insect behavior and ecological habits."

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Tackling the global tuberculosis crisis: An emerging class of antibiotics offers hope

Researchers from the University of Sydney and the Centenary Institute have discovered how a promising class of experimental antibiotics disrupts the bacterium that causes tuberculosis (TB), paving the way for urgently needed new treatments.

Globally, TB remains a major health crisis, claiming around 1.2 million lives each year and ranking among the world's deadliest infectious diseases. The rise of drug-resistant strains, including in the Asia-Pacific region, has made the search for new treatment strategies increasingly urgent.

Investigating three experimental compounds

In a study published in Nature Communications, the team investigated how three naturally occurring antibiotic compounds—ecumicin, ilamycin and cyclomarin—act on a vital protein degradation machine inside Mycobacterium tuberculosis, the bacterium that causes TB.

The molecular machine, known as the ClpC1–ClpP1P2 complex, allows the bacterium to break down damaged or unneeded proteins, helping it to survive stress and maintain essential functions. Without it, the TB bacterium can't survive, making it an attractive drug target.

How the compounds disrupt TB bacteria

Co-senior author Professor Warwick Britton, Laboratory Head in the Centenary Institute's Center for Infection & Immunity, said the study uncovers surprising complexity in how the three antibiotic compounds affect this system.

"TB bacteria depend on this recycling system to stay alive, particularly under stressful conditions inside the human body," Professor Britton said.

"Our findings show these compounds don't simply shut the system down. Instead, each one interferes with it in a different way, triggering widespread imbalances across the whole bacterium. This disruption weakens its ability to function and survive."

Mapping protein-level changes inside bacteria

First author Isabel Barter, Ph.D. candidate at the University of Sydney, who also conducted part of the study at the Centenary Institute, said they had measured changes across over 3,000 proteins in Mycobacterium tuberculosis.

"By tracking changes across most of the bacterium's protein network, we were able to see how disrupting a single essential complex can reshape the bacterium's entire internal protein landscape," she said.

"This deeper understanding gives us valuable insight into how we might refine these compounds and design more precise and effective anti-TB treatments."

Implications for next-generation TB drugs

Co-senior author Professor Richard Payne from the University of Sydney said the ClpC1–ClpP1P2 complex represents a promising but still relatively underexplored drug target.

"Our study highlights the potential of directly targeting this protein degradation system," Professor Payne said. "By understanding how different compounds interact with it and disrupt its normal function, we can more strategically design the next-generation of anti-TB drugs."

The team believes the study marks an important step towards expanding the pipeline of potential new treatment options for TB, including drug-resistant forms.

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Bacterial pathogens build antibiotic-resistant 'bunkers' using filament scaffolds

Researchers have discovered and characterized at the atomic level a mechanism that enables bacterial pathogens—including hospital bacteria Acinetobacter baumannii and Pseudomonas aeruginosa—to assemble antibiotic-resistant three-dimensional (3D) biofilms. These findings open a new avenue for developing therapies against multidrug-resistant bacterial infections by targeting the biofilm assembly. The work is published in the journal Nature Communications.

Many pathogenic bacteria form 3D biofilms to protect themselves from the immune system, antibiotic treatments, and drying on environmental surfaces. Some of the most problematic hospital bacteria, such as multidrug-resistant A. baumannii and P. aeruginosa, use specialized hair-like filaments called adhesive pili to attach to tissues or abiotic surfaces. After attaching, the bacteria then grow into thick 3D biofilms consisting of multiple layers of bacteria. This process is also mediated by adhesive pili, but until now it has been unclear how they prevent the growing 3D biofilm from falling apart.

Using a combination of advanced electron microscopy methods, the researchers at the MediCity Research Laboratory of the University of Turku in Finland, led by S. Jusélius Senior Researcher Anton Zavialov, discovered that adhesive Csu pili from neighboring A. baumannii bacteria attach to each other in an antiparallel manner. These pili rapidly assemble into flat sheets that link bacteria together and shield them from hostile environments.

"Impressively, Csu pili can self-assemble into huge, complex networks connecting hundreds of bacterial cells," says Dr. Zavialov.

The team demonstrated that Csu pili can form at least two types of flat structures and resolved them at a near-atomic resolution.

"Cryo-electron microscopy methods are developing very rapidly. To obtain the first model, I initially developed a manual approach, and only later did we apply computational tools to solve these exceptionally large assemblies in 3D," explains first author Doctoral Researcher Henri Malmi.

The researchers also found that the pilus network becomes embedded in a less defined matrix composed of polysaccharides and DNA secreted by the bacteria.

"This final structure somewhat resembles reinforced concrete: the pili act like steel bars, while polysaccharides and DNA form the concrete. In this way, the bacteria effectively hide in a bunker," adds Dr. Zavialov.

The team is now focused on developing inhibitors that target the connections between pili. Such inhibitors could be used in combination therapies to prevent 3D biofilm assembly and help antibiotics eliminate the pathogens more effectively.

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