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Cheetah runs faster because of its physical ‘sweet spot’

“The key to our model is understanding that maximum running speed is constrained both by how fast muscles contract, as well as by how much they can shorten during a contraction,” says a scientist.

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Image of a cheetah. Credit: Sammy Wong / Unsplash

It’s common knowledge that medium-sized animals like cheetahs, tigers or even dogs are known to be faster than bigger animals like elephants, or even smaller ants. However, there are exceptions.

An interdisciplinary team of scientists provide a biomechanical explanation – combining biology with mechanics (as in physics). Apparently, their findings can inform robot designs, inspired by animal biomechanics. 

“The key to our model is understanding that maximum running speed is constrained both by how fast muscles contract, as well as by how much they can shorten during a contraction,” said Professor Christofer Clemente, a biomechanics researcher from University of the Sunshine Coast and The University of Queensland, in Australia, in a press release

Their paper was published in Nature Communications

Their model uses two physical constraints. The first is by kinetic energy capacity, dictated by how fast do the muscles contract to generate forces much bigger than its own body weight. The second limit is by work capacity, dictated by how far the muscle contracts. 

“For large animals like rhinos or elephants, running might feel like lifting an enormous weight, because their muscles are relatively weaker and gravity demands a larger cost,” said Peter Bishop, a biomechanics researcher at Harvard University, US. “As a result of both, animals eventually have to slow down as they get bigger.”

Apparently, this model offers an explanation as to why crocodiles, despite being medium-sized in a sense, aren’t so quick. 

“One possible explanation for this may be that limb muscle is a smaller percentage of reptiles’ bodies, by weight, meaning that they hit the work limit at a smaller body weight, and thus have to remain small to move quickly,” said Taylor Dick, a biomechanics researcher at The University of Queensland, Australia. 

Cheetahs, in contrast, which can attain a maximum speed of 65 km/hr, hits the physical sweet spot of 50 kg, when the two constraints set by kinetic energy and work capacity are equal. 

The team tested their hypothesis against data gathered from 400 species of various sizes and body weights, including mites weighing just 0.1 mg, to six-tonne elephants. 

The model doesn’t just offer explanations to known facts about speeds in present animals. It can be extrapolated to extinct animals such as dinosaurs, although with some caveats. 

It predicts land animals heavier than 40 tonnes would be immobilized. The heaviest land animal, the African elephant, weighs around 6.6 tonnes. Although it was known that land-based dinosaurs such as the Patagotitan, possibly exceeded even 40 tonnes.

And this is where researchers erred on the side of caution, saying that their model was based on known anatomies of non-extinct animals. In fact, extinct giants might have evolved unique muscular anatomies, thus warranting more study. 

This research was funded by the Australian Research Council, the international Human Frontier Science Program, and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program.

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The Sciences

Scientists Crack the Genetic Code Behind Seedless Grapes

Indian researchers reveal how genetic mutations create the popular seedless varieties consumers love, opening doors to better grape breeding

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Scientists have finally unlocked the mystery behind one of our favourite fruit features – seedless grapes. A study by Indian researchers has decoded the genetic mechanisms that create seedless grapes, potentially revolutionizing how we breed these popular fruits.

The Science Behind Seedless Success

The research, led by Dr. Ravindra Patil at the Agharkar Research Institute (ARI) in Pune, India, examined why some grapes develop without seeds while others don’t. Published in BMC Plant Biology, the study focused on a seedless mutant derived from the high-yielding grape variety ARI-516.

Using advanced genomic tools, the team discovered that pollen sterility is the key culprit behind seedlessness. The seedless grapes showed:

  • Abnormal pollen structure with very low viability
  • Complete inability of pollen grains to germinate
  • Smaller female reproductive structures compared to seeded varieties
  • Disrupted fertilization processes leading to seedless berry formation

Genetic Detective Work

The researchers employed cutting-edge techniques to crack the code:

Transcriptomic Analysis: RNA sequencing revealed that genes crucial for pollen development, cell division, and hormone signaling were significantly “switched off” in seedless varieties.

Whole-Genome Sequencing: This identified multiple insertion-deletion mutations (InDels) in genes responsible for pollen development, essentially breaking the normal seed formation process.

The evidence points to parthenocarpy – a natural process where fruits develop without fertilization due to reproductive defects.

Why This Matters

This discovery isn’t just academic curiosity. Seedless grapes represent a massive global market, with consumers strongly preferring them for:

  • Fresh consumption
  • Raisins and dried products
  • Juices and processed foods

The research provides molecular markers that grape breeders can use to:

  • Develop new seedless varieties faster
  • Improve fruit quality and yield
  • Create grapes better adapted to different climates

Impact on Agriculture

Dr. Patil’s team has conducted one of the most comprehensive studies on grape seedlessness using modern genomic tools. This breakthrough could significantly accelerate breeding programs worldwide, benefiting both grape growers and consumers who enjoy these convenient, seed-free fruits.

The study represents a perfect example of how understanding nature’s genetic mechanisms can lead to practical agricultural improvements, potentially transforming grape cultivation and meeting growing global demand for high-quality seedless varieties.

The research was conducted in collaboration with Savitribai Phule Pune University and represents a significant advancement in horticultural genomics.

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Climate

Study Finds Warming Could Slightly Boost Atmosphere’s Methane-Cleaning Capacity

New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.

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New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.
Image credit: MIT News; iStock

New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.

A new study by researchers at the Massachusetts Institute of Technology (MIT) finds that rising global temperatures could slightly increase the atmosphere’s ability to break down methane, one of the most potent greenhouse gases.

Methane is a major driver of global warming, second only to carbon dioxide. However, it does not persist as long in the atmosphere due to the presence of hydroxyl radicals—highly reactive molecules often described as the “atmosphere’s detergent” for their role in breaking down pollutants.

Balancing Effects of Water Vapour and Natural Emissions

The MIT team developed a new atmospheric model to understand how hydroxyl radical (OH) levels may respond to warming temperatures. Their findings reveal a complex balance of competing effects.

As global temperatures rise, atmospheric water vapour is expected to increase, boosting OH levels by about 9%. However, higher temperatures will also lead to increased emissions of natural gases from plants—known as biogenic volatile organic compounds—which can reduce OH levels by approximately 6%.

The net effect, according to the study, is a modest increase of around 3% in the atmosphere’s capacity to break down methane under a 2°C warming scenario.

Why Hydroxyl Radicals Matter

Hydroxyl radicals play a critical role in regulating atmospheric chemistry. They react with methane and other gases, breaking them down into less harmful compounds.

“About 90 percent of the methane that’s removed from the atmosphere is due to the reaction with OH,” said study author Qindan Zhu in a statement.

Beyond methane, OH also helps remove air pollutants and gases that affect public health, including ozone.

“There’s a whole range of environmental reasons why we want to understand what’s going on with this molecule,” said Arlene Fiore, a professor at MIT.

New Model Offers Deeper Insights

To conduct the study, researchers developed a model called “AquaChem,” which simulates atmospheric chemistry under different climate scenarios. The model builds on simplified “aquaplanet” systems, allowing scientists to isolate atmospheric processes without the complexity of land and ice interactions.

Using this model, the team compared current climate conditions with a scenario in which global temperatures rise by 2°C—widely considered a likely outcome without significant emissions reductions.

Uncertainty Around Natural Emissions

Despite the findings, researchers caution that there is still significant uncertainty—particularly regarding how plant emissions will respond to climate change.

Biogenic emissions, such as isoprene released by trees, appear to play a major role in influencing OH levels but remain difficult to predict accurately.

Future research will aim to refine these estimates and better understand how different climate scenarios could affect atmospheric chemistry.

Implications for Climate Projections

Even small changes in hydroxyl radical levels can have significant implications for how methane accumulates in the atmosphere.

“Understanding future trends of OH will allow us to determine future trends of methane,” Zhu said.

As methane continues to rise alongside carbon dioxide, insights into these chemical processes will be critical for improving climate models and informing mitigation strategies.

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Earth

Study Reveals How Ocean Bacteria Drive Plastic Biodegradation

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MIT researchers uncover how ocean bacteria collaborate to degrade biodegradable plastics, offering new hope for tackling plastic waste.
Image credit: Mali Maeder/Pexels

Plastic biodegradation is emerging as a critical solution to the global waste crisis, and new research from Massachusetts Institute of Technology offers important insights into how this process actually works in nature.

A new study by researchers at Massachusetts Institute of Technology has shed fresh light on how bacteria in marine environments collaborate to break down biodegradable plastics—offering critical insights into tackling the global plastic waste crisis.

Biodegradable plastics have long been seen as a potential solution to mounting environmental pollution. However, scientists have struggled to determine how long these materials persist in real-world conditions and how microbial communities contribute to their breakdown.

The study, published in Environmental Science and Technology, marks one of the first efforts to identify the specific roles individual bacterial species play in plastic biodegradation.

“Plastic biodegradation is highly dependent on the microbial community where the plastic ends up,” says lead author Marc Foster, a PhD researcher in the MIT-WHOI Joint Program. “It’s also dependent on the chemistry of the plastic itself.”

Unlike earlier studies that focused on single microbes, the MIT team examined how multiple bacterial species work together—a more realistic representation of how plastics degrade in nature.

The researchers studied a widely used biodegradable plastic known as an aromatic aliphatic co-polyester, commonly found in shopping bags, food packaging, and agricultural films.

Samples of this plastic were first exposed to seawater in the Mediterranean, allowing natural bacterial communities to form biofilms on their surface. Scientists then isolated and analysed these microbes in the lab.

Key findings include:

  • One bacterium, Pseudomonas pachastrellae, was able to break down the plastic polymer into smaller chemical components.
  • Other bacterial species were needed to consume those individual chemicals, including terephthalic acid, sebacic acid, and butanediol.
  • No single bacterium could complete the entire degradation process alone.

When researchers combined five complementary bacterial species, they were able to replicate the full degradation process observed in a larger microbial community.

“This complementary function was essential,” Foster explains. “None of the bacteria alone could achieve the same level of degradation as when they worked together.”

Why Plastic Biodegradation Rates Vary

The findings suggest that the speed and efficiency of plastic biodegradation depend on several key factors:

  • Microbial diversity in the environment
  • Chemical composition of the plastic
  • Environmental conditions such as temperature and depth

Notably, the study also found that the same bacterial community could not degrade a different type of plastic, indicating that microbial systems may be highly material-specific.

Implications for Future Plastic Recycling Solutions

The research represents an important step toward developing microbial recycling systems that could convert plastic waste into useful materials.

Plastic biodegradation challenge with discarded plastic materials
Image credit: Lars H Knudsen/Pexels

By understanding how bacteria interact with plastics at a molecular level, scientists could:

  • Design plastics that degrade more predictably
  • Engineer microbial communities for faster plastic breakdown
  • Develop biological recycling technologies

Foster notes that future work will explore how to optimise bacterial combinations and improve enzyme interactions with plastic surfaces.

A Step Forward in Tackling the Plastic Waste Crisis

With more than half of global plastic waste ending up in landfills or the environment, understanding plastic biodegradation is crucial for sustainable material design.

This study highlights a fundamental shift in perspective: plastic degradation is not driven by a single organism, but by complex microbial collaboration.

As research advances, such insights could help bridge the gap between biodegradable materials and real-world environmental outcomes—bringing science closer to solving one of the planet’s most pressing pollution challenges.The study, published in Environmental Science and Technology, marks one of the first efforts to identify the specific roles individual bacterial species play in plastic biodegradation.

“Plastic biodegradation is highly dependent on the microbial community where the plastic ends up,” says lead author Marc Foster, a PhD researcher in the MIT-WHOI Joint Program. “It’s also dependent on the chemistry of the plastic itself.”

Unlike earlier studies that focused on single microbes, the MIT team examined how multiple bacterial species work together—a more realistic representation of how plastics degrade in nature.

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