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Category: evolution

Scientists say evolution works differently than we thought

As species evolve, random genetic mutations arise. Some of these mutations become fixed, meaning they spread until every individual in a population carries the change. The Neutral Theory of Molecular Evolution argues that most mutations that reach this stage are neutral. Harmful mutations are quickly eliminated, while helpful ones are assumed to be extremely rare, explains evolutionary biologist Jianzhi Zhang.

Zhang and his colleagues set out to test whether this idea holds up when examined more closely. Their results pointed to a major problem. The researchers found that beneficial mutations occur far more often than the Neutral Theory allows. At the same time, they observed that the overall rate at which mutations become fixed in populations is much lower than would be expected if so many helpful mutations were taking hold.

Astronomers Witness ‘Missing Link’ in Planet Formation

“What’s so exciting is that we’re seeing a preview of what will become a very normal planetary system,” said Dr. John Livingston.

How are the most common types of planets made? This is what a recent study published in Nature hopes to address as a team of scientists investigated the intricate processes responsible for the most common types of exoplanets—super-Earths and sub-Neptunes—to form and evolve. This study has the potential to help scientists better understand not only planetary formation and evolution, but for solar systems, as our solar system doesn’t have super-Earths or sub-Neptunes.

For the study, the researchers conducted a multi-year examination of the V1298 Tau system, which is an approximately 20-million-year-old system located about 350 light-years from Earth and hosts four growing exoplanets orbiting in a tight formation, and each being between 5 to 10 Earth radii. Given the young age of the system, as our solar system is about 4.5 billion-years-old, the goal of the study was to predict the sizes of the four planets when they stop evolving.

In the end, the researchers ascertained that while the four young planets are between 5–10 Earth radii right now, they will end up being between 1–4.5 Earth radii when they are done forming. They note this is due to the rapid cooling they underwent after initial formation due to their small masses and large radii, resulting in their shrinking while losing their atmospheres, with one of the researchers calling this the “missing link” in understanding the formation of super-Earth and sub-Neptunes, which are the most common types of exoplanets.

Young galaxies grow up fast: Research reveals unexpected chemical maturity

Astronomers have captured the most detailed look yet at faraway galaxies at the peak of their youth, an active time when the adolescent galaxies were fervently producing new stars.

The observations focused on 18 galaxies located 12.5 billion light-years away. They were imaged across a range of wavelengths from ultraviolet to radio over the past eight years by a trio of telescopes: NASA’s Hubble Space Telescope; NASA’s James Webb Space Telescope (JWST); and ALMA (Atacama Large Millimeter/submillimeter Array) in Chile, of which the U.S. National Science Foundation National Radio Astronomy Observatory is a partner. Data from other ground-based telescopes were also used to make measurements, such as the total mass of stars in the galaxies.

“With this sample, we are uniquely poised to study galaxy evolution during a key epoch in the universe that has been hard to image until now,” says Andreas Faisst, a staff scientist at IPAC, a science and data center for astronomy at Caltech. “Thanks to these exceptional telescopes, we have spatially resolved these galaxies and can observe the stages of star formation as they were happening and their chemical properties when our universe was less than a billion years old.”

New framework unifies space and time in quantum systems

Quantum mechanics and relativity are the two pillars of modern physics. However, for over a century, their treatment of space and time has remained fundamentally disconnected. Relativity unifies space and time into a single fabric called spacetime, describing it seamlessly. In contrast, traditional quantum theory employs different languages: quantum states (density matrix) for spatial systems and quantum channels for temporal evolution.

A recent breakthrough by Assistant Professor Seok Hyung Lie from the Department of Physics at UNIST offers a way to describe quantum correlations across both space and time within a single, unified framework. Assistant Professor Lie is first author, with Professor James Fullwood from Hainan University serving as the corresponding author. Their collaboration creates new tools that could significantly impact future studies in quantum science and beyond. The study has been published in Physical Review Letters.

In this study, the team developed a new theoretical approach that treats the entire timeline as one quantum state. This concept introduces what they call the multipartite quantum states over time. In essence, it allows us to describe quantum processes at different points in time as parts of a single, larger quantum state. This means that both spatially separated systems and systems separated in time can be analyzed using the same mathematical language.

‘Fish Mouth’ Filter Removes 99% of Microplastics From Laundry Waste

The ancient evolution of fish mouths could help solve a modern source of plastic pollution.

Inspired by these natural filtration systems, scientists in Germany have invented a way to remove 99 percent of plastic particles from water. It’s based on how some fish filter-feed to eat microscopic prey.

The research team has already filed a patent in Germany, and in the future, they hope their creation will help curb a ubiquitous form of plastic pollution that many are unaware of.

Bird feeders have caused a dramatic evolution of California hummingbirds

Evolution doesn’t always take thousands or millions of years. Sometimes it happens right before our eyes.

Such is the case with the Anna’s hummingbird, a species that has undergone a dramatic transformation in just a few generations, all thanks to the advent of hummingbird feeders.

Beaks have grown longer and larger, and ranges have expanded to follow the feeders.

Study unveils the dual nature of a young stellar object

Astronomers from the Aryabhatta Research Institute of Observational Sciences (ARIES) in India and elsewhere have conducted a long-term photometric and spectroscopic study of a young stellar object known as V1180 Cassiopeiae. Results of the study, published December 23 on the arXiv preprint server, unveil the dual nature of this object.

Young stellar objects (YSOs) are stars in the early stages of evolution; in particular, protostars and pre-main sequence (PMS) stars. They are usually observed embedded in dense molecular clumps, environments containing plenty of molecular gas and interstellar dust.

Given that episodic accretion processes occur in YSOs, these objects may experience accretion-driven outbursts. Astronomers usually divide such events into EX Lup (also known as EXors) and FU Ori outbursts (or FUors). EXors are a few magnitudes in amplitude, and last from a few months to one or two years. FUors are more extreme and rare as they can be up to 5–6 magnitudes in amplitude and last from decades to even centuries.

Blood–Brain Barrier Permeability Dynamics and Mediation of Triglyceride–Glucose Index on Acute Ischemic Stroke Outcomes

In acute ischemic stroke, insulin resistance worsens outcomes by increasing blood-brain barrier permeability in the ischemic core.

Acute large‐vessel occlusion of head and neck severely affect quality of life. One of the critical pathological events associated with prognosis of acute ischemic stroke (AIS) is the disruption of the blood–brain barrier (BBB), a highly selective barrier maintaining the brain’s microenvironment.1 Ischemia causes BBB dysfunction,2 exacerbated by peripheral immune cell infiltration,3 leading to increased parenchymal injury, hemorrhage,4 and edema.4, 5 Therefore, accurately determining the evolution and severity of BBB permeability are crucial for prognostic evaluation in patients with AIS.

Research on BBB disruption in patients with AIS primarily focuses on pathological mechanisms and imaging evaluations. Numerous studies use animal models and cell culture experiments to elucidate the physiological and molecular bases of BBB disruption.2, 5, 6, 7, 8 Additionally, imaging techniques like magnetic resonance imaging are widely used to assess evolution of BBB permeability1, 9, 10, 11, 12 and demonstrate correlations between BBB damage, cerebral edema, hemorrhagic transformation, and poor prognosis. Despite significant advances, several issues remain unresolved. First, differences between animal models and human disease limit clinical applicability. Second, while magnetic resonance imaging is widely used to provide quantitative data on BBB disruption, they still face the limitations of being time consuming and inconvenient in the clinical environment. However, BBB disruption in patients with AIS based on computed tomography perfusion (CTP) needs further study.

Insulin resistance (IR) is linked to adverse cardiovascular13, 14 and metabolic outcomes.15, 16 Therefore, identifying patients with IR aids early risk stratification and management. The triglyceride–glucose (TyG) index, which combines fasting triglyceride and glucose levels, has been proposed as a marker of IR. Currently, research on the TyG index primarily focuses on type 2 diabetes,17 obesity,18 and cardiovascular diseases.19 Recent studies have found that an elevated TyG index is associated with higher stroke recurrence,19, 20 functional deterioration,21, 22 and death.23 However, whether the underlying mechanisms involved in the association of IR with stroke outcomes have not been fully understood. IR exacerbated vascular inflammation and endothelial dysfunction,24, 25, 26 which were critical contributors to BBB disruption in AIS. Previous studies have shown that metabolic dysregulation, including hypertriglyceridemia27 and hyperglycemia,28 aggravates BBB permeability by triggering oxidative stress and inflammatory pathways.29, 30 Specifically, IR leads to the generation of reactive oxygen species and the activation of NADPH oxidase, which contribute to oxidative stress and endothelial damage.30, 31 Inflammatory cytokines such as tumor necrosis factor‐α, interleukin‐1β, and interleukin‐6 are also elevated in the insulin‐resistant state, activating nuclear factor‐κB and Janus kinase signaling pathways that further compromise endothelial tight junction proteins such as occludin, claudin‐5, and zonula occludens‐1, crucial for BBB integrity.29, 32 These mechanisms are known to increase BBB permeability, facilitating the entry of harmful substances into the brain and contributing to worsened stroke outcomes. These findings indicated that the relationship between IR and stroke outcomes may be mediated by increased BBB permeability. However, the TyG index’s relationship with BBB disruption and outcomes in patients with AIS is not well studied.

Injury and inflammation promote cancer progression at the anorectal junction

Petitpas et al. dissect the single-cell transcriptome underlying the sequential steps of pre-malignant lesions and early anorectal cancer, mimicking disease evolution seen in patients, at the epithelial and immune level. They reveal a key epithelial-immune cell crosstalk involving IL-17-producing T lymphocytes and neutrophils as essential for the dysplasia-carcinoma progression.

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