Category: 7. Science

As carbon emissions rise, oceans absorb more CO₂, lowering pH and increasing acidity — a shift that threatens a wide range of marine species and ecosystems.

“Shark teeth, despite being composed of highly mineralized phosphates, are still vulnerable to corrosion under future ocean acidification scenarios,” said Maximilian Baum, lead author of the study and biologist at Heinrich Heine University Düsseldorf in Germany.

Maximilian Baum and his team collected 600 naturally shed teeth from 10 blacktip reef sharks (Carcharhinus melanopterus) at the Sea Life Oberhausen aquarium in Germany.

While most sharks continuously lose and replace their teeth, the replacement rate varies by species from a few days to several weeks.

For the experiment, researchers selected 16 intact teeth and 36 slightly damaged teeth and placed them in two separate 20-liter tanks for eight weeks, each with different pH conditions. The control tank held seawater at pH 8.2, reflecting current ocean levels, while the other tank contained more acidic water at pH 7.

Sebastian Fraune, the study’s senior author and professor at Heinrich Heine University, said that teeth exposed to more acidic water showed “visible surface damage such as cracks and holes, increased root corrosion, and structural degradation” compared with those incubated at pH 8.2.

The researchers noted that damage to shark teeth caused by acidified water could potentially affect how sharks capture and process their prey, which in turn might influence feeding efficiency and digestion.

The study examined only discarded, non-living shark teeth, so potential repair or replacement processes in living sharks were not considered.

The researchers noted that blacktip reef sharks swim with their mouths open, exposing teeth continuously to seawater, and even moderate drops in pH could cause damage, particularly in species with slower tooth replacement.

The study indicates that even microscopic damage could pose a significant threat to animals that rely on their teeth for survival.

“It’s a reminder that climate change impacts cascade through entire food webs and ecosystems,” Baum added.

Earlier it was reported that Australia’s Great Barrier Reef suffered worst coral decline on record.

Locked beneath a single-plate crust, Mars’ mantle holds a frozen record of the red planet’s primordial past, according to a new study of Martian seismic data collected by NASA’s InSight mission. The findings reveal a highly heterogenous and disordered mantle, born from ancient impacts and chaotic convection in the planet’s early history. “Whereas Earth’s early geological records remain elusive, the identification of preserved ancient mantle heterogeneity on Mars offers an unprecedented window into the geological history and thermochemical evolution of a terrestrial planet under a stagnant lid, the prevalent tectonic regime in our Solar System,” write the authors. “This evolution holds key implications for understanding the preconditions for habitability of rocky bodies across our Solar System and beyond.” A planet’s mantle – the vast layer that lies sandwiched between its crust and core – preserves crucial evidence about planetary origin and evolution. Unlike Earth, where active plate tectonics continually stirs the mantle, Mars is a smaller planet with a single-plate surface. As such, Mars’ mantle undergoes far less mixing, meaning it may preserve a record of the planet’s early internal history, which could offer valuable insights into how rocky worlds form and evolve. Using data from NASA’s InSight lander, Constantinos Charalambous and colleagues studied the seismic signatures of marsquakes to better constrain the nature of Mars’ mantle. By analyzing eight well-recorded quakes, including those triggered by meteorite impacts, Charalambous et al. discovered that high-frequency P-wave arrivals were systematically delayed as they traversed the deeper portions of the mantle. According to the authors, these delays reveal subtle, kilometer-scale compositional variations within the planet’s mantle. Because Mars lacks plate tectonics and large-scale recycling, these small-scale irregularities must instead be remnants of its earliest history. The scaling of Mars’ mantle heterogeneity suggests an origin in highly energetic and disruptive processes, including massive impacts early in the planet’s history, which fractured the planet’s interior, mixing both foreign and crustal materials into the mantle at a planetary scale. Moreover, the crystallization of vast magma oceans generated in the aftermath likely introduced additional variations. Instead of being erased, these features became frozen in place as Mars’ crust cooled and mantle convection stalled.

Rocky material that impacted Mars lies scattered in giant lumps throughout the planet’s mantle, offering clues about Mars’ interior and its ancient past.

What appear to be fragments from the aftermath of massive impacts on Mars that occurred 4.5 billion years ago have been detected deep below the planet’s surface. The discovery was made thanks to NASA’s now-retired InSight lander, which recorded the findings before the mission’s end in 2022. The ancient impacts released enough energy to melt continent-size swaths of the early crust and mantle into vast magma oceans, simultaneously injecting the impactor fragments and Martian debris deep into the planet’s interior.

There’s no way to tell exactly what struck Mars: The early solar system was filled with a range of different rocky objects that could have done so, including some so large they were effectively protoplanets. The remains of these impacts still exist in the form of lumps that are as large as 2.5 miles (4 kilometers) across and scattered throughout the Martian mantle. They offer a record preserved only on worlds like Mars, whose lack of tectonic plates has kept its interior from being churned up the way Earth’s is through a process known as convection.

The finding was reported Thursday, Aug. 28, in a study published by the journal Science.

“We’ve never seen the inside of a planet in such fine detail and clarity before,” said the paper’s lead author, Constantinos Charalambous of Imperial College London. “What we’re seeing is a mantle studded with ancient fragments. Their survival to this day tells us Mars’ mantle has evolved sluggishly over billions of years. On Earth, features like these may well have been largely erased.”

InSight, which was managed by NASA’s Jet Propulsion Laboratory in Southern California, placed the first seismometer on Mars’ surface in 2018. The extremely sensitive instrument recorded 1,319 marsquakes before the lander’s end of mission in 2022.

Quakes produce seismic waves that change as they pass through different kinds of material, providing scientists a way to study the interior of a planetary body. To date, the InSight team has measured the size, depth, and composition of Mars’ crust, mantle, and core. This latest discovery regarding the mantle’s composition suggests how much is still waiting to be discovered within InSight’s data.

“We knew Mars was a time capsule bearing records of its early formation, but we didn’t anticipate just how clearly we’d be able to see with InSight,” said Tom Pike of Imperial College London, coauthor of the paper.

Mars lacks the tectonic plates that produce the temblors many people in seismically active areas are familiar with. But there are two other types of quakes on Earth that also occur on Mars: those caused by rocks cracking under heat and pressure, and those caused by meteoroid impacts.

Of the two types, meteoroid impacts on Mars produce high-frequency seismic waves that travel from the crust deep into the planet’s mantle, according to a paper published earlier this year in Geophysical Research Letters. Located beneath the planet’s crust, the Martian mantle can be as much as 960 miles (1,550 kilometers) thick and is made of solid rock that can reach temperatures as high as 2,732 degrees Fahrenheit (1,500 degrees Celsius).

The new Science paper identifies eight marsquakes whose seismic waves contained strong, high-frequency energy that reached deep into the mantle, where their seismic waves were distinctly altered.

“When we first saw this in our quake data, we thought the slowdowns were happening in the Martian crust,” Pike said. “But then we noticed that the farther seismic waves travel through the mantle, the more these high-frequency signals were being delayed.”

Using planetwide computer simulations, the team saw that the slowing down and scrambling happened only when the signals passed through small, localized regions within the mantle. They also determined that these regions appear to be lumps of material with a different composition than the surrounding mantle.

With one riddle solved, the team focused on another: how those lumps got there.

Turning back the clock, they concluded that the lumps likely arrived as giant asteroids or other rocky material that struck Mars during the early solar system, generating those oceans of magma as they drove deep into the mantle, bringing with them fragments of crust and mantle.

Charalambous likens the pattern to shattered glass — a few large shards with many smaller fragments. The pattern is consistent with a large release of energy that scattered many fragments of material throughout the mantle. It also fits well with current thinking that in the early solar system, asteroids and other planetary bodies regularly bombarded the young planets.

On Earth, the crust and uppermost mantle is continuously recycled by plate tectonics pushing a plate’s edge into the hot interior, where, through convection, hotter, less-dense material rises and cooler, denser material sinks. Mars, by contrast, lacks tectonic plates, and its interior circulates far more sluggishly. The fact that such fine structures are still visible today, Charalambous said, “tells us Mars hasn’t undergone the vigorous churning that would have smoothed out these lumps.”

And in that way, Mars could point to what may be lurking beneath the surface of other rocky planets that lack plate tectonics, including Venus and Mercury.

JPL managed InSight for NASA’s Science Mission Directorate. InSight was part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission.

A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), supported the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP³) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.

Andrew Good
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-2433
andrew.c.good@jpl.nasa.gov

Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov

2025-110

The interior of Mars is as chunky as a delicious macadamia cookie.

A new analysis of the acoustic waves that ripple through and bounce around the red planet’s guts reveals that the ancient, early crust of Mars is sequestered in its mantle. It takes the form of huge chunks of drifting rock, preserved geological fossils from the time of the planet’s formation.

These chunks indicate a violent history that is startlingly similar to that suspected for Earth, involving a giant collision with a massive object while the planet was still young and forming.

Related: In an Incredible First, Scientists Have Discovered What’s at The Core of Mars

Mars fascinates us because it is at once both like and unlike our own planet. The crust of Mars is, unlike the tectonic plates of Earth, one single piece. In addition, Mars doesn’t have a global magnetic field, a feature of our home world generated by sloshing conductive material deep in Earth’s center. This has led scientists to speculate about the structure of the Martian interior.

In the last few years, answers have finally begun to arrive. NASA sent a special instrument to Mars to sit on the surface and monitor the rumbles of seismic activity therein. Scientists can use the rumbles of quakes as a sort of acoustic X-ray to see what’s inside a cosmic object.

Any quakes, or even rumbles from meteorite impacts, propagate outward from their point of origin, bouncing around inside a planet or moon or star before stilling to quietness. The way they travel through, and reflect off, certain materials allows scientists to generate maps of the interior compositions of these bodies.

During its relatively short time monitoring the interior of Mars from 2018 to 2022, NASA’s InSight lander detected hundreds of marsquakes, giving us detailed information about the Martian interior. From this, scientists were able to compile the first detailed map of the guts of Mars, and learn more about Mars’ interior activity.

Led by planetary scientist and engineer Constantinos Charalambous of Imperial College London, a team of scientists has now pored over data from eight clear events to reconstruct the composition of Mars’ mantle – the gooey, squishy bit between the crust and the core – by studying the way seismic waves spread.

When they had crunched all the data, the researchers found giant fragments of material, some up to 4 kilometers (2.5 miles) across, surrounded by smatterings of smaller ones, preserved in the mantle of Mars from the time of its formation 4.5 billion years ago.

During this time, the Solar System was a chaotic mess, with large chunks of rock flying around and smashing into each other. The inner planets, including Earth, would have taken an absolute pummeling. It was during this time that scientists think a large object smacked into Earth, spraying planetary debris into space that then formed the Moon.

This bombardment, the researchers believe, disrupted the still-forming crust of Mars.

“These colossal impacts unleashed enough energy to melt large parts of the young planet into vast magma oceans,” Charalambous says. “As those magma oceans cooled and crystallized, they left behind compositionally distinct chunks of material – and we believe it’s these we’re now detecting deep inside Mars.”

After being whacked with space rocks, the researchers believe, the crust of Mars re-formed and sealed over the mantle, preserving the chunks within. Here on Earth, such chunks would be long gone by now; our crust and mantle are in constant motion, undergoing tectonic processes that constantly recycle them into each other.

Mars is a single-crust planet, and its interior evolution would be far more primitive and slow, retaining material like a time capsule from the birth of the Solar System.

“Most of this chaos likely unfolded in Mars’s first 100 million years,” Charalambous says. “The fact that we can still detect its traces after four and a half billion years shows just how sluggishly Mars’s interior has been churning ever since.”

This is in stark contrast to Earth, and a finding that gives us an invaluable data point for understanding the various ways rocky planets can evolve. Earth is the only planet in the Solar System with a crust divided into tectonic plates, so knowing more about Mars can also help us understand what’s going on inside Mercury and Venus, whose interiors remain mysterious to us.

“Whereas Earth’s early geological records remain elusive, the identification of preserved ancient mantle heterogeneity on Mars offers an unprecedented window into the geological history and thermochemical evolution of a terrestrial planet under a stagnant lid, the prevalent tectonic regime in our Solar System,” the researchers write in their paper.

“This evolution holds key implications for understanding the preconditions for habitability of rocky bodies across our Solar System and beyond.”

The research has been published in Science.

A key challenge in modeling (exo)planetary atmospheres lies in generating extensive opacity datasets that cover the wide variety of possible atmospheric composition, pressure, and temperature conditions.

This critical step requires specific knowledge and can be considerably time-consuming. To circumvent this issue, most available codes approximate the total opacity by summing the contributions of individual molecular species during the radiative transfer calculation. This approach neglects inter-species interactions, which can be an issue for precisely estimating the climate of planets.

To produce accurate opacity data, such as correlated-k tables, chi factor corrections of the far-wings of the line profile are required. We propose an update of the chi factors of CO₂ absorption lines that are relevant for terrestrial planets (pure CO₂, CO₂-N₂ and CO₂-H₂O). These new factors are already implemented in an original user-friendly open-source tool designed to calculate high resolution spectra, named SpeCT.

The latter enables to produce correlated-k tables for mixtures made of H₂O, CO₂ and N₂, accounting for inter-species broadening. In order to facilitate future updates of these chi factors, we also provide a review of all the relevant laboratory measurements available in the literature for the considered mixtures.

Finally, we provide in this work 8 different correlated-k tables and continua for pure CO₂, CO₂-N₂, CO₂-H₂O and CO₂-H₂O-N₂ mixtures based on the MT_CKD formalism (for H₂O), and calculated using SpeCT. These opacity data can be used to study various planets and atmospheric conditions, such as Earth’s paleo-climates, Mars, Venus, Magma ocean exoplanets, telluric exoplanets.

G. Chaverot, M. Turbet, H. Tran, J.-M. Hartmann, A. Campargue, D. Mondelain, E. Bolmont

Comments: Accepted for publication in A&A: 18 August 2025
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2508.18049 [astro-ph.EP] (or arXiv:2508.18049v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.18049
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From: Guillaume Chaverot
[v1] Mon, 25 Aug 2025 14:07:33 UTC (2,879 KB)
https://arxiv.org/abs/2508.18049
Astrobiology,

Context. Active regions on the stellar surface can induce quasi-periodic radial velocity (RV) variations that can mimic planets and mask true planetary signals. These spurious signals can be problematic for RV surveys such as those carried out by the ESPRESSO consortium.

Aims. Using ESPRESSO and HARPS RVs and activity indicators, we aim to confirm and characterize two candidate transiting planets from TESS orbiting a K4 star with strong activity signals.

Methods. From the ESPRESSO FWHM, TESS photometry, and ASAS-SN photometry, we measure a stellar rotation period of 21.28 ± 0.08 d. We jointly model the TESS photometry, ESPRESSO and HARPS RVs, and activity indicators, applying a multivariate Gaussian Process (GP) framework to the spectroscopic data.

Results. We are able to disentangle the planetary and activity components, finding that TOI-2322 b has a 11.307170+0.000085−0.000079 d period, close to the first harmonic of the rotation period, a ≤2.03M_⊕ mass upper limit and a 0.994+0.057−0.059 R_⊕ radius. TOI-2322 c orbits close to the stellar rotation period, with a 20.225528+0.000039−0.000044 d period; it has a 18.10+4.34−5.36 M_⊕ mass and a 1.874+0.066−0.057 R_⊕ radius.

Conclusions. The multivariate GP framework is crucial to separating the stellar and planetary signals, significantly outperforming a one-dimensional GP. Likewise, the transit data is fundamental to constraining the periods and epochs, enabling the retrieval of the planetary signals in the RVs. The internal structure of TOI-2322 c is very similar to that of Earth, making it one of the most massive planets with an Earth-like composition known.

M. J. Hobson (1), A. Suárez Mascareño (2 and 3), C. Lovis (1), F. Bouchy (1), B. Lavie (1), M. Cretignier (4), A. M. Silva (5 and 6), S. G. Sousa (5 and 6), H. M. Tabernero (7and 8), V. Adibekyan (5 and 6), C. Allende Prieto (2 and 3), Y. Alibert (9 and 10), S. C. C. Barros (5 and 6), A. Castro-González (11), K. A. Collins (12), S. Cristiani (13 and 14), V. D’Odorico (13), M. Damasso (15), D. Dragomir (16), X. Dumusque (1), D. Ehrenreich (1), P. Figueira (5 and 6 and 17), R. Génova Santos (2), B. Goeke (18), J. I. González Hernández (2 and 3), K. Hesse (18), J. Lillo-Box (11), G. Lo Curto (17), C. J. A. P. Martins (19 and 5), A. Mehner (17), G. Micela (20), P. Molaro (13), N. J. Nunes (21), E. Palle (2 and 3), V. M. Passegger (23 and 2 and 3 and 22), F. Pepe (1), R. Rebolo (2), J. Rodrigues (5 and 6), N. Santos (5 and 6), A. Sozzetti (15), B. M. Tofflemire (24), S. Udry (1), C. Watkins (12), M.-R. Zapatero Osorio (11), C. Ziegler (25) ((1) Observatoire de Genève, Département d’Astronomie, Université de Genève, (2) Instituto de Astrofísica de Canarias, (3) Departamento de Astrofísica, Universidad de La Laguna, (4) Department of Physics, University of Oxford, (5) Instituto de Astrofísica e Ciências do Espaço, CAUP, Universidade do Porto, (6) Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, (7) Institut d’Estudis Espacials de Catalunya (IEEC),(8) Institut de Ciències de l’Espai (ICE, CSIC), Campus UAB, (9) Physics Institute, University of Bern, (10) Center for Space and Habitability, University of Bern, (11) Centro de Astrobiología, CSIC-INTA, (12) Center for Astrophysics | Harvard & Smithsonian, (13) INAF- Osservatorio Astronomico di Trieste, (14) IFPU-Institute for Fundamental Physics of the Universe, (15) INAF – Osservatorio Astrofisico di Torino, (16) Department of Physics and Astronomy, University of New Mexico, (17) European Southern Observatory, (18) Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, (19) Centro de Astrofísica da Universidade do Porto, (20) INAF – Osservatorio Astronomico di Palermo, (21) Instituto de Astrofísica e Ciências do Espaço, Faculdade de Ciências da Universidade de Lisboa, (22) Hamburger Sternwarte, (23) Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), (24) SETI Institute, USA/NASA Ames Research Center, (25) Department of Physics, Engineering and Astronomy, Stephen F. Austin State University)

Comments: 22 pages, 20 figures. Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2508.18094 [astro-ph.EP] (or arXiv:2508.18094v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.18094
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From: Melissa Hobson
[v1] Mon, 25 Aug 2025 14:55:35 UTC (8,412 KB)
https://arxiv.org/abs/2508.18094
Astrobiology,

The nights surrounding Aug. 29 are a great time to spot the stars of the famous ‘Summer Triangle’ asterism, bisected by the glowing band of the Milky Way, with an early-setting crescent moon providing a perfect setting for the stellar hunt.

Each of the stars of the Summer Triangle belongs to a separate constellation in the night sky. Altair, the lowest point of the triangle, can be found twinkling to the left of the Milky Way in the constellation Aquila, high above the southern horizon after sunset in August. Blue-white Vega, the brightest star of the constellation Lyra, sits to its upper right on the opposite side of the ribbon of dust, gas and stars representing the galactic disk.

We present the confirmation of HD 190360 d, a warm (P=88.690+0.051−0.049 d), low-mass (msini=10.23+0.81−0.80 M_⊕) planet orbiting the nearby (d=16.0 pc), Sun-like (G7) star HD 190360.

We detect HD 190360 d at high statistical significance even though its radial velocity (RV) semi-amplitude is only K=1.48±0.11 m s^−1. Such low-amplitude signals are often challenging to confirm due to potential confusion with low-amplitude stellar signals.

The HD 190360 system previously had two known planets: the 1.7 M_J (true mass) HD 190360 b on a 7.9 yr orbit and the 21 M_⊕ (minimum mass) HD 190360 c on a 17.1 d orbit. Here, we present an in-depth analysis of the HD 190360 planetary system that comprises more than 30 years of RV measurements and absolute astrometry from the Hipparcos and Gaia spacecrafts.

Our analysis uses more than 1400 RVs, including nearly 100 from NEID. The proper motion anomaly as measured by these two astrometric missions solves for the dynamical mass of HD 190360 b and contributes to our understanding of the overall system architecture, while the long baseline of RVs enables the robust characterization of HD 190360 c and confirms the discovery of HD 190360 d.

Mark R. Giovinazzi, Evan Fitzmaurice, Arvind F. Gupta, Paul Robertson, Suvrath Mahadevan, Eric B. Ford, Jaime A. Alvarado-Montes, Chad F. Bender, Cullen H. Blake, Jiayin Dong, Rachel B. Fernandes, Samuel Halverson, Te Han, Shubham Kanodia, Daniel M. Krolikowski, Sarah E. Logsdon, Joe P. Ninan, Arpita Roy, Christian Schwab, Gudmundur Stefansson, Ryan C. Terrien, Jason T. Wright

Comments: 12 pages, 6 figures, 3 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2508.18169 [astro-ph.EP] (or arXiv:2508.18169v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2508.18169
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Submission history
From: Mark Giovinazzi
[v1] Mon, 25 Aug 2025 16:17:42 UTC (1,443 KB)
https://arxiv.org/abs/2508.18169
Astrobiology,

In a new study, researchers show when cavefishes lost their eyes, which provides a method for dating cave systems.

Small, colorless, and blind, amblyopsid cavefishes inhabit subterranean waters throughout the eastern United States.

In an analysis of the genomes of all known amblyopsid species, the researchers found that the different species colonized caves systems independently of each other and separately evolved similar traits—such as the loss of eyes and pigment—as they adapted to their dark cave environments.

Their findings appear in the journal Molecular Biology and Evolution.

By studying the genetic mutations that caused the fishes’ eyes to degenerate, the researchers developed a sort of mutational clock that allowed them to estimate when each species began losing their eyes. They found that vision-related genes of the oldest cavefish species, the Ozark cavefish (Troglichthys rosae), began degenerating up to 11 million years ago.

The technique provides a minimum age for the caves that the fishes colonized since the cavefish must have been inhabiting subterranean waters when their eyesight began devolving, the researchers say.

“The ancient subterranean ecosystems of eastern North America are very challenging to date using traditional geochronological cave-dating techniques, which are unreliable beyond an upper limit of about 3 to 5 million years,” says Chase Brownstein, a student in Yale’s Graduate School of Arts and Sciences, in the ecology and evolutionary biology department, and the study’s co-lead author.

“Determining the ages of cave-adapted fish lineages allows us to infer the minimum age of the caves they inhabit because the fishes wouldn’t have started losing their eyes while living in broad daylight. In this case we estimate a minimum age of some caves of over 11 million years.”

Maxime Policarpo of the Max Planck Institute for Biological Intelligence and the University of Basel is the co-lead author.

For the study, the researchers reconstructed a time-calibrated evolutionary tree for amblyopsids, which belong to an ancient, species-poor order of freshwater fishes called Percopsiformes, using the fossil record as well as genomic data and high-resolution scans of all living relevant species.

All the cavefish species have similar anatomies, including elongated bodies and flattened skulls, and their pelvic fins have either been lost or severely reduced. Swampfish (Chologaster cornuta), a sister to cavefish lineage that inhabits murky surface waters, also has a flattened skull, elongated body, and no pelvic fin. While it maintains sight and pigment, there is softening of the bones around its eyes, which disappear in cavefishes. This suggests that cavefishes evolved from a common ancestor that was already equipped to inhabit low-light environments, Brownstein says.

To understand when the cavefish began populating caves—something impossible to discern from the branches of an evolutionary tree—the researchers studied the fishes’ genomes, examining 88 vision-related genes for mutations. The analysis revealed that the various cavefish lineages had completely different sets of genetic mutations involved in the loss of vision. This, they say, suggests that separate species colonized caves and adapted to those subterranean ecosystems independently of each other.

From there, the researchers developed a method for calculating the number of generations that have passed since cavefish species began adapting to life in caves by losing the functional copies of vision-related genes.

Their analysis suggests that cave adaptations occurred between 2.25 and 11.3 million years ago in Ozark cavefish and between 342,000 to 1.70 million years ago (at minimum) and 1.7 to 8.7 million years ago (at maximum) for other cavefish lineages. The findings support the conclusion that at least four amblyopsid lineages independently colonized caves after evolving from surface-dwelling ancestors, the researchers say.

The maximum ages exceed the ranges of traditional cave-dating methods, which includes isotope analysis of cosmogenic nuclides that are produced within rocks and soils by cosmic rays, the researchers note.

The findings also suggest potential implications for human health, says Thomas Near, professor of ecology and evolutionary biology at Yale, and senior author of the study.

“A number of the mutations we see in the cavefish genomes that lead to degeneration of the eyes are similar to mutations that cause ocular diseases in humans,” says Near, who is also the Bingham Oceanographic Curator of Ichthyology at the Yale Peabody Museum.

“There is the possibility for translational medicine through which by studying this natural system in cavefishes, we can glean insights into the genomic mechanisms of eye diseases in humans.”

Additional coauthors are from the South Carolina Department of Natural Resources, the American Museum of Natural History, Florida State University, and Paris-Cité University.

Source: Yale

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Materials scientists at the University of California San Diego have performed powerful laser shock experiments on a perovskite mineral to better understand the geophysical processes in Earth’s deep interior and the mechanisms behind earthquakes deep within the planet.

Perovskites are a class of materials used in light-based technologies such as solar cells, LEDs and lasers. They are also the most abundant minerals in Earth’s mantle. Two of the mantle’s most abundant mineral perovskites, bridgmanite and wollastonite, are difficult to study directly because they are unstable under standard laboratory conditions. To get around this, researchers use a chemically different but structurally similar mineral, calcium titanate, as an analogue.

In a new study, researchers used high power laser shock compression to recreate the extreme pressures and temperatures found deep inside the Earth. They discovered that calcium titanate deforms more like metals by forming dense networks of line and planar defects in contrast to completely disordered amorphization typically found in covalent materials like diamond — that may explain how mantle rocks respond to stress. These findings provide new insights into the processes that drive deep-focus earthquakes, which occur hundreds of kilometers beneath the Earth’s surface, and may also inform the effects of meteorite impacts on planets.

The study, published in Acta Materialia, was led by UC San Diego researchers Boya Li and Marc Meyers. This research was partially supported by the Department of Energy, National Nuclear Security Administration (award DE-NA0004147).