How did humans learn to walk? New evolutionary study offers an earful

Humans and our closest relatives, living apes, display a remarkable diversity of types of locomotion -- from walking upright on two legs to climbing in trees and walking using all four limbs.

While scientists have long been intrigued by the question of how humans' bipedal stance and movement evolved from a quadrupedal ancestor, neither past studies nor fossil records have permitted the reconstruction of a clear and definitive history of the early evolutionary stages that led to human bipedalism.

However, a new study, which centers on recently discovered evidence from skulls of a 6-million-year-old fossil ape, Lufengpithecus, offers important clues about the origins of bipedal locomotion courtesy of a novel method: analyzing its bony inner ear region using three-dimensional CT-scanning.

"The semicircular canals, located in the skull between our brains and the external ear, are critical to providing our sense of balance and position when we move, and they provide a fundamental component of our locomotion that most people are probably unaware of," explains Yinan Zhang, a doctoral student at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP) and the lead author of the paper, which appears in the journal the Innovation. "The size and shape of the semicircular canals correlate with how mammals, including apes and humans, move around their environment. Using modern imaging technologies, we were able to visualize the internal structure of fossil skulls and study the anatomical details of the semicircular canals to reveal how extinct mammals moved."

"Our study points to a three-step evolution of human bipedalism," adds Terry Harrison, a New York University anthropologist and one of the paper's co-authors.

"First, the earliest apes moved in the trees in a style that was most similar to aspects of the way that gibbons in Asia do today. Second, the last common ancestor of apes and humans was similar in its locomotor repertoire to Lufengpithecus, using a combination of climbing and clambering, forelimb suspension, arboreal bipedalism, and terrestrial quadrupedalism. It is from this broad ancestral locomotor repertoire that human bipedalism evolved."

Most studies of the evolution of ape locomotion had focused on comparisons of the bones of the limbs, shoulders, pelvis, and spine and the way they are associated with the different types of locomotor behaviors seen in living apes and humans.

However, the diversity of locomotor behaviors in living apes and the incompleteness of the fossil record have hampered the development of a clear picture of human bipedalism's origins.

The skulls of Lufengpithecus -- originally discovered in China's Yunnan Province in the early 1980s -- have given scientists the opportunity to address, in new ways, unanswered questions about the evolution of locomotion.

However, the heavy compression and distortion of the skulls obscured the bony ear region and led previous researchers to believe that the delicate semicircular canals were not preserved.

To better explore this region, Zhang, Ni and Harrison, along with other researchers at IVPP and the Yunnan Institute of Cultural Relics and Archaeology (YICRA), used three dimensional scanning technologies to illuminate these portions of the skulls to create a virtual reconstruction of the inner ear's bony canals.

They then compared these scans to those collected from other living and fossil apes and humans from Asia, Europe, and Africa.

"Our analyses show that early apes shared a locomotor repertoire that was ancestral to human bipedalism," explains IVPP Professor Xijun Ni, who led the project.

"It appears that the inner ear provides a unique record of the evolutionary history of ape locomotion that offers an invaluable alternative to the study of the postcranial skeleton."

"Most fossil apes and their inferred ancestors are intermediate in locomotor mode between gibbons and African apes," adds Ni. "Later, the human lineage diverged from the great apes with the acquisition of bipedalism, as seen in Australopithecus, an early human relative from Africa."

By studying the rate of evolutionary change in the bony labyrinth, the international team proposed that climate change may have been an important environmental catalyst in promoting the locomotor diversification of apes and humans.

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Lightest black hole or heaviest neutron star? MeerKAT uncovers a mysterious object in Milky Way

An international team of astronomers have found a new and unknown object in the Milky Way that is heavier than the heaviest neutron stars known and yet simultaneously lighter than the lightest black holes known.

Using the MeerKAT Radio Telescope, astronomers from a number of institutions including The University of Manchester and the Max Planck Institute for Radio Astronomy in Germany found an object in orbit around a rapidly spinning millisecond pulsarlocated around 40,000 light years away in a dense group of stars known as a globular cluster.

Using the clock-like ticks from the millisecond pulsar they showed that the massive object lies in the so-called black hole mass gap.

It could be the first discovery of the much-coveted radio pulsar -- black hole binary; a stellar pairing that could allow new tests of Einstein's general relativity and open doors to the study of black holes.

The results are published today in the journal Science.

UK project lead Ben Stappers, Professor of Astrophysics at The University of Manchester, said: "Either possibility for the nature of the companion is exciting. A pulsar-black hole system will be an important target for testing theories of gravity and a heavy neutron star will provide new insights in nuclear physics at very high densities."

When a neutron star -- the ultra-dense remains of dead star -- acquire too much mass, usually by consuming or colliding with another star, they will collapse. What they become after they collapse is the cause of much speculation, but it is believed that they could become black holes -- objects so gravitationally attractive that even light cannot escape them.

Astronomers believe that the total mass required for a neutron star to collapse is 2.2 times the mass of the sun. Theory, backed by observation, tells us that the lightest black holes created by these stars are much larger, at about five times more massive than the Sun, giving rise to what is known as the 'black hole mass gap'.

The nature of compact objects in this mass gap is unknown and detailed study has so far proved challenging. The discovery of the object may help finally understand these objects.

Prof Stappers, added: "The ability of the extremely sensitive MeerKAT telescope to reveal and study these objects is a enabling a great step forward and provides us with a glimpse of what will be possible with the Square Kilometre Array."

The discovery of the object was made while observing a large cluster of stars known as NGC 1851 located in the southern constellation of Columba, using the MeerKAT telescope.

The globular cluster NGC 1851 is a dense collection of old stars that are much more tightly packed than the stars in the rest of the Galaxy. Here, it is so crowded that the stars can interact with each other, disrupting orbits and in the most extreme cases colliding.

The astronomers, part of the international Transients and Pulsars with MeerKAT (TRAPUM) collaboration, believe that it is one such collision between two neutron stars that is proposed to have created the massive object that now orbits the radio pulsar.

The team were able to detect faint pulses from one of the stars, identifying it as a radio pulsar -- a type of neutron star that spins rapidly and shines beams of radio light into the Universe like a cosmic lighthouse.

The pulsar spins more than 170 times a second, with every rotation producing a rhythmic pulse, like the ticking of a clock. The ticking of these pulses is incredibly regular and by observing how the times of the ticks change, using a technique called pulsar timing, they were able to make extremely precise measurements of its orbital motion.

Ewan Barr from Max Planck Institute for Radio Astronomy, who led the study with his colleague Arunima Dutta, explained: "Think of it like being able to drop an almost perfect stopwatch into orbit around a star almost 40,000 light years away and then being able to time those orbits with microsecond precision."

The regular timing also allowed a very precise measurement of the system's location, showing that the object in orbit with the pulsar was no regular star but an extremely dense remnant of a collapsed star. Observations also showed that the companion has a mass that was simultaneously bigger than that of any known neutron star and yet smaller than that of any known black hole, placing it squarely in the black-hole mass gap.

While the team cannot conclusively say whether they have discovered the most massive neutron star known, the lightest black hole known or even some new exotic star variant, what is certain is that they have uncovered a unique laboratory for probing the properties of matter under the most extreme conditions in the Universe.

Arunima Dutta concludes: "We're not done with this system yet.

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Paper provides a clearer picture of severe hydro hazards

Over the last two decades an estimated three billion people have been affected by water-related natural disasters such as droughts and floods. Climate change is expected to increase the frequency of these hydro hazards, with some prognosticators estimating there will be upwards of $3.7 trillion in water-related damage over the next 30 years in the U.S. alone. Beyond damaging homes and infrastructure, severe wet and dry spells will also devastate crops and deplete water reservoirs.

An increasing area of interest to researchers is the frequency of compound drought and pluvial flooding (caused by quick, heavy rainfall or sustained rainfall beyond the norm), which is when both occur in succession in the same area within a year of each other.

Historically, this level of coincidence has been under-examined.

Of similar interest is when the reverse happens: extreme rainfall followed by a meteorological drought.

Meteorological drought is when dry weather patterns prevail, which can eventually trigger hydrological drought, leading to dry streams and plunging reservoir levels, such as what happened at Lake Mead in 2022.

A new study co-authored by researchers in the University of Arkansas Department of Geosciences, as well as colleagues in China, now provides a global examination of drought-pluvial volatility -- or the tendency to shift from one extreme to another (from dry to wet or wet to dry) in a short period of time.

Yichan Li, a Ph.D. candidate at the U of A, was the first of four authors on the paper, "Observational Uncertainty for Global Drought-Pluvial Volatility," published in Water Resources Research, while Linyin Cheng, an assistant professor of geosciences, was second author.

The study looks at extreme dry-to-wet and wet-to-dry transitions over the past seven decades through event coincidence analysis, a method of quantifying the number of consecutive extreme events that also considers instantaneous or lagged responses within an uncertain period between them.

The study used three widely used climate data sets to provide evidence of increased drought-pluvial volatility on time scales of less than a year.

The team also evaluated the accuracy of these data sets, finding varying strengths and weaknesses of each due to observational uncertainties in data collection.

For instance, the remoteness of a region may play a role in collecting accurate data.

Averaged out at the global scale, the team found that 15.46% of all meteorological droughts were succeeded by a pluvial the following season.

The wet-to-dry transition percentage proved remarkably similar: 15.49%. However, prominent differences exist when looking at particular regions.

Toward that end, the study provides a map demonstrating how incidents of these two phenomena are distributed globally.

Overall, the spatial pattern of extreme dry-to-wet and wet-to-dry events' coincidence rates is largely in agreement among the three data sets, though there is prominent regional variability.

For instance, in Eurasia since the mid-20th century, there is a relatively low probability for meteorological droughts transitioning to pluvials, but a higher chance for the opposite scenario, rapid shifts from wet to dry events.

A similar pattern also exists over western North America, which sees severe wet to dry transitions at a frequency greater than 17% on average.

Conversely, South Asia and Australia are more prone to immediate transitions from meteorological droughts to pluvials.

The authors noted: "Our findings indicate that differences associated with drought-pluvial volatility among the considered observations are in many regions larger than that of their single events [droughts or pluvials alone], highlighting a need of to use multiple independent observation-based data sets for more robust examinations when studying such compound extreme events."

Ultimately, the authors stress the need to use multiple independent observation-based data sets when analyzing extreme, compound dry-to-wet events.

This will provide clearer guidelines for climate-related decision making, especially water resources planning, as well as ensure better accuracy when modeling future weather events.

Read more at Science Daily

New video camera system captures the colored world that animals see, in motion

A new camera system allows ecologists and filmmakers to produce videos that accurately replicate the colors that different animals see in natural settings, Vera Vasas at the University of Sussex, UK, and colleagues from the Hanley Color Lab at George Mason University, US, report in the open access journal PLOS Biology, publishing January 23rd.

Different animals perceive the world differently because of the capabilities of the photoreceptors in their eyes.

For example, animals like honeybees and some birds can see UV light, which are outside the range of human perception.

Reconstructing the colors that animals actually see can help scientists better understand how they communicate and navigate the world around them.

False color images give us a glimpse into this dynamic world, but traditional methods such as spectrophotometry are often time consuming, require specific lighting conditions, and cannot capture moving images.

To address these limitations, researchers developed a novel camera and software system that captures animal-view videos of moving objects under natural lighting conditions.

The camera simultaneously records video in four color channels: blue, green, red and UV. This data can be processed into "perceptual units" to produce an accurate video of how those colors are perceived by animals, based on existing knowledge of the photoreceptors in their eyes.

The team tested the system against a traditional method that uses spectrophotometry and found that the new system predicted perceived colors with an accuracy of over 92%.

This novel camera system will open new avenues of research for scientists, and allow filmmakers to produce dynamic, accurate depictions of how animals see the world around them, the authors say.

The system is built from commercially available cameras, housed in a modular, 3D-printed casing, and the software is available open-source, allowing other researchers to use and build on the technology in the future.

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The fountain of youth is ... a T cell?

The fountain of youth has eluded explorers for ages. It turns out the magic anti-aging elixir might have been inside us all along.

Cold Spring Harbor Laboratory (CSHL) Assistant Professor Corina Amor Vegas and colleagues have discovered that T cells can be reprogrammed to fight aging, so to speak.

Given the right set of genetic modifications, these white blood cells can attack another group of cells known as senescent cells.

These cells are thought to be responsible for many of the diseases we grapple with later in life.

Senescent cells are those that stop replicating. As we age, they build up in our bodies, resulting in harmful inflammation.

While several drugs currently exist that can eliminate these cells, many must be taken repeatedly over time.

As an alternative, Amor Vegas and colleagues turned to a "living" drug called CAR (chimeric antigen receptor) T cells.

They discovered CAR T cells could be manipulated to eliminate senescent cells in mice.

As a result, the mice ended up living healthier lives. They had lower body weight, improved metabolism and glucose tolerance, and increased physical activity.

All benefits came without any tissue damage or toxicity.

"If we give it to aged mice, they rejuvenate. If we give it to young mice, they age slower. No other therapy right now can do this, " says Amor Vegas.

Perhaps the greatest power of CAR T cells is their longevity.

The team found that just one dose at a young age can have lifelong effects.

That single treatment can protect against conditions that commonly occur later in life, like obesity and diabetes.

"T cells have the ability to develop memory and persist in your body for really long periods, which is very different from a chemical drug, " explains Amor Vegas.

"With CAR T cells, you have the potential of getting this one treatment, and then that's it. For chronic pathologies, that's a huge advantage. Think about patients who need treatment multiple times per day versus you get an infusion, and then you're good to go for multiple years."

CAR T cells have been used to treat a variety of blood cancers, receiving FDA approval for this purpose in 2017.

But Amor Vegas is one of the first scientists to show that CAR T cells' medical potential goes even further than cancer.

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Atmospheric pressure changes could be driving Mars' elusive methane pulses

New research shows that atmospheric pressure fluctuations that pull gases up from underground could be responsible for releasing subsurface methane into Mars' atmosphere; knowing when and where to look for methane can help the Curiosity rover search for signs of life.

"Understanding Mars' methane variations has been highlighted by NASA's Curiosity team as the next key step towards figuring out where it comes from," said John Ortiz, a graduate student at Los Alamos National Laboratory who led the research team.

"There are several challenges associated with meeting that goal, and a big one is knowing what time of a given sol (Martian day) is best for Curiosity to perform an atmospheric sampling experiment."

The paper was published the week of Jan. 22 in the Journal of Geophysical Research: Planets.

A primary focus of NASA's Mars missions, including Curiosity and Perseverance, is to detect and understand past or present signs of life, such as methane.

However, with the source of methane on Mars likely being underground, short-term variations in atmospheric methane levels have posed a research challenge.

To better understand Mars' methane levels, Ortiz and his team used high-performance computing clusters to simulate how methane travels through networks of underground fractures and is released into the atmosphere, where it then mixes within the atmospheric column.

They also modeled how methane is adsorbed onto the pores of rocks, which is a temperature-dependent process that may contribute to the methane level fluctuations.

Their simulations predicted methane pulses from the ground surface into the atmosphere just before the Martian sunrise in the planet's northern summer season, which just recently ended.

This corroborates previous rover data suggesting that methane levels fluctuated not only seasonally, but also daily.

This valuable data is helping inform the Curiosity rover's ongoing sampling campaign.

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Complex green organisms emerged a billion years ago

Of all the organisms that photosynthesize, land plants have the most complex bodies. How did this morphology emerge? A team of scientists led by the University of Göttingen has taken a deep dive into the evolutionary history of morphological complexity in streptophytes, which include land plants and many green algae. Their research allowed them to go back in time to investigate lineages that emerged long before land plants existed. Their results revise the understanding of the relationships of a group of filamentous algal land colonizers much older than land plants. Using modern gene sequencing data, researchers pinpoint the emergence of multicellularity to almost a billion years ago. The results were published in the journal Current Biology.

The study focused on Klebsormidiophyceae, a class of green algae known for its ability to colonize diverse habitats worldwide.

The team of researchers conducted extensive sampling, investigating habitats ranging from streams, rivers, and lake shores to bogs, soil, natural rocks, tree bark, acidic post-mining sites, sand dunes, urban walls, and building façades.

"It's really fascinating that these tiny robust little organisms have such a high diversity in their morphology and also are extremely well adapted to live in sometimes very harsh environments," says Dr Tatyana Darienko, University of Göttingen's Institute for Microbiology and Genetics.

This comprehensive sampling aimed to create a global distribution map for Klebsormidiophyceae, emphasizing their adaptability, ecological significance, and hidden diversity.

Based on genetic data calibrated by fossils, the researchers performed "molecular clock analyses."

While delving into the complex evolutionary history of Klebsormidiophyceae, the researchers faced challenges in resolving phylogenetic relationships using traditional markers.

To overcome this, they employed hundreds of genes obtained from the transcriptomes of 24 isolates from different continents and habitats.

"Our approach, known as phylogenomics, was to reconstruct the evolutionary history taking into account whole genomes or large fractions of genomes," explains Dr Iker Irisarri, Leibniz Institute for the Analysis of Biodiversity Change.

"This extremely powerful method can reconstruct evolutionary relationships with very high precision."

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Global groundwater depletion is accelerating, but is not inevitable

Groundwater is rapidly declining across the globe, often at accelerating rates. Writing in the journal Nature, UC Santa Barbara researchers present the largest assessment of groundwater levels around the world, spanning nearly 1,700 aquifers. In addition to raising the alarm over declining water resources, the work offers instructive examples of where things are going well, and how groundwater depletion can be solved. The study is a boon for scientists, policy makers and resource managers working to understand global groundwater dynamics.

"This study was driven by curiosity. We wanted to better understand the state of global groundwater by wrangling millions of groundwater level measurements," said lead author Debra Perrone, an associate professor in UC Santa Barbara's Environmental Studies Program.

The team compiled data from national and subnational records and the work of other agencies. The study took three years, two of which were spent just cleaning and sorting data. That's what it takes to make sense of 300 million water level measurements from 1.5 million wells over the past 100 years.

Next came the task of translating the deluge of data into actual insights about global groundwater trends. The researchers then scoured over 1,200 publications to reconstruct aquifer boundaries in the regions of inquiry and evaluate groundwater level trends in 1,693 aquifers.

Their findings provide the most comprehensive analysis of global groundwater levels to date, and demonstrate the prevalence of groundwater depletion. The work revealed that groundwater is dropping in 71% of the aquifers. And this depletion is accelerating in many places: the rates of groundwater decline in the 1980s and '90s sped up from 2000 to the present, highlighting how a bad problem became even worse. The accelerating declines are occurring in nearly three times as many places as they would expect by chance.

Groundwater deepening is more common in drier climates, with accelerated decline especially prevalent in arid and semi-arid lands under cultivation -- "an intuitive finding," said co-lead author Scott Jasechko, an associate professor in the university's Bren School of Environmental Science & Management. "But it's one thing for something to be intuitive. It's quite another to show that it's happening with real-world data."

On the other hand, there are places where levels have stabilized or recovered. Groundwater declines of the 1980s and '90s reversed in 16% of the aquifer systems the authors had historical data for. However, these cases are only half as common as would be expected by chance.

"This study shows that humans can turn things around with deliberate, concentrated efforts," Jasechko said.

Take Tucson, Arizona for instance. Water allotted from the Colorado River is used to replenish the aquifer in the nearby Avra Valley. The project stores water for future use. "Groundwater is often viewed as a bank account for water," Jasechko explained. "Intentionally refilling aquifers allows us to store that water until a time of need."

Communities can spend a lot of money building infrastructure to hold water above ground. But if you have the right geology, you can store vast quantities of water underground, which is much cheaper, less disruptive and less dangerous. The stored groundwater can also benefit the region's ecology. In fact, while preparing a research brief in 2014, Perrone found that aquifer recharge can store six times more water per dollar than surface reservoirs.

Tucson's groundwater recharge is a boon for the local aquifer; however, withdrawals have caused the mighty river to dwindle above ground. The Colorado rarely reaches its delta in the California Gulf anymore. "These groundwater interventions can have tradeoffs," Jasechko acknowledged.

Another option is to focus on reducing demand. Often this involves regulations, permitting and fees for groundwater use, Perrone explained. To this end, she is currently examining water law in the western U.S. to understand these diverse interventions. Regardless of whether it comes from supply or demand, aquifer recovery seemed to require intervention, the study revealed.

The authors complemented measurements from monitoring wells with data from the Gravity Recovery and Climate Experiment (GRACE). The GRACE mission consists of twin satellites that precisely measure the distance between them as they orbit the Earth. In this way, the crafts detect small fluctuations in the planet's gravity, which can reveal the dynamics of aquifers at large scales.

"The beauty of GRACE is that it allows us to explore groundwater conditions where we don't have in-situ data," Perrone said. "Our assessment complements GRACE. Where we do have in-situ data, we can explore groundwater conditions locally, a crucial level of resolution when you're managing depletion." This local resolution is critical, as the authors found out, because adjacent aquifers can display different trends.

That said, groundwater level trends don't present the whole picture. Even where aquifers remain stable, withdrawing groundwater can still affect nearby streams and surface water, causing them to leak into the subsurface, as Perrone and Jasechko detailed in another Nature paper in 2021.

The authors also analyzed precipitation variability over the past four decades for 542 aquifers. They found that 90% of aquifers where declines were accelerating are in places where conditions have gotten drier over the last 40 years. These trends have likely reduced groundwater recharge and increased demand. On the other hand, climate variability can also enable groundwater to rebound where conditions become wetter.

This study of monitoring wells complements a paper Perrone and Jasechko released in 2021. That study represented the largest assessment of global groundwater wells, and made the cover of the journal Science. "The monitoring wells are telling us information about supply. And the groundwater wells are telling us information about demand," Perrone said.

"Taken together, they allow us to understand which wells have run dry already, or are most likely to run dry if groundwater-level declines occur," Jasechko added.

Perrone and Jasechko are now examining how groundwater levels vary over time in the context of climate change. Connecting these rates of change to the depths of actual wells will provide better predictions of where groundwater access is at risk.

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World's first successful embryo transfer in rhinos paves the way for saving the northern white rhinos from extinction

BioRescue, an international consortium of scientists and conservationists, succeeded in achieving the world's first pregnancy of a rhinoceros after an embryo transfer. The southern white rhino embryo was produced in vitro from collected egg cells and sperm and transferred into a southern white rhino surrogate mother at the Ol Pejeta Conservancy in Kenya on September 24, 2023. The BioRescue team confirmed a pregnancy of 70 days with a well-developed 6.4 cm long male embryo. The successful embryo transfer and pregnancy are a proof of concept and allow to now safely move to the transfer of northern white rhino embryos -- a cornerstone in the mission to save the northern white rhino from extinction.

On September 24, 2023, the BioRescue scientists and veterinarians, led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), transferred two southern white rhino embryos into Curra, a southern white rhinoceros, selected as a surrogate mother at the Ol Pejeta Conservancy in Kenya. The oocytes used in producing the embryos were retrieved from Elenore, a southern white rhinoceros living in the Pairi Daiza Zoo in Belgium. The sperm used for fertilisation originated from the male Athos from the Zoo Salzburg in Hellbrunn, Austria. The oocytes from Elenore were fertilised in vitro by intracytoplasmic sperm injection (ICSI) and developed into blastoscysts at Avantea's laboratories in Cremona, Italy. For the embryo transfer in Kenya, the BioRescue scientists transferred two embryos to increase the chance of a successful outcome.

So far, the BioRescue team has performed 13 embryo transfers in rhinoceroses, three in Kenya and ten in Europe. Previously, an embryo transfer, which is a widely used technique in domestic species, has never been attempted in rhinos. BioRescue scientists developed the necessary techniques, by building on decades of their own research.

Currently, there are only two northern white rhinos left in the world: The female Najin and her daughter Fatu. Additionally, living cells from 12 different northern white rhino individuals are stored in liquid nitrogen. The last two females currently live in Kenya, at Ol Pejeta Conservancy, where they are guarded and cared for day and night. Since 2019, the BioRescue conservation science programme produced and cryopreserved 30 northern white rhino embryos. These are currently stored in liquid nitrogen at minus 196 degrees Celsius in Berlin, Germany, and Cremona, Italy, awaiting embryo transfer into southern white rhino surrogate mothers. The successful transfer of a southern white rhino embryo is a proof of concept that allows to take this crucial step -- an embryo transfer with a northern white rhino embryo -- for the first time.

The embryo transfer in this subspecies is entirely new ground as a veterinary and scientific procedure, and all protocols, methods and pieces of equipment had to be newly developed from scratch. As it is the established routine with all BioRescue procedures, the embryo transfers are accompanied by an ethical assessment conducted by Padua University. This was also the case in September, when all participants of the embryo transfer filled out a questionnaire that proposed any possible scenarios during the procedure, and attendant risks to animals and participants.

The vasectomised, sterile teaser bull Ouwan mated with Curra on September 17 and 18, signalling the ideal timing for the embryo transfer, which took place on September 24. After the procedure until November 2023, Curra was monitored on a daily basis in the enclosure at the Ol Pejeta Conservancy. During this period, Ouwan showed no further interest in Curra, a first sign of a successful embryo transfer resulting in pregnancy. The BioRescue team was scheduled for November 28 to perform a pregnancy check in Curra, but the teaser bull Ouwan was found dead on November 22 and Curra was found dead on November 25. Apparently, extremely heavy rains led to a flooding of the surrogate enclosure and set free dormant clostridianbacteria spores. The dissection of the animals revealed a severe systemic infection by a clostridian bacterial strain and resultant intoxication by the bacterial toxin. It also revealed that Curra was pregnant with a 70 days old male fetus that was 6.4 cm long. Tissue samples of the fetus were collected and transported to the Max Delbrück Centre for Molecular Medicine and the Leibniz-IZW in Berlin, Germany. In January 2024, it was confirmed through the analysis of the fetus DNA that the pregnancy resulted from the embryo transfer.

When the BioRescue team arrived in Kenya on November 28, the preliminary results indicated an intoxication with the clostridian bacterial strains Paraclostridium bifermentans and Paenicolostridium sordellii. Immediately after the incident, the BioRescue team, including Kenya Wildlife Service, Wildlife Training Research Institute, Ol Pejeta Conservancy and Safari Park Dvur Králové formed a crisis team on site and established fast and effective measures to protect all current semi-captive rhinos including the last two northern white rhinos Najin and Fatu. The measures included a vaccination programme, quarantine of affected areas and fencing of new emergency enclosures.

The next steps in the BioRescue research programme included the selection and preparation of a new teaser bull. The bull will allow the scientists to know when a possible surrogate female is ready to receive an embryo implantation. The team also has to select the next surrogate mothers. After these steps, which will take several months, an embryo transfer with a northern white rhino embryo will be attempted.

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Records of cometary dust hitting the asteroid Ryugu

Ryugu is a near-Earth asteroid that gained significant attention when the Japanese Hayabusa2 mission collected samples and returned them to Earth. These samples have proven to offer a treasure trove of insights into the solar systems, including the possible role of asteroids in delivering organic molecules to earth.

Now, a team of scientists have performed an intensive investigation of Ryugu samples, discovering evidence that points to cometary organic matter being transported from space to the near-Earth region.

The team included Megumi Matsumoto, an assistant professor from the Earth Science Department at Tohoku University Graduate School of Science.

Details of their findings were published in the journal Science Advances on January 19, 2024.

Asteroid Ryugu has no protective atmospheres, and its surface layer is directly exposed to space.

Small interplanetary dust in space can hit the asteroid surface, causing changes to the composition of the asteroid surface materials.

Matsumoto and her colleagues revealed that the sample surfaces contain small 'melt splashes,' ranging in size from 5 to 20 micrometers.

These melt splashes were created when micrometeoroids of cometary dust bombarded Ryugu.

"Our 3D CT imaging and chemical analyses showed that the melt splashes consist mainly of silicate glasses with voids and small inclusions of spherical iron sulfides," says Matsumoto.

"The chemical compositions of the melt splashes suggest that Ryugu's hydrous silicates mixed with cometary dust."

The mixing and melting of Ryugu's surface materials and cometary dust during impact induced heating and rapid cooling formed the melt splashes.

The voids correspond to the water vapor released from the Ryugu's hydrous silicates and subsequently captured in the melt splashes.

Analysis also revealed small carbonaceous materials with abundant nano-pores and iron sulfide inclusions in the melt splashes.

The carbonaceous materials are texturally similar to primitive organic matter in cometary dust, though they lack nitrogen and oxygen, making them chemically different from organic matter.

"We propose that the carbonaceous materials formed from cometary organic matter via the evaporation of volatiles, such as nitrogen and oxygen, during the impact-induced heating. This suggests that cometary matter was transported to the near-Earth region from the outer solar system," adds Matsumoto.

"This organic matter might be the small seeds of life once delivered from space to Earth."

Read more at Science Daily