How Saharan dust regulates hurricane rainfall

Giant plumes of Sahara Desert dust that gust across the Atlantic can suppress hurricane formation over the ocean and affect weather in North America.

But thick dust plumes can also lead to heavier rainfall -- and potentially more destruction -- from landfalling storms, according to a July 24 study in Science Advances. The research shows a previously unknown relationship between hurricane rainfall and Saharan dust plumes.

"Surprisingly, the leading factor controlling hurricane precipitation is not, as traditionally thought, sea surface temperature or humidity in the atmosphere. Instead, it's Sahara dust," said the corresponding author Yuan Wang, an assistant professor of Earth system science at the Stanford Doerr School of Sustainability.

Previous studies have found that Saharan dust transport may decline dramatically in the coming decades and hurricane rainfall will likely increase due to human-caused climate change.

However, uncertainty remains around the questions of how climate change will affect outflows of dust from the Sahara and how much more rainfall we should expect from future hurricanes. Additional questions surround the complex relationships among Saharan dust, ocean temperatures, and hurricane formation, intensity, and precipitation. Filling in the gaps will be critical to anticipating and mitigating the impacts of climate change.

"Hurricanes are among the most destructive weather phenomena on Earth," said Wang. Even relatively weak hurricanes can produce heavy rains and flooding hundreds of miles inland. "For conventional weather predictions, especially hurricane predictions, I don't think dust has received sufficient attention to this point."

Competing effects

Dust can have competing effects on tropical cyclones, which are classified as hurricanes in the North Atlantic, central North Pacific, and eastern North Pacific when maximum sustained wind speeds reach 74 miles per hour or higher.

"A dust particle can make ice clouds form more efficiently in the core of the hurricane, which can produce more precipitation," Wang explained, referring to this effect as microphysical enhancement. Dust can also block solar radiation and cool sea surface temperatures around a storm's core, which weakens the tropical cyclone.

Wang and colleagues set out to first develop a machine learning model capable of predicting hurricane rainfall, and then identify the underlying mathematical and physical relationships.

The researchers used 19 years of meteorological data and hourly satellite precipitation observations to predict rainfall from individual hurricanes.

The results show a key predictor of rainfall is dust optical depth, a measure of how much light filters through a dusty plume. They revealed a boomerang-shaped relationship in which rainfall increases with dust optical depths between 0.03 and 0.06, and sharply decreases thereafter. In other words, at high concentrations, dust shifts from boosting to suppressing rainfall.

"Normally, when dust loading is low, the microphysical enhancement effect is more pronounced. If dust loading is high, it can more efficiently shield [the ocean] surface from sunlight, and what we call the 'radiative suppression effect' will be dominant," Wang said.

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New geological datings place the first European hominids in the south of the Iberian Peninsula 1.3 million years ago

One of the most important controversies about human evolution and expansion is when and by what route the first hominids arrived in Europe from the African continent. Now, geological dating techniques at the Orce sites (Baza basin, Granada, Spain) place the human remains found in this area as the oldest in Europe, at approximately 1.3 million years old. These results reinforce the hypothesis that humans arrived in Europe through the south of the Iberian Peninsula, through the Strait of Gibraltar, instead of returning to the Mediterranean via the Asian route. The study, led by Lluís Gibert, researcher and lecturer at the University of Barcelona's Faculty of Earth Sciences, has involved the participation of researchers from the Berkeley Geochronology Centre and Murray State University (United States).

Analysis of a new sampling area

The new dating has been based on the analysis of the paleomagnetism of an area of the Orce region, which has never been sampled before and which has been protected from the erosion that this basin has suffered over the years. This technique is a relative dating method based on the study of the inversion of the magnetic poles of the planet due to the internal dynamics of the Earth. These changes do not have a specific periodicity, but they are recorded in the minerals and make it possible to establish time periods from the different magnetic events.

These new data are very precise thanks to the long sedimentary sequence that outcrops in Orce. "The uniqueness of these sites is that they are stratified and within a very long sedimentary sequence, more than eighty metres long. Normally, the sites are found in caves or within very short stratigraphic sequences, which do not allow you to develop long palaeomagnetic sequences in which you can find different magnetic reversals," says Lluís Gibert.

The researchers have been able to identify a magnetic polarity sequence "with five magnetic events that allow them to place the three Orce sites with human presence between the Olduvai and Jaramillo subchron, that is, between 1.77 and 1.07 million years ago (Ma)," says the researcher. Subsequently, they have applied a statistical age model to accurately refine the chronology of the different stratigraphic levels with a margin of error of only 70,000 years. The result of this innovative methodology is that the oldest site with human presence in Europe would be Venta Micena with an age of 1.32 Ma, followed by Barranco León, with an age of 1.28 and finally Fuente Nueva 3, with an age of 1.23 Ma. "With these data, the other major site on the peninsula, the Sima del Elefante in Atapuerca, would be relegated to second place, far behind Orce, between 0.2 and 0.4 Ma more modern," adds the researcher.

Fauna underpins the antiquity of the site

To complete the dating, the study has also analyzed the fauna found at the different sites in Orce, as this is different depending on the period, and compared it with that found at other Early Pleistocene sites in other parts of Europe.

In this sense, the paper presents a detailed analysis of the micromammals and large mammals from all the Orce sites, carried out by the expert Robert Martin, based on the palaeontological collections stored at the Museum of the Catalan Institute of Palaeontology Miguel Crusafont (IPS) in Sabadell. "The results indicate that the small and large fauna of Orce is more primitive than, for example, that of the Sima del Elefante, where the evidence shows that the rodent Allophaiomys lavocati is more evolved than the Allophaiomys recovered from the Orce sites," Gibert explains.Another relevant indicator of the age of the Orce sites is the absence of the ancestors of the pigs. "These animals are considered to be Asian immigrants and have not been found in any European site between 1 and 1.5 Ma, while they have been found in the Sima del Elefante, supporting that the Orce fauna is older," explains the researcher.

Evidence pointing to passage through Gibraltar

This new dating would be added, according to the researcher, to other evidence that would tip the balance in favour of the colonization of Europe through the Strait of Gibraltar, rather than the alternative route: the return to the Mediterranean via Asia, such as "the existence of a lithic industry with similarities to that found in the north of the African continent and also the presence of remains of African fauna in the south of the peninsula, such as those of Hippopotamus, found in the sites of Orce, and those of Theropithecus oswaldi, an African primate similar to a baboon, found in the Victoria cave, a site near Cartagena (Murcia), non-existent anywhere else in Europe."

"We also defend the hypothesis -- adds the researcher -- that they arrived from Gibraltar because no older evidence has been found at any other site along the alternative route."

These new data are very precise thanks to the long sedimentary sequence that outcrops in Orce.

Similarity with hominids from the island of Flores

With these results, the researchers point to a "diachronism" between the oldest occupation of Asia, measuring 1.8 Ma, and the oldest occupation of Europe, which would be 1.3 Ma ago, so that African hominids would have arrived in southwestern Europe more than 0.5 Ma after leaving Africa for the first time about 2 Ma ago. "These differences in human expansion can be explained by the fact that Europe is isolated from Asia and Africa by biogeographical barriers that are difficult to overcome, both to the east (Bosphorus Strait, Dardanelles, Sea of Marmara) and to the west (Strait of Gibraltar). Humanity arrived in Europe when it had the necessary technology to cross maritime barriers, as happened before a million years ago on the island of Flores (Indonesia)," says Gibert. In this sense, the researcher adds that the Gibraltar route currently requires crossing up to fourteen kilometres of sea route, but "perhaps in the past this distance was shorter at certain times due to the high tectonic activity in this region and the fluctuations in sea level that favoured migrations."

"As cited in the paper -- he adds -- , we have identified other migrations of African fauna through Gibraltar at earlier times, 6.2 and 5.5 Ma ago when the Strait of Gibraltar was very narrow."

Human remains in Orce

A total of five human remains were found at the Orce sites since excavations began in 1982 by the palaeoanthropologist Josep Gibert. Firstly, two fragments of humerus bitten by hyenas were found at Venta Micena, as well as parts of a cranial fragment consisting of two parietals and an occipital, associated with an abundant Early Pleistocene fauna. The human provenance of these remains generated great controversy for years, although independent palaeoproteomic studies by the universities of Granada and San Francisco identified human proteins in the remains.

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Rock solid evidence: Angola geology reveals prehistoric split between South America and Africa

An SMU-led research team has found that ancient rocks and fossils from long-extinct marine reptiles in Angola clearly show a key part of Earth's past -- the splitting of South America and Africa and the subsequent formation of the South Atlantic Ocean.

With their easily visualized "jigsaw-puzzle fit," it has long been known that the western coast of Africa and the eastern coast of South America once nestled together in the supercontinent Gondwana -- which broke off from the larger landmass of Pangea.

The research team says the southern coast of Angola, where they dug up the samples, arguably provides the most complete geological record ever recorded on land of the two continents moving apart and the opening of the South Atlantic Ocean. Rocks and fossils found date back from 130 million years ago to 71 million years.

"There are places that you can go to in South America, for instance, where you can see this part of the split or that part of it, but in Angola, it's all laid out in one place," said Louis L. Jacobs, SMU professor emeritus of Earth Sciences and president of ISEM. Jacobs is the lead author of a study published in The Geological Society, London, Special Publications.

"Before this, there was not a place known to go and see the rocks on the surface that really reflected the opening of the South Atlantic Ocean, because they're now in the ocean or eroded away," Jacobs said.

Angola rocks and fossils tell the whole story

Africa and South America started to split around 140 million years ago, causing gashes in Earth's crust called rifts to open up along pre-existing weaknesses. As the tectonic plates beneath South America and Africa moved apart, magma from the Earth's mantle rose to the surface, creating a new oceanic crust and pushing the continents away from each other. And eventually, the South Atlantic Ocean filled the void between these two newly-formed continents.

Scientists have previously found evidence of these events through geophysics and well cores drilled through the ocean floor.

But these tell-tale signs have never been found in one place, or been so clearly visible for anyone to see, said study co-author Michael J. Polcyn, research associate in the Huffington Department of Earth Sciences and senior research fellow, ISEM at SMU.

"It's one thing for a geophysicist to be able to look at seismic data and make inferences from that," he said. "It's quite another thing to be able to take a school field trip out to the rock formations, or outcrops, and say this is when the lava was spreading from eastern South America. Or this was when it was a continuous land."

Essentially, Angola presents the opportunity for someone to easily walk through each phase of this geologically significant chapter in Earth's history.

"That gives Angola major bragging rights," Jacobs said.

Jacobs, Polcyn and Diana P. Vineyard -- who is a research associate at SMU -- worked with an international team of paleontologists, geologists and others to analyze both the rock formations they found in eight different locations on the coast and the fossils within them.

Fieldwork in Angola's Namibe Province began in 2005. At that time, the research team recognized particular types of sediments, which gave them a good indication of what the western coast of Africa had been like at various stages millions of years ago. For instance, fields of lava revealed volcanic outpourings, and faults or breaks showed where the continents were being rifted apart. Sediments and salt deposits showed ocean flooding and evaporation, while overlying oceanic sediments and marine reptiles showed completion of the South Atlantic Ocean.

Paleontologists, meanwhile, discovered fossils in Angola from large marine reptiles that had lived late during the Cretaceous Period, right after the Atlantic Ocean was completed and while it grew wider.

By bringing together experts from a wide range of fields, "we were able to document when there was no ocean at all, to when there was a fresh enough ocean for those reptiles to thrive and have enough to eat," Vineyard said.

Many of the ancient fossils are currently on display at the Smithsonian's National Museum of Natural History "Sea Monsters Unearthed: Life in Angola's Ancient Seas" exhibit, which was co-produced with SMU -- a nationally-ranked Dallas-based private university.

Read more at Science Daily

Africa's iconic flamingos threatened by rising lake levels

It is one of the world's most spectacular sights -- huge flocks or "flamboyances" of flamingos around East Africa's lakes -- as seen in the film Out of Africa or David Attenborough's A Perfect Planet.

But new research led by King's College London has revealed how the lesser flamingo is at danger of being flushed out of its historic feeding grounds, with serious consequences for the future of the species.

For the first time satellite earth observation data has been used to study all the key flamingo feeding lakes in Ethiopia, Kenya and Tanzania over two decades and it identified how rising water levels are reducing the birds' main food source.

The authors warn the birds are likely to be pushed into new unprotected areas in the search for food, especially given predicted higher levels of rainfall linked to climate change.

They are now calling for coordinated conservation action across international borders, improved monitoring and more sustainable management of land surrounding important flamingo lakes.

Lead author Aidan Byrne, a PhD student jointly supervised by King's College London and the Natural History Museum, said the region was home to more than three quarters of the global population of lesser flamingos, but their numbers are declining.

"Lesser flamingos in East Africa are increasingly vulnerable, particularly with increased rainfall predicted for the region under climate change. Without improved lake monitoring and catchment management practices, the highly specialised species found in soda lake ecosystems -- including lesser flamingos -- could be lost," he said.

The study, published in the journal Current Biology, is the first in which satellite earth observation data has been used to study all 22 key flamingo feeding soda lakes in East Africa. This analysis was combined with climate records and bird observation data over more than two decades.

By studying on this large scale, for the first time researchers were able to see changing food availability across the whole network of lakes, including significant declines in recent years, and how bird numbers decreased as lake surface area increased. They also identified the lakes the birds might move to in the future.

Co-author, Dr Emma Tebbs, from King's College London said whilst flamingos naturally travel in search of food, the degradation of their historic feeding and breeding sites was a serious concern.

"East African populations could potentially move north or south away from the equator in search of food resources. And whilst six study lakes increased in habitat suitability from 2010 to 2022, only three of those have some level of conservation protection.

"Increases in water levels could lead to lesser flamingos becoming more reliant on lakes that are unprotected, outside of current nature reserves and protected sites, which has implications for conservation and ecotourism revenues."

Soda lakes are some of the harshest environments on Earth, being both highly saline and very alkaline. Despite this, many species have evolved to thrive in these conditions, including the flamingo and its phytoplankton prey, which they filter from the water using their sieve-like beaks.

The research found rising water levels across the region's soda lakes were diluting their normally salty and alkaline nature, leading to a decline in populations of phytoplankton, which was measured by the amount of a photosynthetic pigment called chlorophyll-a present in the lakes.

The team found that phytoplankton levels have been declining over the 23 years of study and linked this to increases in the surface areas of the lakes over the same period.

The largest losses in phytoplankton biomass occurred in the equatorial Kenyan lakes, notably at the important tourist lakes Bogoria, Nakuru and Elmenteita, and in the northern Tanzanian lakes that saw the largest increases in surface area.

Nakuru is one of the most important flamingo feeding lakes in East Africa, historically supporting over one million birds at a time. The lake increased in surface area by 91% from 2009 to 2022 whilst its mean chlorophyll-a concentrations halved.

Natron in Tanzania is the only regular breeding site for lesser flamingos in East Africa and it has experienced declining productivity alongside rising water levels in recent years. If phytoplankton biomass continues to decline there and at other nearby feeding lakes, it will no longer be a suitable breeding site.

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Persian plateau unveiled as crucial hub for early human migration out of Africa

A new study combining genetic, palaeoecological, and archaeological evidence has unveiled the Persian Plateau as a pivotal geographic location serving as a hub for Homo sapiens during the early stages of their migration out of Africa.

This revelation sheds new light on the complex journey of human populations, challenging previous understandings of our species' expansion into Eurasia.

The study, published in Nature Communications, highlights a crucial period between approximately 70,000 to 45,000 years ago when human populations did not uniformly spread across Eurasia, leaving a gap in our understanding of their whereabouts during this time frame.

Key findings from the research include:

• The Persian plateau as a hub for early human settlement: Using a novel genetic approach combined with palaeoecological modelling, the study revealed the Persian Plateau as the region where from population waves that settled all of Eurasia originated.
• This region emerged as a suitable habitat capable of supporting a larger population compared with other areas in West Asia.
• Genetic resemblance in ancient and modern populations: The genetic component identified in populations from the Persian Plateau underlines its long-lasting differentiation in the area, compatible with the hub nature of the region, and is ancestral to the genetic components already known to have inhabited the Plateau.
• Such a genetic signature was detected thanks to a new approach that disentangles 40,000 years of admixture and other confounding events. This genetic connection underscores the Plateau's significance as a pivotal location for early human settlement and subsequent migrations.

Study co-author Professor Michael Petraglia, Director of Griffith University's Australian Research Centre for Human Evolution, provided a much clearer picture of these early human movements.

"Our multidisciplinary study provides a more coherent view of the ancient past, offering insights into the critical period between the Out of Africa expansion and the differentiation of Eurasian populations," Professor Petraglia said.

"The Persian Plateau emerges as a key region, underlining the need for further archaeological explorations."

First author Leonardo Vallini of the University of Padova, Italy, said: "The discovery elucidates a 20,000 year long portion of the history of Homo sapiens outside of Africa, a timeframe during which we interacted with Neanderthal populations, and sheds light on the relationships between various Eurasian populations, providing crucial clues for understanding the demographic history of our species across Europe, East Asia, and Oceania."

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Toba supereruption unveils new insights into early human migration

Modern humans dispersed from Africa multiple times, but the event that led to global expansion occurred less than 100,000 years ago. Some researchers hypothesize that dispersals were restricted to "green corridors" formed during humid intervals when food was abundant and human populations expanded in lockstep with their environments. But a new study in Nature, including ASU researchers Curtis Marean, Christopher Campisano, and Jayde Hirniak, suggests that humans also may have dispersed during arid intervals along "blue highways" created by seasonal rivers. Researchers also found evidence of cooking and stone tools that represent the oldest evidence of archery.

Working in the Horn of Africa, researchers have uncovered evidence showing how early modern humans survived in the wake of the eruption of Toba, one of the largest supervolcanoes in history, some 74,000 years ago. The behavioral flexibility of these people not only helped them live through the supereruption but may have facilitated the later dispersal of modern humans out of Africa and across the rest of the world.

"This study confirms the results from Pinnacle Point in South Africa -- the eruption of Toba may have changed the environment in Africa, but people adapted and survived that eruption-caused environmental change," said Marean, research scientist with the Institute of Human Origins and Foundation Professor with the School of Human Evolution and Social Change.

The team investigated the Shinfa-Metema 1 site in the lowlands of present-day northwestern Ethiopia along the Shinfa River, a tributary of the Blue Nile River.

The supereruption occurred during the middle of the time when the site was occupied and is documented by tiny glass shards whose chemistry matches that of Toba.

Pinpoint timing through cryptotephra

"One of the ground-breaking implications of this study," said Marean, "is that with the new cryptotephra methods developed for our prior study in South Africa, and now applied here to Ethiopia, we can correlate sites across Africa, and perhaps the world, at a resolution of several weeks of time."

Cryptotephra are signature volcanic glass shards that can range from 80-20 microns in size, which is smaller than the diameter of a human hair. To extract these microscopic shards from archaeological sediment requires patience and great attention to detail.

"Searching for cryptotephra at these archaeological sites is like looking for a needle in a haystack, but not knowing if there is even a needle. However, having the ability to correlate sites 5,000 miles apart, and potentially further, to within weeks instead of thousands of years makes it all worth it," said Christopher Campisano, research scientist with the Institute of Human Origins and professor with the School of Human Evolution and Social Change.

"This study, once again," said Campisano, "highlights the importance of the University of Nevada-Las Vegas/Arizona State University team pushing the limits for successfully analyzing extremely low abundance cryptotephra to date and correlate archaeological sites across Africa."

The methods for identifying low abundance cryptotephra at Pinnacle Point were first developed at University of Nevada Las Vegas led by the late Gene Smith and Racheal Johnsen and now carried on at Arizona State University's Sediment and TEphra Preparation (STEP) Lab.

School of Human Evolution and Social Change graduate student Jayde Hirniak led ASU's effort to create its own cryptotephra lab -- the STEP Lab -- working with Campisano and building on methods developed at UNLV. Hirniak also collaborated with cryptotephra labs in the United Kingdom that work with sediment samples preserving hundreds or thousands of glass shards. Now Hirniak's primary expertise is in tephrochronology, which involves the use of volcanic ash to link archaeological and paleoenvironmental records and place them on the same timeline, which was her contribution to this research.

"Our lab at ASU was built to process extremely low abundance cryptotephra horizons (<10 shards per gram) using a highly specialized technique. There are only a few labs in the world with these capabilities," said Hirniak.

Migrations along "blue highways"

Based on isotope geochemistry of the teeth of fossil mammals and ostrich eggshells, they concluded that the site was occupied by humans during a time with long dry seasons on a par with some of the most seasonally arid habitats in East Africa today. Additional findings suggest that when river flows stopped during dry periods, people adapted by hunting animals that came to the remaining waterholes to drink. As waterholes continued to shrink, it became easier to capture fish without any special equipment, and diets shifted more heavily to fish.

Its climatic effects appear to have produced a longer dry season, causing people in the area to rely even more on fish. The shrinking of the waterholes may also have pushed humans to migrate outward in search of more food.

"As people depleted food in and around a given dry season waterhole, they were likely forced to move to new waterholes," said John Kappelman, a UT anthropology and earth and planetary sciences professor and lead author of the study. "Seasonal rivers thus functioned as 'pumps' that siphoned populations out along the channels from one waterhole to another, potentially driving the most recent out-of-Africa dispersal.

The humans who lived at Shinfa-Metema 1 are unlikely to have been members of the group that left Africa. However, the behavioral flexibility that helped them adapt to challenging climatic conditions such as the Toba supereruption was probably a key trait of Middle Stone Age humans that allowed our species to ultimately disperse from Africa and expand across the globe.

The people living in the Shinfa-Metema 1 site hunted a variety of terrestrial animals, from antelope to monkey, as attested to by cut marks on the bones, and apparently cooked their meals as shown by evidence of controlled fire at the site. The most distinctive stone tools are small, symmetrical triangular points. Analyses show that the points are most likely arrowheads that, at 74,000 years in age, represent the oldest evidence of archery.

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Reforestation programs could threaten vast area of tropical grasslands

New research led by the University of Liverpool reveals the scale of inappropriate reforestation projects across Africa.

A study published in the journal Science reveals that an area the size of France is under threat by forest restoration initiatives due to inappropriate restoration in the form of tree-planting.

Researchers analysed the areas of land committed to restoration via reforestation and found that many programmes include areas classified as non-forest systems.

They believe that the inclusion of non-forest systems such as savannas and grasslands, which are threatened by increased tree cover, is the key issue.

They warn that planting trees in these grassy areas, which are structurally, functionally and compositionally distinct from forests, could be a risk to wildlife such as rhinos and wildebeest, as well as people who depend on these ecosystems.

Kate Parr, Professor of Tropical Ecology at the University's School of Environmental Sciences and author of the study, said: "Restoration of ecosystems is needed and important, but it must be done in a way that is appropriate to each system.

"Non-forest systems such as savannas are misclassified as forest and therefore considered in need of restoration with trees.

"There is an urgent need to revise definitions so that savannas are not confused with forest because increasing trees is a threat to the integrity and persistence of savannas and grasslands."

"Highlighting this issue now means there is still time to negate this threat and ensure that non-forest systems receive appropriate restoration."

Dr Nicola Stevens, Trapnell Research Fellow in African Environments at the University of Oxford and co-author of the paper said: "The urgency of implementing large-scale tree planting is prompting funding of inadequately assessed projects that will most likely have negligible sequestration benefits and cause potential social and ecological harm."

The study highlights that the issues raised are not unique to Africa and many other non-forest areas, for example the open savannas and grasslands of India and Brazil, could face a similar future due to inappropriate 'restoration' with trees.

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How did the bushpig cross the strait? A great puzzle in African mammal biogeography solved by genomics

Africa has a huge diversity of large mammals, but their evolutionary relationships and movement across the continent over time often remain a mystery. A new scientific study sheds light on longstanding questions about the interplay between evolution and geography in one of these mammals, namely the iconic African bushpig, and helps settle a major question regarding prehistoric human activities shaping biodiversity patterns in Africa.

In the ongoing biodiversity crisis, large terrestrial animals are more threatened by extinction than any other group of organisms. The African continent holds an impressively intact large-mammal community, but there is still a lot we do not know about how these species evolved, became diverse and adapted to the changing climate and habitats. Many of these questions can be addressed by investigating the genomes and genetic variation across species.

New research, published in Nature Communications, uses genomics to answer these evolutionary questions that have been debated amongst scientists for decades: 1) how and when did bushpigs cross the Mozambique Channel and arrive at the island of Madagascar, 2) is there one or two species of bushpigs?

"This study is a result of a large international collaboration with researchers from Africa and Europe. We sequenced 67 complete bushpig genomes and by using a range of different genetic analyses, we were able to address these long-standing puzzles in African evolution and biogeography," explains one of the senior authors of the study, Associate Professor at the Department of Biology, Rasmus Heller.

Were pigs ferried across the channel during the Medieval era?

The island of Madagascar separated from the African mainland around 160 million years ago, resulting in a largely unique flora and fauna. Remarkably, the bushpig is the only large, wild terrestrial mammal species that has somehow historically crossed the 400-kilometer-wide Mozambique Channel and made it from mainland Africa to the island of Madagascar.

"Our study establishes that the bushpig was introduced to Madagascar ≈1,000-5,000 years ago from South/South-East Africa," Rasmus states. Their arrival therefore coincides with the arrival of humans to Madagascar from a region around southern Africa. Rasmus continues: "The likely explanation for this is that people transported these bushpigs across the channel. These results contradict previously published studies which dated the arrival of bushpigs ≈480,000 years ago, well before humans were present on the island." It has been suggested that some endemic Madagascar species might have arrived by rafting as passengers on floats of vegetation.

"Intriguingly, our results raise a host of new questions: was the bushpig actually brought to Madagascar as a somewhat domesticated species? There is no archaeological or other evidence of bushpig domestication ever occurring, despite them being an important source of protein for many rural communities. And who was it that transported these animals to Madagascar? Was it Bantu-speakers, Austronesian-speakers or both? These questions and others still remain to be explored," explains Renzo F. Balboa, postdoc at the Department of Biology and one of the leading authors of the study.

Does two actually equal one?

African bushpigs, which primarily are found in East/Southern Africa, and red river hogs, which are found in West/Central Africa, were considered the same species in the past, but were subsequently redefined as two species around the 1990s, largely due to their quite distinctive looks.

The red river hogs are, as the name implies red, and have long, tufted ears reminiscent of a comical Star Wars character, while eastern and southern African bushpigs are greyish and look more like our own wild boar, although with a beautiful white mane thrown in for good measure.

Biologists have been arguing for decades about whether these two forms are actually one or two different species -- a debate that is characteristic of similar scientific uncertainty surrounding many other African mammals.

"In this study, we were able to conclude that red river hogs and bushpigs have had lots of gene flow, which means they are not only able to potentially interbreed, but they have in fact done so extensively when they have met in central Africa. Furthermore, the branching of the two types in the Tree of Life is not all that old, only a few hundred thousand years, which is not long in the evolutionary scheme of things. Hence, we now know that although there are two quite different-looking lineages of bushpigs, their biological separation is incomplete, depending on how you define species," explains Laura D. Bertola, postdoc at the Department of Biology and the other leading author of the study.

Laura continues: "Genomic data can give us insights into patterns of biodiversity on a much higher resolution than previously possible. For example, we can infer detailed population structure, but also underlying processes like gene flow and selection. Gaining improved insights into patterns of biodiversity and the underlying processes that drive them, will be crucial for effective conservation measures."

Africa is a unique continent regarding the diversity of the megafauna which is still around. Studying the evolutionary history of these species can give us important insights into African biodiversity, which is highly relevant at a time where biodiversity is being lost at an alarming pace. The new findings contribute to our understanding of prehistoric relations between Africa's humans and wildlife, but also the very fundamentals about how much biodiversity there is on this amazing continent.

"This study is a great example of how involving local researchers and wildlife management authorities can lead to more robust and inclusive scientific research," co-author Vincent Muwanika, Associate Professor of Conservation Biology, at Makerere University, Uganda, concludes.

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Protected areas for elephants work best if they are connected

Conservation measures have successfully stopped declines in the African savanna elephant population across southern Africa, but the pattern varies locally, according to a new study.

The evidence suggests that the long-term solution to elephant survival requires not only that areas are protected but that they are also connected to allow populations to stabilize naturally, an international research team says.

Their study, published on January 5th in the peer-reviewed journal Science Advances, collected survey estimates and calculated growth rates for more than 100 elephant populations in southern Africa between 1995 and 2020, accounting for an estimated 70% of the global savanna elephant population.

"This is the most comprehensive analysis of growth rates for any large mammal population in the world," said co-author Rob Guldemond, director of the Conservation Ecological Research Unit (CERU) at the University of Pretoria, in South Africa.

Overall, the survey's results are positive: There are the same number of elephants now as there were 25 years ago, a rare conservation win at a time when the planet is rapidly losing biodiversity.

However, the pattern is not consistent across regions. Some areas, such as south Tanzania, eastern Zambia, and northern Zimbabwe, experienced severe declines due to illegal ivory poaching.

In contrast, populations in other regions like north Botswana are booming.

"Unchecked growth isn't necessarily a good thing, however," says study co-author Stuart Pimm, the Doris Duke Professor of Conservation at Duke University in North Carolina.

"Rapidly increasing populations can outgrow and damage their local environment and prove hard to manage -- introducing a threat to their long-term stability," Pimm says.

In addition to documenting local growth rates, the team also looked at the features of the local populations to identify what makes them stable, that is neither growing nor declining.

Elephant populations in well-protected but isolated parks, sometimes called "fortress conservation," grow rapidly in the absence of threats but are unsustainable in the long term.

These elephants will likely need future conservation interventions, such as translocation or birth control, which are both costly and intensive endeavors.

The team found that the most stable populations occur in large, core areas that are surrounded by buffer zones.

The core areas are defined by their strong levels of environmental protection and minimal human impact, whereas the buffers allow some activities such as sustainable farming, forestry, or trophy hunting.

Unlike the insular fortresses, core areas are connected to other parks, allowing herds to move naturally.

"What's crucial is that you need a mix of areas with more stable core populations linked to more variable buffer areas," said lead author Ryan Huang, a Duke Ph.D. now doing postdoctoral research at CERU.

"These buffers absorb immigrants when core populations get too high, but also provide escape routes when elephants face poor environmental conditions or other threats such as poaching," Huang said.

Connecting protected areas means elephants can freely move in and out.

This allows a natural equilibrium to occur without human intervention, sparing conservationists from using their limited resources to maintain balance.

"Calling for connecting parks isn't something new. Many have done so," Huang said.

"But surprisingly, there has not been a lot of published evidence of its effectiveness so far. This study helps quantify why this works."

Read more at Science Daily

Africa's dangerous air pollution levels are a global problem, says new research

A new report in Nature Geoscience has brought to light the challenge of air pollution levels in Africa and why international action is needed to combat it.

Over the last 50 years African nations have suffered from rapidly deteriorating air quality, making their cities some of the most polluted in the world. Particulate matter concentration levels are now five to ten levels greater than that recommended by the World Health Organisation, with the situation predicted to worsen as populations grow and industrialization accelerates.

However, far too little has been done to try and combat the dangerous air quality with just 0.01% of global air pollution funding currently spent in Africa.

The new perspective piece from the University of Birmingham, the University of Cambridge, Imperial College London, South Eastern Kenya University and the African Centre for Clean Air, published today (7 Nov) in Nature Geoscience, argues that tackling this issue requires collective efforts from African countries, regionally tailored solutions, and global collaboration.

Francis Pope, Professor of Atmospheric Science at the University of Birmingham and one of the co-authors, said: "The burning of biomass fuel for cooking, heating, and lighting, the crude oil exploitation and coal mining industries, and old vehicles being shipped in from Europe are all causes for the poor air quality in African nations. This dangerous air can cause complex and sometimes deadly health issues for those breathing it in. If this wasn't enough of a reason to tackle this issue, air pollution in Africa is not just a problem for people living on the continent, but for the wider world, limiting the ability to meet global climate targets and combat the climate emergency."

Multiple efforts have been made over the years to tackle air pollution, such as the signing of C40 Clean Air Declaration by ten major African cities. Initiatives to monitor air-pollution levels and collect much needed data have also begun to gather momentum.

But there is still much to be done. The researchers argue that regional and international efforts must be coordinated to achieve real change and leverage existing knowledge on controlling and cutting air pollution.

They call for urgent collaboration on:

• Continuous air monitoring via a network of sensors in order to build a detailed picture of air pollution variations and track progress.
• Investment in clean energy such as solar, hydropower and wind to meet Africa's energy demand which is expected to double by 2040.
• Improved solid waste management to prevent dumping and burning of waste and improve reuse, recycling, and recovery rates.
• Investment in environmentally friendly technology to ensure African countries can grow economically whilst avoiding dirty and obsolete technology from the Global North.
• Infrastructure improvements to curb emissions from the transport sector, improving public transport provision and adopting higher emission standards for fuel and imported vehicles.

Co-author of the article, Dr Gabriel Okello, from the Institute for Sustainability Leadership at the University of Cambridge and the African Centre for Clean Air, said: "Air pollution is complex and multifaceted with different sources and patterns within society. Addressing it requires more ambitious, collaborative, and participatory approaches centred on involvement of stakeholders in policy, academia, business, communities to co-design and co-produce context-specific interventions. This should be catalysed by increased investment in interventions that are addressing air pollution. Africa has the opportunity to leverage the growing political will and tap into the young population to accelerate action towards the five broad suggestions in our paper."

Dr Andriannah Mbandi, from South Eastern Kenya University and co-author of the article, said: "The burden of air pollution unjustly rests on poorer populations, and women and children, as they most likely face higher exposure to pollutants and most probably experience more impacts. Thus, clean air actions will go some ways in redressing some of these inequalities in Africa, in addition to the benefits to health and the environment."

Read more at Science Daily

Chimpanzees use hilltops to conduct reconnaissance on rival groups -- study

Chimpanzees use high ground to conduct reconnaissance on rival groups, often before making forays into enemy territory at times when there is reduced risk of confrontation, a new study suggests.

Tactical use of elevated terrain in warfare situations is considered unique to humans -- until now. For the first time, one of the oldest military strategies has been observed in our closest evolutionary relatives.

Researchers conducted a three-year study of two neighbouring chimpanzee groups in the West African forests of Côte d'Ivoire, tracking the primates as they traversed their respective territories, including an overlapping border area where skirmishes occasionally took place.

The team found that chimpanzees were more than twice as likely to climb hills when heading towards this contested frontier as when they were travelling into the heart of their own territory.*

While atop border hills, chimpanzees were more likely to refrain from noisily eating or foraging and spend time quietly resting -- enabling them to hear distant sounds of rival groups, say researchers.

The further away the location of hostile chimpanzees, the greater the likelihood of an advance into dangerous territory upon descending the hill. This suggests that chimpanzees on high ground gauge the distance of rivals, and act accordingly to make incursions while avoiding costly fights.

Other mammal species such as meerkats use high ground to keep watch for predators or call to mates. However, researchers say this is the first evidence for an animal other than humans making strategic use of elevation to assess the risks of "intergroup conflict."

"Tactical warfare is considered a driver of human evolution," said Dr Sylvain Lemoine, a biological anthropologist from the University of Cambridge's Department of Archaeology, and lead author of the study published in the journal PLOS Biology.

"This chimpanzee behaviour requires complex cognitive abilities that help to defend or expand their territories, and would be favoured by natural selection."

"Exploiting the landscape for territorial control is deeply rooted in our evolutionary history. In this use of war-like strategy by chimpanzees we are perhaps seeing traces of the small scale proto-warfare that probably existed in prehistoric hunter-gatherer populations."

The study was conducted at the Taï Chimpanzee Project, where Lemoine worked during his PhD. The project is currently led by study senior author Dr Roman Wittig from CNRS in France.**

Teams of researchers spend 8-12 hours a day following four groups that are "habituated" to the presence of humans. It is one of the few sites where data is collected simultaneously on multiple communities of wild chimpanzees.

The project researchers have GPS trackers, through which the study authors were able to reproduce maps of two chimpanzee territories that border each other, including elevation data. These were matched to old French colonial maps to confirm topography.

Each group consisted of 30-40 adult chimpanzees at any one time. The study used over 21,000 hours of track logs from a total of 58 animals recorded between 2013 and 2016.

To establish and protect their territory, chimpanzees perform regular tours of the periphery that form a sort of "border patrol," says Lemoine. "Patrols are often conducted in subgroups that stay close and limit noise. As an observer, you get a sense that patrolling has begun. They move and stop at the same time, a bit like a hunt," he said.

The type of hills near the border used for reconnaissance are known as "inselbergs": isolated rocky outcrops that break up the forest canopy.*** Chimpanzees repeatedly returned to some of these inselbergs, where time on the summit was passed in a more muted state.

"These aren't so much lookout points as listen-out points," said Lemoine. "Chimpanzees drum on tree trunks and make excitable vocalisations called pant-hoots to communicate with group members or assert their territory. These sounds can be heard over a kilometre away, even in dense forest."

"It may be that chimpanzees climb hilltops near the edge of their territory when they have yet to hear signs of rival groups. Resting quietly on an elevated rock formation is an ideal condition for the auditory detection of distant adversaries."

Researchers analysed tactical movements in the half an hour after a stop longer than five minutes on a hill near the border, and compared it to movements after stops in low-lying border areas.

Following a hilltop recce, the likelihood of advancing into enemy territory increased from 40% when rivals were 500 metres away, to 50% when rivals were at 1000m, to 60% when rivals were at 3000m.

"Chimpanzees often expand their territory by encroaching and patrolling in that of their neighbours. Hilltop information-gathering will help them to do this while reducing risks of encountering any enemies," said Lemoine. "The border zone between the two groups was in a state of flux."

More territory can boost food provision and mating chances, says Lemoine. His previous work suggests that larger chimpanzee groups live in bigger territories with reduced pressure from rivals, which in turn increases birth rates within communities.

The latest research suggests that chimpanzees use hilltop reconnaissance to avoid confrontation, and violence is relatively rare, says Lemoine. But fights, and even kidnappings and killings, did occur between rival group members.

"Occasionally, raiding parties of two or three males venture deep into enemy territory, which can lead to fighting. Confrontations between rival chimpanzees are extremely noisy. The animals go into an intimidating frenzy, screaming and defecating and gripping each other's genitals."

Read more at Science Daily

The remains of an ancient planet lie deep within Earth

In the 1980s, geophysicists made a startling discovery: two continent-sized blobs of unusual material were found deep near the center of the Earth, one beneath the African continent and one beneath the Pacific Ocean. Each blob is twice the size of the Moon and likely composed of different proportions of elements than the mantle surrounding it.

Where did these strange blobs -- formally known as large low-velocity provinces (LLVPs) -- come from? A new study led by Caltech researchers suggests that they are remnants of an ancient planet that violently collided with Earth billions of years ago in the same giant impact that created our Moon.

The study, published in the journal Nature on November 1, also proposes an answer to another planetary science mystery. Researchers have long hypothesized that the Moon was created in the aftermath of a giant impact between Earth and a smaller planet dubbed Theia, but no trace of Theia has ever been found in the asteroid belt or in meteorites. This new study suggests that most of Theia was absorbed into the young Earth, forming the LLVPs, while residual debris from the impact coalesced into the Moon.

The research was led by Qian Yuan, O.K. Earl Postdoctoral Scholar Research Associate in the laboratories of both Paul Asimow (MS '93, PhD '97), the Eleanor and John R. McMillan Professor of Geology and Geochemistry; and Michael Gurnis, the John E. And Hazel S. Smits Professor of Geophysics and Clarence R. Allen Leadership Chair, director of Caltech's Seismological Laboratory, and director of the Schmidt Academy for Software Engineering at Caltech.

Scientists first discovered the LLVPs by measuring seismic waves traveling through the earth. Seismic waves travel at different speeds through different materials, and in the 1980s, the first hints emerged of large-scale three-dimensional variations deep within the structure of Earth. In the deepest mantle, the seismic wave pattern is dominated by the signatures of two large structures near the Earth's core that researchers believe possess an unusually high level of iron. This high iron content means the regions are denser than their surroundings, causing seismic waves passing through them to slow down and leading to the name "large low velocity provinces."

Yuan, a geophysicist by training, was attending a seminar about planet formation given by Mikhail Zolotov, a professor at Arizona State University, in 2019. Zolotov presented the giant-impact hypothesis, while Qian noted that the Moon is relatively rich in iron. Zolotov added that no trace had been found of the impactor that must have collided with the Earth.

"Right after Mikhail had said that no one knows where the impactor is now, I had a 'eureka moment' and realized that the iron-rich impactor could have transformed into mantle blobs," says Yuan.

Yuan worked with multidisciplinary collaborators to model different scenarios for Theia's chemical composition and its impact with Earth. The simulations confirmed that the physics of the collision could have led to the formation of both the LLVPs and the Moon. Some of Theia's mantle could have become incorporated into the Earth's own, where it ultimately clumped and crystallized together to form the two distinct blobs detectable today at Earth's core-mantle boundary today; other debris from the collision mixed together to form the Moon.

Given such a violent impact, why did Theia's material clump into the two distinct blobs instead of mixing together with the rest of the forming planet? The researchers' simulations showed that much of the energy delivered by Theia's impact remained in the upper half of the mantle, leaving Earth's lower mantle cooler than estimated by earlier, lower-resolution impact models. Because the lower mantle was not totally melted by the impact, the blobs of iron-rich material from Theia stayed largely intact as they sifted down to the base of the mantle, like the colored masses of paraffin wax in a turned-off lava lamp. Had the lower mantle been hotter (that is, if it had received more energy from the impact), it would have mixed more thoroughly with the iron-rich material, like the colors in a stirred pot of paints.

The next steps are to examine how the early presence of Theia's heterogeneous material deep within the earth might have influenced our planet's interior processes, such as plate tectonics.

Read more at Science Daily

Probing the deep genetic structure of Africa

Using ancestry decomposition techniques an international research team has revealed a deeply divergent ancestry among admixed populations from the Angolan Namib desert. This unique genetic heritage brings the researchers closer to understanding the distribution of genetic variation in the broader region of southern Africa before the spread of food production.

Africa is the birthplace of modern humans and the continent with the highest level of genetic diversity. While ancient DNA studies are revealing some aspects of the genetic structure of Africa before the spread of food production, issues concerning DNA preservation have limited the insights from ancient DNA.

Hoping to find clues in modern populations, researchers from a Portuguese-Angolan TwinLab ventured into the Angolan Namib desert -- a remote, multi-ethnic region where different traditions met. "We were able to locate groups which were thought to have disappeared more than 50 years ago," states Jorge Rocha, a population geneticist from Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO, University of Porto) who led the fieldwork, together with Angolan anthropologists Samuel and Teresa Aço from the Centro de Estudos do Deserto (CEDO).

Among the communities the team encountered are the Kwepe, a pastoral group who used to speak a language known as Kwadi. "Kwadi was a click-language that shared a common ancestor with the Khoe languages spoken by foragers and herders across southern Africa," explains Anne-Maria Fehn, a linguist from CIBIO who participated in the fieldwork and was able to interview what may well be the last two speakers of Kwadi. "Khoe-Kwadi languages have been linked to a prehistoric migration of eastern African pastoralists," adds Rocha, whose research focuses on southern African population history. In addition, the team contacted Bantu-speaking groups that are part of the dominant pastoral tradition of southwest Africa, as well as marginalized groups whose origins have been associated with a foraging tradition, distinct from that of the neighboring Kalahari peoples, and whose original language was supposedly lost.

Modern DNA research can complement ancient DNA studies

The team's new study shows that the inhabitants of the Angolan Namib are quite divergent from other modern populations but also highly structured among themselves. "In agreement with our previous studies on the maternally-inherited DNA, most genome-wide diversity segregates according to socio-economic status. A lot of our efforts were placed in understanding how much of this local variation and global excentricity was caused by genetic drift -- a random process that disproportionally affects small populations -- and by admixture from vanished populations," says Sandra Oliveira, a researcher at the University of Bern in Switzerland who worked with these populations during her PhD and post-doc studies with Rocha and Mark Stoneking at CIBIO and the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig, Germany. The team demonstrated that besides the high impact of genetic drift, which contributed to differences among neighboring groups of different socio-economic status, the descendants of Kwadi speakers and the marginalized communities of the Namib Desert retain a unique Pre-Bantu ancestry that is only found in populations from the Namib desert.

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Newly discovered 'primitive cousins of T rex' shed light on the end of the age of dinosaurs in Africa

Fossils of primitive cousins of T. rex that had short, bulldog snouts and even shorter arms have been discovered by scientists in Morocco. The two new dinosaur species belong to the Abelisauridae, a family of carnivorous dinosaurs that were counterparts to the tyrannosaurs of the Northern Hemisphere. They lived at the end of the Cretaceous period and show that dinosaurs were diverse in Africa just before their mass extinction by an asteroid 66 million years ago.

Two new species of dinosaur have been found from the end of the Cretaceous in Morocco, just outside of Casablanca. One species, found near the town of Sidi Daoui, is represented by a foot bone from a predator about two and a half metres (eight feet) long. The other, from nearby Sidi Chennane, is the shin bone of a carnivore that grew to around five metres (15 feet) in length.

Both were part of a family of primitive carnivorous dinosaurs known as abelisaurs, and lived alongside the much larger abelisaur Chenanisaurus barbaricus, showing that Morocco was home to diverse dinosaur species just before a giant asteroid struck at the end of the Cretaceous, ending the age of dinosaurs.

Dr Nick Longrich, from the Milner Centre for Evolution at the University of Bath, led the study. He said: "What's surprising here is that these are marine beds.

"It's a shallow, tropical sea full of plesiosaurs, mosasaurs, and sharks. It's not exactly a place you'd expect to find a lot of dinosaurs. But we're finding them."

Even though dinosaurs account for a small proportion of the fossils, the region is so rich in fossils, it has produced the best picture of African dinosaurs from the end of the age of dinosaurs.

Rather than finding the same few species, palaeontologists often recover fossils from new species, suggesting the beds host an extremely diverse dinosaur fauna.

So far, the small number of dinosaur fossils that have been recovered represent five different species -- a small duckbill dinosaur named Ajnabia, a long-necked titanosaur, the giant abelisaur Chenanisaurus, and now the two new abelisaurs.

Dr Longrich said: "We have other fossils as well, but they're currently under study. So we can't say much about them at the moment, except that this was an amazingly diverse dinosaur fauna."

The last dinosaurs vanished around 66 million years ago, along with as much as 90% of all species on earth, including mosasaurs, plesiosaurs, pterosaurs and ammonites. The pattern of the end-Cretaceous extinction and its causes have been debated for over two hundred years.

A giant asteroid impact in the Yucatan peninsula has been linked to their demise, although it's been argued that dinosaurs were already in decline. The Moroccan dinosaurs suggest that they thrived in North Africa up to the very end.

"The end of the Cretaceous in western North America definitely seems to become less diverse at the end," said Longrich. "But that's just one small part of the world. It's not clear that you can generalise from the dinosaurs of Wyoming and Montana to the whole world.

"It also grew colder near the end, so it might not be surprising if dinosaurs at higher latitudes became less diverse. But we don't know much about dinosaurs from lower latitudes."

In Morocco at least, they seem to have remained diverse and successful up until the end.

"When T. rex reigned as a megapredator in North America, abelisaurs sat at the top of the food chains in North Africa," said Nour-Eddine Jalil, a professor at the Natural History Museum and a researcher at Universite Cadi Ayyad in Morocco, who was a co-author on the paper.

"The dinosaur remains, despite their rarity, give the same messages as the more abundant marine reptile remains.

"They tell us that, just before the Cretaceous-Paleogene crisis, biodiversity was not declining but on the contrary, was diverse."

Read more at Science Daily

Elephant ancestors´ teeth evolved in response to long term changes in diet and climate in Africa

A new study shows that the cheek teeth of proboscideans (elephants and their ancient relatives) evolved in response to dietary changes due to vegetation changes and climate change in East Africa during the last 26 million years.

The latest study about of proboscideans (elephants and their ancient relatives) from the University of Helsinki provides proof that some proboscideans started to adapt to locally grass-rich environments in East Africa first by changing their behavior and starting to feed more on grasses. This happened in some lineages of proboscideans, such as choerolophodonts, much earlier than has been thought until now, about 23 to 11 million years ago in parts of East Africa

Also, around 7 million years ago in the lake Turkana region, increasingly grass-rich diets of the earliest true elephants were associated with dryer and more grass-rich savanna environments than elsewhere in East Africa.

"This supports the hypothesis of such regions as "species-factories" where evolutionary adaptation to changing environmental conditions first centered around," says Juha Saarinen from the University of Helsinki, who led the research.

Feeding on grasses is more demanding on teeth than feeding on most other kinds of plants due to a high content of mineral grains called phytoliths in their leaves, causing heavy abrasion on teeth.

Nonetheless, during the Early and Middle Miocene the choerolophodont lineage of proboscideans were able to shift to more grass-rich diets with relatively modest changes in the morphology of their teeth.

Since about 10 million years ago, major changes in climate had a more profound effect on the evolution of proboscidean teeth in East Africa, especially the evolution of true elephants (Elephantidae) with highly specialized high-crowned, multi-ridged molar teeth.

"We were able to show that the strongest peaks of drying of the East African climate during the last 7 million years (for example about 4 and 2 million years ago) correspond with evolutionary bursts in the increase of tooth crown height and the number of ridges on the molar teeth, while these evolutionary changes did not reverse during periods of less harsh climatic conditions" says Saarinen.

"This supports earlier suggestions that adaptive traits in organisms are adaptations to extreme rather than average environmental conditions."

Comparing evidence of past vegetation and the diet of elephants during the last 7 million years also showed an increase of grasslands and increasing dominance of grass-feeding elephants with highly specialized teeth throughout that period in most parts of East Africa. However, during the last 100,000 years this situation changed probably because of drastic fluctuations in global climate and eventually only the dietarily more generalist modern African savanna elephant (Loxodonta africana) with less specialized teeth survived in East Africa. Ecological generalism might similarly explain the survival of Asian elephant (Elephas maximus) in Asia, while the African forest elephant (L. cyclotis) was able to find refuge in more forested parts of Central and Western Africa.

Read more at Science Daily

Study explains unusual deformation in Earth's largest continental rift

Computer models confirm that the African Superplume is responsible for the unusual deformations as well as rift-parallel seismic anisotropy observed beneath the East African Rift System.

In continental rifting, there's a mix of stretching and breaking that reaches deep into the Earth, said geophysicist D. Sarah Stamps. Continental rifting involves the stretching of the lithosphere -- the outermost, rigid layer of the Earth. As the lithosphere stretches thin, its shallow regions experience brittle deformation, with the breaking of rock and earthquakes.

Stamps, who studies these processes by using computer modeling and GPS to map surface motions with millimeter precision, compares a rifting continent's different deformation styles with playing with Silly Putty.

"If you hit Silly Putty with a hammer, it can actually crack and break," said Stamps, associate professor in the Department of Geosciences, part of the Virginia Tech College of Science. "But if you slowly pull it apart, the Silly Putty stretches. So on different time scales, Earth's lithosphere behaves in different ways."

Whether in stretching or breaking, the deformation that comes with continental rifting usually follows predictable directional patterns in relation to the rift: The deformation tends to be perpendicular to the rift. The East African Rift System, the Earth's largest continental rift system, has those rift-perpendicular deformations. But after measuring the rift system with GPS instruments for more than 12 years, Stamps also observed deformation that went in the opposite direction, parallel to the system's rifts. Her team at the Geodesy and Tectonophysics Labhas worked to find out why.

In a recent study published in theJournal of Geophysical Research, the team explored the processes behind the East African Rift System using 3D thermomechanical modeling developed by the study's first author, Tahiry Rajaonarison, a postdoctoral researcher at New Mexico Tech who earned his Ph.D. at Virginia Tech as a member of Stamps's lab. His models showed that the rift system's unusual, rift-parallel deformation is driven by northward mantle flow associated with the African Superplume, a massive upwelling of mantle that rises from deep within the Earth beneath southwest Africa and goes northeast across the continent, becoming more shallow as it extends northward.

Their findings, combined with insights from a study the researchers published in 2021 using Rajaonarison's modeling techniques, could help clear up scientific debate on which plate-driving forces dominate the East African Rift System, accounting for both its rift-perpendicular and rift-parallel deformation: lithospheric buoyancy forces, mantle traction forces, or both.

As a postdoctoral researcher, Stamps began observing the East African Rift System's unusual, rift-parallel deformation using data from GPS stations that measured signals from more than 30 satellites orbiting Earth, from about 25,000 kilometers away. Her observations have added a layer of complexity to the debate around what drives the rift system.

Some scientists see the rifting in East Africa as driven primarily by lithospheric buoyancy forces, which are relatively shallow forces attributed mainly to the rift system's high topography, known as the African Superswell, and to density variations in the lithosphere. Others point to horizontal mantle traction forces, the deeper forces arising from interactions with mantle flowing horizontally beneath East Africa, as the primary driver.

The team's 2021 study found through 3D computational simulations that the rift and its deformation could be driven by a combination of the two forces. Their models showed that lithospheric buoyancy forces were responsible for the more predictable, rift-perpendicular deformation, but those forces couldn't account for the anomalous, rift-parallel deformation picked up by Stamps's GPS measurements.

In their newly published study, Rajaonarison again used 3D thermomechanical modeling, this time to focus on the source of the rift-parallel deformations. His models confirm that the African Superplume is responsible for the unusual deformations as well as rift-parallel seismic anisotropy observed beneath the East African Rift System.

Seismic anisotropy is the orientation or alignment of rocks in a particular direction in response to mantle flow, melt pockets, or pre-existing structural fabrics in the lithosphere, Stamps said. In this case, the rocks' alignment followed the direction of the African Superplume's northward mantle flow, which suggests mantle flow as their source.

"We are saying that the mantle flow is not driving the east-west, rift-perpendicular direction of some of the deformations, but that it may be causing the anomalous northward deformation parallel to the rift," Rajaonarison said. "We confirmed previous ideas that lithospheric buoyancy forces are driving the rift, but we're bringing new insight that anomalous deformation can happen in East Africa."

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Lost giants: New study reveals the abundance decline of African megafauna

Faysal Bibi (Museum für Naturkunde, Berlin) and Juan L. Cantalapiedra (University of Alcalá, Madrid) used measurements of thousands of fossil teeth to reconstruct the size and abundance of African large mammals (>15 kg) over the last 10 million years. Despite many uncertainties affecting preservation in the fossil record, the study revealed a highly similar relationship between an animal's size and its abundance between fossil and extant communities, indicating that fundamental ecological processes governing the structure of living communities are also preserved in the fossil record.

Above 45 kg, the researchers found evidence for decreasing abundance with increasing size, a pattern that aligns with the ecological 'rule of metabolic scaling', whereby larger species have lower population densities compared to smaller ones. A deviation from the predicted ecological pattern was that mammals between ~15 and 45 kg were far less numerous than expected, both in living and fossil communities. They interpreted this as a signature of savanna habitats (where monkeys and small forest-living antelopes are rare).

The big surprise came when the researchers examined how size-abundance distributions changed over time. They discovered that earlier communities, older than ~4 million years ago, had a considerably higher number of large-sized individuals and a greater proportion of total biomass in larger size categories, than did younger communities. The high abundance of large individuals in these fossil African communities -- with some individual elephants reaching sizes over 10 tons -- is unparalleled in ecosystems today. Since that time, there has been a gradual loss of large-sized individuals from the fossil record, reflecting the long-term decline of late Pliocene and Pleistocene large mammal diversity, and resulting in the impoverished and 'miniaturized' communities we know today.

The study confirms recent work arguing for the deep-time antiquity of African megafaunal losses and challenging the idea that the decline of African megafauna was primarily driven by human activities. While the spread of humans across the globe during the late Pleistocene and Holocene (the last ~100,000 years) coincided with major extinction of many large animals, the research supports the idea that megafaunal losses in Africa began much earlier, around 4 million years ago, and long before humans learned to engage in efficient hunting. Instead, the study highlights environmental factors, such as the long-term decrease in global temperatures and the expansion of tropical grasslands, as potential drivers of megafaunal extinctions.

The study also found that the loss of large individuals and the restructuring of biomass distributions in African large mammal communities could have been linked to decreases in primary productivity. Using an established relationship between the types of mammalian tooth shapes (morphological traits) and plant productivity (net primary productivity) today, the researchers calculated productivity for African communities in the past. They found an approximately two-thirds decrease in productivity since the Late Miocene (> 5 million years ago), a pattern observed globally, and that could have significantly diminished the carrying capacity of large mammal communities, leading to reduced diversity and accelerated extinction of large species.

The research opens new avenues for understanding the dynamics of ecosystems and the complex interactions between individuals, species, and their environment. By analyzing fossil abundance data and incorporating size-based approaches, scientists can gain valuable insights into the ecological dynamics underlying extinction.

Read more at Science Daily

Lingering effects of Neanderthal DNA found in modern humans

Recent scientific discoveries have shown that Neanderthal genes comprise some 1 to 4% of the genome of present-day humans whose ancestors migrated out of Africa, but the question remained open on how much those genes are still actively influencing human traits -- until now.

A multi-institution research team including Cornell University has developed a new suite of computational genetic tools to address the genetic effects of interbreeding between humans of non-African ancestry and Neanderthals that took place some 50,000 years ago. (The study applies only to descendants of those who migrated from Africa before Neanderthals died out, and in particular, those of European ancestry.)

In a study published in eLife, the researchers reported that some Neanderthal genes are responsible for certain traits in modern humans, including several with a significant influence on the immune system. Overall, however, the study shows that modern human genes are winning out over successive generations.

"Interestingly, we found that several of the identified genes involved in modern human immune, metabolic and developmental systems might have influenced human evolution after the ancestors' migration out of Africa," said study co-lead author April (Xinzhu) Wei, an assistant professor of computational biology in the College of Arts and Sciences. "We have made our custom software available for free download and use by anyone interested in further research."

Using a vast dataset from the UK Biobank consisting of genetic and trait information of nearly 300,000 Brits of non-African ancestry, the researchers analyzed more than 235,000 genetic variants likely to have originated from Neanderthals. They found that 4,303 of those differences in DNA are playing a substantial role in modern humans and influencing 47 distinct genetic traits, such as how fast someone can burn calories or a person's natural immune resistance to certain diseases.

Unlike previous studies that could not fully exclude genes from modern human variants, the new study leveraged more precise statistical methods to focus on the variants attributable to Neanderthal genes.

While the study used a dataset of almost exclusively white individuals living in the United Kingdom, the new computational methods developed by the team could offer a path forward in gleaning evolutionary insights from other large databases to delve deeper into archaic humans' genetic influences on modern humans.

"For scientists studying human evolution interested in understanding how interbreeding with archaic humans tens of thousands of years ago still shapes the biology of many present-day humans, this study can fill in some of those blanks," said senior investigator Sriram Sankararaman, an associate professor at the University of California, Los Angeles. "More broadly, our findings can also provide new insights for evolutionary biologists looking at how the echoes of these types of events may have both beneficial and detrimental consequences."

Read more at Science Daily

Ecosystem evolution in Africa

Ohio University's Nancy J. Stevens Ph.D., distinguished professor in the Department of Biomedical Sciences in the Heritage College of Osteopathic Medicine, is coauthor on a paper published in the journal Science and funded by the National Science Foundation that documents the evolution of grassland ecosystems on continental Africa.

Collaborating with an extensive team of geologists and paleoanthropologists from universities around the world, led by researchers from Baylor University and the University of Minnesota, the team synthesized data from nine Early Miocene fossil localities in the East African Rift of Kenya and Uganda to determine that the expansion of grassy biomes dominated by grasses with the C4 photosynthetic pathway in Eastern Africa occurred more than 10 million years earlier.

According to the paper, previous reconstructions of early Miocene ecosystems, 15-20 million years ago, have suggested that equatorial Africa was covered by a semi-continuous forest, with open habitats dominated by warm-season, or C4, grasses that were uncommon until 8-10 million years ago. C4 refers to the different pathways that plants use to capture carbon dioxide during photosynthesis. C4 plants produce a four-carbon molecule and are more adapted to warm or hot season condition under moist or dry environments.

As the researchers gathered expertise about geological features, isotopes and fossils found at the sites, the paradigm of a continuous forest blanketing equatorial Africa during the early Miocene shifted to a more complex mosaic of habitats that already included open environments with C4 grasses.

The result of this research pushes back the oldest evidence of C4 grass-dominated habitats in Africa -- and globally -- by more than 10 million years, with important implications for primate evolution and the origins of tropical C4 grasslands and savanna ecosystems across the African continent and around the world.

"We suspected that we would find C4 plants at some sites, but we didn't expect to find them at as many sites as we did, and in such high abundance," Daniel Peppe, lead author and associate professor at Baylor University, said.

A critical aspect of this work was that the team combined many different lines of evidence together: geology, fossil soils, isotopes and phytoliths (plant silica microfossils) to reach their conclusions.

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Ancient DNA reveals Asian ancestry introduced to East Africa in early modern times

While serfs toiled and knights jousted in Europe and samurai and shoguns rose to power in Japan, the medieval peoples of the Swahili civilization on the coast of East Africa lived in multicultural, coral-stone towns and engaged in trade networks spanning the Indian Ocean.

Archaeologists, anthropologists, and linguists have been locked in a century-long debate about how much people from outside Africa contributed to Swahili culture and ancestry. Swahili communities have their own histories, and evidence points in multiple directions.

The largest-yet analysis of ancient DNA in Africa, which includes the first ancient DNA recovered from members of the Swahili civilization, has now broken the stalemate.

The study reveals that a significant number of people from Southwest Asia moved to the Swahili coast in medieval and early modern times and had children with the people living there. Yet the research also shows that hallmarks of the Swahili civilization predated those arrivals.

"Archaeological evidence overwhelmingly showed that the medieval Swahili civilization was an African one, but we still wanted to understand and contextualize the nonlocal heritage," said co-senior author Chapurukha Kusimba, professor of anthropology at the University of South Florida.

"Taking a genetics pathway to find the answers took courage and opened doors beyond which lie answers that force us to think in new ways," he said.

The analyses, published online March 29 in Nature, included the newly sequenced ancient DNA of 80 individuals from the Swahili coast and inland neighbors dating from 1300 CE to 1900 CE.

They also included new genomic sequences from 93 present-day Swahili speakers and previously published genetic data from a variety of ancient and present-day eastern African and Eurasian groups.

The international team was led by Kusimba and David Reich, professor of genetics in the Blatavnik Institute at Harvard Medical School and professor of human evolutionary biology at Harvard University.

Mixing between Asia and Africa

The study revealed that around 1000 CE, a stream of migrants from Southwest Asia intermingled with African people at multiple locations along the Swahili coast, contributing close to half of the ancestry of the analyzed ancient individuals.

"The results provide unambiguous evidence of ongoing cultural mixing on the East African coast for more than a millennium, in which African people interacted and had families with immigrants from other parts of Africa and the Indian Ocean world," said Reich.

The study confirmed that the bedrock of Swahili culture remained unchanged even as the newcomers arrived and Islam became a dominant regional religion, said Kusimba; the primary language, tomb architecture, cuisine, material culture, and matrilocal marriage residence and matriarchal kinship remained African and Bantu in nature.

The findings contradict one widely discussed scholarly view, which held that there was little contribution from foreigners to Swahili peoples, the authors said.

The researchers added that the findings also refute a diametrically opposed viewpoint prevalent in colonial times, which held that Africans provided little contribution to the Swahili towns.

"Ancient DNA allowed us to address a longstanding controversy that could not be tested without genetic data from these times and places," Reich said.

The researchers found that the initial waves of newcomers were mainly from Persia. These findings align with the oldest Swahili oral stories, which tell of Persian (Shirazi) merchants or princes arriving on the Swahili shores.

"It was exciting to find biological evidence that Swahili oral history probably depicts Swahili genetic ancestry as well as cultural legacy," said Esther Brielle, research fellow in genetics in the Reich lab.

Brielle is co-first author of the paper with Stephanie Wynne-Jones at the University of York and Jeffrey Fleisher at Rice University.

After about 1500 CE, ancestry sources became increasingly Arabian. In later centuries, intermingling with other populations from Asia and Africa further changed the genetic makeup of Swahili-coast communities.

Ancestry contributions from women from India

Analyses also showed that the initial stream of migrants had about 90 percent ancestry from Persian men and 10 percent ancestry from Indian women.

Although South Asian-associated artifacts are well documented at Swahili archaeological sites and Indian words have been integrated into Swahili, "no one had previously hypothesized an important role for Indian people in contributing to the populations of the medieval Swahili towns," said Reich.

Extreme sex differences in genetic contributions

The predominant groups that contributed to Swahili-coast populations during the initial influx in 1000 CE were male Persians and femaleAfricans. Similar genetic signatures of sex imbalances in other populations around the world sometimes indicate that incoming men forcibly married local women, but that scenario does not align with the tradition of matriarchal Swahili societies, the authors said.

A more likely explanation, said Reich, is that "Persian men allied with and married into local trading families and adopted local customs to enable them to be more successful traders."

The authors say their hypothesis is supported by the fact that the children of Persian fathers and Swahili-coast mothers passed down the language of their mothers and that the region's matriarchal traditions did not change even after locals settled down with people from traditionally patriarchal regions in Persia and Arabia and practiced the Islamic religion of their male ancestors.

Genetics and identity

The team found that the proportion of Persian-Indian ancestry has decreased among many people of the Swahili coast in the last several centuries. Many among those in present-day Kenya who identify as Swahili and had their genomes analyzed were "genetically very different" from the people who lived in the region during medieval times, the authors found, while others retained substantial medieval ancestry.

"These results highlight an important lesson from ancient DNA: While we can learn about the past with genetics, it does not define present-day identity," said Reich.

Decolonizing history

In addition to helping to diversify the populations included in ancient DNA research, the study pushes back against "a profoundly difficult history" of more than 500 years of colonization in this region of Africa, which continues to be a major problem today, said Reich.

"The story of Swahili origins has been molded almost entirely by non-Swahili people," he said.

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