Countries need to co-operate on migration as climate crisis worsens

Humanity must rethink migration as the climate crisis drives rapid global changes, researchers say.

With significant migration expected -- and border policies hardening -- the researchers say the "time is ripe to highlight the benefits of collaboration between nations and regions."

By promoting the benefits of migration, especially in an era of ageing populations, global leaders could ensure a better future for people and societies.

The paper, published in the journal One Earth, comes from an international team of climate and social scientists including the universities of Wageningen, Exeter and Nanjing.

"Millions of people are projected to be displaced by sea-level rise in the next decades, and two billion could be exposed to extreme heat beyond their experience by the end of the century," said Professor Marten Scheffer, of Wageningen University.

"Ignoring or downplaying the inevitable global redistribution of people would lead to geo-political instability, and a polarised and fractured world.

"Instead, the international community must come together to rethink mobility and cultural integration to ensure a benign transition to this new world."

So far, most migration with significant climate dimensions has happened within countries, with people leaving areas affected by long-term decline in agricultural productivity or escaping conditions such as coastal erosion or extreme events.

While some large nations have different climate zones that can accommodate this, small countries do not.

The paper also warns that a "skewed distribution of wealth and associated power" makes it difficult for people to move, both within and between states.

Professor Tim Lenton, from Exeter's Global Systems Institute, said: "While many animal species are already changing their geographical distribution in response to climate change, and humans have done so for thousands of years, humanity now faces increasing barriers to this.

"Global warming exacerbates existing inequalities, making habitability a major political challenge of this century.

"Concrete cooperation is now needed to match migrant flows with demand for labour, to the benefit of the Global South and the developed world alike."

The paper says major reform of the food system, supported by movement of workers, could increase production while conserving nature -- especially if meat consumption is reduced in favour of plant-based diets.

Migration can therefore be a win-win for people and the climate, but leaders must make a positive case for economic benefits and effective integration.

"Playing up the social costs of migration appeals to national identity motivations, but fails to overcome problems from ageing populations," said Professor Neil Adger.

"Instead, leaders should focus on the economic and social benefits of new populations and effective integration, which benefits newcomers and original inhabitants alike.

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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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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."

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The surprising science behind long-distance bird migration

A team of scientists led by researchers at the University of Massachusetts Amherst has recently made a surprising discovery, with the help of a wind tunnel and a flock of birds. Songbirds, many of which make twice-yearly, non-stop flights of more than 1,000 miles to get from breeding range to wintering range, fuel themselves by burning lots of fat and a surprising amount of the protein making up lean body mass, including muscle, early in the flight. This flips the conventional wisdom on its head, which had assumed that migrating birds only ramped up protein consumption at the very end of their journeys, because they would need to use every ounce of muscle for wing-flapping, not fuel. The results appeared recently in the Proceedings of the National Academy of Sciences.

"Birds are amazing animals," says Cory Elowe, the paper's lead author and a postdoctoral researcher in biology at UMass Amherst, where he received his Ph.D. "They are extreme endurance athletes; a bird that weighs half an ounce can fly, non-stop, flapping for 100 hours at a time, from Canada to South America. How is this possible? How do they fuel their flight?"

For a very long time, biologists assumed that birds fueled such feats of endurance by burning fat reserves. And indeed, fat is an important part of migratory birds' secret mix. "The birds in our tests burned fat at a consistent rate throughout their flights," says Elowe. "But we also found that they burn protein at an extremely high rate very early in their flights, and that the rate at which they burn protein tapers off as the duration of the flight increases."

"This is a new insight," says Alexander Gerson, associate professor of biology at UMass Amherst and the paper's senior author. "No one has been able to measure protein burn to this extent in birds before."

"We knew that birds burned protein, but not at this rate, and not so early in their flights," continues Gerson. "What's more, these small songbirds can burn 20% of their muscle mass and then build it all back in a matter of days."

To make this breakthrough, Elowe had help from the bird banding operators at Long Point Bird Observatory, in Ontario, along the northern shore of Lake Erie. Every fall, millions of birds gather near the observatory on their journey to their wintering grounds -- including the blackpoll warbler, a small songbird that travels thousands of miles during its migration. After capturing 20 blackpolls and 44 yellow-rumped warblers -- a shorter distance migrant -- using mist nets, Elowe and his colleagues then transported the birds to the Advanced Facility for Avian Research at Western University, which has a specialized wind tunnel built specifically for observing birds in flight.

Elowe measured the birds' fat and lean body mass pre-flight, then, when the sun set, let the birds free in the wind tunnel. Because the birds naturally migrate at night, Elowe and his colleagues would then stay awake -- at one point, for 28 hours -- watching for when a bird would decide to rest. At that point, the researchers would collect the bird and again measure its fat and lean body mass content, comparing them with the pre-flight measurements.

"One of the biggest surprises was that every bird still had plenty of fat left when it chose to end its flight," says Elowe. "But their muscles were emaciated. Protein, not fat, seems to be a limiting factor in determining how far birds can fly."

The researchers still don't quite know why the birds are burning such vast stores of protein so early in their journeys, but the possible answers open up a wide range of future research avenues.

"How exactly is it possible to burn up your muscles and internal organs, and then rebuild them as quickly as these birds do," wonders Gerson. "What insights into the evolution of metabolism might these birds yield?"

Read more at Science Daily

A reconstruction of prehistoric temperatures for some of the oldest archaeological sites in North America

Scientists often look to the past for clues about how Earth's landscapes might shift under a changing climate, and for insight into the migrations of human communities through time. A new study offers both by providing, for the first time, a reconstruction of prehistoric temperatures for some of the first known North American settlements.

The study, published in Quaternary Science Reviews, uses new techniques to examine the past climate of Alaska's Tanana Valley. With a temperature record that reaches back 14,000 years, researchers now have a glimpse into the environment that supported humans living at some of the continent's oldest archaeological sites, where mammoth bones are preserved alongside evidence of human occupation. Reconstructing the past environment can help scientists understand the importance of the region for human migration into the Americas.

"When you think about what was happening in the Last Glacial Maximum, all these regions on Earth were super cold, with massive ice sheets, but this area was never fully glaciated," says Jennifer Kielhofer, Ph.D., a paleoclimatologist at DRI and lead author of the study. "We're hypothesizing that if this area was comparatively warm, maybe that would have been an attractive reason to come there and settle."

Kielhofer conducted the research during her doctoral studies at the University of Arizona, and was attracted to the Alaska location because of the wealth of research expertise being focused on the area. She also saw an opportunity to contribute to scientific understanding of a part of the world that is particularly sensitive to global climate change.

"We have to look to the past to try to better constrain how these areas have responded previously," she said, "and how they might respond in the future under climate scenarios that we predict."

Earlier research had relied on coarse temperature records by examining changes in vegetation and pollen. However, this information can only provide a general sense of whether a region was warming or cooling over time. To obtain a more precise history of temperatures, Kielhofer examined soil samples from the archeological sites. Using a technique known as brGDGT paleothermometry, she examined temperature records stored in bacteria to obtain a record of mean annual air temperature above freezing with a precision within about 2.8 degrees Celsius.

"Bacteria are everywhere," she said. "That's great because in areas where you might not have other means of recording or assessing past temperature, you have bacteria. They can preserve for millions of years, so it's a great opportunity to look at pretty much anywhere on Earth."

The results were surprising, she said, because many scientists had previously believed that the region experienced large swings in temperature, which may have contributed to the movement of early humans. But Kielhofer's data showed that temperatures in the Tanana Valley remained fairly stable over time.

"The region wasn't really responding to these global scale climate changes as we might expect," she said. "Because temperatures are really stable through this record, we can't necessarily use temperature as a way to explain changes in human occupation or adaptation through time, as scientists have previously tried to do."

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Short-distance migration critical for climate change adaptation

Short-distance migration, which accounts for the vast majority of migratory movements in the world, is crucial for climate change adaptation, according to new research from the University of East Anglia (UEA).

Contrary to common assumptions, most migratory movements are people moving short distances, largely due to economic, social and environmental factors, such as climate change.

A study of people living in the drylands of India and parts of Africa was carried out by UEA researchers in the School of International Development.

The paper, 'Everyday mobility and changing livelihood trajectories: implications for vulnerability and adaptation in dryland regions', is published today in a special issue on Everyday Adaptations in the journal Ecology and Society.

The research was led by Dr Mark Tebboth, Associate Professor in the Environment and International Development.

Dr Tebboth said: "Most attention is on international migration and how climate change will lead to huge numbers of people fleeing across borders, but actually the vast majority of people move short distances within their own country in order to take advantage of opportunities or in response to shocks and stresses in their lives.

"Supporting and enabling this migration will help people to continue to adapt the pressures in their lives."

The research looked at drivers and outcomes of people's mobility in the drylands of India, Ghana, Kenya and Namibia. Interviews were conducted during 2016 and 2017 with people living in those regions.

Drylands are the largest global biome, covering about 45 per cent of the Earth's land surface and accommodating more than a third of the globe's population.

Drylands are characterized by low and highly variable water availability and high temperatures. These regions are experiencing multiple pressures, including increasing rates of aridity and soil degradation; poorly planned and implemented development interventions; rapid population growth; historically high rates of poverty; poor communication infrastructure; and isolation from national centres of power -- stressing livelihoods reliant on natural resources.

In India, the study sites were in North Karnataka's Kolar district, where diversification to non-farm labour and daily commuting to Bangalore is common, and the Gulburga district, where agricultural livelihoods dominate and there has been historical outmigration to large cities.

In Kenya, the study sites were in Isiolo, the 'gateway to the north', where pastoralism, farming and tourism are common. Water is a scarce resource and this looks like it will become more severe in the future.

The study also included locations in the Upper West region of Ghana and the Omusati region of north-central Namibia.

Dr Tebboth said: "Far from being exceptional, this everyday mobility is ubiquitous and much removed from alarmist discourses of 'climate migration' that views movement as solely climate-driven.

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Prehistoric human migration in Southeast Asia driven by sea-level rise

An interdisciplinary team of scientists at Nanyang Technological University, Singapore (NTU, Singapore) has found that rapid sea-level rise drove early settlers in Southeast Asia to migrate during the prehistoric period, increasing the genetic diversity of the region today.

The Malay Peninsula and the islands of Sumatra, Borneo, and Java were originally part of a large landmass of rainforests and coastal mangroves in the South Asia continental shelf known as 'The Sundaland' some 26,000 years ago.

But during the last major period of global warming in Earth's history, from the Last Glacial Maximum period (approximately 26,000 -- 20,000 years ago) to the mid-50 Holocene (approximately 6,000 years ago), sea level rose 130 metres. The rise in sea level flooded and submerged half of The Sundaland, breaking land bridges and splitting the large landmass into smaller islands of the region today.

To understand the impact on humans living in The Sundaland during one of the most dramatic sea-level rises in the Earth's history, the team of NTU Singapore scientists reconstructed the history of the landmass using two different approaches: paleogeography -- the study of historical physical landscapes, and population genetics.

Lead investigator, Assistant ProfessorKim Hie Lim from NTU's Asian School of the Environment (ASE), and the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) at NTU said, "Environmental changes have profound impacts on human history, driving population migration, growth, and distribution. However, less discussed is how environmental changes can shape the genetics of populations. Our work is the first reported instance to provide proof that sea-level rise changed the genetic makeup of human populations in Southeast Asia -- a legacy that continues to impact current populations."

Using data for Southeast and South Asia's sea-level history, including ancient Singapore records established by the NTU's Earth Observatory of Singapore (EOS) and ASE, the research team constructed paleogeographic maps dating from 26,000 years ago to the present.

The NTU team also used whole-genome sequence data from 59 ethnic groups, including that belonging to populations native to Southeast and South Asia from 50,000 years ago. By analysing the high-quality genome data, the team was able to infer the genetic ancestry and demographic history of the groups, including their population size and distribution.

While researchers elsewhere have studied population history based on genetics, most of them used mitochondrial DNA (genes inherited from the mother), which does not tell the full picture of individual ancestry.

By using whole-genome sequence data -- precise information of an individual's entire genetic makeup inherited from both the mother and the father -- the NTU study offers an unbiased demographic history of the indigenous populations inhabiting The Sundaland.

The whole-genome sequence data was generated by the non-profit organisation GenomeAsia 100K. Launched in 2016 and hosted by NTU, the initiative aims to better understand the genome diversity of Asian ethnicities by sequencing 100,000 genomes of people living in Asia.

Contributing author, Professor Stephan Schuster, President's Chair in Genomics at NTU's School of Biological Sciences, Research Director of SCELSE, and Scientific Chair of GenomeAsia 100K, said, "GenomeAsia 100K systematically generates maps of Asian human genetic diversity, including indigenous ethnicities who have occupied the region for a long time. Integrating those maps with paleoclimatic data allows us now to understand exactly how past climatic events have resulted in ancient human migrations, as well as their impact on today's population structure."

The research is aligned with the NTU 2025 strategy, where the University adopts more collaborative, global and interdisciplinary means of research to address Singapore's national research priorities, such as health & society.

Piecing together the story of human migration in ancient Sundaland

Combining findings from the two approaches, the scientists inferred the changes in population density from the high quality historical paleogeographic maps generated.

The map paints a picture of prehistoric human migration in The Sundaland, showing that the earliest documented instance of forced human migration was driven by sea level rise.

The scientists found that two periods of rapid sea level rise (rates of sea level rise at46 mm/year and 22 mm/year)promoted the separation of populations into smaller groups across The Sundaland, as the large landmass became split into smaller islands, forcing people to disperse.

Even as the landmass decreased after the rapid sea level rises, temperature increased from the Last Glacial Maximum, creating a favourable living environment to support human population growth. This caused population density to surge by at least eight times from the Last Glacial Maximum, especially in the Island Southeast Asian region, including Malay Peninsula, Sumatra, and Borneo.

As a result, overpopulation drove people to migrate in search of new places to settle and the people in The Sundaland later migrated back northwards, towards Mainland Southeast Asia and South Asia.

This finding is supported by evidence of migration by the ancestors of the Malaysian indigenous group (Malaysia Negrito, or commonly referred to as 'Orang Asli') into South Asian tribal groups (Austroasiatic speakers). Genetic analysis confirmed common genetic ancestry between the Malaysian and South Asian indigenous groups.

The entire process of migration therefore shaped the diverse ethnicities across Southeast and South Asian regions, as early settlers of The Sundaland interbred across different indigenous groups.

Co-author of the study, Dr Li Tanghua, Senior Research Fellow at NTU's EOS said, "Based on our findings, the Orang Asli Malaysian indigenous group can be considered the first 'casualties' of sea-level rise, or what are known as 'climate refugees' today. The population had no choice but to move from their original territory due to environmental pressures. This forced migration caused an indelible change to the genetic footprint of South Asians, contributing to one of the most ethnically diverse regions in the world."

Findings useful to understand impact of sea level rise on human ancestry

The study, published in the peer-reviewed journal Communications Biology in February, is the first to trace the impact of prehistoric sea level rise to human ancestry in Southeast Asia.

Co-author of the study, Professor Benjamin Horton, Director of NTU's EOS, said, "The study of past sea levels is essential to predicting how increasing amounts of atmospheric carbon dioxide will alter Earth's climate and raise future sea levels. These projections inform how societies can mitigate and adapt to climate change impacts."

Read more at Science Daily

Tumultuous migration on the edge of the Hot Neptune Desert

All kinds of exoplanets orbit very close to their star. Some look like the Earth, others like Jupiter. Very few, however, are similar to Neptune. Why this anomaly in the distribution of exoplanets? Researchers from the University of Geneva (UNIGE) and the National Centre of Competence in Research (NCCR) PlanetS have observed a sample of planets located at the edge of this Hot Neptune Desert to understand its creation. Using a technique combining the two main methods of studying exoplanets (radial velocities and transits), they were able to establish that a part of these exoplanets has migrated in a turbulent way near their star, which pushed them out of the orbital plane where they were formed. These results are published in the specialized journal Astronomy & Astrophysics.

Since the discovery of the first exoplanet in 1995, researchers have detected more than 5'000 planets in our galactic neighborhood, most of them orbiting very close to their star. If the diversity of these new worlds ranges from gas giants the size of Jupiter or Saturn to smaller planets the size of Mercury, including rocky planets larger than the Earth, gas planets the size of Neptune seem to be missing. Astronomers call this empty ''box'' in the distribution of close-in planets the Hot Neptune Desert.

''The distribution of planets close to their star is shaped by a complex interaction between atmospheric and dynamical processes, i.e. the motions of the planets over time,'' comments Vincent Bourrier, assistant professor in the Department of Astronomy at the UNIGE Faculty of Science. ''Today we have several hypotheses to explain this desert but nothing is certain yet and the mystery remains''. Did these planets lose their atmosphere entirely, eroded by the intense radiation of their star? Did they migrate from their birthplace to the outer parts of the system by a different mechanism than other types of planets, preventing them from reaching the same close orbits?

Disrupted migration

In a recent work, a team of scientists from the UNIGE brings some answers by looking at the orbital architecture of the planets located at the edge of this desert. By surveying fourteen planets around this area, ranging from small planets to gas giants, the astronomers were interested in the way their orbits are oriented with respect to the axis of rotation of their star. This information makes it possible to distinguish the processes of soft migration (the planets move in the equatorial plane of their star where they were formed) from the processes of disruptive migration (the planets migrate and are pushed out of the plane where they were formed).

The researchers were able to show that most of the planets in their sample have an orbit misaligned with the stellar equator. ''We found that three-quarters of these planets have a polar orbit (they rotate above the poles of their star), which is a larger fraction than for planets further away from the desert. This reflects the role of disruptive migration processes in the formation of the desert,'' summarizes Vincent Bourrier, first author.

Two methods combined

To achieve these results, the scientists used the radial velocity method and the transit method, which are employed to study exoplanets. ''Analyzing the radial velocities during the transit of a planet allows us to determine if it orbits around the stellar equator, around the poles, or if the system is in an intermediate configuration, because different architectures will produce different signatures,'' explains Omar Attia, a doctoral student in the Department of Astronomy at the UNIGE Faculty of Science and second author of the study. These two methods were combined with data obtained with the HARPS and HARPS-North spectrographs, created at UNIGE and located on the 3.6m telescope of ESO (European Southern Observatory) and TNG (Telescopio Nazionale Galileo).

The path to understand all of the mechanisms involved in the formation of the Hot Neptune Desert is still long. It will be necessary in particular to explore with this technique the smallest planets at the edge of the desert, today difficult to access even with instruments of last generation such as the spectrograph ESPRESSO, built by the UNIGE and installed on the largest European telescopes. It will be necessary to wait for the commissioning of the ELT, the 39-meter super telescope of ESO, planned for 2027.

Read more at Science Daily

What are whale sharks up to?

The largest fish in the ocean is a globe-trotter that can occasionally be found basking in the coastal waters of the Panamanian Pacific. However, little more is known about the habits of the whale shark (Rhincodon typus) in the region. By satellite-tracking the whereabouts of 30 of them, scientists from the Smithsonian Tropical Research Institute (STRI), the Anderson Cabot Center for Ocean Life and the University of Panama explored the factors influencing this endangered species' behavior.

The R. typus, like other large sharks, may take years or even decades to reach maturity and reproduce, making them vulnerable to population declines, especially when combined with human threats. For instance, they may be caught in fishing nets as bycatch or face the risk of vessel strikes when shipping lanes overlap with their feeding sites. Being able to understand and predict whale shark behavior is a necessary step for protecting the species.

The satellite monitoring of this species, led by STRI marine ecologist Héctor Guzmán, found that whale sharks feed mainly in coastal waters, seamounts and ridges of the Panamanian Pacific, where they can find an abundance of their favorite foods: small fish and plankton. They were also spotted swimming north and southbound along the coast, towards Mexico and Ecuador, and towards the open ocean to feed.

"This species requires clear regional planning," said Guzmán. "Once the feeding and breeding aggregation areas are identified, some protection measures should be implemented. The newly announced marine protected area expansions across the region provide an interesting platform for large-scale conservation practices."

Although they used marine protected areas, the whale sharks also spent time in industrial fishing and vessel traffic zones, which could endanger them according to the new article published in Frontiers in Marine Science.

"The study shows how complex it is to protect whale sharks: tagged individuals visited 17 marine protected areas in 5 countries, but more than 77% of their time they were in areas without any protection," said Catalina Gómez, co-author of the study and marine ecologist at the University of Panama.

Thus, for highly migratory and endangered species such as the whale shark, conservation measures should go beyond the establishment of local marine protected areas.

Efforts should focus on protecting large oceanic areas and establishing marine corridors that transcend national borders, for example: the newly expanded Cordillera de Coiba Marine Protected Area in Panama or the Marine Conservation Corridor of the Eastern Tropical Pacific which connects Coiba with Costa Rica's Cocos Islands, the Galapagos in Ecuador and Colombia's Malpelo Island.

"A periodic tagging program should continue for two main reasons: first, we still don't know where the species reproduces and tracking may lead us in the right direction," said Guzmán. "Second, we know that they are moving across extensive areas. We have identified potential corridors or seaways, as well as aggregation areas, that require management attention and clear protection rules. Tracking will allow us to better identify those regional routes."

The satellite tracking also revealed a whale shark migratory pattern that seems to be associated with circular ocean currents called eddies.

"Eddies are recognized as potential feeding areas for migratory species or food epicenters in the oceans, so they can swim in those areas for a long time while foraging and feeding," said Guzman. "However, eddies are dynamic systems and change constantly in speed or strength, size and location, even seasonally. These feeding areas are important for conservation, especially considering their dynamics and potential changes associated with climate change."

Read more at Science Daily

Migratory birds have lighter-colored feathers

Migratory birds are specially adapted to find their way over extreme distances that represent remarkable tests of endurance. Now, researchers reporting December 6 in the journal Current Biology have discovered an unexpected way that migratory birds keep their cool during such arduous journeys: lighter-colored feathers.

"We found across nearly all species of birds, migratory species tend to be lighter colored than non-migratory species," said Kaspar Delhey of the Max Planck Institute for Ornithology, Seewiesen, Germany. "We think that lighter plumage coloration is selected in migratory species because it reduces the risk of overheating when exposed to sunshine. Lighter surfaces absorb less heat than darker ones, as anybody wearing dark clothes on a sunny day can attest! This would be particularly important for long-distance migrants that undertake extensive flights during which they cannot stop to rest in the shade."

Delhey and colleagues had been studying the effects of climate on bird coloration. Their earlier studies showed that, in general, lighter colored birds are found where temperatures are high and there is little shade. Presumably that's at least in part because the birds' lighter plumage helps to keep them cooler in the hot sun. Around that same time, the researchers came across studies by others showing that some birds fly at much higher altitudes during the day compared to at night.

"Because flying at high altitude is likely costly, these changes required an explanation," Delhey says. "One possibility was that flying higher, where it is colder, would offset the heat absorbed by the plumage when the sun was shining."

If so, they realized, another way to reduce the risk of overheating would be to absorb less solar radiation in the first place. It raised a question: have migratory species evolved lighter feathers?

To find out, they quantified overall plumage lightness (from 0 = black to 100 = white) for all bird species, using bird images from the Handbook of the Birds of the World. Next, they compared the data on coloration with the species' migratory behavior, while controlling for other factors known to effect plumage color.

Overall, the findings show that bird species get increasingly lighter as they migrate more. So, resident birds tend to be darker than short-distance migrants. Short-distance migrants are darker than bird species that travel farther. Delhey said that the one of the biggest surprises was how consistent the effect was across different types of birds. They saw the same pattern in birds large and small. The same held true in waterbirds and land-dwelling birds, too.

The findings are another reminder of the important role of temperature and climate factors more broadly in shaping the evolution of animal coloration. They also have clear implications for understanding the impacts of global warming and potential adaptive evolutionary responses, the researchers say.

Read more at Science Daily

Climate change and human pressure mean migration may be 'no longer worth it'

Animals that migrate north to breed are being put at risk by ongoing climate change and increasing human pressure, losing earlier advantages for migration, declining in numbers and faring much worse than their resident counterparts, according to scientists writing in Trends in Ecology & Evolution.

Many animals, including mammals, birds and insects migrate long distances north to breed, taking advantage of the seasonally plentiful food, fewer parasites and diseases, and the relative safety from predators.

However, the international research team, including scientists from the University of Bath, found changes in climate and increasing human pressure have eroded these benefits and in many cases led to lower reproductive success and higher mortality in migrating species.

The researchers warn that reduced advantages for long-distance migration have potentially serious consequences for the structure and function of ecosystems.

They highlighted 25 recent studies, describing how migration is becoming less profitable for various terrestrial animals, including caribou, shorebirds and Monarch butterflies, which migrate over 1000km during the summer to north temperate and arctic regions to breed, returning south in the winter.

Travelling such long distances is very costly in terms of energy but the benefits of food supply, fewer diseases and predators meant the benefits outweighed the cost, however the researchers say this is no longer the case for many populations.

Whilst some animals might shift their breeding ranges slightly further north to compensate for the change in environmental conditions, migratory animals are hardwired to continue the dangerous trip each year to breed, despite the lack of benefit.

Dr Vojt?ch Kubelka, the leading author and former Visiting Researcher at the University of Bath's Milner Centre for Evolution, said: "These findings are alarming. We have lived with the notion that northern breeding grounds represent safe harbours for migratory animals.

"On the contrary, numerous Arctic and North temperate sites may now represent ecological traps or even worse degraded environments for diverse migratory animals, including shorebirds, caribou or butterflies."

Food supplies and availability in the North may be climatically mismatched with reproduction of migratory animals, incurring higher offspring mortality, as described for many migratory birds.

Also new parasites and pathogens are emerging in the Arctic, creating new pressures, and top predators are increasingly preying on nests and eating eggs and chicks before they get a chance to fledge.

Dr Kubelka said: "Lemmings and voles used to be the main food source for predators such as foxes in the Arctic, however the milder winters can cause rain to fall on snow and then re-freeze, preventing the lemmings from reaching their food."

"With fewer lemmings and voles to feed on, foxes eat the eggs and chicks of migratory birds instead.

"We've seen that rates of nest predation of Arctic migratory shorebirds has tripled over the last 70 years, in large part due to climate change."

The authors suggest that Arctic and northern temperate breeding grounds need substantial conservation attention, in addition to well-recognised problems at stopover sites and wintering areas of migratory species.

Next to the concrete conservation measures, the authors propose a simple framework on how to map the stressors for migratory animals across the space and time, helping to distinguish among suitable, naturally improved or protected habitats on one hand and the ecological traps or degraded environments with reduced or eroded benefits for migratory behaviour on the other hand.

Dr Kubelka said: "The recognition of emerging threats and the proposed framework of migration profitability classification will help to identify the most endangered populations and regions, enabling the implementation of suitable conservation measures."

Professor Tamás Székely, Royal Society Wolfson Research Merit Award holder at the University of Bath's Milner Centre for Evolution, said: "Animal migration from equatorial regions to the North temperate and the Arctic is one of the largest movements of biomass in the world. But with reduced profitability of migration behaviour and smaller number of offspring joining the population, the negative trend will continue and fewer and fewer individuals will be returning back to the North.

"The Earth is a complex ecosystem -- changes in migration profitability affect populations of migrating animals which precipitate in alterations of species composition, trophic food webs as well as the whole ecosystem functioning.

"These patterns are particularly threatening for migratory animals as large numbers of those species are already negatively affected outside the breeding period, at their stopover sites and wintering grounds -- and many have formerly relied on the northern latitudes to provide relative safe breeding grounds."

Read more at Science Daily

Dragonflies likely migrate across the Indian Ocean

Can dragonflies migrate thousands of miles across the Indian Ocean, from India via the Maldives to Africa, and back again? An international research team led by Lund University in Sweden has used models and simulations to find out if the hypothesis could be true.

In 2009, marine biologist Charles Anderson put forward a hypothesis after observing globe skimmer dragonflies(Pantala flavescens) on the Maldives, that had flown in from what he assumed was India. When they flew off again, it was towards East Africa. Now, 12 years later, a group of researchers decided to investigate his claim.

Globe skimmer dragonflies are too small to be fitted with transmitters. Instead, the researchers examined its physiological aspects and calculated how long a globe skimmer dragonfly could stay airborne using the energy that can be stored in its body. In addition, the researchers used meteorological wind models to determine if there are winds that can facilitate the migration in both directions.

"Our study shows that this migration from India to East Africa is actually possible. However, the globe skimmer dragonfly can't manage it using only the fat it can store in its body. It also requires favourable winds and these are present during certain periods of the year," says Johanna Hedlund, a biology researcher at Lund University.

According to the simulated migration experiments using wind models, about 15 per cent of the dragonflies could manage the migration from India to Africa in the spring. In the autumn, 40 per cent could make the same journey in the opposite direction.

Johanna Hedlund and her colleagues consider it impressive that dragonflies can do this at all. Even more impressive is the fact that the globe skimmer dragonfly migration across the Indian Ocean is the longest in the animal kingdom in relation to an animal's size.

"We have got a lot closer to solving the mystery of how a tiny dragonfly, which only weighs 300 milligrams, can cross 2,000 kilometres of open sea," says Johanna Hedlund.

Other animals also rely on favourable wind conditions when they migrate. Two examples are the amur falcon and the Jacobin cuckoo, which also fly across the Indian Ocean. The researchers behind the study in question warn that climate change may affect the chances of these birds and the globe skimmer dragonfly in the future. There is a risk that wind patterns will change when the water surface gets warmer.

Read more at Science Daily

Milk enabled massive steppe migration

The long-distance migrations of early Bronze Age pastoralists in the Eurasian steppe have captured widespread interest. But the factors behind their remarkable spread have been heavily debated by archaeologists. Now a new study in Nature provides clues regarding a critical component of the herders' lifestyle that was likely instrumental to their success: dairying.

From the Xiongnu to the Mongols, the pastoralist populations of the Eurasian steppe have long been a source of fascination. Amongst the earliest herding groups in this region were the Yamnaya, Bronze Age pastoralists who began expanding out of the Pontic-Caspian steppe more than 5000 years ago. These Bronze Age migrations resulted in gene flow across vast areas, ultimately linking pastoralist populations in Scandinavia with groups that expanded into Siberia.

Just how and why these pastoralists travelled such extraordinary distances in the Bronze Age has remained a mystery. Now a new study led by researchers from the Max Planck Institute for the Science of Human History in Jena, Germany has revealed a critical clue and it might come as a surprise. It appears that the Bronze Age migrations coincided with a simple but important dietary shift -- the adoption of milk drinking.

The researchers drew on a humble but extraordinary source of information from the archaeological record -- they looked at ancient tartar (dental calculus) on the teeth of preserved skeletons. By carefully removing samples of the built-up calculus, and using advanced molecular methods to extract and then analyse the proteins still preserved within this resistant and protective material, the researchers were able to identify which ancient individuals likely drank milk, and which did not.

Their results surprised them. "The pattern was incredibly strong," observes study leader and palaeoproteomics specialist Dr. Shevan Wilkin, "The majority of pre-Bronze Age Eneolithic individuals we tested -- over 90% -- showed absolutely no evidence of consuming dairy. In contrast, a remarkable 94% of the Early Bronze Age individuals had clearly been milk drinkers."

The researchers realized they had uncovered a significant pattern. They then further analysed the data in order to examine what kind of milk the herders were consuming. "The differences between the milk peptides of different species are minor but critical," explains Dr. Wilkin. "They can allow us to reconstruct what species the consumed milk comes from." While most of the milk peptides pointed to species like cow, sheep and goat, which was not surprising in light of the associated archaeological remains, calculus from a couple of individuals revealed an unexpected species: horse.

"Horse domestication is a heavily debated topic in Eurasian archaeology," notes Dr. Wilkin. One site where early Central Asian milk drinking had been proposed was the 3500-year-old site of Botai in Kazakhstan. The researchers tested calculus from a couple of Botai individuals, but found no evidence of milk drinking. This fits with the idea that Przewalskii horses -- an early form of which were excavated from the site -- were not the ancestors of today's domestic horse, as shown by recent archaeogenetic study. Instead, horse domestication -- and the drinking of horse milk -- likely began about 1500 kilometers to the west in the Pontic Caspian steppe.

"Our results won't make everyone happy, but they are very clear," says Professor Nicole Boivin, senior author of the study and Director of the Department of Archaeology at the MPI Science of Human History. "We see a major transition to dairying right at the point that pastoralists began expanding eastwards." Domesticated horses likely had a role to play too. "Steppe populations were no longer just using animals for meat, but exploiting their additional properties -milking them and using them for transport, for example," states Professor Boivin.

Read more at Science Daily

How land birds cross the open ocean

Researchers at the Max Planck Institute of Animal Behavior and University of Konstanz in Germany have identified how large land birds fly nonstop for hundreds of kilometers over the open ocean—without taking a break for food or rest. Using GPS tracking technology, the team monitored the global migration of five species of large land birds that complete long sea crossings. They found that all birds exploited wind and uplift to reduce energy costs during flight—even adjusting their migratory routes to benefit from the best atmospheric conditions. This is the most wide-ranging study of sea-crossing behavior yet and reveals the important role of the atmosphere in facilitating migration over the open sea for many terrestrial birds.

Flying over the open sea can be dangerous for land birds. Unlike seabirds, land birds are not able to rest or feed on water, and so sea crossings must be conducted as nonstop flights. For centuries, bird-watchers assumed that large land birds only managed short sea crossings of less than 100 kilometers and completely avoided flying over the open ocean.

However, recent advances in GPS tracking technology have overturned that assumption. Data obtained by attaching small tracking devices on wild birds has shown that many land birds fly for hundreds or even thousands of kilometers over the open seas and oceans as a regular part of their migration.

But scientists are still unraveling how land birds are able to accomplish this. Flapping is an energetically costly activity, and trying to sustain nonstop flapping flight for hundreds of kilometers would not be possible for large, heavy land birds. Some studies have suggested that birds sustain such journeys using tailwind, a horizontal wind blowing in the bird’s direction of flight, which helps them save energy. Most recently, a study revealed that a single species—the osprey—used rising air thermals known as “uplift” to soar over the open sea.

Now, the new study has examined sea-crossing behavior of 65 birds across five species to gain the most wide-ranging insight yet into how land birds survive long flights over the open sea. The researchers analyzed 112 sea-crossing tracks, collected over nine years, with global atmospheric information to pinpoint the criteria that the birds use for selecting their migration routes over the open sea. A large international collaboration of scientists shared their tracking data to make this study possible.

The findings not only confirm the role of tailwind in facilitating sea-crossing behavior, but also reveal the widespread use of uplift for saving energy during these nonstop flights. Suitable uplift means less drag, making sea crossing less energetically demanding.

“Until recently, uplift was assumed to be weak or absent over the sea surface. We show that is not the case,” says first author Elham Nourani, a DAAD PRIME postdoctoral fellow at the Department of Biology at the University of Konstanz, who did the work when she was at the Max Planck Institute of Animal Behavior.

“Instead, we find that migratory birds adjust their flight routes to benefit from the best wind and uplift conditions when they fly over the sea. This helps them sustain flight for hundreds of kilometers,” says Nourani.

The oriental honey buzzard, for example, flies 700 kilometers over the East China Sea during its annual migration from Japan to southeast Asia. The roughly 18-hour nonstop sea crossing is conducted in autumn when the air movement conditions are optimal. “By making use of uplift, these birds can soar up to one kilometer above the sea surface,” says Nourani.

Read more at Science Daily

Turning off lights can save migrating birds from crashing into buildings

Every night during the spring and fall migration seasons, thousands of birds are killed when they crash into illuminated windows, disoriented by the light. But a new study in PNAS shows that darkening just half of a building's windows can make a big difference for birds. Using decades' worth of data and birds collected by Field Museum scientists at Chicago's McCormick Place convention center, the researchers found that on nights when half the windows were darkened, there were 11 times fewer bird collisions during spring migration and 6 times fewer collisions during fall migration than when all the windows were lit.

"Our research provides the best evidence yet that migrating birds are attracted to building lights, often causing them to collide with windows and die," says Benjamin Van Doren, a postdoctoral associate at the Cornell Lab of Ornithology and the paper's lead author. "These insights were only possible thanks to over 40 years of work by David Willard at the Field Museum, who led collisions and light monitoring efforts."

In 1978, Willard, the museum's collections manager emeritus, heard an offhand remark about birds hitting the McCormick Place, North America's largest convention center that happens to be just a mile south of the museum. So, he investigated.

"I went down early one morning, just out of curiosity, and wandered around and actually found four or five dead birds," says Willard. "I might not have gone back if I hadn't found anything that first day, and now here we are, 40 years later and 40,000 birds later."

Willard and his colleagues, including Field Museum co-author Mary Hennen and other Field staff and volunteers, have visited the site every day before sunrise during migration season, sometimes as early as 3:30 in the morning. Some days there are no birds; other times, there are as many as 200. Willard collects the dead birds and brings them back to the museum, where he records each one in a ledger and adds them to the museum's collection.

Around twenty years ago, Willard began to notice a pattern -- on nights when the lights were out at McCormick Place, around holidays or construction work, there were fewer birds on the ground the next morning. As the building's lighting patterns began to vary more, he began gathering data on which windows were illuminated each night, in addition to collecting the birds he found on the pavement.

The new PNAS study is the most in-depth use of the data on lighting patterns to date, combining Willard's specimens and lighting observations with other conditions that might play a role in bird mortality, including weather records and radar data revealing the number of birds in the sky on a given night. "We developed a statistical model based on the number of windows illuminated at McCormick Place, weather conditions, migratory passage, and time of season. This allowed us to isolate the relationship between window lighting and collisions while accounting for these other factors," says Van Doren. "By joining these different sources of data, we were able to understand how lights, weather, and migration each contribute to collision mortality."

The team found that the total number of birds in the sky on a given night and the direction of the wind both play a role in mortality, but the biggest determining factor was light: when more windows were darkened, fewer birds died. "The sheer strength of the link between lighting and collisions was surprising," says Van Doren. "It speaks to the exciting potential to save birds simply by reducing light pollution."

The researchers were able to quantify that bird-saving potential: they predict that halving the lighted window area could decrease collision counts by 11 times in spring and 6 times in fall. By turning out half the lights during migration seasons, bird mortality at McCormick Place could be reduced by 59%.

The researchers note that McCormick Place is far from unique -- it's been monitored for longer than any other Chicago building, but, Willard says, "There's hardly an address in downtown Chicago that doesn't have a bird in the Field Museum's collection, thanks to the efforts of the Chicago Bird Collision Monitors." However, there are a few factors that make the McCormick Center especially dangerous for birds, including its massive size, its isolation from other buildings, and its proximity to Lake Michigan, which birds are sometimes hesitant to fly over.

"Buildings all across North America, all across the world, are killing birds, and those add up," says Doug Stotz, a senior conservation ecologist at the Field. "What we've learned in the past 20 years about lights being on has caused the city of Chicago to create its Lights Out program, which requires buildings' external lights to be turned off during peak migration. I hope this paper will show why it's important to turn off internal lighting as well, especially in Chicago, which is the country's deadliest city for migrating birds."

Van Doren is also eager to see the project's findings applied. "Our study contains a hopeful message: we can save birds simply by turning off lights during a handful of high-risk days each spring and fall," he says. "By adapting our existing public migration forecasts to identify nights with high collision risk, we will be able to issue targeted lights-out advisories several days in advance."

In addition to the study's implications for bird conservation, it also speaks to the importance of natural history collections in documenting global change. "These collision data are even more valuable because they are backed up by specimens that are available for study in the Field Museum," says Ben Winger, one of the paper's senior authors, an assistant professor and curator at the University of Michigan and a Field Museum graduate student alumnus . "This will allow future scientists to go a step further and study the connections between many aspects of avian biology and conservation relevant questions."

Read more at Science Daily

Climate change in antiquity: Mass emigration due to water scarcity

 The absence of monsoon rains at the source of the Nile was the cause of migrations and the demise of entire settlements in the late Roman province of Egypt. This demographic development has been compared with environmental data for the first time by professor of ancient history, Sabine Huebner of the University of Basel -- leading to a discovery of climate change and its consequences.

The oasis-like Faiyum region, roughly 130 km south-west of Cairo, was the breadbasket of the Roman Empire. Yet at the end of the third century CE, numerous formerly thriving settlements there declined and were ultimately abandoned by their inhabitants. Previous excavations and contemporary papyri have shown that problems with field irrigation were the cause. Attempts by local farmers to adapt to the dryness and desertification of the farmland -- for example, by changing their agricultural practices -- are also documented.

Volcanic eruption and monsoon rains

Basel professor of ancient history Sabine R. Huebner has now shown in the US journal Studies in Late Antiquity that changing environmental conditions were behind this development. Existing climate data indicates that the monsoon rains at the headwaters of the Nile in the Ethiopian Highlands suddenly and permanently weakened. The result was lower high-water levels of the river in summer. Evidence supporting this has been found in geological sediment from the Nile Delta, Faiyum and the Ethiopian Highlands, which provides long-term climate data on the monsoons and the water level of the Nile.

A powerful tropical volcanic eruption around 266 CE, which in the following year brought a below-average flood of the Nile, presumably also played a role. Major eruptions are known from sulfuric acid deposits in ice cores from Greenland and Antarctica, and can be dated to within three years. Particles hurled up into the stratosphere lead to a cooling of the climate, disrupting the local monsoon system.

New insights into climate, environment, and society

In the third century CE, the entire Roman Empire was hit by crises that are relatively well documented in the province of Egypt by more than 26,000 preserved papyri (documents written on sheets of papyrus). In the Faiyum region, these include records of inhabitants who switched to growing vines instead of grain or to sheep farming due to the scarcity of water. Others accused their neighbors of water theft or turned to the Roman authorities for tax relief. These and other adaptive strategies of the population delayed the death of their villages for several decades.

Read more at Science Daily

Climate change triggers migration, particularly in middle-income countries

 Environmental hazards affect populations worldwide and can drive migration under specific conditions. Changes in temperature levels, increased rainfall variability, and rapid-onset disasters, such as tropical storms, are important factors as shown by a new study led by the Potsdam Institute for Climate Impact Research (PIK). Environmental migration is most pronounced in middle-income and agricultural countries but weaker in low-income countries, where populations often lack resources needed for migration. The findings make it possible to identify geographical regions that may be especially susceptible to migration movements in the future.

"Environmental factors can drive migration, but the size of the effects depends on the particular economic and sociopolitical conditions in the countries," says lead author Roman Hoffmann from PIK and the Vienna Institute of Demography of the Austrian Academy of Sciences. "In both low and high income countries environmental impacts on migration are weaker -- presumably because either people are too poor to leave and become basically trapped, or, in wealthy countries, have enough financial means to absorb the consequences. It is mainly in regions with middle incomes and a dependency on agriculture that we see strong effects."

Environmental impacts differ by contexts and types of hazards

The meta-study, which analyzed 30 previously published studies on the topic, reveals a number of fascinating patterns. It shows, for example, that impacts on migration vary by types of environmental hazards and that different hazards can re-inforce each other. "While changing temperatures in a region are found to have the strongest impact on migration, also rapid-onset disasters and changing rainfall variability and anomalies can play a role. Especially smallholder farmers rely on steady climatic conditions and suffer from changes and shocks as they have insufficient capacities to adapt," says co-author Raya Muttarak from the International Institute of Applied Systems Analysis and the Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/ÖAW, University of Vienna).

The researchers emphasize that there is no automatism at play -- environmental migration always depends on a number of economic and sociopolitical factors. The narrative of climate refugees pushing towards Europe or the US may be too simplistic. For instance, the researchers found compelling evidence that environmental changes in vulnerable countries predominantly lead to internal migration or migration to other low- and middle-income countries, rather than cross-border migration to high-income countries. Affected populations often migrate to places within their own region and eventually return to their homes within a relatively short period of time.

Localizing potential migration hotspots

The findings, published in the latest issue of Nature Climate Change, also hint at regions highly vulnerable to climate change where environmental migration may be particularly prevalent. "Our research suggests that populations in Latin America and the Caribbean, several countries in Sub-Saharan Africa, especially in the Sahel region and East Africa, as well as Western, South and Southeast Asia are particularly at risk," says co-author Anna Dimitrova from the Vienna Institute of Demography, Austrian Academy of Sciences.

Read more at Science Daily

Migration patterns reveal an Eden for ancient humans and animals

Pinnacle Point, a series of archaeological sites that overlook a now submerged section of South Africa's coastline and one of the world's most important localities for the study of modern human origins, was as much of an Eden for animals as it was for early humans. Jamie Hodgkins, PhD, assistant professor of anthropology at University of Colorado Denver, and her team drilled ancient herbivore teeth to find that many local animals stayed put in the ecologically rich ecosystem, which may explain why humans flourished there, too.

Home to the Earliest Modern Humans

Home to some of the richest evidence for the behavior and culture of the earliest clearly modern humans, the submerged shelf called the Palaeo-Agulhas Plain (PAP) once formed its own ecosystem. Co-author Curtis Marean, PhD, Arizona State University, has worked with teams of scientists for decades to reconstruct the locale back into the Pleistocene, the time period that spanned from 2.6 million to 11,700 years ago.

In this study, the researchers looked specifically at antelope migratory patterns at Pinnacle Point. This series of cave sites that sit on the modern South African coast offers archaeological materials from humans who were living and hunting there back to 170,000 years ago.

"During glacial cycles, the coastal shelf was exposed," said Hodgkins. "There would have been a huge amount of land in front of the cave sites. We thought it was likely that humans and carnivores were hunting animals as they migrated east and west over the exposed shelve."

A Lack of Migratory Pattern

Hodgkins and her team wanted to understand those migratory patterns. They studied the carbon and oxygen isotopes within the tooth enamel of many large herbivores, including Redunca, or reedbuck, a nonmigratory antelope. Tooth enamel can reveal a pattern of migration by tracking changing levels of carbon from the plants an animal eats as its teeth grow.

In general, wetter, cooler environments are home to C3 plants; hotter, drier environments are home to C4 plants. Animals like lush vegetation, which means they tend to follow the rain patterns: in this case east for summer rain (C4 grasses), and west for winter rain (C3 grasses). If animals were migrating between summer and winter rainfall zones, their tooth enamel would register that annual C3 and C4 plant rotation as a sinusoidal curve as their teeth grew.

A) Map of South Africa (SA) showing the distribution of C4 grasses associated with the percentage of summer rain from east to west along the coast, and with the winter rainfall zone in the west (modified from Vogel, 1978); B) A map of SA showing the area of the Greater Cape Floristic Region with the expanded PAP and hypothesized animals migration (i.e. It is hypothesized that animals would have been undertaking long-distance migrations between the east coast in summer rainfall zone and west coast in the winter rainfall zone)

But when Hodgkins and her team used the nonmigratory reedbuck as their control animal, they found that the enamel from its typically migratory pals -- like the wildebeest, hartebeest, and springbok -- showed no discernible migratory pattern. Most animals seemed happy right where they were.

"They weren't struggling at Pinnacle Point," says Hodgkins. "We now know that powerful river systems supplied the expanded coast, thus animals didn't have to be migratory. It was a great location, resource-wise. During interglacials when the coast moved closer to the caves humans had shellfish and other marine resources, and when the coast expanded in glacial times hunters had access to a rich, terrestrial environment. Hunters wouldn't need to be as mobile with all of these herbivores wandering around."

Thriving in an Ecogeological Haven

Hodgkins' team's findings of this prehistoric Eden echoed another recent discovery. Seventy-four-thousand years ago, one of Earth's largest known eruptions at Mount Toba in Sumatra, Indonesia, created a global winter, causing population crashes. In 2018, researchers from Marean's group found that humans at Pinnacle Point not only survived, but thrived in the haven.

Hodgkins says this is just a first attempt at using isotopic data to test the hypothesis of east and west migration patterns at these sites and further research will be done.

"It is quite possible that animal migration patterns changed as the coastline moved in and out during glacial and interglacial cycles," said Hodgkins.

Read more at Science Dialy

Ancient teeth from Peru hint now-extinct monkeys crossed Atlantic from Africa

Marmoset. Ucayalipithecus perdita would have been very small, similar in size to a modern-day marmoset.

Four fossilized monkey teeth discovered deep in the Peruvian Amazon provide new evidence that more than one group of ancient primates journeyed across the Atlantic Ocean from Africa, according to new USC research just published in the journal Science.

The teeth are from a newly discovered species belonging to an extinct family of African primates known as parapithecids. Fossils discovered at the same site in Peru had earlier offered the first proof that South American monkeys evolved from African primates.

The monkeys are believed to have made the more than 900-mile trip on floating rafts of vegetation that broke off from coastlines, possibly during a storm.

"This is a completely unique discovery," said Erik Seiffert, the study's lead author and Professor of Clinical Integrative Anatomical Sciences at Keck School of Medicine of USC. "It shows that in addition to the New World monkeys and a group of rodents known as caviomorphs -- there is this third lineage of mammals that somehow made this very improbable transatlantic journey to get from Africa to South America."

Researchers have named the extinct monkey Ucayalipithecus perdita. The name comes from Ucayali, the area of the Peruvian Amazon where the teeth were found, pithikos, the Greek word for monkey and perdita, the Latin word for lost.

Ucayalipithecus perdita would have been very small, similar in size to a modern-day marmoset.

Dating the migration

Researchers believe the site in Ucayali where the teeth were found is from a geological epoch known as the Oligocene, which extended from about 34 million to 23 million years ago.

Based on the age of the site and the closeness of Ucayalipithecus to its fossil relatives from Egypt, researchers estimate the migration might have occurred around 34 million years ago.

"We're suggesting that this group might have made it over to South America right around what we call the Eocene-Oligocene Boundary, a time period between two geological epochs, when the Antarctic ice sheet started to build up and the sea level fell," said Seiffert. "That might have played a role in making it a bit easier for these primates to actually get across the Atlantic Ocean."

An improbable discovery

Two of the Ucayalipithecus perdita teeth were identified by Argentinean co-authors of the study in 2015 showing that New World monkeys had African forebears. When Seiffert was asked to help describe these specimens in 2016, he noticed the similarity of the two broken upper molars to an extinct 32 million-year-old parapithecid monkey species from Egypt he had studied previously.

An expedition to the Peruvian fossil site in 2016 led to the discovery of two more teeth belonging to this new species. The resemblance of these additional lower teeth to those of the Egyptian monkey teeth confirmed to Seiffert that Ucayalipithecus was descended from African ancestors.

"The thing that strikes me about this study more than any other I've been involved in is just how improbable all of it is," said Seiffert. "The fact that it's this remote site in the middle of nowhere, that the chances of finding these pieces is extremely small, to the fact that we're revealing this very improbable journey that was made by these early monkeys, it's all quite remarkable."

About this study

In addition to Seiffert, the study's other authors are Marcelo Tejedor and Nelson Novo from the Instituto Patagónico de Geología y Paleontología (CCT CONICET -- CENPAT); John G. Fleagle from the Department of Anatomical Sciences, Renaissance School of Medicine, Stony Brook University; Fanny Cornejo and Dorien de Vries from the Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University; Mariano Bond from CONICET, División Paleontología Vertebrados, Museo de Ciencias Naturales de La Plata and Kenneth E. Campbell Jr. from the Department of Vertebrate Zoology, Natural History Museum of Los Angeles County.

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