Ostrich eggshell beads reveal 10,000 years of cultural interaction across Africa

By: Thomas Schmitt Attorney on November 27, 2019 / comment : 0 Africa, Archaeology, Early Humans

Ostrich eggshell beads are some of the oldest ornaments made by humankind, and they can be found dating back at least 50,000 years in Africa. Previous research in southern Africa has shown that the beads increase in size about 2,000 years ago, when herding populations first enter the region.

A string of modern ostrich eggshell beads from eastern Africa [Credit: Hans Sell]

In the current study, researchers Jennifer Miller and Elizabeth Sawchuk investigate this idea using increased data and evaluate the hypothesis in a new region where it has never before been tested.

Review of old ideas, analysis of old collections

To conduct their study, the researchers recorded the diameters of 1,200 ostrich eggshell beads unearthed from 30 sites in Africa dating to the last 10,000 years. Many of these bead measurements were taken from decades-old unstudied collections, and so are being reported here for the first time. This new data increases the published bead diameter measurements from less than 100 to over 1,000, and reveals new trends that oppose longstanding beliefs.

The ostrich eggshell beads reflect different responses to the introduction of herding between eastern and southern Africa. In southern Africa, new bead styles appear alongside signs of herding, but do not replace the existing forager bead traditions. On the other hand, beads from the eastern Africa sites showed no change in style with the introduction of herding.

Archaeological ostrich eggshell beads from southern Africa (a,b) and eastern Africa (c,d) [Credit: Jennifer Miller]

Although eastern African bead sizes are consistently larger than those from southern Africa, the larger southern African herder beads fall within the eastern African forager size range, hinting at contact between these regions as herding spread. "These beads are symbols that were made by hunter-gatherers from both regions for more than 40,000 years," says lead author Jennifer Miller, "so changes - or lack thereof - in these symbols tells us how these communities responded to cultural contact and economic change."

Ostrich eggshell beads tell the story of ancient interaction

The story told by ostrich eggshell beads is more nuanced than previously believed. Contact with outside groups of herders likely introduced new bead styles along with domesticated animals, but the archaeological record suggests the incoming influence did not overwhelm existing local traditions. The existing customs were not replaced with new ones; rather they continued and incorporated some of the new elements.

In eastern Africa, studied here for the first time, there was no apparent change in bead style with the arrival of herding groups from the north. This may be because local foragers adopted herding while retaining their bead-making traditions, because migrant herders possessed similar traditions prior to contact, and/or because incoming herders adopted local styles.

The current study reports ostrich eggshell bead data from 11 new sites, including Magubike Rockshelter [Credit: Jennifer Miller]

"In the modern world, migration, cultural contact, and economic change often create tension," says Sawchuk, "ancient peoples experienced these situations too, and the patterns in cultural objects like ostrich eggshell beads give us a chance to study how they navigated these experiences."

The researchers hope that this work inspires a renewed interest into ostrich eggshell beads, and recommend that future studies present individual bead diameters rather than a single average of many. Future research should also investigate questions related to manufacture, chemical identification, and the effects of taphonomic processes and wear on bead diameter.

"This study shows that examining old collections can generate important findings without new excavation," says Miller, "and we hope that future studies will take advantage of the wealth of artifacts that have been excavated but not yet studied."

The study is published in the open-access journal PLOS ONE.

Source: Max Planck Institute for the Science of Human History [November 27, 2019]

Almost a third of tropical Africa's flora faces extinction

By: Thomas Schmitt Attorney on November 21, 2019 / comment : 0 Africa, Biodiversity, Ecosystems, Endangered Species, Natural Heritage

31.7% of tropical Africa’s vascular plant species could be threatened with extinction, reveals an international study coordinated by an IRD researcher, published in the journal Science Advances. Using a new approach based on the key elements of the assessment process used by the International Union for Conservation of Nature (IUCN), for the first time researchers have been able to assess the potential conservation status of tropical flora on the scale of a continent.

Mountains of the eastern arch of Tanzania. The flora of this region is threatened with extinction [Credit: IRD - Thomas Couvreur]

Given the anthropological and climate threats facing nature, the conservation of tropical biodiversity is a major challenge. To encourage the implementation of better biodiversity management practices, countries and international agreements on biodiversity refer to the assessments of species "at risk of extinction" performed by the IUCN as part of a standardised procedure (See Red List of Threatened Species). This approach remains the most comprehensive and objective means of identifying species in need of protection.

However, while the conservation status of the majority of vertebrate species has been assessed, the same cannot be said for plants, although they are critical to earth ecosystems. This is especially true in tropical regions where the flora is very diverse but remains poorly documented.

In this study, the researchers developed a new fast and automatic approach based on key elements of the conservation assessment process used by the IUCN. Their objective was to provide relevant information on the conservation status of a large number of plant species at broad scales, in the form of Preliminary Automated Conservation Assessments (PACA).

The researchers therefore applied this methodology to the RAINBIO database, which contains over 600,000 georeferenced occurrences of plants in tropical Africa across more than 20,000 vascular plant species.

Infographic of the main results [Credit: Thomas L.P. Couvreur]

After classifying these species into six categories - which include species that are "probably or potentially threatened", those that are "potentially rare" and those that are "potentially not threatened" - they reveal that almost a third (31.7%) of the 22,036 vascular plant species studied are potentially threatened with extinction, and an additional 33.2% are potentially rare (they could be threatened in the near future).

After determining the most endangered species, the researchers identified four regions in Africa that are particularly exposed: Ethiopia, central Tanzania, the south of the Democratic Republic of the Congo and the West African tropical rainforests.

They highlight the advantages of this approach, based on the preliminary automated conservation assessments, in terms of cost reduction, time saving and the potential to carry out large-scale assessments. "This study is the first large-scale assessment of the potential conservation status of the tropical African flora, explicitly using the IUCN's methodology", explains botanist Thomas Couvreur from the IRD who coordinated the study.

"These assessments could provide crucial information for improving biodiversity management and promoting sustainable economic development in Africa. They are, however, not intended to replace the comprehensive assessments carried out by the IUCN which lead to official statuses. The two approaches are complementary, and a significant international effort is still needed to assess all plant species in Africa", he urges.

"These results were possible because the partners involved agreed to share their data", says Bonaventure Sonke, Professor at the Laboratory of Systematic Botany and Ecology of the Ecole Normale Superieure (University Yaounde 1, Cameroon). "This is a strong signal to encourage researchers to share their data, in order to obtain results on a larger scale".

Source: Institut de recherche pour le developpement [November 21, 2019]

Global climate change concerns for Africa's Lake Victoria

By: Thomas Schmitt Attorney on November 14, 2019 / comment : 0 Africa, Climate Change, Earth Science, Ecosystems, Natural Heritage

Global climate change could cause Africa's Lake Victoria, the world's largest tropical lake and source of the Nile River, to dry up in the next 500 years, according to new findings from a team of researchers led by the University of Houston. Even more imminent, the White Nile -- one of the two main tributaries of the Nile -- could lose its source waters in just a decade.

View of modern Lake Victoria from the Kenya shoreline where fishing is a vital part of economy and very  susceptible to changes in climate that affect the amount of rainfall and levels of the lake [Credit: Emily Beverly]

Using ancient sediment from outcrops along the edge of the lake, Emily Beverly, assistant professor of sedimentary geology at the UH College of Natural Sciences and Mathematics, along with researchers at Baylor University, generated a water-budget model to see how Lake Victoria's levels respond to changes in evaporation, temperature, rainfall and solar energy. Their findings, published in Earth and Planetary Science Letters, indicate a rapid lake level decline was very possible tens of thousands of years ago and could happen again in the future.

"Our model predicts that at current rates of temperature change and previous rates of lake level fall, Lake Victoria could have no outlet to the White Nile in as little as 10 years. Every major port in Lake Victoria could be landlocked within a century, and Kenya could lose access to the lake in 400 years," Beverly explained.

The result would significantly affect the economic resources supplied by the lake and the livelihoods of approximately 40 million people living in the Lake Victoria Basin.

- Kenya and Tanzania depend on the lake's freshwaters to support their fishing industries because the lake harvests more than one million tons of fish annually.

Members of the team explored outcrops along Lake Victoria in western Kenya. These sediments were used to understand the history of the lake over the past 100,000 years [Credit: Emily Beverly]

- Uganda would be deprived of its primary source of electricity via hydropower and the water that sustains the Nile during non-flood stages.

- The Kagera River basin, which is the main river that flows into Lake Victoria, feeds rainwater to Rwanda and Burundi which rely on agriculture and livestock production.

Lake Victoria gets most of its water from rain, and each year, the area gets about 55 inches of rainfall. The sediment analyzed from along the lake shows rainfall levels from 35,000 to 100,000 years ago were about 28 inches, or almost half of what they are today. The water-budget model in the study shows low amounts of rainfall caused the lake to dry up at least three times in the past 100,000 years and could happen again.

"It's so warm there and the sun is so strong because you are at the equator that evaporation is very high," said Beverly. "If the water balance is thrown off, the lake can dry up very quickly. It doesn't take much of a drop in precipitation to change it."

Author: Sara Tubbs | Source: University of Houston [November 14, 2019]

First experimental study for traceological interpretation at Olduvai sites

By: Thomas Schmitt Attorney on October 28, 2019 / comment : 0 Africa, Archaeology, Early Humans, Tanzania

Patricia Bello-Alonso of the Centro Nacional de Investigacion sobre la Evolucion Humana (CENIEH) has reported on experimental results for the traceological interpretation of activities carried out using stone tools made from the most representative raw material at the Olduvai Gorge sites (Tanzania), naibor soit quartzite. The results are published in Quaternary International.

Fossil bones and rocks unearthed from one of the archaeological levels at an Olduvai Gorge site [Credit: Lindsay Mchenry]

This study presents the macro and micro-marks produced on the edges of experimental stone tools during their use on a diversity of types of plants (roots, tubers, herbaceous plants, canes and wood), and bone and carcass processing, with the objective of identifying these kinds of marks in the archaeological record.

"By doing this, we have obtained an extensive reference collection of unretouched flakes made by knapping blocks of naibor quartzite," says Bello-Alonso, whose paper forms part of the traceological studies she is conducting at the Acheulean site of Thiongo Korongo (TK), around 1.3 million years old.

Classic viewpoint of Olduvai Gorge, with the Naibor Soit hills in the distance and the so-called castle’ (made of red sediments belonging to Bed III) to the bottom right [Credit: Lindsay Mchenry]

One of the novelties included in the work is the description and interpretation of the macro and micro-topographical changes in the surface of naibor soit quartzite. Based on the results, the researchers have developed criteria to distinguish the kinds of activities and materials by recording attributes including pitting and micro-polish.

This has made it possible to compile an interpretive database, both macroscopic and microscopic, which could enable and enhance functional interpretation of lithic utensils from the Acheulean site of TK and the majority of the other Olduvai Gorge sites where this same raw material was employed.

Source: CENIEH [October 28, 2019]

The homeland of modern humans

By: Thomas Schmitt Attorney on October 28, 2019 / comment : 0 Africa, Anthropology, Early Humans, Genetics, Human Evolution

A study has concluded that the earliest ancestors of anatomically modern humans (Homo sapiens sapiens) emerged in a southern African 'homeland' and thrived there for 70 thousand years. The breakthrough findings are published in the journal Nature.

Credit: AFP

The authors propose that changes in Africa's climate triggered the first human explorations, which initiated the development of humans' genetic, ethnic and cultural diversity. This study provides a window into the first 100 thousand years of modern humans' history.

DNA as a time capsule

"It has been clear for some time that anatomically modern humans appeared in Africa roughly 200 thousand years ago. What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors," says study lead Professor Vanessa Hayes from the Garvan Institute of Medical Research and University of Sydney, and Extraordinary Professor at the University of Pretoria.

"Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations. Comparing the complete DNA code, or mitogenome, from different individuals provides information on how closely they are related."

In their study, Professor Hayes and her colleagues collected blood samples to establish a comprehensive catalogue of modern human's earliest mitogenomes from the so-called 'L0' lineage. "Our work would not have been possible without the generous contributions of local communities and study participants in Namibia and South Africa, which allowed us to uncover rare and new L0 sub-branches," says study author and public health Professor Riana Bornman from the University of Pretoria.

"We merged 198 new, rare mitogenomes to the current database of modern human's earliest known population, the L0 lineage. This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before," says first author Dr Eva Chan from the Garvan Institute of Medical Research, who led the phylogenetic analyses.

By combining the L0 lineage timeline with the linguistic, cultural and geographic distributions of different sub-lineages, the study authors revealed that 200 thousand years ago, the first Homo sapiens sapiens maternal lineage emerged in a 'homeland' south of the Greater Zambezi River Basin region, which includes the entire expanse of northern Botswana into Namibia to the west and Zimbabwe to the east.

A homeland perfect for life to thrive

Investigating existing geological, archeological and fossil evidence, geologist Dr Andy Moore, from Rhodes University, revealed that the homeland region once held Africa's largest ever lake system, Lake Makgadikgadi.

"Prior to modern human emergence, the lake had begun to drain due to shifts in underlying tectonic plates. This would have created, a vast wetland, which is known to be one of the most productive ecosystems for sustaining life," says Dr Moore.

Modern humans' first migrations

The authors' new evolutionary timelines suggest that the ancient wetland ecosystem provided a stable ecological environment for modern humans' first ancestors to thrive for 70 thousand years.

"We observed significant genetic divergence in the modern humans' earliest maternal sub-lineages, that indicates our ancestors migrated out of the homeland between 130 and 110 thousand years ago," explains Professor Hayes. "The first migrants ventured northeast, followed by a second wave of migrants who travelled southwest. A third population remained in the homeland until today."

"In contrast to the northeasterly migrants, the southwesterly explorers appear to flourish, experiencing steady population growth," says Professor Hayes. The authors speculate that the success of this migration was most likely a result of adaptation to marine foraging, which is further supported by extensive archaeological evidence along the southern tip of Africa.

Climate effects

To investigate what may have driven these early human migrations, co-corresponding author Professor Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University, analysed climate computer model simulations and geological data, which capture Southern Africa's climate history of the past 250 thousand years.

"Our simulations suggest that the slow wobble of Earth's axis changes summer solar radiation in the Southern Hemisphere, leading to periodic shifts in rainfall across southern Africa," says Professor Timmermann. "These shifts in climate would have opened green, vegetated corridors, first 130 thousand years ago to the northeast, and then around 110 thousand years ago to the southwest, allowing our earliest ancestors to migrate away from the homeland for the first time."

"These first migrants left behind a homeland population," remarks Professor Hayes. "Eventually adapting to the drying lands, maternal descendants of the homeland population can be found in the greater Kalahari region today."

This study uniquely combined the disciplines of genetics, geology and climatic physics to rewrite our earliest human history.

Source: Garvan Institute of Medical Research [October 28, 2019]

Large-scale afforestation of African savannas will destroy valuable ecosystems

By: Thomas Schmitt Attorney on October 21, 2019 / comment : 0 Africa, Ecosystems, Endangered Species, Natural Heritage, Wildlife

The suggested afforestation of large areas of Africa to mitigate climate change will destroy valuable ecological, agricultural, and tourist areas, while doing little to reduce global CO2 levels. This is the view of 46 scientists from around the world - many of whom are leading scientists in Africa - in a Technical Comment published in the journal Science.

The large-scale afforestation of African savannas will destroy valuable ecosystems and related ecotourism sites [Credit: Wits University/Schalk Mouton]

The Technical Comment is a critique of another recent paper in Science, led by Jean-Francois Bastin and Thomas Crowther of the Swiss Federal Institute of Technology in Zurich. These researchers, funded by a Dutch non-profit foundation (DOB Ecology), a tree planting advocacy group (Plant-for-the-Planet), and the German Federal Ministry for Economic Cooperation and Development, claimed that global tree planting could capture 205 gigatons of carbon, or one-third of the carbon dioxide emitted since the industrial revolution, which totals 660 gigatons.

Using remote sensing and machine learning to estimate the amount of atmospheric carbon that could be sequestered by global tree restoration, the Bastin study highlighted large tracts of land in southern Africa - and the tropics in general - as potential sites for large scale afforestation in efforts to fight against climate change. Because the estimate of 205 gigatons of carbon was so large, in July of 2019, headlines around the world declared tree planting to be the best solution to climate change.

"Firstly, their numbers are wrong," said Professor Sally Archibald, co-author of the critique and ecologist at the University of the Witwatersrand, South Africa. "It is irresponsible to give people false hope that our global change problems can be fixed in this way. Secondly, the impacts on our natural ecosystems in Africa would be devastating."

The technical commentary, led by Joseph Veldman of Texas A&M University, demonstrates that the Bastin study dramatically overstated the potential for tree planting to mitigate climate change, and that planting trees in the wrong places can destroy ecosystems, increase wildfire intensity, and exacerbate global warming.

"Many of the areas suggested for afforestation are areas where ecologists and land managers are fighting bush encroachment," said Archibald. Higher tree cover in Namibian and Botswanan savannas is considered degradation by the people living there. In the Miombo woodlands in Zambia, Mozambique, and Tanzania wood fuels are used as a renewable energy source by millions of people, and no one has considered what alternative energy sources might be required if these important resources are taken away though global tree planting programs.

"While tree planting can be good in some deforested areas, tree planting in Earth's natural grasslands destroys plant and animal habitat and will not sequester enough carbon to compensate for fossil fuel emissions," says Veldman.

African scientists have highlighted a lack of awareness on the part of the European researchers: "This paper shows that the authors have little knowledge of savanna ecology," says Alfan Rija from the Sokoine University of Agriculture, Tanzania. "I am worried that these programs could be used by stronger countries - the G20 - to craft global policies to exploit land and forests of the tropical world."

In their critique, Veldman and his collaborators write that the Swiss research had serious flaws that led to a five-fold overestimate of the potential for new trees to mitigate climate change. Among the problems, the original study assumed that soils in ecosystems without trees contain no carbon, when in fact many ecosystems, such as savannas and peatlands, contain more carbon in soils than in the aboveground vegetation.

The Swiss research also neglected the fact that coniferous forests in boreal and high mountain regions absorb more sunlight and emit more heat than treeless areas, and actually exacerbate rather than mitigate global warming. Finally, tree planting in grasslands and savannas, as proposed by the Swiss researcher team, is damaging to the environment as ancient grasslands and savannas contain immense biodiversity and provide services to humanity, such as livestock forage and groundwater recharge.

The group of scientists' main concern is that a myopic focus on tree planting will retract from the real issue of fighting climate change through reducing CO2 emissions and reduce the capacity of people to adapt to climate change while distracting from efforts to conserve intact ecosystems and reduce fossil fuel consumption.

"It is high time we begin to speak for Africa," says Steven Syampungani from the Copperbelt University in Zambia. He and his colleagues across the region believe that ecological restoration involves working to restore not just forests, but also grasslands, savannas, and shrublands.

Source: University of the Witwatersrand [October 21, 2019]

Researchers confirm timeline of human presence on Madagascar

By: Thomas Schmitt Attorney on October 08, 2019 / comment : 0 Africa, Archaeology, Madagascar

A team of researchers has confirmed that humans arrived on Madagascar about 11,000 years ago, much earlier than commonly accepted estimates of 2,000 years.

Kristina Douglass and her team systematically reviewed all of the archaeological radiocarbon dates for Madagascar and confirmed the timeline of human presence on Madagascar [Credit: Roland Schmitt/SIPA]

Kristina Douglass, assistant professor of anthropology in the College of the Liberal Arts and a faculty member in the Institutes of Energy and the Environment, led the team of researchers who worked on this project. She said the debate over when people came to Madagascar has long been contentious.

For example, in 2018, two papers by different teams of researchers presented wildly different estimates of when people first arrived on the island, one estimating that Madagascar was settled 11,000 years ago, and the other arguing that people first arrived only 1,500 years ago.

To settle this debate, Douglass and her team collected all of the radiocarbon dates that have ever been generated for archaeological sites on the African island. Their work resulted in the most comprehensive database of radiocarbon dates for the island.

"The African continent has some of the oldest human remains on record, some of which are millions of years old," Douglass said. "Yet, previous research suggested that this huge island that is not that far off the coast of Africa doesn't get settled by people until about 2,000 years ago."

To determine the timeline of human settlement, the researchers used statistical models to rank the dates using specific criteria, including whether the dated samples were clearly associated with human activities and whether the samples came from long or short-lived species, so that both the reliability and precision of radiocarbon dates could be evaluated. This method of "chronometric hygiene" had never been done for Madagascar.

"We looked at the type of material to see whether or not there was built in error based on the type of material," Douglass said. "We took all of those criteria that we called 'quality control' for those dates, and we fed that into a system where we ranked the dates to know which dates are the most reliable based on our criteria and which are the least reliable."

What Douglass and her team suggest in their paper is that the 11,000-year estimate of human presence is reliable.

A map of sites in Madagascar used in the systematic review of archaeological radiocarbon dates by Kristina Douglass and her team [Credit: Kristina Douglass]

Despite the reliability of this early arrival estimate, it is still unclear whether the evidence from 11,000 years ago is from permanent human settlements or if humans just visited the island temporarily, Douglass said.

"Somebody could have floated over to Madagascar by accident and left some remains," she said.

The team's paper also supports current evidence that cities started to emerge on Madagascar about 1,000 years ago.

Douglass said that confirming the timeline of human settlement is important for historical reasons, but it also has critical meaning for today's changing world.

"The bigger context of why this matters is because this island with some of the world's greatest biodiversity hotspots is going through significant environmental change, today and within the last 2,000 years," Douglass said. "A huge number of animals went extinct on the island about 1,000 years ago—pygmy hippos, giant elephant birds, man-sized lemurs, giant tortoises."

Douglass said it is important for understanding today's environmental challenges to determine if these animals went extinct rapidly after a short co-existence with newly arrived people or if the extinctions were a more complex, longer-term process, involving climate change and human activity.

"If people arrived 1,500 years ago, then within 500 years, all of these animals go extinct and all of these changes happen," Douglass said. "If people arrived 11,000 years ago, people have been coexisting with these environments for a much longer time, so the changes we see may be less abrupt or may have been caused by a significant shift in how people were using the landscape."

Douglass added that human presence should not be used as the only indication of whether an environment is going to change. Human activity should be considered within a constellation of human-environment-climate dynamics.

"If people were there 11,000 years ago and practicing a certain kind of subsistence, that might be very different from 1,000 years ago when Madagascar is swept into booming Indian Ocean trade networks and people start building ports and cities," Douglass said. "That is when we start to see the extinctions happen."

The paper was published in Quaternary Science Reviews.

Author: Kevin Sliman | Source: Pennsylvania State University [October 08, 2019]

Early humans evolved in ecosystems unlike any found today

By: Thomas Schmitt Attorney on October 07, 2019 / comment : 0 Africa, Early Humans, Earth Science, Ecosystems, Fossils, Palaeoclimate, Palaeontology

To understand the environmental pressures that shaped human evolution, scientists must first piece together the details of the ancient plant and animal communities that our fossil ancestors lived in over the past 7 million years. Because putting together the puzzle of millions-of-years-old ecosystems is a difficult task, many studies have reconstructed the environments by drawing analogies with present-day African ecosystems, such as the Serengeti. A study led by a University of Utah scientist calls into question such approaches and suggests that the vast majority of human evolution occurred in ecosystems unlike any found today. The paper was published in the Proceedings of the National Academy of Sciences.

Artist Heinrich Harder's illustration of the extinct Deinotherium, an ancient relative to modern-day elephants that appeared in the Middle Miocene 20 million years ago and lived until the Early Pleistocene, around 2 million  years ago. Harder completed the illustration in the early 1900s using fossils as his model [Credit: Heinrich Harder]

To test for differences between modern and ancient environments, the researchers analyzed a dataset of more than 200 present-day African mammal communities and more than 100 fossil communities spanning the past 7 million years in eastern Africa, a time period encompassing all of human evolution. They found that prior to 700,000 years ago, mammal communities looked far different from those today. For example, fossil communities supported a greater diversity of megaherbivores, species over 2,000 pounds, such as elephants.

Likewise, the dietary structure of fossil communities frequently departed from those seen today, with patterns of grass- and leaf-eating species fluctuating in abundance. Around 1 million years ago, fossil communities began transitioning to a more modern makeup, which the authors suggest is the likely the outcome of long-term grassland expansion coupled with arid climate pulses. The new paper adds to growing evidence that scientists need to critically re-evaluate our understanding of the ancient ecosystems in which early humans evolved.

"For a long time, our field has been trying to pin down how environmental changes influenced human evolution, but we've got to be able to reconstruct past environments right in the first place," said lead author Tyler Faith, curator of archaeology at the Natural History Museum of Utah and assistant professor of anthropology at the U. "If we continue to reconstruct ancient environments on the basis of modern African ecosystems, we are likely missing an entire realm of possibilities in how past ecosystems functioned. Our study invites our fellow researchers to think more critically about that."

Linking changes in mammal communities to ecosystem functions

Eastern Africa is a boon for mammal fossils, making it an ideal region to piece together ancient ecosystems over the past 7 million years. With their extensive database of both ancient and modern mammal communities, the researchers focused on three traits: diet, body size, and digestive strategy. For all of these traits, they found that the makeup of ancient herbivore communities differed significantly from those of today. This is key, as herbivores directly shape the structure of ecosystems in ways that impact a wide variety of animal and plant species.

"Large herbivores aren't just passive parts of an ecosystem, we know that they can shape the landscape. They're eating the plants, and the biggest ones are knocking down trees or trampling soils, which collectively influences vegetation structure, fire regimes, nutrient cycling, and impacts other organisms, including humans," said Faith.

The geographic distribution of the modern (left) and fossil (right) larger herbivore  communities analyzed in the paper [Credit: Faith et. al., 2019]

For example, modern African ecosystems are dominated by ruminants--relatives of cows and antelopes that have four compartments in their stomachs to thoroughly break down food. Non-ruminants equipped with simple stomachs are comparatively rare, with at most eight species coexisting in the same area today. Non-ruminants, including relatives of elephants, zebras, hippos, rhinos and pigs, are like digestive conveyor belts, said Faith. They eat larger quantities of plants to make up for their inefficient digestion. In contrast to the present-day pattern, eastern African fossil records document landscapes rich in non-ruminant communities, with dozens of species co-existing within the same area.

Fossil and modern communities were also vastly different in terms of body sizes. The fossil records document lots more megaherbivores than their modern counterparts. A steady decline of megaherbivores began 4.5 million years ago until they represented a more modern distribution 700,000 years ago.

What is the impact of these eating machines all living together in the same places, when it's not the case today?

"These ancient herbivore communities were probably consuming far more vegetation, which means less fuel for wildfires. Because fire is an important part of modern ecosystems in Africa and favors grasslands over woodlands, it's going to fundamentally alter how things are working at the level of entire ecosystems, starting with the plant communities," adds John Rowan, co-author and postdoctoral researcher at the University of Massachusetts Amherst. "Paleontologists have been aware of that, but until now, no one's really tried to measure just how different the past was compared to the present."

Drying climate and grasslands drive a shift

What drove shifts in mammal communities over the past 7 million years? One of the most well-documented changes is the expansion of grasslands throughout the past 4 million years. Many of the fossil megaherbivores preferred wooded environments, whereas ruminants thrive in the wide-open savannas that dominate parts of eastern Africa today. The fossil record of herbivores closely follows the shifting environments, with changes in the representation of these groups tracking long-term grassland expansion.

A comparative analysis of fossil (gray shaded) and modern (light gray shaded) mammal communities. The study found little overlap between the types of mammals that thrived in the past versus in modern East African ecosystems [Credit: Faith et. al., 2019]

Around 1 million years ago, fossils show a shift in mammal community dietary structure that grassland expansion alone fails to explain. The non-ruminants that had dominated eastern African ecosystems fell into a sharp decline. This corresponds to marine dust records suggesting the region experienced pulses of climate drying that would have hit non-ruminants especially hard because they depend on reliable access to surface water, meaning that many species may have disappeared alongside the rivers and lakes they depended on. Additionally, the conveyor belt eating strategy of non-ruminants relies on accessing abundant vegetation, which would have declined during periods of drought.

Looking forward

The authors do not fault previous researchers for relying so heavily on analogies with present-day African ecosystems, emphasizing that a study of this scope has only recently become possible.

"Paleontology has hit a big data era," said Faith. Co-author and Colorado State University assistant professor Andrew Du added, "With the assembly of large, comprehensive datasets, we can now ask important questions that are fundamentally different from those asked in the past. We can investigate larger-scale patterns and dynamics that undoubtedly influenced the course of human evolution."

Source: University of Utah [October 07, 2019]

Croc-like carnivores terrorised Triassic dinosaurs in southern Africa 210 million years ago

By: Thomas Schmitt Attorney on September 23, 2019 / comment : 0 Africa, Dinosaurs, Fossils, Palaeontology

Giant, predatory croc-like animals that lived during the Triassic period in southern Africa preyed on early dinosaurs and mammal relatives 210 million years ago. These predators, known as "rauisuchians" preyed on early herbivore dinosaurs and their mammal relatives living at the time, according to Wits Masters student Rick Tolchard.

Artist's reconstruction of two rauisuchians fighting over a desiccated corpse of a mammal-relative in the Triassic of southern Africa. In the background, dinosaurs and mammal-like reptiles form other parts of the ecosystem [Credit: copyright Viktor Radermacher]

"These ancient fossils provide us with evidence of how at least two predator species hunted these vegetarian dinosaurs 210 million-years-ago. It is amazing to follow the clues left behind in fossilised teeth, jaws, limbs and other fossils to help us tell the ancient story of life in southern Africa," says Tolchard.

The fossils studied by Tolchard include teeth, pieces of jaws, hind limbs and body armour, all of which are can be described as parts of rauisuchians.

Rauisuchians are closely related to crocodiles as we know them today. They had a diversity of body shapes and sizes during the Triassic period. The specimens described in this research include some of the largest carnivorous members of this group, that were possibly up to 10 metres long, with huge skulls full of serrated, curved teeth.

Example of rauisuchian teeth in the Wits collections [Credit: Wits University]

The study, published online in the Journal of African Earth Sciences last week, shows that the rauisuchians were some of the latest-surviving members of their group, and that when they were alive, they were thriving close to the Antarctic Circle -- the theoretical limit for their physiology.

"In the Triassic period, rauisuchians were widespread and their fossils are known from all continents except Antarctica," adds Tolchard. "They went extinct about 200 million years ago, paving the way for dinosaurs to become the dominant large land animals."

"Rick's study demonstrates the value of re-examining old specimens, and now we finally know what was preying on all those herbivorous dinosaurs!" says Professor Jonah Choiniere, Rick's advisor and Professor of Comparative Palaeobiology at the Wits Evolutionary Studies Institute.

Rick Tolchard studying rauisuchians in the Geological Survey in Namibia [Credit: Helke Mocke]

Tolchard studied fossils from collections based at the the University of the Witwatersrand, the Iziko South African Museum and the National Museum in Bloemfontein. He was joined in the research by an international team, including researchers from the USA, Argentina and the UK.

Source: Wits University [September 23, 2019]

French archaeologists restore three Sudanese artefacts

By: Thomas Schmitt Attorney on September 19, 2019 / comment : 0 Africa, Archaeology, France, Heritage, Sudan

A team of French diggers has restored three Sudanese artefacts, including a 3,500-year-old wall relief, and handed them to the African country's national museum on Thursday, a French archaeologist said.

A visitor looks at a wall relief inscription, discovered at the temple of Soleb, on display at the Sudan National Museum [Credit: Ebrahim Hamid/AFP]

The three artefacts were discovered at separate archaeological sites in recent years in Sudan and were restored by a French team of experts.

The items are a wall painting of an ancient Kandaka Nubian queen, a Meroite stela and a wall relief inscription believed to be almost 3,500 years old.

Marc Maillot, director of the French archaeological unit in Sudan, stands next to an ancient wall painting displayed at the National Museum of Sudan in Khartoum [Credit: Ebrahim Hamid/AFP]

"The idea is to give back to the museum the most important archaeological pieces discovered and restored," said Marc Maillot, director of the French archaeological unit deployed in Sudan.

The wall painting was found at El-Hassa site, the stela discovered at Sedeinga and the relief at the temple of Soleb, where French diggers along with Sudanese counterparts have conducted extensive archaeological work for several years.

A stela, discovered at Sedeinga pyramids, is displayed at the National Museum of Sudan in Khartoum [Credit: Ebrahim Hamid/AFP]

On Thursday the three artefacts were handed over to the Sudan National Museum to mark the completion of 50 years of French archaeologists' presence in the country.

For decades international archaeologists have worked extensively in Sudan, proving that the northeast African nation has its own extensive wealth of ancient relics and was not merely a satellite of neighbouring Egypt.

Archaeologists are convinced that many kingdoms still lie buried, waiting to be discovered.

Source: AFP [September 19, 2019]

Scientists solve lingering mystery of poorly understood frog

By: Thomas Schmitt Attorney on September 11, 2019 / comment : 0 Africa, Biology, Evolution, Genetics, Wildlife

An international team of scientists, led by researchers at McMaster University, has solved a centuries-old mystery of 'Fraser's Clawed Frog', an unusual and elusive species found in West Africa.

CT scan of Xenopus fraseri [Credit: Edward L. Stanley]

The findings, published in the journal PLOS ONE, dispel previous myths and shed new light on Xenopus fraseri including its geographic origin, evolutionary relationships, ecology, and distinctive species traits.

Two specimens of the frog, with a distinctive combination of four claws on the hind legs as well as small bony protrusions on the roof of their mouths known as vomerine teeth, were collected by British zoologist Louis Fraser in 1852 and housed at the Natural History Museum (NHM) in London.

In 1905, Fraser's clawed frog was designated as a distinct species, but its place on the evolutionary tree, geographic distribution, and ecology has since stumped scientists --due to a lack of genetic samples and poor records of its origin.

"The ancient condition of the only two specimens available to us posed many challenges for understanding its distinctiveness using DNA and knowing exactly where they came from" explains Ben Evans, lead author of the study and a professor of biology at McMaster University.

"The accurate identification of species is so important because it allows us to study change in populations, better understand how evolution occurs, and explore the processes that drive diversification, extinction and adaption," he says.

Xenopus fraseri [Credit: Trustees Natural History Museum 2019]

The team, which included researchers from the NHM, the Max Planck Institute in Germany and the University of Florida, used sensitive techniques -similar to approaches used to sequence the genomes of Neanderthals--to sequence the mitochondrial genome from the delicate specimens.

In addition, scientists sequenced complete or nearly complete mitochondrial genomes from 29 other Xenopus species, used high-resolution CT scanning to compare the internal and external anatomy of these and other specimens and, through intensive field work, managed to collect additional specimens of Fraser's frog in several remote regions of West Africa.

By doing so, they determined Fraser's Clawed Frog was indeed distinct from all others. And while it was previously thought to have lived in lowland tropical forests in West Africa, researchers found it actually inhabits the relatively hot and arid regions of northern Cameroon and northern Ghana.

"Obtaining DNA from specimens that have been preserved in spirit for well over a hundred years is something that has only become achievable in the last few decades. The recent advances in DNA extraction and sequencing are allowing us to revisit specimens and challenge assumptions made in the past," says Jeff Streicher, senior curator of amphibians and reptiles at the NHM.

In the summer of 2020, the team plans to travel to Nigeria to continue their efforts to understand biodiversity and genome evolution of African clawed frogs.

Source: McMaster University [September 11, 2019]

What the cranium of modern humans' ancestor would have looked like

By: Thomas Schmitt Attorney on September 10, 2019 / comment : 0 Africa, Anthropology, Early Humans, Human Evolution

Despite having lived about 300,000 years ago, the oldest ancestor of all members of Homo sapiens had a surprisingly modern skull--as suggested by a model created by CNRS researcher Aurelien Mounier of the Histoire Naturelle de l'Homme Prehistorique laboratory (CNRS / Museum National d'Histoire Naturelle) and Cambridge University professor Marta Mirazon Lahr. After comparing the virtually rendered skull to those of five African fossil specimens contemporaneous with the first appearance of Homo sapiens, the two researchers posit that our species emerged through interbreeding of South and East African populations. Their findings are published in Nature Communications.

The grey skulls were drawn from the sample used to model the skull of the virtual ancestor, shown in red. From left to right: KNM-ER 3733 (H. ergaster), La Ferrassie (H. neanderthalensis), Qafzeh 6 (fossil H. sapiens), Kh-1739 (South Africa, Khoikhoi), AUS001 (Australia), Eu.34.4.1 (Hungary), EAS-ORSA0427 (China) and NA82 (Huron, Canada) [Credit: Aurelien Mounier, CNRS/MNHN]

Our species, Homo sapiens, arose in Africa roughly 300,000 years ago. But how and where exactly? Because few African fossils less than 500,000 years old have been discovered to date, we're missing pieces to complete the puzzle of the history of our species. In this new study, the researchers wanted to expand the pool of available fossils ... by creating virtual ones.

Accordingly, they took exhaustive measurements of 263 skulls of fossil and modern hominins from 29 different populations, to prepare 3D models. Mounier and Mirazon Lahr demonstrated there was a close connection between the average cranial dimensions for each of the 29 populations and the respective positions of these populations in a phylogenetic tree largely constructed using genetic data.

Virtual model of ancestor shared by all members of Homo sapiens [Credit: © Aurelien Mounier/CNRS-MNHN]

This relationship allowed the researchers to calculate the likely skull dimensions of the most recent ancestor of all Homo sapiens groups. The virtual 300,000-year-old fossil has relatively modern features: its round cranium, relatively high forehead, and slight brow ridges and facial projection make it similar in morphology to some fossils that are only 100,000 years old.

The researchers compared their virtual fossil skull to five real fossil skulls from African members of the genus Homo who lived 130,000 to 350,000 years ago and are occasionally thought to have been our ancestors. Their analysis suggests our species arose through the hybridization of populations from South and East Africa.


On the other hand, North African populations--possibly represented by the Jebel Shroud fossil--are believed to have interbred with Neanderthals after migration into Europe, accounting to a lesser extent for the makeup of our species.

This study also sheds light on the history of our species outside of Africa. It supports the hypothesis, advanced by others on the basis of genetic evidence, that after an initial exodus from Africa that only left its mark in Oceania, a second migration allowed Homo sapiens to successively populate Europe, Asia, and finally, the Americas.

Source: CNRS [September 10, 2019]

Gentle giraffes threatened with 'silent extinction'

By: Thomas Schmitt Attorney on August 16, 2019 / comment : 0 Africa, Endangered Species, Natural Heritage, Wildlife

For most of his life as a Samburu warrior, Lesaiton Lengoloni thought nothing of hunting giraffes, the graceful giants so common a feature of the Kenyan plains where he roamed.

Giraffe numbers across the continent fell 40 percent between 1985 and 2015, to just under 100,000 animals [Credit: Tony Karumba/AFP]

"There was no particular pride in killing a giraffe, not like a lion... (But) a single giraffe could feed the village for more than a week," the community elder told AFP, leaning on a walking stick and gazing out to the broad plateau of Laikipia.

But fewer amble across his path these days: in Kenya, as across Africa, populations of the world's tallest mammals are quietly, yet sharply, in decline.

Giraffe numbers across the continent fell 40 percent between 1985 and 2015, to just under 100,000 animals, according to the best figures available to the International Union for Conservation of Nature (IUCN).

But unlike the clarion calls sounded over the catastrophic collapse of elephant, lion and rhino populations, less attention was paid to the giraffe's private crisis.

"The giraffe is a big animal, and you can see it pretty easily in parks and reserves. This may have created a false impression that the species was doing well," said Julian Fennessy, co-chair of the IUCN's specialist group for giraffes and okapis.

The rate of decline is much higher in central and eastern regions, with poaching, habitat destruction and conflict the main drivers blamed for thinning herds of these gentle creatures.

In Kenya, Somalia and Ethiopia, reticulated giraffe numbers fell 60 percent in the roughly three decades to 2018, the IUCN says.

The Nubian giraffe meanwhile has suffered a tragic decline of 97 percent, pushing this rarer variety toward total extinction.

Further afield in Central Africa, the Kordofan giraffe, another of the multitude subspecies, has witnessed an 85 percent decrease.

In 2010, giraffes were a species of "least concern" on the IUCN red list. But six years later they leapt to "vulnerable", one step down from critical, catching many by surprise.

"This is why for the giraffe we speak of the threat of a silent extinction," said Jenna Stacy-Dawes, research coordinator at the San Diego Zoo Institute for Conservation Research.

Mysterious giants

Despite this, an international effort underway to put giraffes squarely on the global conservation agenda has divided professional opinion.

Credit: Aude Genet/AFP

Six African nations are pushing to regulate the international trade in giraffes under the UN Convention on Trade in Endangered Species (CITES), which meets from August 17 to 28 in Geneva.

Those advocating for the change, including Kenya, want the giraffe classified as "a species that, although not necessarily currently threatened with extinction, could become so if trade in their specimens were not closely controlled".

Critics however say there is little evidence the international wildlife trade is responsible for dwindling giraffe numbers. A lack of reliable data has long hindered efforts to protect them.

"Compared to other charismatic species like elephants, lions and rhinos, we know very little about giraffes," said Symon Masiaine, a coordinator in the Twiga Walinzi giraffe study and protection program, which began in Kenya in 2016. "Nowadays, we are still far behind, but we are making progress."

Almost nothing is reliably known about giraffe populations in Somalia, South Sudan and eastern parts of Democratic Republic of Congo, where collecting such information is perilously difficult.

But even research outside conflict zones has been patchy.

Arthur Muneza, from the Giraffe Preservation Foundation, said the first long-term study of giraffes was not carried out until 2004. Data on giraffes is often gathered as an afterthought by researchers focussing on other wildlife, he added.

"Without reliable data, it is more difficult to take appropriate conservation measures," Muneza said.

It was not until 2018 that the IUCN had enough statistics to be able to differentiate the threat levels facing many giraffe subspecies.

The reticulated and Masai giraffes, for examples, were classified as "endangered" while the Nubian and Kordofan were "critically endangered".

Trophy hunting

Under the proposal before CITES, the legal trade in giraffe parts, including those obtained by trophy hunters on Africa's legal game reserves, would be globally regulated.

In Kenya, Somalia and Ethiopia, reticulated giraffe numbers fell 60 percent in the roughly three decades to 2018 [Credit: Tony Karumba/AFP]

Member countries would be required to record the export of giraffe parts or artefacts, something only the United States currently does, and permits would be required for their trade.

But observers say the limited information available suggests most of this trade originates from places where giraffe numbers are actually rebounding, like South Africa and Namibia, where game hunting is legal.

Muneza says there isn't a clear enough picture that the legal trade is linked to declining giraffe numbers.

"The first step should be to conduct a study to find out the extent of international trade and its influence on giraffe populations," he said.

Those supporting the proposal before Geneva talk of a "precautionary principle"—doing something now before it is too late.

For Masiaine, the Kenyan giraffe researcher, any publicity is good publicity for these poorly-understood long-necked herbivores.

"It means that people are talking about the giraffe," he said. "And the species really needs that."

Factfile on Africa's under-studied giant: the giraffe

One of the most under-studied large mammals in Africa, the giraffe may be on a slow path to extinction, with numbers dropping 40 percent in the three decades to 2015.

Here are unusual facts about one of the world's most distinctive-looking creatures.

Neck

The giraffe's best-known feature can be longer than most people are tall. However, like humans, its neck still only has seven vertebrae. Each is about 25 centimetres (10 inches) long.

It is used to reach high up into trees for food but too short to reach the ground, so the animals have to splay their legs or kneel down to drink water. Luckily they only drink every few days and get most of their hydration from plants.

The neck is also used in an elaborate ritual fight known as "necking" in which giraffes swing at each other to establish dominance.

Markings

With its spotted pattern and long legs and neck, the giraffe was given the Latin name "camelopardalis", meaning "camel marked like a leopard". But the spots are not only for camouflage.

Six African nations are pushing to regulate the international trade in giraffes under the UN Convention on Trade in Endangered Species [Credit: Tony Karumba/AFP]

According to the Giraffe Conservation Foundation (GCF), each patch is surrounded by a sophisticated system of blood vessels which act as thermal windows to release body heat.

A thermal scan of a giraffe shows the intensity of heat in its body matching the pattern of the spots.

Like the human fingerprint, each giraffe has its own unique pattern.

Big tongue, big heart

It's not just the neck and legs which are outsized on a giraffe, which despite its iconic status is not one of Africa's "Big Five" wildlife.

Its tongue can measure up to 50 cm to give the animal even more leverage in nibbling from the top of its favoured tree, the acacia.

The tongue's blue-black colour is believed to shield the organ from sun exposure and it is widely accepted that a giraffe's sticky saliva has antiseptic properties to protect it from spiky thorns on the acacia.

A giraffe's heart weights up to 11 kilogrammes (24 pounds)—to power blood up a neck of nearly two metres (six and a half feet)—and beats up to 170 times per minute, double the speed of a human heart.

The blood vessels inside giraffe legs have been studied by NASA engineers trying to improve spacesuit design.

Breeding

Giraffes have one of the longest gestation periods, at 15 months. They give birth standing up, which means their calves drop just under two metres to the ground.

This startling introduction to life gets them up and running around in less than an hour. A newborn calf is bigger than the average adult.

In the wild, giraffes can live up to 25 years, while in captivity they can survive over 35 years.

Genetics

Giraffes evolved from an antelope-like animal of about three metres tall that roamed the forests of Asia and Europe 30 to 50 million years ago. Its closest living relative is the okapi.

In September 2016 scientists revealed there were in fact four distinct giraffe species and not one divided into nine subspecies, as initially thought. Discussions are underway to have this recognised by the IUCN, so specific initiatives can be tailored for each subspecies.

Author: Nicolas Delaunay | Source: AF [August 16, 2019]