Scientists find a place on Earth where there is no life

By: Thomas Schmitt Attorney on November 22, 2019 / comment : 0 Astrobiology, Biology, Earth Science, Ethiopia, Geology, Palaeontology

Living beings, especially microorganisms, have a surprising ability to adapt to the most extreme environments on our planet, but there are still places where they cannot live. European researchers have confirmed the absence of microbial life in hot, saline, hyperacid ponds in the Dallol geothermal field in Ethiopia.

Hyperacid, hypersaline and hot ponds in the geothermal field of Dallol (Ethiopia). Despite the presence of liquid water, this multi-extreme system does not allow the development of life, according to a new study. The yellow-greenish colour is due to the presence of reduced iron [Credit: Puri Lopez-Garcia]

The infernal landscape of Dallol, located in the Ethiopian depression of Danakil, extends over a volcanic crater full of salt, where toxic gases emanate and water boils in the midst of intense hydrothermal activity. It is one of the most torrid environments on Earth. There, daily temperatures in winter can exceed 45° C and there are abundant hypersaline and hyperacid pools, with pH values that are even negative.

A recent study, published this year, pointed out that certain microorganisms can develop in this multi-extreme environment (simultaneously very hot, saline and acid), which has led its authors to present this place as an example of the limits that life can support, and even to propose it as a terrestrial analogue of early Mars.

However, now a French-Spanish team of scientists led by biologist Purificacion Lopez Garcia of the French National Centre for Scientific Research (CNRS) has published an article in Nature Ecology & Evolution that concludes otherwise. According to these researchers, there is no life in Dallol's multi-extreme ponds.

Measuring hydrothermal fluid temperature among acid gases in active chimneys [Credit: Puri Lopez-Garcia]

"After analysing many more samples than in previous works, with adequate controls so as not to contaminate them and a well-calibrated methodology, we have verified that there's no microbial life in these salty, hot and hyperacid pools or in the adjacent magnesium-rich brine lakes," stresses Lopez Garcia.

"What does exist is a great diversity of halophilic archaea (a type of primitive salt-loving microorganisms) in the desert and the saline canyons around the hydrothermal site," the biologist explains, "but neither in the hyperacid and hypersaline pools themselves, nor in the so-called Black and Yellow lakes of Dallol, where magnesium abounds. And all this despite the fact that microbial dispersion in this area, due to the wind and to human visitors, is intense."

This is confirmed by the results of all the various methods used by the team, including the massive sequencing of genetic markers to detect and classify microorganisms, microbial culture attempts, fluorescent flow cytometry to identify individual cells, chemical analysis of brines and scanning electron microscopy combined with X-ray spectroscopy.

Microbial cells (on the left) can be easily confounded with silica-rich mineral precipitates (on the right) [Credit: Puri Lopez-Garcia]

Lopez Garcia alerts that some silica-rich Dallol mineral precipitates may look like microbial cells under a microscope, so what is seen must be analysed well: "In other studies, apart from the possible contamination of samples with archaea from adjacent lands, these mineral particles may have been interpreted as fossilized cells, when in reality they form spontaneously in the brines even though there is no life."

According to the authors, this work "helps to circumscribe the limits of habitability and demands caution when interpreting morphological bio-signatures on Earth and beyond," that is, one should not rely on the apparently cellular or 'biological' aspect of a structure, because it could have an abiotic origin.

"In addition, our study presents evidence that there are places on the Earth's surface, such as the Dallol pools, which are sterile even though they contain liquid water," stresses Lopez Garcia. This means that the presence of liquid water on a planet, which is often used as a habitability criterion, does not directly imply that it has life.

Colourful hyperacid and hypersline hydrothermal ponds at the geothermal field of Dallol [Credit: Puri Lopez-Garcia]

In this case, the researchers have found two physical-chemical barriers that prevent the presence of living organisms in ponds: the abundance of chaotropic magnesium salts (an agent that breaks hydrogen bridges and denatures biomolecules) and the simultaneous confluence of hypersaline, hyperacid and high-temperature conditions.

"We would not expect to find life forms in similar environments on other planets, at least not based on a biochemistry similar to terrestrial biochemistry," points out Lopez Garcia, who insists on the need to have multiple indications, to analyse all types of alternatives and to be very prudent with interpretations before reaching any conclusions in astrobiology.

Both the French-Spanish group, in which researchers from the Geological and Mining Institute of Spain and the Autonomous University of Madrid participate, and other international teams continue to investigate the extreme environment of Dallol, where completely sterile pools could alternate with others with slightly better biophysical conditions that allow the presence of archaea and other extremophilic microorganisms. In any case, this is an exceptional environment to continue studying the limits of life.

Source: Plataforma SINC [November 22, 2019]

A 3.8-million-year-old cranium from Ethiopia reveals the face of Lucy's ancestor

By: Thomas Schmitt Attorney on August 28, 2019 / comment : 0 Anthropology, Early Humans, Ethiopia, Fossils, Human Evolution

The 3.8 million-year-old fossil cranium represents a time interval between 4.1 and 3.6 million years ago, when A. anamensis gave rise to A. afarensis. Researchers used morphological features of the cranium to identify which species the fossil represents. "Features of the upper jaw and canine tooth were fundamental in determining that MRD was attributable to A. anamensis", said Melillo. "It is good to finally be able to put a face to the name."

The facial reconstruction of "MRD" by John Gurche was made possible through generous contribution by Susan and George Klein [Credit: © Matt Crow, Cleveland Museum of Natural History]

The MRD cranium, together with other fossils previously known from the Afar, show that A. anamensis and A. afarensis co-existed for approximately 100,000 years. This temporal overlap challenges the widely-accepted idea of a linear transition between these two early human ancestors. Haile-Selassie said: "This is a game changer in our understanding of human evolution during the Pliocene."

Working for the past 15 years at the site, the team discovered the cranium (MRD-VP-1/1, here referred to as "MRD") in February 2016. In the years following their discovery, paleoanthropologists of the project conducted extensive analyses of MRD, while project geologists worked on determining the age and context of the specimen. The results of the team's findings are published online in the international scientific journal Nature.

Discovery of the cranium

The Woranso-Mille project has been conducting field research in the central Afar region of Ethiopia since 2004. The project has collected more than 12,600 fossil specimens representing about 85 mammalian species. The fossil collection includes about 230 fossil hominin specimens dating to between more than 3.8 and about 3.0 million years ago.

The cranium was discovered in 2016 at Miro Dora, Mille district of the Afar Regional State in Ethiopia [Credit: © Yohannes Haile-Selassie, Cleveland Museum of Natural History]

The first piece of MRD, the upper jaw, was found by Ali Bereino (a local Afar worker) on February 10, 2016 at a locality known as Miro Dora, Mille district of the Afar Regional State. The specimen was exposed on the surface and further investigation of the area resulted in the recovery of the rest of the cranium. "I couldn't believe my eyes when I spotted the rest of the cranium. It was a eureka moment and a dream come true", said Haile-Selassie.

Geology and age determination

In a companion paper published in the same issue of Nature, Beverly Saylor of Case Western Reserve University and her colleagues determined the age of the fossil as 3.8 million years by dating minerals in layers of volcanic rocks nearby. They mapped the dated levels to the fossil site using field observations and the chemistry and magnetic properties of rock layers. Saylor and her colleagues combined the field observations with analysis of microscopic biological remains to reconstruct the landscape, vegetation and hydrology where MRD died.

MRD was found in the sandy deposits of a delta where a river entered a lake. The river likely originated in the highlands of the Ethiopian plateau while the lake developed at lower elevations where rift activity caused the Earth surface to stretch and thin, creating the lowlands of the Afar region. Fossil pollen grains and chemical remains of fossil plant and algae that are preserved in the lake and delta sediments provide clues about the ancient environmental conditions.

The 3.8 million-year-old cranium of Australopithecus anamensis is remarkably complete [Credit: © Dale Omori, Cleveland Museum of Natural History]

Specifically they indicate that the watershed of the lake was mostly dry but that there were also forested areas on the shores of the delta or along the side the river that fed the delta and lake system. "MRD lived near a large lake in a region that was dry. We're eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change and how it affected human evolution, if at all", said Naomi Levin, a co-author on the study from University of Michigan.

A new face in the crowd

Australopithecus anamensis is the oldest known member of the genus Australopithecus. Due to the cranium's rare near-complete state, the researchers identified never-before-seen facial features in the species. "MRD has a mix of primitive and derived facial and cranial features that I didn't expect to see on a single individual", Haile-Selassie said.

Some characteristics were shared with later species, while others had more in common with those of even older and more primitive early human ancestor groups such as Ardipithecus and Sahelanthropus. "Until now, we had a big gap between the earliest-known human ancestors, which are about 6 million years old, and species like 'Lucy', which are two to three million years old. One of the most exciting aspects of this discovery is how it bridges the morphological space between these two groups", said Melillo.

Branching out

Among the most important findings was the team's conclusion that A. anamensis and its descendant species, the well-known A. afarensis, coexisted for a period of at least 100,000 years. This finding contradicts the long-held notion of an anagenetic relationship between these two taxa, instead supporting a branching pattern of evolution.

A composite of the 3.8 million-year-old cranium of Australopithecus anamensis and its facial morphology reconstruction [Credit: Human ancestor photomontage by Jennifer Taylor, courtesy of the Cleveland Museum of Natural History. Facial reconstruction by John Gurche, made possible through a generous contribution by Susan and George Klein]

Melillo explains: "We used to think that A. anamensis gradually turned into A. afarensis over time. We still think that these two species had an ancestor-descendent relationship, but this new discovery suggests that the two species were actually living together in the Afar for quite some time. It changes our understanding of the evolutionary process and brings up new questions - were these animals competing for food or space?"

This conclusion is based on the assignment of the 3.8-million-year-old MRD to A. anamensis and the 3.9-million-year-old hominin cranial fragment commonly known as the Belohdelie frontal, to A. afarensis. The Belohdelie frontal was discovered in the Middle Awash of Ethiopia by a team of paleontologists in 1981, but its taxonomic status has been questioned in the intervening years.

The new MRD cranium enabled the researchers to characterize frontal morphology in A. anamensis for the first time and to recognize that these features differed from the morphology common to the Belohdelie frontal and to other cranial specimens already known for Lucy's species.

As a result, the new study confirms that the Belohdelie frontal belonged to an individual of Lucy's species. This identification extends the earliest record of A. afarensis back to 3.9 million years ago, while the discovery of MRD nudges the last appearance date of A. anamensis forward to 3.8 million years - indicating the overlap period of at least 100,000 years.

Source: Max Planck Institute for Evolutionary Anthropology [August 28, 2019]

Why humans in Africa fled to the mountains during the last Ice Age

By: Thomas Schmitt Attorney on August 08, 2019 / comment : 0 Archaeology, Early Humans, Earth Science, Ethiopia

People in Ethiopia did not live in low valleys during the last ice age. Instead they lived high up in the inhospitable Bale Mountains. There they had enough water, built tools out of obsidian and relied mainly on giant rodents for nourishment. This discovery was made by an international team of researchers led by Martin Luther University Halle-Wittenberg (MLU) in cooperation with the Universities of Cologne, Bern, Marburg, Addis Ababa and Rostock. In the current issue of Science, the researchers provide the first evidence that our African ancestors had already settled in the mountains during the Palaeolithic period, about 45,000 years ago.

The Fincha Habera rock shelter in the Ethiopian Bale Mountains served as a residence for prehistoric hunter-gatherers [Credit: Gotz Ossendorf]

At around 4,000 metres above sea level, the Bale Mountains in southern Ethiopia are a rather inhospitable region. There is a low level of oxygen in the air, temperatures fluctuate sharply, and it rains a lot. "Because of these adverse living conditions, it was previously assumed that humans settled in the Afro-Alpine region only very lately and for short periods of time," says Professor Bruno Glaser, an expert in soil biogeochemistry at MLU.

Together with an international team of archaeologists, soil scientists, palaeoecologists, and biologists, he has been able to show that this assumption is incorrect. People had already begun living for long periods of time on the ice-free plateaus of the Bale Mountains about 45,000 years ago during the Middle Pleistocene Epoch. By then the lower valleys were already too dry for survival.

Wasama Valley in the Bale Mountains [Credit: Gotz Ossendorf]

For several years, the research team investigated a rocky outcrop near the settlement of Fincha Habera in the Bale Mountains in southern Ethiopia. During their field campaigns, the scientists found a number of stone artefacts, clay fragments and a glass bead. "We also extracted information from the soil as part of our subproject," says Glaser. Based on the sediment deposits in the soil, the researchers from Halle were able to carry out extensive biomarker and nutrient analyses as well as radiocarbon dating and thus draw conclusions as to how many people lived in the region and when they lived there.

For this work, the scientists also developed a new type of palaeothermometer which could be used to roughly track the weather in the region - including temperature, humidity and precipitation. Such analyses can only be done in natural areas with little contamination, otherwise the soil profile will have changed too much by more recent influences. The inhospitable conditions of the Bale Mountains present ideal conditions for such research since the soil has only changed on the surface during the last millennia.

Boulders deposited by a glacier in the Harcha Valley during the last glacial period [Credit: Heinz Veit]

Using this data, the researchers were not only able to show that people have been there for a longer period of time. The analyses may also have uncovered the reasons for this: during the last ice age the settlement of Fincha Habera was located beyond the edge of the glaciers. According to Glaser, there was a sufficient amount of water available since the glaciers melted in phases.

The researchers are even able to say what people ate: giant mole rats, endemic rodents in the region the researchers investigated. These were easy to hunt and provided enough meat, thereby providing the energy required to survive in the rough terrain. Humans probably also settled in the area because there was deposit of volcanic obsidian rock nearby from which they could mine obsidian and make tools out of it. "The settlement was therefore not only comparatively habitable, but also practical," concludes Glaser.

Stone tool made of obsidian from the Middle Stone Age [Credit: Gotz Ossendorf]

The soil samples also reveal a further detail about the history of the settlement. Starting around 10,000 years before the Common Era, the location was populated by humans for a second time. At this time, the site was increasingly used as a hearth. And: "For the first time, the soil layer dating from this period also contains the excrement of grazing animals," says Glaser.

According to the research team, the new study in Science not only provides new insights into the history of human settlement in Africa, it also imparts important information about the human potential to adapt physically, genetically and culturally to changing environmental conditions. For example, some groups of people living in the Ethiopian mountains today can easily contend with low levels of oxygen in the air.

Source: Martin-Luther-Universitat Halle-Wittenberg [August 08, 2019]

Oldest axial fossils discovered for the genus Australopithecus

By: Thomas Schmitt Attorney on June 14, 2019 / comment : 0 Anthropology, Early Humans, Ethiopia, Fossils

Scientists have published an article describing the oldest axial fossils yet discovered for the genus Australopithecus. Dated 4.2 million years ago, these and other fossils recovered from the Assa Issie site in the Middle Awash extend the known range of A. anamensis into northeastern Ethiopia. The fossils from the Assa Issie are extremely fragmentary, but each represents an important element previously unknown for the species Australopithecus anamensis.

One of the fossils is an axis, or second cervical vertebra (C2) shown here in (a) ventral view, (b) dorsal view, (c) lateral view, and D) ventral view in articulation with modern H. sapiens atlas (C1). Note the correspondence between the Assa Issie axis and human atlas [Credit: Meyer & Williams, 2019]

In an upcoming article in the Journal of Human Evolution, paleoanthropologists Dr. Marc Meyer of Chaffey College and Scott Williams of New York University describe tell-tale signs that these early hominins had already evolved a human-like posture of the head and neck. "The bilobated facets of the first cervical vertebra are something we don't see in the great apes, but in humans is thought to provide a passive locking mechanism that keeps the head stable in erect posture," explains Meyer.

The scientists also point to the lack the pronounced retroglenoid tubercle of the great apes on two of the atlas (C1) fossils that indicate that like humans, anamensis lacked the atlantoclavicularis muscle, which would have reduced their capacity for climbing relative to the great apes—something scientists did not know until now.

Other features of the non-human ape spine are also absent in the hominin fossils, such as the ponticulus posticus, the bony form of a membrane in apes that protects the vertebral artery from being crushed when the head is cantilevered in front of the spine. The scientists report "lack of this feature in anamensis is consistent with a humanlike posture where the head is more centered above the spine".

The spinal column reveals other surprisingly human characters, such as an enlarged epiphyseal surface area that is a hallmark feature of bipedalism, as it improves the ability to resist the increased load magnitudes of upright posture. "Such a feature would also provide energy return during bipedal locomotion from the intervertebral discs in the form of elastic strain energy with rotary spinal movement" explain the scientists.

Finally, despite their great antiquity, like humans, the A. anamensis fossils from Issie exhibit an enlarged spinal canal compared to the apes. "This would confer an increase in the neurovascular contents of the canal, including the motor pool in the ventral horn of the australopith spinal cord well before the advent of genus Homo", says Meyer.

The enlarged spinal canal provides the earliest evidence for an enlarged spinal cord in the hominin lineage and imparts significant neurological and vascular benefits for bipedal locomotion, and shatters the notion that spinal cord size in early hominins was small and apelike. This was another surprise, say the scientists, and provides evidence that a human-sized spinal cord evolved well before human brain size.

Source: Chaffey College [June 14, 2019]

Human ancestors invented stone tools several times

By: Thomas Schmitt Attorney on June 03, 2019 / comment : 0 Africa, Anthropology, Early Humans, Ethiopia, Human Evolution

The excavation site, known as Bokol Dora 1 or BD 1, is close to the 2013 discovery of the oldest fossil attributed to our genus Homo discovered at Ledi-Geraru in the Afar region of northeastern Ethiopia. The fossil, a jaw bone, dates to about 2.78 million years ago, some 200,000 years before the then oldest flaked stone tools. The Ledi-Geraru team has been working for the last five years to find out if there is a connection between the origins of our genus and the origins of systematic stone tool manufacture.

A large green artefact found in situ at the Bokol Dora site. Right: Image of the same artefact and a three dimensional model of the same artefact [Credit: David R. Braun]

A significant step forward in this search was uncovered when Arizona State University geologist Christopher Campisano saw sharp-edged stone tools sticking out of the sediments on a steep, eroded slope. "At first we found several artifacts lying on the surface, but we didn’t know what sediments they were coming from," says Campisano. "But when I peered over the edge of a small cliff, I saw rocks sticking out from the mudstone face. I scaled up from the bottom using my rock hammer and found two nice stone tools starting to weather out."

Sediment layer with animal bones and stone chips

It took several years to excavate through meters of sediments by hand before exposing an archaeological layer of animal bones and hundreds of small pieces of chipped stone representing the earliest evidence of our direct ancestors making and using stone knives. The site records a wealth of information about how and when humans began to use stone tools.

Blade Engda of the University of Poitiers lifts an artefact from 2.6 million year old sediment exposing an imprint of the artefact on the ancient surface below [Credit: David R. Braun]

Preservation of the artifacts comes from originally being buried close to a water source. "Looking at the sediments under a microscope, we could see that the site was exposed only for a very short time. These tools were dropped by early humans at the edge of a water source and then quickly buried. The site then stayed that way for millions of years," noted geoarchaeologist Vera Aldeias of the Interdisciplinary Center for Archaeology and Behavioral Evolution at the University of Algarve, Portugal.

Habitat change

Kaye Reed, who studies the site’s ecology, is director of the Ledi-Geraru Research Project and a research associate with Arizona State University’s Institute of Human Origins along with Campisano, notes that the animals found with these tools were similar to those found only a few kilometers away with the earliest Homo fossils.

"The early humans that made these stone tools lived in a totally different habitat than 'Lucy' did," says Reed. Lucy is the nickname for an older species of hominin known as Australopithecus afarensis, which was discovered at the site of Hadar, Ethiopia, about 45 kilometers southwest of the new BD 1 site. "The habitat changed from one of shrubland with occasional trees and riverine forests to open grasslands with few trees. Even the fossil giraffes were eating grass!"

Archaeologists from the Max Planck Institute, and the Ethiopian Authority for Research and the Conservation of Cultural Heritage as well as geologists from University of Algarve study the sediments at the Bokol Dora site. Stones were placed on the contact surface during the excavation to preserve the fragile stratigraphic contacts [Credit: Erin DiMaggio]

In addition to dating a volcanic ash several meters below the site, project geologists analyzed the magnetic signature of the site’s sediments. Over the Earth’s history, its magnetic polarity has reversed at intervals that can be identified. Other earlier archaeological sites near the age of BD 1 are in "reversed" polarity sediments. The BD 1 site is in "normal" polarity sediments. Because the reversal from "normal" to "reversed" happened at about 2.58 million years ago, the geologists knew that BD 1 was older than all the previously known sites.

The recent discovery of older hammering or "percussive" stone tools in Kenya dated to 3.3 million years ago, described as "Lomekwian", and butchered bones in Ethiopia shows the deep history of our ancestors making and using tools. However, recent discoveries of tools made by chimpanzees and monkeys have challenged "technological ape" ideas of human origins.

Archaeologists working at the BD 1 site wondered how their new stone tool discovery fit into this increasingly complex picture of hominin behavioural evolution. What they found was that not only were these new tools the oldest artifacts yet ascribed to the "Oldowan", a technology originally named after finds from Olduvai Gorge in Tanzania, but also were distinct from tools made by chimpanzees, monkeys or even earlier human ancestors.

Little in common with other tools

"We expected to see some indication of an evolution from the Lomekwian to these earliest Oldowan tools. Yet when we looked closely at the statistical patterns in the stone artefacts, there was very little connection to what has been described from older archaeological sites or to the stone tools modern primates are making," said Will Archer of the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University of Cape Town, South Africa.

An image of the Bokol Dora excavation during the 2015 excavation. Stones were placed on  the contact surface during the excavation to preserve the fragile stratigraphic contacts [Credit: David Feary]

The major differences appear to be the ability for our ancestors to systematically chip off smaller sharp-edged tools from larger nodules of stone. Chimpanzees and monkeys generally use tools for percussive activities, to hammer and bash food items like nuts and shellfish, which seems to have been the case with the 3.3 million year old Lomekwian tools as well.

Something changed by 2.6 million years ago, and our ancestors became more accurate and skilled at striking the edge of stones to make tools. The BD 1 artifacts captures this shift. It appears that this shift in tool making occurred around the same time that our ancestor’s teeth began to change. This can be seen in the Homo jaw from Ledi-Geraru. As our ancestors began to process food prior to eating using stone tools, we start to see a reduction in the size of their teeth. Our technology and biology were intimately intertwined even as early as 2.6 million years ago.

New ways of manufacturing tools

The lack of clear connections with earlier stone tool technology suggests that tool use was invented multiple times in the past. David Braun, an archaeologist with George Washington University and the lead author on the paper, noted, "Given that primate species throughout the world routinely use stone hammers to forage for new resources, it seems very possible that throughout Africa many different human ancestors found new ways of using stone artifacts to extract resources from their environment. If our hypothesis is correct then we would expect to find some type of continuity in artifact form after 2.6 million years ago, but not prior to this time period. We need to find more sites."

By 2.6 million years ago, there appears to be a long-term investment in tool use as part of the human condition. Continued field investigations at the Ledi-Geraru project area are already producing more insights into the patterns of behavior in our earliest ancestors. New sites have already been found, and the Ledi-Geraru team will begin excavating them this year.

The findings are published in the Proceedings of the National Academy of Sciences.

Source: Max-Planck-Gesellschaft [June 03, 2019]

Complex of rock-hewn churches in Ethiopia slowly yielding its secrets

By: Thomas Schmitt Attorney on March 27, 2019 / comment : 0 Africa, Archaeology, Ethiopia

The rock-cut monolithic churches of Lalibela never fail to prompt the curiosity and admiration of tourists. This site nestled atop Ethiopia’s high plateaus, 500 kilometres north of the capital Addis Abeba, is a destination for hundreds of thousands of pilgrims, who for centuries have been thronging to these sacred sites, considered to be a holy land for Christians of the Ethiopian Church.

View of the top of the monolithic church of St. George (Bet Giyorgis), a UNESCO World Heritage Site [Credit: (c) Westend 61/hemis.fr]

Aside from its spectacular architecture—which UNESCO recognised as a World Heritage Site in 1978—Lalibela is remarkable for its complexity. “There are many rock-cut churches throughout Ethiopia,” explains Claire Bosc-Tiessé, an art historian at the CNRS and scientific advisor at the INHA (Institut National de l’Histoire de l’Art). “But such a concentration of buildings in such a small space is entirely unique.” With its tangle of churches, trenches, underground galleries, and immense rooms carved into the rock, Lalibela is like no other known site, and therefore raises many questions.

The historian Marie-Laure Derat, a specialist in medieval Ethiopia, has also asked herself these same questions. The two researchers naturally combined their efforts in an attempt to find answers. “The site is so famous that we're under the false impression that we know everything about it,” explains Derat, a senior researcher with the laboratoire Orient et Méditerranée. “We ultimately know little about its history, origins, or role in Ethiopian society.”

In an effort to make their research project a reality, they took full advantage of their assignment at the Centre français des études éthiopiennes—a joint unit with a French research institute abroad (UMIFRE) and the successor of the archaeological mission backed by the National museum, created by the French at the request of the Ethiopian government during the 1950s—to launch the Lalibela Mission in 2008. Lalibela?

Monolithic Church of St. Mary (Beta Maryam) [Credit: (c) Mission Lalibela]

The site takes its name from an Ethiopian king who made it the centre of his kingdom in the 13th century, and gave it its emphatic religious dimension. His reign and character left a strong impression, as Lalibela was considered a saint approximately two centuries after his death, with the site beginning to receive its first pilgrimages. Yet information about how it was created and administered was sorely lacking.

The two researchers began their investigation by drawing up a precise map of the site, which allowed them to make a first observation: the relics that have survived demonstrate that there were multiple sequences of successive digging. Some churches actually have a door or stairway leading nowhere, showing that the original structure disappeared. Others show improbable outlines, suggesting that they were laid out in accordance with pre-existing edifices.

Since the rock does not allow for dating the buildings, research has concentrated on all other available traces, including an important body of manuscripts, paintings, and various objects found in churches. “There are no sources for the period before the 13th century,” Derat points out, “although they are very revealing from that period onwards.” A key role in this history is played by a small portable wooden altar, which bears a dedication, in the classical Ethiopian language of Ge’ez, from Lalibela himself, stating that the object is a gift to the church.

Gospel from the 15th century: above the painting of the evangelist. It is written in Ge'ez, Ethiopia's classical language, and describes the donation of the land of King Lalibela to the clergy [Credit: (c) Mission Lalibela]

The manuscripts, written in the same language, confirm that it was at the initiative of this same king that the religious complex was founded. “The archives we possess never discuss construction work,” Bosc-Tiessé notes, “but they are very clear with regard to property, relating that King Lalibela gave land to the clergy so that they could benefit from it.”

This form of organisation was all in all fairly similar to certain monastic orders established in Europe during the same period. “At the same time, these documents demonstrate the king’s omnipotence in the political system,” Derat adds. “He is the one who possesses land and disposes of it at his discretion, and who also regulates the life of the Church, its institutions, and clergy.”

As the picture became clearer with the completion of this research, a new discovery came along and expanded knowledge of the site. During excavations, the archaeologists and their teams identified a tremendous amount of rubble that the workers had piled up as they dug into the rock, a genuine goldmine for archaeologists. “This rubble includes traces that predate the 13th century, suggesting that the Lalibela site was inhabited before the founding of the religious complex. We found animal remains, as well as traces of hearths and ceramics, both signs of domestic occupation.”

Wooden altar of the Church of the Savior of the World, 13th century, with an inscription by King Lalibela written in Ge'ez which claims to donate this object to the church [Credit: (c) Mission Lalibela]

Excavation of the rubble also revealed that it was sitting atop traces of older buildings, which were most probably meant to disappear in favour of churches. The leaders of the Lalibela Mission see this as additional proof of the existence of a powerful society around the 10th or 11th century, one that was capable of constructing imposing buildings comparable to fortresses, for instance. All of these new signs are so many pathways towards understanding an Ethiopian society and culture about which we know virtually nothing, and that coexisted with the kingdom founded in the 4th century CE, always more or less attached to Christianity.

“We now know enough to construct a scenario,” Derat concludes. “A powerful elite occupied the site around the 10th century, building substantial infrastructure. In the many tombs that are still accessible, the orientation of bodies reveals that there were Christians at the time, but also many non-Christian subjects. During the 13th century Lalibela moved to the site, and engaged in an energetic assumption of power by transforming some buildings into churches and carving out new ones. Incidentally, this coincides with a period in which the kingdom expanded towards the south.”

Over the course of excavations, knowledge regarding more recent time periods also emerged. That is the paradox of such rock-hewn edifices, for unlike a traditional archaeological site, the oldest traces were erased as stone carvers reworked monuments. In addition, over the centuries the occupants of the premises always dug deeper in order to strengthen the foundations of the churches, which are threatened by the rock’s friability when in contact with water. “We can already conclude that the site continued to evolve until very recently, which is to say up to its inscription on UNESCO's World Heritage list,” underscores Bosc-Tiessé.

The discovery of structures predating the churches under the excavation of the second group of churches [Credit: (c) Mission Lalibela]

This represents a millennium in the history of a country that has had intense relations with the Eastern and later the Western worlds since antiquity. The research possibilities are immense for these two historians, beginning with the complete excavation of the rubble remaining from the hollowing out of the churches, which they would like to pursue.

However, two difficulties complicate their task. The first is the location of this rubble, which is in the middle of the site, precisely where pilgrims converge. This means that they will have to work the old-fashioned way, with a pail and a pickaxe, as the use of machinery would be too intrusive at these sacred sites. “People are interested in our excavations, and have generally been kind, but things can change very fast.”

The other factor relates to politics. Since October, the Ethiopian Prime Minister Abiy Ahmed has shown great interest in the site, whose conservation he actively supports. The two researchers believe that there is a need to make research central to the measures, in order to recommend appropriate restoration and development operations that do not endanger these final vestiges of the past.

Author: Francis Lecompte | Source: CNRS News [March 27, 2019]

New light into the recent evolution of the African rift valley

By: Thomas Schmitt Attorney on March 21, 2019 / comment : 0 Earth Science, Ethiopia, Geology, Kenya, Palaeontology

Continental rift valleys are huge fractures on the surface of our planet that progressively break continental plates with the eventual development of new oceans. The African rift valley between Ethiopia and Kenya is a classical example of this geodynamic process. There, volcanism, earthquakes, and fracturing of the Earth's surface result from the enormous forces that tear the eastern portion of the African continent apart.

The East African Rift System stretches from the Red Sea to Mocambique. It is marked by the African Great Lakes and is currently the largest rift of the world [Credit: S. Brune; Kartengrundlage: Nasa-World-Wind]

This system of linear valleys extending for thousands of kilometers is believed to result from the growth and propagation of isolated rift segments that evolve into a continuous zone of deformation. However, although instrumental in driving climate and biosphere of that region which in turn may have influenced habitats and the pattern of migration of human species in East Africa, and possibly even conditioned hominin evolution, this process is poorly documented and understood.

In a study published in Nature Communications and funded by the National Geographic Society, an international group of scientists from universities and research institutions from Ethiopia, France, Germany, Italy, New Zealand and the United Kingdom, of which Sascha Brune from the GFZ German Research Centre for Geosciences was a part, has shed new light into the recent evolution of the African rift valley. Its focus was on the spatial and temporal sequence of the propagation, interaction and linking of the Ethiopian rift section with the Kenyan part of the rift fracture.

Explosive volcanic crater (maar) with small lake at the bottom close to Dilo [Credit: Giacomo Corti, National Research Council Italy]

By conducting fieldwork in a remote area at the border between Ethiopia and Kenya, and integrating the results of that field campaign with laboratory analysis of volcanic rocks, analysis of the seismicity, morphology and numerical modelling, the authors have been able to reconstruct the geological history of an almost unknown sector of the African rift valley: the Ririba rift in South Ethiopia. The scientists showed that the Ririba trench formed about 3.7 million years ago as the southernmost advance of the Ethiopian rift segment.

Sascha Brune says: "In my research group at the GFZ we were able to substantiate the geological observations with numerical experiments. To this end, we brought together regional structures, deformation laws and basic physical equations to modelling in a supercomputer. In this way, we were able to show how the focusing of the rift valley contributed to a direct connection between the Kenyan and Ethiopian Rift."

Normal faults at the western margin of the Ririba rift [Credit: Giacomo Corti, National Research Council Italy]

In contrast with previous theories of rifting in the region, the new data indicate that the southward growth was short-lived and aborted around 2.5 million years ago. At this time, deformation migrated westward into the Lake Turkana region, where the Ethiopian and Kenyan sectors of the rift valley are now directly connected. A later phase of volcanism, expressed by numerous lava flows and impressive explosive volcanic craters (maars), have since affected the Ririba area; however, this volcanic activity was unrelated to tectonic activity, opening new questions on how volcanism and faulting interact during rifting.

Overall, the results of this work provide new insights into the break-up of continents: "In the East African rift, we can observe processes that are important far beyond the region," says Sascha Brune. "The same dynamics that determine the rift development in East Africa led to the opening of the Atlantic and Indian Oceans many millions of years ago and thus had a decisive influence on the face of the Earth."

Source: GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre [March 21, 2019]

New findings shed light on origin of upright walking in human ancestors

By: Thomas Schmitt Attorney on February 28, 2019 / comment : 0 Anthropology, Early Humans, Ethiopia, Fossils, Human Evolution

The oldest distinguishing feature between humans and our ape cousins is our ability to walk on two legs - a trait known as bipedalism. Among mammals, only humans and our ancestors perform this atypical balancing act. New research led by a Case Western Reserve University School of Medicine professor of anatomy provides evidence for greater reliance on terrestrial bipedalism by a human ancestor than previously suggested in the ancient fossil record.

Fossil hominin talus from site GWM67 (2005) at the time of its discovery [Credit: Case Western Reserve University School of Medicine]

Scott W. Simpson, PhD, led an analysis of a 4.5 million-year-old fragmentary female skeleton of the human ancestor Ardipithecus ramidus that was discovered in the Gona Project study area in the Afar Regional State of Ethiopia.

The newly analyzed fossils document a greater, but far from perfect, adaptation to bipedalism in the Ar. ramidus ankle and hallux (big toe) than previously recognized. "Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before," said Simpson.

Fossils of this age are rare and represent a poorly known period of human evolution. By documenting more fully the function of the hip, ankle, and foot in Ardipithecus locomotion, Simpson's analysis helps illuminate current understanding of the timing, context, and anatomical details of ancient upright walking.

Previous studies of other Ardipithecus fossils showed that it was capable of terrestrial bipedalism as well as being able to clamber in trees, but lacked the anatomical specializations seen in the Gona fossil examined by Simpson. The new analysis, published in the Journal of Human Evolution, thus points to a diversity of adaptations during the transition to how modern humans walk today. "The fact that Ardipithecus could both walk upright, albeit imperfectly, and scurry in trees marks it out as a pivotal transitional figure in our human lineage," said Simpson.

Key to the adaptation of bipedality are changes in the lower limbs. For example, unlike monkeys and apes, the human big toe is parallel with the other toes, allowing the foot to function as a propulsive lever when walking. While Ardipithecus had an offset grasping big toe useful for climbing in trees, Simpson's analysis shows that it also used its big toe to help propel it forward, demonstrating a mixed, transitional adaptation to terrestrial bipedalism.

Specifically, Simpson looked at the area of the joints between the arch of the foot and the big toe, enabling him to reconstruct the range of motion of the foot. While joint cartilage no longer remains for the Ardipithecus fossil, the surface of the bone has a characteristic texture which shows that it had once been covered by cartilage. "This evidence for cartilage shows that the big toe was used in a more human-like manner to push off," said Simpson. "It is a foot in transition, one that shows primitive, tree-climbing physical characteristics but one that also features a more human-like use of the foot for upright walking." Additionally, when chimpanzees stand, their knees are "outside" the ankle, i.e., they are bow-legged. When humans stand, the knees are directly above the ankle - which Simpson found was also true for the Ardipithecus fossil.

The Gona Project has conducted continuous field research since 1999. The study area is located in the Afar Depression portion of the eastern Africa rift and its fossil-rich deposits span the last 6.3 million years. Gona is best known as documenting the earliest evidence of the Oldowan stone tool technology. The first Ardipithecus ramidus fossils at Gona were discovered in 1999 and described in the journal Nature in 2005. Gona has also documented one of the earliest known human fossil ancestors - dated to 6.3 million years ago. The Gona Project is co-directed by Sileshi Semaw, PhD, a research scientist with the CENIEH research center in Burgos, Spain, and Michael Rogers, PhD, of Southern Connecticut State University. The geological and contextual research for the current research was led by Naomi Levin, PhD, of the University of Michigan, and Jay Quade, PhD, of the University of Arizona.

Source: Case Western Reserve University [February 28, 2019]