"Our ancestors first developed humanlike brains 1.7 million years ago"

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For nearly two centuries, scientists have known that humans descended from the great apes. But it’s proven difficult to precisely map out the branches of that evolutionary tree, especially in terms of determining when and where early Homo species first developed brains similar to modern humans.

There are clear differences between ape and human brains. Compared to apes, the Homo sapiens brain is larger, and its frontal lobe is organized such that we can engage in toolmaking, planning, and language. Other Homo species also enjoyed some of these cognitive innovations, from the Neanderthals to Homo floresiensis, the hobbit-like people who once inhabited Indonesia.

One reason it’s been difficult to discern the details of this cognitive evolution from apes to Homo species is that brains don’t fossilize, so scientists can’t directly study early primate brains. But primate skulls offer clues.

Brains of yore

In a new study published in Science, an international team of researchers analyzed impressions left on the skulls of Homo species to better understand the evolution of primate brains. Using computer tomography on fossil skulls, the team generated images of what the brain structures of early Homo species probably looked like, and then compared those structures to the brains of great apes and modern humans.

The results suggest that Homo species first developed humanlike brains approximately 1.7 to 1.5 million years ago in Africa. This cognitive evolution occurred at roughly the same time Homo species’ technology and culture were becoming more complex, with these species developing more sophisticated stone tools and animal food resources.

The team hypothesized that “this pattern reflects interdependent processes of brain-culture coevolution, where cultural innovation triggered changes in cortical interconnectivity and ultimately in external frontal lobe topography.”

The team also found that these structural changes occurred after Homo species migrated out of Africa for regions like modern-day Georgia and Southeast Asia, which is where the fossils in the study were discovered. In other words, Homo species still had ape-like brains when some groups first left Africa.

While the study sheds new light on the evolution of primate brains, the team said there’s still much to learn about the history of early Homo species, particularly in terms of explaining the morphological diversity of Homo fossils discovered in Africa.

“Deciphering evolutionary process in early Homo remains a challenge that will be met only through the recovery of expanded fossil samples from well-controlled chronological contexts,” the researchers wrote.

 

"Escaping the Mongols: A Survivor’s Account from the 13th century"

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In the year 1241, a Mongol army invaded eastern Europe, ravaging Poland, Hungary, Croatia and Romania. In battles they swept aside European forces and for over a year had little opposition as they plundered the conquered territories. Then the Mongols would withdraw back to Russia, taking with them thousands of captives.

There are several accounts of the Mongol invasion, all of which are filled with stories of death and destruction. One of the most vivid reports comes from an Italian named Master Roger, who was the archdeacon of the cathedral of Oradea in Hungary.

His letter to Giacomo di Pecorari, Bishop of Palestrina, begins by narrating the greater political events that surrounded the Mongol invasion – how the nomadic Cuman peoples came to Hungary and received protection from King Bela IV, the animosity between Bela and the Hungarian nobility, and how the Mongols invaded and defeated the Hungarians at the Battle of Mohi on April 11, 1241.

The second half of his letter then describes the personal experiences of Roger, who had decided to stay at Oradea even though the local bishop had already fled. In the following section, he explains how the Mongols (who he calls Tatars) reached his city:

“But when one day the Tatars suddenly arrived and my situation in the city was precarious, I did not want to go to the castle, but ran away into the forest and hid there as long as I could. They, however, suddenly took the city and burnt most of it and left nothing outside the walls of the castle. Having collected the booty, they killed men and women, commoners and nobles alike, on the streets houses, and fields. What more? They pardoned neither sex nor age. That done, they suddenly retreated, gathered up everything in the retreat, and settled at five miles away from the castle.”

The reprieve from the Mongol attack did not last long, and after they brought siege engines against the castle, it too fell. Master Roger, however, remained in hiding in the forests, and survived as he watched many others were captured or killed.

His story continues, as he moved from place to place, seeking somewhere to hide from the Mongols. When he heard that a strongly fortified island, which he had stayed at just a few days previously, was captured and its inhabitants beheaded, Roger writes despondently:

“Hearing this, my hair stood on end, my body shivered with fear, my tongue stuttered miserably, for I saw that the inevitable moment of dreadful death was menacing me. I already beheld my murderers in my mind’s eye; my body exuded the cold sweat of death. I also saw human beings, when earnestly expecting death, unable to grab weapons, raise their arms, move their steps to places of safety, or survey the land with their eyes. What more? I saw people half dead of fear.”

Roger writes how he had to hide in the forest, returning to the island and rummaging through the corpses to look for food. He writes, “I had to seek caves, excavate pits, or find hollow trees to have shelter, while the Tatars, like hounds tracking rabbits and boars, rushed through the thick of the thorn bushes, the shadows of the groves, the depths of the waters and the heart of the wasteland.”

However, after weeks or months of hiding, eventually a Hungarian Roger befriended turned him over to the Mongols, and he was taken as a captive. He watched as other towns and monasteries were attacked and destroyed, and then saw the Mongols beginning to withdraw back east. Believing that he would be executed once they left Hungary, Master Roger and his servant decided to escape. He writes:

“Therefore, I left the highway as if following the call of nature, and rushed towards the dense forest with my only servant and hid in the hollow of a creek, covering myself with leaves and branches. My servant hid farther away, so that the chance detection of the one should not cause the unhappy capture of the other. We lay thus for two full days, as in graves, not raising our heads and heard the terrible voices of those who, following the footprints of erring beasts, passed close by in the forest and often shouted after the prisoners who were in hiding. And when we could no more repress in the deep silence of our hearts the very just demands of hunger and the troubling desire for food in the closed silence of our hearts, we lifted our heads and began to crawl like snakes, using arms and legs.”

Together they looked for food, and climbed up trees to see if they could spot any Mongols. They would walk through abandoned villages and towns, where “leeks, purslane, onions and garlic, left in the gardens of the peasants, were, when they could be found, brought to me as the choicest delicacies.”

After passing through more destroyed places, Master Roger and his servant met up with other survivors. Eventually they reached a mountain:

“On the peak of it was a rock, a looming crag, where a great number of men and women had taken refuge. They received us with joy among tears and inquired about the perils we had passed through, all of which we could not tell them in a few words. Finally they gave us black bread, baked of flour and ground bark of oak trees, and it tasted sweeter than any simnel-cake we had ever eaten.”

It would be another month before Master Roger would leave the mountain, as he and the others feared that Mongol scouts were still in the area. Once the King of Hungary returned with more troops, Roger felt it was safe enough to go back home. He ends his letter by noting “I have written all this to you, father, without adding in anything false, so that you, father, who knows about the felicitous turn of my fortune, may know as well the true nature of my misfortune and danger.”

 

"An ancient piece of chewing gum offers surprising insights into the human genome"

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Five thousand and seven hundred years ago, “Lola” — a blue-eyed woman with dark skin and hair — was chewing on a piece of pitch derived from heating birch bark. Then, this woman spit her chewing gum out into the mud on an island in Denmark that we call Syltholm today, where it was unearthed by archaeologists thousands of years later. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.

This represents the first time that the human genome has been extracted from material such as this. “It is amazing to have gotten a complete ancient human genome from anything other than bone,” said lead researcher Hannes Schroeder in a statement.

“What is more,” he added, “we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains.”

In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.

INSIGHTS INTO ANCIENT PEOPLES

The birch pitch was found on the island of Lolland (the inspiration for Lola’s name) at a site called Syltholm. “Syltholm is completely unique,” said Theis Jensen, who worked on the study for his PhD. “Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal.

“It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia.”

Since Lola’s genome doesn’t show any of the markers associated with the agricultural populations that had begun to appear in this region around her time, she provides evidence for a growing idea that hunter-gatherers persisted alongside agricultural communities in northern Europe longer than previously thought.

Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they’ve weaned off of their mother’s milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn’t have needed this adaptation.

These findings are encouraging for researchers focusing on ancient peoples from this part of the world. Before this study, ancient genomes were really only ever recovered from human remains, but now, scientists have another tool in their kit. Birch pitch is commonly found in archaeological sites, often with tooth imprints.

Ancient peoples used and chewed on birch pitch for a variety of reasons. It was commonly heated up to make it pliable, enabling it to be molded as an adhesive or hafting agent before it settled. Chewing the pitch may have kept it pliable as it cooled down. It also contains a natural antiseptic, and so chewing birch pitch may have been a folk medicine for dental issues. And, considering that we chew gum today for no other reason than to pass the time, it may be that ancient peoples chewed pitch for fun.

Whatever their reasons, chewed and discarded pieces of birch pitch offer us the mind-boggling option of learning what someone several thousands of years ago ate for lunch, or what the color of their hair was, their health, where their ancestors came from, and more. It’s an unlikely treasure trove of information to be found in a mere piece of gum.

Une fleur à l’origine de la rage guerrière des Vikings

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Les guerriers vikings continuent de fasciner plusieurs siècles après leurs légendaires combats. Dans l'imaginaire collectif, c'est souvent aux berserkers que l'on pense lorsque l'on parle des Vikings. Ces guerriers étaient réputés pour leur violence et leur rage aveugle (berserkergang), leurs hurlements sauvages et leur incapacité à distinguer leurs ennemis de leurs amis durant les affrontements.

Dès le XIIIe siècle, l'historien et poète islandais Snorri Sturluson décrivait les berserkers d'Odin comme aussi «fous que des chiens ou des loups» et aussi «forts que des ours ou des bœufs sauvages», capables de tuer leurs ennemis d'un seul coup. Une fois atteint le stade du berserkergang, les guerriers étaient saisis de tremblements et de claquements de dents incontrôlés, tandis que leur visage devenait de plus en plus rouge.

Après deux cuissons à l'étuvée, l'amanite tue-mouches perd de sa toxicité au profit de propriétés psychoactives réputées chez les peuples de Sibérie. | Jaanus Leoste via Pixabay

On attribue souvent l'origine de cette rage incontrôlée à la consommation d'un champignon aux propriétés psychoactives, l'amanite tue-mouches. Cette hypothèse, controversée, est remise en question par Karsten Fatur, un ethnobotaniste de l'université de Ljubljana, dans un article paru dans le Journal of Ethnopharmacology. Il soutient l'idée selon laquelle le champignon rouge à pois blancs explique certains des symptômes attribués au berserkergang, tels que les contractions et tremblements, les rougeurs au visage, le délire et les convulsions –mais pas le plus important: la fureur aveugle.

Les fleurs de la fureur

Selon l'ethnobotaniste, les raisons de cette rage seraient plutôt à trouver du côté de l'aconit, et plus particulièrement de la jusquiame noire. Cette fleur existe depuis la Grèce antique et a été utilisée comme narcotique, analgésique, anesthésique et somnifère. Elle est également connue pour provoquer des comportements colériques, qui peuvent «aller de l'agitation à la rage et la combativité, selon le dosage et l'état d'esprit de l'individu», indique le chercheur.

Auriez-vous aimé vous marier à la Viking?

Le chercheur fait également état de la capacité de la jusquiame à atténuer la douleur, une propriété qui explique l'invulnérabilité prétendue des guerriers. La plante exerce aussi une influence sur la faculté de pouvoir reconnaître les visages. C'est encore à elle que l'on pourrait attribuer les effets secondaires pénibles dont souffraient les guerriers plusieurs jours après l'arrêt des combats: maux de tête, vision trouble et pupilles dilatées.

Côté culture, Karsten Fatur remarque que l'amanite tue-mouches ne pousse pas aussi facilement en Scandinavie et qu'elle était bien plus rare que la jusquiame noire, considérée comme une mauvaise herbe ayant prospéré à l'époque des berserkers. Toutefois, le chercheur ne parvient pas encore à expliquer pourquoi les guerriers claquaient des dents et mordaient leur bouclier. Avis aux historiens et ethnologues, la question reste en suspend.

 

Indices de la Grande Oxydation

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About 2.4 billion years ago, Earth's atmosphere underwent what is called the Great Oxidation Event (GOE). Prior to the GOE, early Earth had far less molecular oxygen than we have today. After the GOE, molecular oxygen began to increase in abundance, eventually making life like ours possible.

For decades, researchers have tried to understand why and how the GOE occurred.

A team of scientists, led by James Andrew Leong with Tucker Ely, both of whom earned their doctoral degrees from Arizona State University (ASU)'s School of Earth and Space Exploration in 2020, and ASU Professor Everett Shock, has determined that weathering rocks might have contributed to the GOE. Their results were recently published in Nature Communications.

Molecular oxygen is produced by plants and photosynthetic microbes, but molecular oxygen is also consumed by organisms and by the oxidation of iron, sulfur, carbon and other elements in rocks. Molecular oxygen can also be consumed through reaction with reduced gases like hydrogen, which can form during rock weathering.

Scientists studying the early Earth hypothesize that the consumption of oxygen was perhaps more rapid than the production of oxygen by photosynthesis, so oxygen was not able to accumulate in the atmosphere.

"It's like when your bills exceed your income, money can't accumulate in a savings account. This appears to have been the situation on the early Earth," said co-author Shock, of ASU's School of Earth and Space Exploration and the School of Molecular Sciences.

For the GOE to occur under this hypothesis, the consumption of oxygen had to slow with time, so that oxygen could build up in the atmosphere.

Given that, Leong and his team set out to determine what processes could be slowing down the consumption of oxygen on the early Earth to produce an increase in oxygen.

Chemical reactions between ultramafic rocks and groundwater led to the formation of highly alkaline water, which can discharge back into the surface. At the surface, these fluids react with carbon dioxide from the atmosphere to form calcium carbonate, which are the white minerals seen here from a field study the authors conducted in Oman. Credit: Leong/Shock/ASU

"We know it's probably not biological consumption, which does a decent job of keeping up with oxygen production by photosynthesis," Shock said. "So we thought maybe the rate that oxygen was consumed by the weathering of rocks was creating this change."

To test their hypothesis, Leong and his team focused on the weathering of a type of rock known as "ultramafic," an igneous rock, rich in magnesium and iron, with low silica content.

Ultramafic rocks comprise most of the Earth's upper mantle, where they were formed at high temperatures. When these rocks are brought to the surface and come into contact with water, the waterless minerals that make up these rocks transform into minerals containing water. This process is called serpentinization, after the main replacing mineral, serpentine. The process also transforms the reacting groundwater into a highly alkaline water with elevated gas content; in particular, hydrogen.

They were inspired to do this by research they had conducted previously on hyperalkaline and gas-rich fluids found in the ultramafic mountains of present-day Oman that was published in the AGU's Journal of Geophysical Research in 2021.

"Our previous field research in Oman led us to wonder what the early Earth surface and atmosphere would have looked like when high pH and hydrogen-rich fluids were as common as today's near-neutral pH groundwater and rivers," Leong said. "Ultramafic rocks like those found in Oman are rare in the Earth's surface at the present-day, but were abundant during the hotter early Earth."

For their analysis, they conducted computer simulations, based on a computer code that co-author Ely developed, to predict the hydrogen generation potentials of thousands of rock compositions that were common during the early Earth. From there, they could then draw connections between rock compositions and their potentials to generate hydrogen and consume oxygen.

With those simulations, the team then was able to reconstruct the global hydrogen production and oxygen consumption rates via serpentinization during early Earth and determine that the weathering of ultramafic rocks could have helped facilitate the GOE.

"We were able to model the alteration of thousands of rock compositions that are likely to be present on the early Earth," Leong said. "Our calculations show that many of these rocks, especially those that are really ultramafic in composition or rich in magnesium, like those found in Oman today, have very high potentials to generate hydrogen gas and help prevent accumulation of oxygen. The decline in the abundance of ultramafic rocks in the Earth's surface towards the end of the Archean eon could have helped facilitate the Great Oxidation Event."

 

Écrire chez les Gaulois

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Avec un nouveau cycle de conférences consacré à l’archéologie des écritures anciennes, la BnF invite archéologues, historiens et épigraphistes à revenir sur l’histoire des déchiffrements et à raconter l’histoire et l’évolution de ces écritures. Cette séance s’intéresse à la pratique de l’écrit chez les Gaulois.

Notre connaissance actuelle de la langue gauloise est issue de l’étude de multiples inscriptions retrouvées sur le territoire français et ses marges entre le IIe av. J.-C. et le IVe ap. J.-C. Contrairement à ce qu’on pourrait croire, l’épigraphie gauloise est loin d’être uniforme : les Gaulois ont en effet mis à profit leurs rencontres avec plusieurs systèmes graphiques différents pour écrire cette langue celtique continentale. La documentation qui nous est parvenue, bien que fragmentaire, révèle une large variété dans les usages graphiques. Cette conférence sera l’occasion d’illustrer la richesse et la complexité de l’épigraphie gauloise, de mettre en lumière le rôle de l’écriture dans la société gauloise puis gallo-romaine et de présenter le Recueil informatisé des inscriptions gauloises. 

Le gaulois est une langue méconnue, qui a pourtant laissé dans notre langue française beaucoup de mots comme la charrue, le béret, la glaise, la cervoise, la suie, ou encore la ruche. A l’approche de notre prochaine séance du cycle « Archéologie des écritures » dédiée au gaulois, nous vous emmenons à la découverte de cette langue.

𝐄𝐧 𝐆𝐚𝐮𝐥𝐞, 𝐨𝐮𝐢 𝐦𝐚𝐢𝐬 𝐥𝐚𝐪𝐮𝐞𝐥𝐥𝐞 ?

Les linguistes classent le gaulois comme une langue celtique continentale. Il a été parlé et écrit principalement en Gaule. Jusque-là pas de surprise, direz-vous. Mais la Gaule est en fait une région qui couvre, dans sa plus grande étendue, la France moderne, la Belgique, le Luxembourg, la majeure partie de la Suisse, l'Italie du Nord et certaines parties des Pays-Bas et de l'Allemagne !

𝐋’𝐞́𝐜𝐫𝐢𝐭𝐮𝐫𝐞 𝐠𝐚𝐮𝐥𝐨𝐢𝐬𝐞/𝐞́𝐭𝐫𝐮𝐬𝐪𝐮𝐞/𝐥𝐚𝐭𝐢𝐧𝐞/𝐠𝐫𝐞𝐜𝐪𝐮𝐞/𝐢𝐛𝐞́𝐫𝐢𝐪𝐮𝐞 

Pendant longtemps, on a pensé que les Gaulois n’écrivaient pas. L’explication vient en partie d'un passage de la « Guerre des Gaules » de César, dans lequel il explique que les druides ne consacrent pas leur apprentissage à l'écriture. 

Les découvertes archéologiques ont rapidement démontré que les communautés de langue gauloise utilisaient plusieurs écritures, principalement latines et grecques, pour leur propre langue en Gaule, ainsi qu'une variante de l'écriture étrusque en Gaule cisalpine, et ibérique en Gaule du sud-ouest. Plusieurs centaines d'inscriptions en gaulois permettent aux chercheurs aujourd’hui de mieux comprendre cette écriture. 

 

"13,000 Years Ago, a Firestorm Covered 10% of Earth's Surface, Triggering an Ice Age"

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At a point some 12,800 years ago, a tenth of Earth's surface suddenly became covered in roaring fires.

The firestorm rivalled the one that wiped out the dinosaurs, and it was likely caused by fragments of a comet that would have measured around 100 kilometers (62 miles) across.

As dust clouds smothered Earth, they kicked off a mini ice age that kept the planet cool for another thousand years, just as it was emerging from 100,000 years of being covered in glaciers. Once the fires burned out, life could start again.

"The hypothesis is that a large comet fragmented and the chunks impacted the Earth, causing this disaster," said Adrian Melott from the University of Kansas, who co-authored a 2018 study detailing this catastrophic event.