Avant Champlain...: janvier 2021

Origine des cheveux roux

The Norse Origins Of The Red Hair Gene

For some time there has been quite a debate among scholars regarding the origins of the red hair gene. According to some, the gene for red hair is inherent to the Celts, while others claim it to be a genetic trait specific to the Norsemen, being brought to the British Isles during the Viking Age. There is also a third category of historians and scientists who agree on a common Celto-Germanic genetic trait, rather than a separate origin for the gene.

What are the causes behind red hair?
Scientifically speaking, red hair is the result of a recessive genetic trait which has been caused by a series of mutations in the melanocortin 1 receptor (MC1R), a gene which is located on chromosome 16. Being a recessive genetic trait means that both parents must cary the gene in order for their children to be born red haired.

An interesting aspect of this gene is that there are far many carriers of it than people who are actually born with red hair. For instance, Scotland — which is reputed for being one of the homelands of the red hair gene alongside Ireland and Wales — has a rate of 13% of its total population with red hair, as opposed to roughly 40% who actually carry the gene. The red hair gene is very rare worldwide, with only 0.6% of the world population sharing this genetic trait.

Where is red hair most common?
The highest rate of frequency for red hair can be traced to Ireland (ranging from minimum 10% to maximum 30%), Scotland (ranging from minimum 10% to maximum 25%), Wales (ranging from minimum 10% to maximum 15%). As such, one might conclude that the Celts are actually responsible for the red hair gene.

Nonetheless, when referring to the European frequency of red hair, just after Wales one could consider southwest Norway in this top as well. According to Professor Donna Heddle, the director for both the University of the Highlands and Islands’ Centre for Nordic Studies and a leading expert on the Norse, the red hair gene from Scotland is actually part of the Norsemen’s heritage.

Did the Vikings actually bring the red hair gene to the British Isles?
Professor Donna Heddle also explained that the perception according to which the invading Viking raiders of the British Isles were blond is nothing more but a mere misconception. According to the same theory, the Norsemen were likely red headed. This may be true, at least in part. Not that many Viking warriors were naturally blond, indeed. In fact, blond hair was very much sought after in Viking Age Scandinavia and many Norsemen dyed their hair blond.

On this note Professor Donna Heddle stated for The Scotsman:

"The perception that the Norse were blond is nothing more than a prevalent myth. Genetically speaking, the chances of them having blond hair weren’t that likely. The chances are that they would have had red hair. Interestingly, if you look at where red hair occurs in the world you can almost map it to Viking trading routes."

And indeed, this actually holds up to be true even to these days. For example, if we are to take a look at the areas in Ireland where the Norsemen settled, we can also see the highest concentration of red haired Irish people. The Viking warriors who settled coastal parts of both Scotland and Ireland were mainly of Norwegian descent (shortly followed by Danish Vikings as well).

Furthermore, it has been recently discovered that southwest Norway may well be the actual place of origin for the red hair as the gene was successfully linked to the paternal Y-DNA haplogroup R1b-L21, which includes one of its sub-clades defined as R1b-M222 — one that is very common for both northwestern Ireland and Scotland.

A famous Norwegian Viking by the name Eiríkr Þorvaldsson (Erik Thorvaldsson) who was born born in the Jæren district of Rogaland, southern Norway in mid 10th century subsequently got renowned as Erik the Red because of the colour of his hair and beard. He is recounted in the Icelandic sagas as the first Norse settler in Greenland.

In conclusion, analysing the maps from above can hopefully solve the mystery concerning the true origins of the red hair gene and possibly debunk a few myths regarding the Norse culture and the Viking Age in general.

"DNA Reveals the Real Lives of (...) Dire Wolves"

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The dire wolf (...) powerful predator that roamed North America up to about 11,000 years ago, or perhaps even later, preying on large animals like extinct horses, bison, sloths and even mammoths.

(...) The last common ancestor of the gray wolf and the dire wolf was about 5.7 million years ago, the researchers reported. And another surprise was that the dire wolf didn’t seem to interbreed with other species — as dogs, wolves, coyotes and other canids do. In evolutionary terms, it met a lonely end.

(...) The problem was not a lack of old bones. The vast majority come from the La Brea Tar Pits in Los Angeles County, where the remains of about 4,000 animals have been recovered. Tar apparently plays havoc with recoverable DNA and until now, nobody had been able to sequence the dire wolf’s genome.

(...) The long genetic isolation is significant in another way.

Larisa DeSantis, a paleontologist at Vanderbilt University, who was not involved in the research, said it “is consistent with the idea of a North American origin of dire wolves.”

They were here at least 250,000 years ago, and they were still around, although nearing the end of their existence, when the first humans were arriving in the Americas, perhaps 15,000 years ago.

“They were not this ginormous mythical creature, but an animal that most likely interacted with humans,” Dr. Perri said.

(...) As to why the dire wolf went extinct and wolves survived, the authors speculated that its long genetic isolation and lack of interbreeding with other species may have made it less able to adapt to the disappearance of its main prey species. More promiscuous species like gray wolves and coyotes were acquiring potentially useful genes from other species.

Laurent Frantz, an ancient DNA specialist at Ludwig Maximilian University in Munich and one of the paper’s authors, said that finding was a reminder of the evolutionary success of gray wolves. Their wide variation in size and ability to adapt to different prey species helped them escape the fate of the dire wolf. Now, of course, they face many threats in Europe and the United States.

“It’s the ultimate carnivore survivor,” he said, “until it faces humans.”

536, année maudite

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Ce sont les arbres qui en parlent le mieux : les analyses des cernes de spécimens fossiles prélevés en Irlande, Allemagne, Autriche, Suède, Finlande, Californie, Mongolie et plus récemment dans le massif de l'Altai (Russie) révèlent une absence de croissance végétative à partir de l'été de l'an 536, et durant les années suivantes. Comme s'il n'y avait plus de printemps ou d'été pour les plantes… Les reconstructions climatiques à partir de ces troncs, des sédiments et dépôts minéraux suggèrent une chute de température globale de plus de 2 °C à l'été 536 ; et un refroidissement presque aussi brutal en 540. "Nos mesures montrent que l'année 536 est la plus froide des 2 500 dernières années et que la décennie 536-545 est aussi la plus froide enregistrée", lâche Michael Sigl, climatologue à l'université de Berne. Pis, ce climat glacial semble persister, de manière certes moins prononcée, jusque dans les années 660 ; 13 des 20 saisons estivales les plus froides des deux derniers millénaires en Asie centrale se sont produites durant cet épisode.

(...) Ailleurs, les historiens disposent tout de même de quelques bribes de témoignages évocateurs : les annales irlandaises décrivent ainsi plusieurs années sans pain à partir de 536 ; dans le sud de la Chine, on parle de chutes de neige aux mois de juillet et août 536 ; du Japon à la Mésopotamie, on peut lire dans certains manuscrits des histoires de fruits qui ne mûrissent pas et de vins au goût de jus de raisin aigre ; une étude israélienne parue ce mois de juillet relève, vers 536, un effondrement inexplicable de la production de vin blanc dans la région du Néguev.

Requin fossilisé vieux de 150 millions d'années

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Asteracanthus est un membre des Hybodontiformes, un ordre éteint de requins qui a disparu en même temps que les dinosaures, il y a 66 millions d'années, et qui représentent les plus proches parents des requins et des raies actuels. Ces poissons cartilagineux étaient remarquables par leurs puissantes mâchoires capables de croquer n'importe quelle carapace. Il ne mesurait pas loin de 2,5 mètres : c'est le plus grand requin du Jurassique.

Son fossile a été découvert dans les calcaires de Solnhofen en Bavière, en Allemagne, qui se sont formés pendant le Jurassique supérieur, il y a environ 150 millions d'années. Ce gisement est mondialement célèbre pour avoir livré plusieurs spécimens d'Archaeopteryx, ce dinosaure ailé dont on ne sait plus très bien s'il faut le placer à la racine des oiseaux modernes. Ainsi que de nombreux autres fossiles de requins et de raies : à l'époque l'écosystème de cette région formait un paysage lagunaire tropical. Le fossile d'Asteracanthus qui a été découvert est presque entièrement préservé. Ce qui est tout à fait exceptionnel et il s'agit pour ce genre d'une première. S'il est connu depuis près de 180 ans, ce n'était qu'essentiellement à partir de dents et de ses épines dorsales. Les requins sont en effet des poissons cartilagineux dont le squelette se fossilise et se conserve très mal. Par contre, leurs dents qui se renouvellent tout au long de leur vie constituent une des archives fossiles les plus retrouvées lors des fouilles.

Sapiens et Néandertal : il y a 200 000 ans, la rencontre oubliée

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L'aventure met en scène notre lignée, celle d'Homo sapiens, et celle de Neandertal, cette espèce humaine cousine qui vivait encore dans l'ouest de l'Eurasie il y a environ 40 000 ans. Bien entendu, il n'est pas question ici de leur idylle bien connue, survenue juste après que notre espèce est sortie d'Afrique il y a 60 000 ans environ, et dont notre génome conserve toujours la ferveur sous forme de quelques pourcents d'ADN néandertalien. Non, le tout premier coup de foudre entre nos deux humanités a eu lieu bien avant cela : "Il y a entre 350 000 et 100 000 ans, sûre ment quelque part en Eurasie , ébruite Janet Kelso, de l'Institut d'anthropologie évolutive Max-Planck, de Leipzig (Allemagne), qui, avec son équipe, vient d'en révéler l'existence. C'est là, pour la première fois, qu'un groupe de pré-Sapiens s'est hybridé avec des néandertaliens."

Une espèce de mante vieille de 100 millions d’années découverte à Schefferville

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Dans les débris des anciennes mines de fer de Schefferville, sur la Côte-Nord, une équipe de paléontologues a découvert, fossilisée, une espèce inconnue de mante qui vivait à l’époque des dinosaures. Grâce à une collaboration internationale et des techniques d’imagerie innovatrices, ils trouvent réponse à des mystères de l’évolution des insectes.

(...) Le quatuor a prouvé l’existence d’une espèce de mante religieuse du Labrador maintenant éteinte qui était inconnue jusqu’à aujourd'hui. Ils l'ont baptisée Labradormantis guilbaulti.

Inostranzevia (Andrey Atuchin)

Sculptures de bisons

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Perhaps the most exciting discovery of the caverns is a small clay statue in the deepest room of the Tuc d'Audoubert cave—now known as the Room of the Bisons. Supported by a rock in the floor of the cavern is a small clay statue of two bison sculpted in relief. The work is only about 18 inches tall but remarkable for the detail with which it depicts a male and female bison who appear to be close to mating. Thier very realistic appearance was created using a combination of hand and tool. The clay used was clearly carved from the wall of an adjoining cavern. Despite the almost 15,000 years which have passed since its creation, the sculpture is still in generally good condition. This is in part due to the restricted access policy—since almost the day of its discovery—which only allows researchers to enter the caves.

Rome à son apogée (Danila Loginov)

Trouvé ici.

Art du Moyen Âge (Timeline)

La civilisation minoenne (Timeline)

L'empereur Vespasien (Timeline)

Sumer (Fall of Civilizations)

Les Étrusques (Timeline)

536: pire année de l'histoire (Timeline)

Plumes de dinos

Trouvé ici.

Synapsides (RavePaleoArt)

Trouvé ici.

Origine de l'émail

Extraits de cet article:

The hardest bit of your body is the enamel coating your teeth. But new analyses of fish fossils, as well as genetic analyses of a living fish species, suggest that this specialized material once served a very different function: to toughen some bones and scales of ancient fish. The findings bolster earlier suggestions that ancient fish had enamel-armored scales, and they point to a new scenario for exactly how the substance ended up on teeth.

Enamel—an almost pure layer of a mineral called hydroxyapatite—coats the teeth of almost all tetrapods (four-limbed creatures) and lobe-finned fish such as coelacanths. Most living fish do not produce it, but Per Ahlberg, a paleontologist at Uppsala University in Sweden, found an ancient exception. Well-preserved fossils of an ancient fish called Psaroepis romeri reveal that this 20-centimeter-long minipredator, which prowled the seas between 410 million and 415 million years ago, had enamel in its scales and its skull—but not its teeth, according to a paper by Ahlberg and colleagues in the 24 September issue of Nature.

Trouvé ici.

Distribution:

• Triassic of Canada (1: British Columbia collection), Italy (1), United States (1: Nevada)