segunda-feira, 21 de maio de 2018

David Hofmann/Flickr (CC BY 2.0) via Wikimedia Commons

Californian ravens are a fusion of two different species

Hidden within the DNA of California's common ravens (Corvus coraxis the specter of another ancient raven species, The Washington Post reports. Researchers looked at the genomes of hundreds of ravens from across North America, examining mutations within the DNA to trace out their evolutionary history. They found that about 1.5 million years ago, the birds living in California split off into a separate species. After 1 million years of isolation, this lineage began breeding again with other ravens, eventually converging back into the single species of common raven that exists today. Writing in Nature Communications, the authors say that climate change is likely to cause more species to fuse together in this way.


Os corvos californianos são uma fusão de duas espécies diferentes

Escondido dentro do DNA de corvos comuns da Califórnia (Corvus corax) é o espectro de outra espécie de corvo antiga, The Washington Post relatórios.

Pesquisadores analisaram os genomas de centenas de corvos de toda a América do Norte, examinando mutações dentro do DNA para traçar sua história evolutiva. Eles descobriram que cerca de 1,5 milhões de anos atrás, os pássaros que vivem na Califórnia se dividiram em uma espécie separada.

Após 1 milhão de anos de isolamento, esta linhagem começou a se reproduzir novamente com outros corvos, eventualmente convergindo de volta para as únicas espécies de corvo comum que existem hoje. Escrevendo na Nature Communications, os autores dizem que a mudança climática provavelmente fará com que mais espécies se fundam dessa maneira.



Ancient remains of horse discovered at Pompeii

Ancient remains of horse discovered at Pompeii
The plaster cast of a horse, discovered in an ancient stable outside Pompeii. Photo: Parco Archeologico di Pompei
11:30 CEST+02:00 
 
For the first time ever, archaeologists have been able to cast the complete figure of a horse that perished in the volcanic eruption at Pompeii. 
 
The "extraordinary" discovery was made outside the city walls, in Civita Giuliana to the north of Pompeii proper, the site's directors announced this week.

Excavation in the area revealed what archaeologists identified as a stable, complete with the remains of a trough.

Using the same technique that has allowed them to recreate the final poses of dozens of Pompeii's victims, whereby liquid plaster is injected into the cavities left behind when bodies encased in volcanic matter decomposed, they were able to cast the horse as it would have lain when Mount Vesuvius erupted in 79 AD.

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Photo: Parco Archeologico di Pompei
From the remains of its skeleton, they believe the horse was an adult measuring around 150 centimetres tall at the withers: on the short side by today's standards, but given that horses were probably smaller at the time, the experts say it would have been exceptionally large for its time.
That, along with the fact that traces of a harness in valuable iron and bronze were found by its head, suggests that the animal was a specially bred parade horse, probably of considerable value.
While the skeletons of donkeys and mules have been found at Pompeii, in a stable attached to the Casa dei Casti Amanti ('House of the Chaste Lovers'), it's the first time archaeologists have unearthed the complete outline of a horse. The distinct imprint left by its ear, pressed to the ground as the animal lay on its left side, makes them confident this is indeed a horse and not another type of equid.

The imprint of the horse's left ear. Photo: Parco Archeologico di Pompei
Along with a pig and a dog, it is one of the few animals of any species to be successfully cast at Pompeii.
Its survival is all the more remarkable for the fact that the area where it was found – a sort of suburb of ancient Pompeii – has been subjected to illegal excavations in recent decades. Alarmed by the discovery of unauthorized tunnels, the site's archaeologists began new digs at Civita Giuliana in order to halt the intrusions and protect its remaining treasures.
As well as the horse, they also found the remains of jugs, tools and kitchen utensils, as well as the grave of a man buried after the fatal eruption – which indicates that people continued to live around or on top of the ruins even after the disaster.
Intriguing discoveries continue to be made at Pompeii, nearly two millennia and scores of excavations later. Last month, archaeologists discovered the complete skeleton of a young child in a bathhouse long thought to have been fully excavated.
READ ALSO: 'Exceptional discovery' at Pompeii: child's skeleton unearthed

Photo: Parco Archeologico di Pompei
ESO/M. Kornmesser

First carbon-rich asteroid found beyond Neptune

Four billion kilometers from Earth in a region of the outer solar system near Neptune floats a nearly 305-kilometer-long asteroid that looks not like its fellow Kuiper belt objects, but, rather, like those in the asteroid belt between Mars and Jupiter. That’s because the space anomaly, 2004 EW95, is rich with carbon, a first for any object so distant, researchers report in The Astrophysical Journal Letters. They could hardly believe their results when they learned liquid water had likely altered the asteroid, meaning the rock probably came from an area closer to the sun, The New York Times reports. The find may give scientists clues about how planets formed early on, researchers say.

 Primeiro asteroide rico em carbono encontrado além de Netuno

Quatro bilhões de quilômetros da Terra, em uma região do sistema solar externo perto de Netuno, flutua um asteroide de quase 305 quilômetros que não se parece com os objetos do cinturão de Kuiper, mas sim com aqueles no cinturão de asteroides entre Marte e Júpiter.

Isso porque a anomalia do espaço, 2004 EW95, é rica em carbono, a primeira para qualquer objeto tão distante, relatam os pesquisadores no The Astrophysical Journal Letters. Eles mal podiam acreditar em seus resultados quando souberam que a água líquida provavelmente alterou o asteroide, o que significa que a rocha provavelmente veio de uma área mais próxima do sol, informa o New York Times. A descoberta pode dar aos cientistas pistas sobre como os planetas se formaram no início, dizem os pesquisadores.


Ben Mierement, NOAA NOS (ret.)

Plastic debris found in the deepest part of the ocean

Detritos de plástico encontrados na parte mais profunda do oceano

Plastic trash is now so pervasive, it has even made its way to the deepest part of the oceanNational Geographic reports. Scientists found a plastic bag almost 11 kilometers deep in the Mariana Trench in the Pacific Ocean while combing through a database of photos from thousands of submersible dives made over the past 30 years. One-third of all debris in the database, created to provide a record of trash in the ocean depths, were plastics, mostly single-use products. In some photos, deep-sea creatures like sea anemones were entangled in the plastic. Writing in Marine Policy, the researchers say the production of plastic waste needs to be drastically reduced to protect the deep-sea environment.


O lixo de plástico agora é tão difundido que chegou até a parte mais profunda do oceano, segundo a National Geographic. Os cientistas encontraram uma sacola plástica de quase 11 quilômetros de profundidade na Fossa das Marianas, no Oceano Pacífico, enquanto vasculhava um banco de dados de fotos de milhares de mergulhos submersíveis feitos nos últimos 30 anos. Um terço de todos os detritos no banco de dados, criados para fornecer um registro de lixo nas profundezas do oceano, eram plásticos, a maioria produtos de uso único. Em algumas fotos, criaturas do fundo do mar, como anêmonas do mar, estavam enredadas no plástico. Escrevendo em Política Marinha, os pesquisadores dizem que a produção de resíduos plásticos precisa ser drasticamente reduzida para proteger o ambiente do fundo do mar.
NASA/NASA Ozone Watch/Katy Mersmann

Banned ozone-destroying chemical makes a mysterious resurgence

Produto químico destruidor de ozônio proibido faz ressurgência misteriosa

The 1987 Montreal Protocol is widely touted as an environmental success story, one that staved off expansion of the ozone hole above Antarctica (pictured). But someone is cheating on that international agreement, The Washington Post reports. Scientists have detected a 25% uptick in emissions of CFC-11—an ozone-destroying chemical—since 2012. CFC-11 was once commonly used in insulating foams, but it’s now banned under the Montreal Protocol and reported production is close to zero. The startling resurgence of the chemical, reported in Nature, will likely spark an international investigation to track down the mysterious source.



O Protocolo de Montreal de 1987 é amplamente divulgado como uma história de sucesso ambiental, que impediu a expansão do buraco na camada de ozônio acima da Antártica (foto). Mas alguém está traindo esse acordo internacional, informa o Washington Post. 

Os cientistas detectaram um aumento de 25% nas emissões de CFC-11 - um produto químico destruidor de ozônio - desde 2012. CFC-11 já foi comumente usado em espumas isolantes, mas agora está proibido pelo Protocolo de Montreal e a produção é próxima de zero. O surpreendente ressurgimento do produto químico, relatado na Nature, provavelmente desencadeará uma investigação internacional para rastrear a fonte misteriosa.
Franco Banfi/Minden Pictures

Something killed a lot of sperm whales in the past—and it wasn’t whalers

 Algo matou muitos cachalotes no passado - e não eram baleeiros

Sperm whales are a genetic puzzle. The deep-diving, squid-eating giants that inspired Moby Dick are found in every ocean, where they can mate with partners from around the world; as such, they should be quite genetically diverse. Yet, their genetic diversity is actually very low, hinting that something killed a lot of them off in the past. And that something wasn’t whalers.

To reach this conclusion, researchers analyzed mitochondrial genomes (DNA inherited only through the maternal line) from 175 sperm whale samples collected from biopsies of live and dead stranded whales across the globe. Their analysis showed that the current global distribution of sperm whales resulted from a population expansion starting about 100,000 years ago. Sperm whales at that time had apparently been reduced to a small population of about 10,000, when a freezing world caused extensive ice to exclude them from all oceans except the Pacific.

Today’s sperm whales (about 360,000 animals) are all descended from this single population, the team reports online today in Molecular Ecology. They subsequently colonized the Atlantic Ocean multiple times. Whaling has taken another toll, although the full extent is not yet known; it likely depleted some sperm whale populations more than others, the scientists say, noting that collecting information on the population’s overall recovery has proved difficult.

Given today’s warming trends, the habitat of sperm whales may continue to expand, the scientists say. But they caution it’s not clear how climate change will affect the whales’ prey, and urge that protections for large whales remain in place.


Cachalotes são um enigma genético. Os gigantes que se alimentam de lulas que inspiram Moby Dick são encontrados em todos os oceanos, onde podem acasalar com parceiros de todo o mundo; como tal, eles devem ser geneticamente diversos. No entanto, sua diversidade genética é realmente muito baixa, sugerindo que algo matou muitos deles no passado. E esse algo não eram baleeiros.


Para chegar a essa conclusão, os pesquisadores analisaram os genomas mitocondriais (DNA herdado apenas através da linha materna) de 175 amostras de baleias coletadas de biópsias de baleias vivas e mortas em todo o mundo. Sua análise mostrou que a atual distribuição global de cachalotes resultou de uma expansão populacional a partir de cerca de 100.000 anos atrás. Na época, os cachalotes haviam aparentemente sido reduzidos a uma pequena população de cerca de 10 mil, quando um mundo congelante causou gelo extenso para excluí-los de todos os oceanos, exceto o Pacífico.

 Os cachalotes de hoje (cerca de 360.000 animais) são descendentes dessa única população, informou a equipe on-line hoje na revista Molecular Ecology. Eles posteriormente colonizaram o Oceano Atlântico várias vezes. A caça às baleias cobra outro pedágio, embora a extensão total ainda não seja conhecida; É provável que tenha esgotado algumas populações de cachalotes mais do que outras, dizem os cientistas, observando que a coleta de informações sobre a recuperação geral da população se mostrou difícil.

Dadas as tendências atuais de aquecimento, o habitat dos cachalotes pode continuar a se expandir, dizem os cientistas. Mas eles alertam que não está claro como a mudança climática afetará a presa das baleias e pedem que as proteções para as grandes baleias permaneçam em vigor.


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doi:10.1126/science.aau2256

sábado, 19 de maio de 2018

Dmanisi Human: Skull from Georgia Implies All Early Homo Species were One

Oct 18, 2013 by News Staff / Source
An analysis of a complete 1.8-million-year-old hominid skull found at the archaeological site of Dmanisi in Georgia suggests the earliest Homo species – Homo habilis, Homo rudolfensis and so forth – actually belonged to the same species.
Skull 5 from Dmanisi, Georgia. Image credit: Guram Bumbiashvili / Georgian National Museum.
Skull 5 from Dmanisi, Georgia. Image credit: Guram Bumbiashvili / Georgian National Museum.
The skull fossil, called Skull 5, is the world’s first completely preserved adult hominid skull from the early Pleistocene.
Unlike other Homo fossils, Skull 5 combines a small braincase with a long face and large teeth. It was discovered alongside the remains of four other early human ancestors, a variety of animal fossils and some stone tools – all of them associated with the same location and time period – which make the find truly unique.
The archaeological site of Dmanisi, located in the Kvemo Kartli region of Georgia about 93 km southwest of the capital Tbilisi, has only been partially excavated so far, but it’s already providing the first opportunity for anthropologists to compare and contrast the physical traits of multiple human ancestors that apparently coincided in the same time and geological space.
This is an artist's reconstruction of female Homo from Dmanisi, Georgia. Image credit: Elisabeth Daynes, via tabula.ge.
This is an artist’s reconstruction of female Homo from Dmanisi, Georgia. Image credit: Elisabeth Daynes, via tabula.ge.
“The differences between these Dmanisi fossils are no more pronounced than those between five modern humans or five chimpanzees,” said Dr David Lordkipanidze from the Georgian National Museum in Tbilisi, a lead author of a paper in the journal Science and co-author of a paper published in the Proceedings of the National Academy of Sciences.
Traditionally, researchers have used variation among Homo fossils to define different species. But in light of these new findings, Dr Lordkipanidze and his colleagues suggest that early, diverse Homo fossils, with their origins in Africa, actually represent variation among members of a single, evolving lineage – most appropriately, Homo erectus.
“Had the braincase and the face of Skull 5 been found as separate fossils at different sites in Africa, they might have been attributed to different species,” said Dr Christoph Zollikofer from the Anthropological Institute and Museum in Zurich, Switzerland, a co-author of the Science paper.
Computer reconstruction of Skull 5 and other four Dmanisi skulls; background - Dmanisi landscape. Image credit: Marcia Ponce de León / Christoph Zollikofer / University of Zurich.
Computer reconstruction of Skull 5 and other four Dmanisi skulls; background – Dmanisi landscape. Image credit: Marcia Ponce de León / Christoph Zollikofer / University of Zurich.
That’s because Skull 5 unites some key features, like the tiny braincase and large face, which had not been observed together in an early Homo fossil until now.
Given their diverse physical traits, the fossils associated with Skull 5 at Dmanisi can be compared to various Homo fossils, including those found in Africa, dating back to about 2.4 million years ago, as well as others unearthed in Asia and Europe, which are dated between 1.8 and 1.2 million years ago.
“The Dmanisi finds look quite different from one another, so it’s tempting to publish them as different species,” Dr Zollikofer said.
“Yet we know that these individuals came from the same location and the same geological time, so they could, in principle, represent a single population of a single species.”
The fossils from Dmanisi represent ancient human ancestors from the early Pleistocene epoch, soon after early Homo diverged from Australopithecus and dispersed from Africa.
The jaw associated with Skull 5 was found five years before the cranium was discovered but when the two pieces were put together, they formed the most massively built skull ever found at the Dmanisi site. For this reason, the team suggests that the individual to whom Skull 5 belonged was male.
The braincase of Skull 5 is only about 33.3 cubic inches (546 cubic cm), however, which suggests that this early Homo had a small brain despite his modern human-like limb proportions and body size.
“Thanks to the relatively large Dmanisi sample, we see a lot of variation. But the amount of variation does not exceed that found in modern populations of our own species, nor in chimps and bonobos,” Dr Zollikofer said.
“Furthermore, since we see a similar pattern and range of variation in the African fossil record… it is sensible to assume that there was a single Homospecies at that time in Africa. And since the Dmanisi hominids are so similar to the African ones, we further assume that they both represent the same species.”
Skull 5 seemingly indicates that, rather than several ecologically specialized Homo species, a single Homo species – able to cope with a variety of ecosystems – emerged from the African continent.
And accordingly, our classification system for these early human ancestors may never be the same.
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Bibliographic information: David Lordkipanidze et al. 2013. A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo. Science, vol. 342, no. 6156, pp. 326-331; doi: 10.1126/science.1238484
Ann Margvelashvili et al. Tooth wear and dentoalveolar remodeling are key factors of morphological variation in the Dmanisi mandibles. PNAS, published online October 7, 2013; doi: 10.1073/pnas.1316052110