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The first Americans
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ramonmercadoOffline
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PostPosted: 13-03-2014 00:32    Post subject: Reply with quote

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Language 'evolution' may shed light on human migration out-of-Beringia
March 12th, 2014 in Other Sciences / Social Sciences

Language 'evolution' may shed light on human migration out-of-Beringia
Network summarizes all splits with at least 10% support in 3,001 trees sampled. Longer branch lengths indicate higher probabilities for splits. Credit: Mark A. Sicoli; doi:10.1371/journal.pone.0091722.g003

Network summarizes all splits with at least 10% support in 3,001 trees sampled. Longer branch lengths indicate higher probabilities for splits. Credit: Mark A. Sicoli; doi:10.1371/journal.pone.0091722.g003

Evolutionary analysis applied to the relationship between North American and Central Siberian languages may indicate that people moved out from the Bering Land Bridge, with some migrating back to central Asia and others into North America, according to a paper published in the open-access journal PLOS ONE on March 12, 2014 by Mark Sicoli, from Georgetown University and Gary Holton from University of Alaska Fairbanks.

Languages evolve slowly overtime and may even follow human migratory patterns. A proposed language family known as the Dené–Yeniseian suggests that there are common language elements between the North American Na-Dene languages and the Yeniseian languages of Central Siberia. To investigate this further, scientists employed a technique originally developed to investigate evolutionary relationships between biological species called phylogenetic analysis, where a tree is constructed to represent relationships of common ancestry based on shared traits. Scientists used linguistic phylogeny to work out how approximately 40 languages from the area diffused across North America and Asia. The authors first coded a linguistic dataset from the languages, modeled the relationship between the data, and then modeled it against migration patterns from Asia to North America, or out-of-Beringia.

Results show an early dispersal of Na-Dene along the North American coast with a Yeniseian back migration through Siberia and a later dispersal of North American interior Na-Dene languages. Sicoli explained, "we used computational phylogenetic methods to impose constraints on possible family tree relationships modeling both an Out-of-Beringia hypothesis and an Out-of-Asia hypothesis and tested these against the linguistic data. We found substantial support for the out-of-Beringia dispersal adding to a growing body of evidence for an ancestral population in Beringia before the land bridge was inundated by rising sea levels at the end of the last ice age." Although the authors cannot conclusively determine the migration pattern just from these results, and state that this study does not necessarily contradict the popular tale of hunters entering the New World through Beringia, it at the very least indicates that migration may not have been a one-way trip. This work also helps demonstrate the usefulness of evolutionary modeling with linguistic trees for investigating these types of questions.

Language 'evolution' may shed light on human migration out-of-BeringiaEnlarge

This polar projection map of Asia and North America shows the approximate terminal Pleistocene shoreline. The center of geographic distribution of Yeniseian and Na-Dene language is in Beringia. From this center burgundy arrows extend toward the North American coast and into Siberia. A blue arrow indicates Interior dispersals of Na-Dene. Credit: Mark A. Sicoli; doi:10.1371/journal.pone.0091722.g004

These finding suggest that phylogenetics may be used to explore the implications of deep linguistic relationships.

More information: Sicoli MA, Holton G (2014) Linguistic Phylogenies Support Back-Migration from Beringia to Asia. PLoS ONE 9(3): e91722. DOI: 10.1371/journal.pone.0091722
Provided by Public Library of Science

"Language 'evolution' may shed light on human migration out-of-Beringia." March 12th, 2014. http://phys.org/news/2014-03-language-evolution-human-migration-out-of-beringia.html
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PostPosted: 16-05-2014 12:23    Post subject: Reply with quote

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Sunken body clue to American origins

The skull has been removed from the cavern but most of the skeleton remains in place

The ancient remains of a teenage girl discovered deep underground in Mexico are providing additional insights on how the Americas came to be populated.

Divers found the juvenile's bones by chance in a vast, flooded limestone chamber on the Yucatan Peninsula.

Aged 15 or 16 at death, the girl lived at least 12,000 years ago.

Researchers have told Science Magazine her DNA backs the idea that the first Americans and modern Native American Indians share a common ancestry.

This theory argues that people from Siberia settled on the land bridge dubbed Beringia that linked Asia and the Americas some 20,000 years ago before sea levels rose.

These people then moved south to populate the American continents.

The genetics of modern Native Americans would certainly appear to link them into this story. But their facial features set them apart from the oldest skeletons now being unearthed.

These ancient people had narrower, longer skulls. The differences have hinted that perhaps there were multiple immigrations from Siberia (or even Europe).

Evolution link
However, the remains of the Yucatan girl, dubbed Naia - which means "water nymph" in Greek - does not follow that line of thinking, because although she had the slender features associated with the earliest Americans, her DNA shares commonalities with modern Native Americans.

Lab analysis of teeth and bone samples link her to a particular genetic lineage known as Haplogroup D1.

This same marker is found in substantial numbers of modern Native Americans.

"This lineage is thought to have developed in Beringia, the land that now lies beneath the Bering Sea after its ice age occupants became genetically isolated from the rest of Asia," explained lead author Dr Jim Chatters.

"Thus, Naia, one of the earliest occupants of the Americas yet found, suggests that Paleoamericans do not represent an early migration from a part of the world different than that of the Native Americans.

"Rather, Paleoamericans and Native Americans descended from the same homeland in Beringia.

"The differences between them likely arose from evolution that occurred after the Beringian gene pool became separated from the rest of the world."

The chamber where the girl was found represents one of these pits before its roof has collapsed to produce a wide surface opening.

To reach the natural amphitheatre, divers had to swim almost 1km (0.6 miles) through a water-filled tunnel.

"The moment we entered inside, we knew it was an incredible place," recalled Alberto Nava.

"The floor disappeared under us and we could not see across to the other side. We pointed our lights down and to the side; all we could see was darkness.

"We felt as if our powerful underwater lights were being destroyed by this void. So we called it 'black hole', which in Spanish is 'Hoyo Negro'."

Scientists can only speculate as to why Naia had been in the cavern. Skeletal remains of many animals also litter the pit's floor.

The suspicion is that they all were looking for water, because the region had a very dry climate 12,000 years ago and the cavern would have been mostly dry but for a few pools.

Perhaps they stumbled and fell to their death in the darkness.

"Her pelvis is broken and it appears to have been broken at or around the time of her death because it's fractured in a way that relatively young bone would break rather than ancient bone," said Dr Chatters.

"So, it appears she fell quite a distance and struck something hard. I think she died almost instantly, if not instantly."

On the face of it, the new study supports research published in February that looked at the genetics of an infant who died at about the same time in what is now the US State of Montana.

This investigation of "Anzick" boy, as he has become known, was conducted on the main DNA material found in the nuclei of the cells.

Naia's DNA, on the other hand, was sourced from outside the nuclei of her cells - in structures called the mitochondria. These carry much more limited information.

Dr Shane Doyle from Montana State University said Dr Chatters' team therefore still had some ground to travel before very robust conclusions could be drawn.

"In my view they have a way to go before they can say anything substantial," he told BBC News.

"It's extremely difficult to get at the nuclear DNA and decoding it is very complex, but this is what they need to do. Until they do that, they cannot tell us a lot about where Native American Indians came from."

Dr Chatters confirmed that unravelling Naia's nuclear genome was a future priority.
http://www.bbc.com/news/science-environment-27432234
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PostPosted: 12-08-2014 12:20    Post subject: Reply with quote

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Cave Dig Unearths Bones of Ancient Horses, Cheetahs and Bison
Excavations of an ancient Wyoming sinkhole containing a rare trove of fossils of Ice Age mammals have unearthed hundreds of bones of such prehistoric animals as American cheetahs, a paleontologist said on Friday.

Aug 8, 2014
By Laura Zuckerman

(Reuters) - Scientists excavating an ancient Wyoming sinkhole containing a rare trove of fossils of Ice Age mammals have unearthed hundreds of bones of such prehistoric animals as American cheetahs, a paleontologist said on Friday.

The two-week dig by an international team of researchers led by Des Moines University paleontologist Julie Meachen marked the first exploration of Natural Trap Cave at the base of the Bighorn Mountains in north-central Wyoming since its initial discovery in the 1970s.

Meachen said the extensive excavation that began late last month uncovered roughly 200 large bones of animals like horses that roamed North America from 12,000 to 23,000 years ago and an uncounted number of microfossils of creatures such as birds, lizards and snakes.

“We found evidence of bison, a bit of gray wolf and quite a lot of cheetah and horse,” she said of the first of three planned annual digs, which ended on Friday.

Researchers expect their study of the fossils to provide new insights into the climate, diets and genetic diversity of North American creatures that disappeared during the Ice Age extinction more than 10,000 years ago. ...

http://www.scientificamerican.com/article/wyoming-cave-dig-unearths-bones-of-ancient-horses-cheetahs-and-bison/
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