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DNA Evidence Uncovers Two Forgotten North American Migrations

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When you talk about Americans moving south, the first thing that often comes to mind are the throngs of retirees who grab their sunscreen and bolt for Florida every winter. The massive movement of older folks to the Sunshine State has certainly helped shape the Florida economy, but it’s by no means the first example of humans headed for a clean break in warmer climes. In fact, researchers have recently uncovered two migrations from North America to South America dating back some 10,000 years.

Central and South Americans largely draw their ancestry from a combination of three streams of migrations to the regions from North America. That includes two previously unknown movements, according to a research team led by anthropologists at Harvard.

One of those migrations came from the Clovis culture, a prehistoric Paleo-Indian group named after the tools its people carried, and one some believe were the first to inhabit the New World. The Clovis people spread their wings a lot farther south than had previously been believed, moving into Peru and Brazil, according to the new findings. The other group came from Alaska, and perhaps crossed the Bering Strait from Russia.

The researchers used ancient DNA data — from 49 people who lived in Central and South America over a span of some 10,000 years — to find shared ancestry with skeletal remains previously uncovered in North America.

The findings offer some insight into the indigenous history of Central and South America. They also seem to raise more questions than answers. The data shows that the Clovis people were "replaced" by another lineage some 9,000 years ago. What we don’t know is why they disappeared.

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NASA to invite designs for AI lunar robot

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By: PTI | New Delhi |

Published: November 14, 2018 5:45:44 pm

A space robotics challenge in the past aimed to programme NASA’s humanoid Valkyrie to perform human-like tasks.

NASA is planning to launch a challenge for the public and scientific community to design a self-assembling robot with artificial intelligence that can explore the surface of the Moon, William Harris, CEO of Space Centre Houston said. Space Centre Houston in the US, the official visitor centre for NASA Johnson Space Centre, conducts regular public outreach programmes to engage people of various ages and diverse backgrounds in scientific research.

These programmes encourage students and scientists to ideate innovative solutions for problems that the US space agency is trying to overcome in order to carry out successful space exploration missions. “The next challenge is for the Moon — it will be announced next year — to develop a self assembling robot or rover on the Moon’s surface that has an artificial intelligence platform so it can make decisions based on what it is learning about the lunar surface,” Harris told PTI in an interview.

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“The reality is, when we sent humans to the Moon back in the 1960s, just going there and coming back safely was a huge accomplishment. We did not do a huge amount of science during those missions,” he said. Most of the astronauts then were test pilots. The first and only scientist to have visited the Moon is Harrison Schmitt, an American geologist, who is now the last living crew member of Apollo 17, Harris said. There was very little scope to perform scientific experiments, and to date there is a lot we do not know about the Moon, he said. However, the astronauts that NASA recruits now are scientists.

With plans underway to take humans back to the lunar surface, the US space agency is working on efficient technologies that can assist astronauts to conduct scientific experiments on the Moon. In the recent decades, evidence of frozen water beneath the surface of the Moon has emerged. This not only presents the possibility for the Moon to host some form of primitive life, but also opens avenues for future astronauts to harvest water and set up a space colony. The water could also be broken down to provide hydrogen fuel, using which we could send missions into deeper space, Harris said.

Also read: Samsung Galaxy Tab S4 review: The best Android tablet. Period.

“NASA has come to recognise that you can become to insular with your own team. So it is better to open up to the general public to see if somebody has ideas that can help us address different challenges,” he said. Harris gave an example of a space robotics challenge in the past, that aimed to programme NASA’s humanoid Valkyrie to perform human-like tasks.

“Within the group of ten semi-finalists, we had teams from two of the top universities. But the winner of the challenge was a stay-at-home dad, who came with his 6-year-old son,” said Harris. His solutions are now being used by NASA to programme Valkyrie. Involving the public in this way can help space programmes flourish and break new grounds, he said.

Harris was in New Delhi as a part of a delegation of representatives seeking to strengthen ties with Indian companies and to learn about the latest developments in the country’s business environment and industries like aerospace, healthcare and information technology.

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Scientists acknowledge key errors in study of how fast the oceans are warming

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Scientists behind a major study that claimed the Earth’s oceans are warming faster than previously thought now say their work contained inadvertent errors that made their conclusions seem more certain than they actually are.

Two weeks after the high-profile study was published in the journal Nature, its authors have submitted corrections to the publication. The Scripps Institution of Oceanography, home to several of the researchers involved, also noted the problems in the scientists’ work and corrected a news release on its website, which previously had asserted that the study detailed how the Earth’s oceans “have absorbed 60 percent more heat than previously thought.”

“Unfortunately, we made mistakes here,” said Ralph Keeling, a climate scientist at Scripps, who was a co-author of the study. “I think the main lesson is that you work as fast as you can to fix mistakes when you find them.”

The central problem, according to Keeling, came in how the researchers dealt with the uncertainty in their measurements. As a result, the findings suffer from too much doubt to definitively support the paper’s conclusion about just how much heat the oceans have absorbed over time.

The central conclusion of the study — that oceans are retaining ever more energy as more heat is being trapped within Earth’s climate system each year — is in line with other studies that have drawn similar conclusions. And it hasn’t changed much despite the errors. But Keeling said the authors’ miscalculations mean there is actually a much larger margin of error in the findings, which means researchers can weigh in with less certainty than they thought.

Where they don't make sense — with this one, it's fairly obvious it didn't make sense — I look into them more deeply

“I accept responsibility for what happened because it’s my role to make sure that those kind of details got conveyed,” Keeling said.

The study’s lead author was Laure Resplandy of Princeton University. Other researchers were with institutions in China, Paris, Germany and the U.S. National Center for Atmospheric Research and Geophysical Fluid Dynamics Laboratory.

“Maintaining the accuracy of the scientific record is of primary importance to us as publishers and we recognize our responsibility to correct errors in papers that we have published,” Nature said in a statement to The Post. “Issues relating to this paper have been brought to Nature’s attention and we are looking into them carefully. We take all concerns related to papers we have published very seriously and will issue an update once further information is available.”

The original study, which appeared on Oct. 31, derived a new method for measuring how much heat is being absorbed by the oceans. Essentially, the authors measured the volume of gases, specifically oxygen and carbon dioxide, that have escaped the ocean in recent decades and headed into the atmosphere as it heats up. They found that the warming “is at the high end of previous estimates” and suggested that as a result, the rate of global warming itself could be more accelerated.

The results, wrote the authors, may suggest there is less time than previously thought to curb greenhouse gas emissions. The study drew considerable media attention, including from The Post.

However, not long after publication, an independent Britain-based researcher named Nicholas Lewis published a lengthy blog post saying he had found a “major problem” with the research.

I think the main lesson is that you work as fast as you can to fix mistakes when you find them

“So far as I can see, their method vastly underestimates the uncertainty,” Lewis said in an interview Tuesday, “as well as biasing up significantly, nearly 30 percent, the central estimate.”

Lewis added that he tends “to read a large number of papers, and, having a mathematics as well as a physics background, I tend to look at them quite carefully, and see if they make sense. And where they don’t make sense — with this one, it’s fairly obvious it didn’t make sense — I look into them more deeply.”

Lewis has argued in past studies and commentaries that climate scientists are predicting too much warming because of their reliance on computer simulations, and that current data from the planet itself suggests global warming will be less severe than feared.

It isn’t clear whether the authors agree with all of Lewis’ criticisms, but Keeling said “we agree there were problems along the lines he identified.”

Paul Durack, a research scientist at the Lawrence Livermore National Laboratory in California, said promptly acknowledging the errors in the study “is the right approach in the interests of transparency.”

But he added in an email, “This study, although there are additional questions that are arising now, confirms the long known result that the oceans have been warming over the observed record, and the rate of warming has been increasing,” he said.

Gavin Schmidt, head of the NASA Goddard Institute for Space Studies, followed the growing debate over the study closely on Twitter and said that measurements about the uptake of heat in the oceans have been bedeviled with data problems for some time — and that debuting new research in this area is hard.

“Obviously you rely on your co-authors and the reviewers to catch most problems, but things still sometimes slip through,” Schmidt wrote in an email.

Schmidt and Keeling agreed that other studies also support a higher level of ocean heat content than the Intergovernmental Panel on Climate Change, or IPCC, saw in a landmark 2013 report.

Overall, Schmidt said, the episode can be seen as a positive one.

“The key is not whether mistakes are made, but how they are dealt with — and the response from Laure and Ralph here is exemplary. No panic, but a careful reexamination of their working — despite a somewhat hostile environment,” he wrote.

“So, plus one for some post-publication review, and plus one to the authors for reexamining the whole calculation in a constructive way. We will all end up wiser.”

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The dance of the small galaxies that surround the Milky Way

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Credit: Instituto de Astrofísica de Canarias

An international team led by researchers from the IAC used data from the ESA satellite Gaia to measure the motion of 39 dwarf galaxies. This data gives information on the dynamics of these galaxies, their histories and their interactions with the Milky Way.

Around the Milky Way, there are many small galaxies (), which can be tens of thousands of times or even millions of times less luminous than the Milky Way. In comparison with normal or giant galaxies, dwarf galaxies contain fewer stars and have lower luminosity.

These small galaxies have been the subject of the study of an international team of astronomers led by Tobias K. Fritz and Giuseppina Battaglia, both researchers of the Instituto de Astrofísica de Canarias (IAC). Thanks to the data acquired by the ESA Gaia space mission, which became available in a second release in April 2018, the researchers have been able to measure the on-sky motion of 39 dwarf galaxies, determining direction and velocity.

Before the second release of data from the Gaia satellite, it was not possible to perform such measurements for 29 of the galaxies analyzed by the team. The researchers found that many of them are moving in a plane known as the vast polar structure. “It was already known that many of the more massive dwarf galaxies were found in this plane, but now we know that also several of the less massive dwarf galaxies might belong to this structure,” says Fritz, main author of the scientific article .

Battaglia highlights that the origin of the vast polar structure is still not fully understood, but its characteristics appear to challenge cosmological models of galaxy formation. Also, the Large Magellanic Cloud is found in this planar structure, which might imply the two are connected.

By analyzing the data concerning the motions, the team found that several of the dwarf galaxies have orbits that bring them close to the inner regions of the Milky Way. The gravitational attraction that the Milky Way exerts on these galaxies can be compared to the action of tides. It is likely that a few of the dwarf galaxies studied are perturbed by these tides, which stretch them like a stream.

“This could explain observed properties of some of these objects, such as Hercules and Crater II,” says Fritz.

On the other hand, new questions arise. “Over the years, some galaxies have been observed to have peculiar characteristics that could have been potentially due to tidal perturbations by the Milky Way (e.g. Carina I),” says Battaglia. “However, their orbits do not appear to confirm this hypothesis. Perhaps we should postulate that encounters with other dwarf galaxies might have been the culprit.”

The researchers found that the majority of the galaxies studied are close to the pericenter of their orbit (the point closest to the Milky Way center). Nonetheless, basic physics explains that they should spend most of their time close to the apocenter of their orbit (the point farthest from the Milky Way center). “This suggests that there should be many more dwarf galaxies that have yet to be discovered and that are hiding at large distances from the Milky Way center,” states Fritz.

Dwarf galaxies, besides being interesting in their own right, are one of the few tracers of dark matter that can be used in the most external parts of the Milky Way. It is thought that this kind of matter accounts for about 80 percent of the total mass of the universe. However, it cannot be observed directly, and detection is difficult. The movements of celestial bodies such as dwarf can be used to measure the total mass of matter within a volume. This is determined by subtracting the mass of those luminous objects that are detected to obtain an estimate of the amount of dark matter. From this data, the researchers could infer that the amount of dark matter in the Milky Way is high, about 1.6 trillion solar masses.


Explore further:
Four newly discovered Milky Way neighbors

More information:
T. K. Fritz et al. Gaia DR2 proper motions of dwarf galaxies within 420 kpc, Astronomy & Astrophysics (2018). DOI: 10.1051/0004-6361/201833343

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