Clovis People Spread to Central and South America, then Vanished - Canadanewsmedia
Connect with us

Science

Clovis People Spread to Central and South America, then Vanished

Published

on


Summary

Scientists have found DNA evidence for the southward migration of the people who spread the so-called Clovis culture of North America. But starting about 9,000 years ago, these people were replaced by a distinct population.

DNA from the 9,600-year-old bones excavated at the Lapa do Santo site in Brazil (above) shows genetic similarity to the Clovis culture-associated genomes found in North America. Credit: André Strauss

In the last few years, scientists have opened a startling new window into humans’ distant past by extracting and analyzing DNA from the bones of people who lived thousands of years ago. Those peoples’ genes tell surprising tales of vast migrations and genetic mixing before the dawn of history.

Now, for the first time, this powerful approach is illuminating the story of ancient humans in Central and South America. An analysis of 49 individuals who lived as long as 11,000 years ago suggests that the Clovis culture, the first known widespread archaeological culture of North America, was also accompanied by a spread of people southward – a migration that some scientists had already suspected.

And then something wholly unexpected happened. Beginning at least 9,000 years ago in Central and South America, the Clovis culture-associated people vanished, Howard Hughes Medical Investigator David Reich and his colleagues report November 8, 2018 in the journal, Cell. The genetic evidence shows they were replaced by a different population.

“That was not anticipated,” Reich says. “It’s the kind of surprise that ancient DNA can deliver.”

Genetic match

The field of ancient DNA has grown dramatically in recent years, climbing from just a few individuals analyzed in 2010 to more than 1,800 today – the majority of which were analyzed by Reich, a geneticist at Harvard Medical School. He and his collaborators have previously shown that Neanderthals interbred with our ancestors and that nomadic herders roamed all the way to central Europe from the Russian steppes starting about 5,300 years ago, replacing the local hunter-gatherers.

Now, Reich’s team has turned to the prehistory of the Americas. Archeologists have amassed considerable evidence of a population of humans who lived in North America beginning more than 13,000 years ago. Researchers dubbed this the Clovis culture because of the distinctive spear points and other stone tools first found near Clovis, New Mexico, in the 1920s.

<img alt="Map showing movement of Clovis people from North to South America." class="caption" data-delta="1" data-fid="14676" data-media-element="1" src="https://www.hhmi.org/sites/default/files/news/2018/graphical_abstract_final_2.png" title="The people who spread the Clovis culture in North America also had a major impact farther south, in what is now Chile, Brazil, and Belize. But, beginning at least 9,000 years ago, these southern Clovis-linked people were replaced by a different population. Credit: Michelle O’Reilly, C. Posth et al./Cell 2018″>

Scientists believe that the people who spread the Clovis culture descended from migrants from Asia who crossed the Bering Land Bridge to North America. Could they also have made a subsequent journey south into Central and South America? Some archeologists have argued yes because of similar spear points, known as “Fishtail,” found later in Central America and farther south.

Ancient DNA offered a new way to look at the question. Reich and his collaborators compared ancient peoples’ genes from sites in Central and South America to genes from a Clovis-linked individual who lived in today’s Montana between 12,700 and 12,900 years ago. There was a clear match between the Montana individual’s genes and the three oldest genetic samples in the new study, which came from Chile, Brazil, and Belize.

“This genetic match was a striking finding,” Reich says. The new data “provide powerful new evidence” that migrations of people who spread the Clovis culture in North American did in fact have an effect farther south – probably related to the dispersal of the Fishtail culture, he explains.

“These data emphasize that there are great events in our history that we didn’t know about – movements of people and genetic mixing that are a recurrent theme of our history.”

David Reich

But then came the surprise. The great majority of the other individuals analyzed, who lived from Belize to Patagonia between 3,000 and 9,000 years ago, belonged to a different genetic lineage. The data imply that a population separate and distinct from the Clovis group also swept south from North America, largely replacing the Clovis-linked lineages. Their identity? Still a mystery. Reich is hoping that archeologists can help solve the puzzle, in combination with additional ancient DNA data. “That’s an exciting part of the active dialogue between these two fields,” he says.

Restless species

Numerous other questions remain to be answered as well. The oldest known archaeological evidence in South America dates back more than 14,000 years ago ­– older than the Clovis samples in North America. “It is certain the first humans there lived prior to the time of the Clovis culture,” says Reich. “Given that our earliest South American samples all have a clear affinity to a Clovis culture-associated genome, who were they?”

Another striking result is that the genetic signatures Reich and his colleagues found in 2,000-year-old samples from the coast of southeastern Brazil don’t match those of the indigenous people who live in the region now. Instead, the samples’ signatures more closely match groups living farther away. That documents more recent events leading to the formation of present-day groups, Reich says.

The new study adds to the key revelation from the nascent field of ancient DNA – that humans are a much more restless, wandering, and intermingling species than we ever imagined.

“These data emphasize that there are great events in our history that we didn’t know about – movements of people and genetic mixing that are a recurrent theme of our history,” says Reich. “The reality of what happened turns out to be different from what we used to think.”

###

Citation

Cosimo Posth et al., “Reconstructing the deep population history of Central and South America.Cell. Published online November 8, 2018. doi: 10.1016/j.cell.2018.10.027

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Researchers walk back major ocean warming result

Published

on

By



<!–

googletag.cmd.push(function() googletag.display(‘post_link_unit’); );

–>

Scripps Pier after sunset in La Jolla, California. Image via Hayne Palmour IV/ San Diego Union-Tribune/ os Angeles Times.http://www.latimes.com/science/sciencenow/la-sci-sn-oceans-heat-error-20181114-story.html

This is good news. It is less certain today that Earth’s oceans are 60% warmer than we thought (although they may still be that warm). As reported in the Los Angeles Times today (November 14, 2018), researchers with UC San Diego’s Scripps Institution of Oceanography and Princeton University have had to walk back a widely reported scientific result – based on a paper published in Nature last month – showing that showed Earth’s oceans were heating up dramatically faster than previously thought, as a result of climate change.

The October 31 paper in Nature stated the oceans had warmed 60% more than outlined by the United Nations’ Intergovernmental Panel on Climate Change (IPCC). On November 6, mathematician Nic Lewis posted his criticisms of the paper at Judith Curry’s blog. Both Lewis and Curry are critics of the scientific consensus that global warming is ongoing and human-caused.

In his November 6 blog post, Lewis pointed out flaws in the October 31 paper. The authors of the October 31 paper now say they’ve redone their calculations, and – although they find the ocean is still likely warmer than the estimate used by the IPCC – they agree that they “miffed” the range of probability. They can no longer support the earlier statement of a heat increase 60% greater than indicated. They now say there is a larger range of probability, between 10% and 70%, as other studies have already found.

A correction has been submitted to Nature.

The Los Angeles Times reported that one of the co-author’s on the paper – Ralph Keeling at the Scripps Institution of Oceanography – “took full blame” and thanked Lewis for alerting him to the mistake. Keeling told the Los Angeles Times:

When we were confronted with his insight it became immediately clear there was an issue there. We’re grateful to have it be pointed out quickly so that we could correct it quickly.

In the meantime, the Twitter-verse today has done the expected in a situation like this, where a widely reported and dramatic climate result has had to be walked back. Many are making comments like this one:

But cooler heads on Twitter and elsewhere in the media are also weighing in, pointing out – as has been necessary to point out time and again – that science is not a “body of facts.” Science is a process. Part of the reason scientists publish is so that other scientists can find errors in their work, so that the errors can be corrected.

All scientists know this. The Los Angeles Times explained it this way:

While papers are peer-reviewed before they’re published, new findings must always be reproduced before gaining widespread acceptance throughout the scientific community …

The Times quoted Gerald Meehl, a climate scientist at the National Center for Atmospheric Research in Boulder, Colorado, as saying:

This is how the process works. Every paper that comes out is not bulletproof or infallible. If it doesn’t stand up under scrutiny, you review the findings.

Bottom line: An error has been found in the October 31, 2018 paper published in Nature – showing an increase in ocean warming 60% greater than that estimated by the IPCC. The authors have acknowledged the error, and a correction has been submitted to Nature.

October 31 paper in Nature: Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition

November 6 blog post by Nic Lewis: A major problem with the Resplandy et al. ocean heat uptake paper

Deborah Byrd

MORE ARTICLES

Please enable JavaScript to view the comments powered by Disqus.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Upsettingly Large Fungus in Michigan Weighs 440 Tons and Is 2500 Years Old

Published

on

By


[unable to retrieve full-text content]

  1. Upsettingly Large Fungus in Michigan Weighs 440 Tons and Is 2500 Years Old  Gizmodo
  2. Could this giant 2500-year-old fungus hold the cure to cancer?  Mother Nature Network
  3. Full coverage



Source link

Continue Reading

Science

NASA wants Canadian boots on the moon but feds still pondering space options

Published

on

By


OTTAWA — The Trudeau government faced criticism Wednesday for a tepid response to the head of the U.S. space agency saying he wants to see Canadian astronauts walking on the moon in the near future.

Jim Bridenstine, the administrator of he National Aeronautics and Space Administration, said a reconstituted lunar program is the first step toward deeper space exploration, including a mission to Mars.

On a two-day trip to Ottawa, the NASA chief made an impassioned pitch for Canada to continue its decades-long space partnership with the U.S., including by supplying astronauts.

NASA is embarking on the creation of its new Lunar Gateway, a space station it is planning to send into orbit around the moon starting in 2021. The agency wants to create a “sustainable lunar architecture” that would allow people and equipment to go back and forth to the moon regularly, Bridenstine said.

“If Canadians want to be involved in missions to the surface of the moon with astronauts, we welcome that. We want to see that day materialize,” he told a small group of journalists in Ottawa ahead of his keynote speech to the Aerospace Industries Association of Canada.

“We think it would be fantastic for the world to see people on the surface of the moon that are not just wearing the American flag, but wearing the flags of other nations.”

The U.S. is seeking broad international support for its new lunar initiative, Bridenstine told the industry conference. He said NASA wants Canada’s expertise in artificial intelligence and robotics, which could include a next-generation Canadarm on the Lunar Gateway and more Canadian technology inside.

Innovation Minister Navdeep Bains, a vocal booster of Canada’s AI hubs in Ontario and Quebec, said the government is committed to sustaining its partnership with NASA, but he had no specifics.

The minister said the government is still working on a long-awaited space policy that has many dimensions and will be made public before next fall’s federal election.

“At this stage, we would not take anything off the table,” Bains told reporters, when on pressed on the possibility of contributing astronauts to moon missions. “We demonstrated very clearly we want to work with NASA. We want to work with other allies as well.”

The head of one leading Canadian space technology firm said he and many other business leaders at the conference were surprised by the government’s apparent lack of enthusiasm for Bridenstine’s ambitious request.

“There was a lot of excitement about the opportunity that was clearly being given to Canada here,” Mike Greenley, the president of MDA, said in an interview. “I’m a little bit concerned about that lack of response.”

MDA makes sensors, robots and components for satellites.

Greenley said it is possible the government is still considering its options, but given the urgency of the U.S. timetable, that might not be wise.

“The concern would be if we wait too long we can miss the opportunity,” he said. “We best not ponder this too long.”

Greenley said he’d like to see Canadian astronauts on the moon one day, but to get to that stage Canada needs to participate in NASA’s broader lunar program.

Bridenstine said the return to the moon is a stepping stone to a much more ambitious goal: exploration that could include reaching Mars in the next two decades.

“The moon is, in essence, a proving ground for deeper space exploration,” he said.

Marc Garneau, who was the first Canadian to reach outer space in 1984 and is now Canada’s transport minister, told the conference he wants Canada to continue being a “star player” in all fields of the aerospace industry. But he had no new space initiatives to announce.

On Dec. 3, Canadian astronaut David Saint-Jacques will travel to the International Space Station on his first mission.

Mike Blanchfield, The Canadian Press


Let’s block ads! (Why?)



Source link

Continue Reading

Trending

Copyright © 2018 Canada News Media

%d bloggers like this: