Saturday 19 April 2014

No Evidence for Human Evolution in America?

If you want indisputable evidence for human evolution, it seems you will have to look outside the continent of the Americas, for now.

The following is an article, a version of which appeared printed in the New York Times on March 28, 2014, on page A5 of the New York edition, with my comments inserted and 
highlighted in yellow.

My comments are based on the logic that if humans had already fully evolved by 200,000 to 2.5million years ago (as the theory of evolution asserts), then if we aren't even sure whether humans have actually lived in the Americas for longer than merely
thousands of years (and the article below highlights the uncertainty that exists in that regard) - then we really don't have any certain evidence - any certain links, at all - in the whole of the Americas, for human evolution.

My comments point-out that a culture of
making assertions despite uncertainties can exist in the scientific community.


Discoveries Challenge Beliefs on Humans’ Arrival in the Americas



SERRA DA CAPIVARA NATIONAL PARK, Brazil — Niede Guidon still remembers her astonishment when she glimpsed the paintings.
Preserved amid the bromeliad-encrusted plateaus that tower over the thorn forests of northeast Brazil, the ancient rock art depicts fierce battles among tribesmen, orgiastic scenes of prehistoric revelry and hunters pursuing their game, spears in hand.
“These were stunning compositions, people and animals together, not just figures alone,” said Dr. Guidon, 81, remembering what first lured her and other archaeologists in the 1970s to this remote site where jaguars still prowl.
Hidden in the rock shelters where prehistoric humans once lived, the paintings number in the thousands. Some are thought to be more than 9,000 years old and perhaps even far more ancient. Painted in red ocher, they rank among the most revealing testaments anywhere in the Americas to what life was like millenniums before the European conquest began a mere five centuries ago.
But it is what excavators found when they started digging in the shadows of the rock art that is contributing to a pivotal re-evaluation of human history in the hemisphere.






Continue reading the main storySlide Show

Reassessing Human History in the Americas

Researchers here say they have unearthed stone tools proving that humans reached what is now northeast Brazil as early as 22,000 years ago.

So the tools are 22,000 years old, but the paintings right nearby are only 9,000 years old? Hmm. Okay. Moving right along...

Their discovery adds to the growing body of research upending a prevailing belief of 20th-century archaeology in the United States known as the Clovis model, which holds that people first arrived in the Americas from Asia about 13,000 years ago.

According to the theory of common descent, humans had already evolved between 200,000 and 2.5million years ago. Therefore not much evidence can be put forward for human evolution if all we have to go by is only thousands of years old. 
Therefore the statement above basically also implies that any supposed evidence that we thought existed for human evolution - in all of the Americas - is also now being upended!

It means if you want proof of human evolution, you will have to look outside of the Americas.


“If they’re right, and there’s a great possibility that they are, that will change everything we know about the settlement of the Americas,” said Walter Neves, an evolutionary anthropologist at the University of São Paulo whose own analysis of an 11,000-year-old skull in Brazil implies that some ancient Americans resembled aboriginal Australians more than they did Asians.

Change everything that we know? You mean everything that evolutionary anthropoligists knew about the human settlement of the Americas had been hinging on something that is refutable?

This would mean that nothing that anthropoligist know about humans in the Americas is able to tell us with any certainty at all anything about human evolution. If evidence for it can be found outside the Americas, certainly none can be found in the Americas.
Up and down the Americas, scholars say that the peopling of lands empty of humankind may have been far more complex than long believed. The radiocarbon dating of spear points found in the 1920s near Clovis, N.M., placed the arrival of big-game hunters across the Bering Strait about 13,000 years ago, long forming the basis of when humans were believed to have arrived in the Americas.
More recently, numerous findings have challenged that narrative. In Texas,archaeologists said in 2011 that they had found projectile points showing that hunter-gatherers had reached another site, known as Buttermilk Creek, as early as 15,500 years ago. Similarly, analysis of human DNA found at an Oregon cave determined that humans were there 14,000 years ago.
But it is in South America, thousands of miles from the New Mexico site where the Clovis spear points were discovered, where archaeologists are putting forward some of the most profound challenges to the Clovis-first theory.
Paleontologists in Uruguay published findings in November suggesting that humans hunted giant sloths there about 30,000 years ago. All the way in southern Chile, Tom D. Dillehay, an anthropologist at Vanderbilt University, has shown that humans lived at a coastal site called Monte Verde as early as 14,800 years ago.

14,800 years ago. Are they so sure it wasn't say 14,600 years ago? How do they give such a pinpoint figure so confidently, when this whole article shows that all such findings can be disputed by a huge range.
And here in Brazil’s caatinga, a semi-arid region of mesas and canyons, European and Brazilian archaeologists building on decades of earlier excavations said last year that they had found artifacts at a rock shelter showing that humans had arrived in South America almost 10,000 years before Clovis hunters began appearing in North America.
“The Clovis paradigm is finally buried,” said Eric Boëda, the French archaeologist leading the excavations here.

Buried? Strong statement. 
Exposing the tension over competing claims about where and when humans first arrived in the Americas, some scholars in the dwindling Clovis-first camp in the United States quickly rejected the findings.

Tension? Competing claims? Quickly rejected? That sounds a bit emotive, irrational, unscientific. Please give me more confidence in the scientific community and how it draws conclusions!
Gary Haynes, an archaeologist at the University of Nevada, Reno, argued that the stones found here were not tools made by humans, but instead could have become chipped and broken naturally, by rockfall. Stuart Fiedel, an archaeologist with the Louis Berger Group, an environmental consulting company, said that monkeys might have made the tools instead of humans.

Lol. So there are scientists who are in effect willing to upend all the evidence that exists for the theory of human evolution in the entire continent of the Americas, based on the discovery of some tools which other scientists doubt were even tools at all.






Continue reading the main story

Atlantic
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Serra da Capivara
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BRAZIL
Rio de
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“Monkeys, including large extinct forms, have been in South America for 35 million years,” Dr. Fiedel said. He added that the Clovis model was recently bolstered by new DNA analysis ancestrally connecting indigenous peoples in Central and South America to a boy from the Clovis culture whose 12,700-year-old remains were found in 1968 at a site in Montana.
Such dismissive positions have invited equally sharp responses from scholars like Dr. Dillehay, the American archaeologist who discovered Monte Verde. “Fiedel does not know what he is talking about,” he said, explaining that similarities existed between the stone tools found here and at the site across South America in Chile. “To say monkeys produced the tools is stupid.”

"Does not know what he is talking about". "Stupid". Doesn't sound like the scientific community has ever been very sure of each other in this field.
Having their findings disputed is nothing new for the archaeologists working at Serra da Capivara. Dr. Guidon, the Brazilian archaeologist who pioneered the excavations, asserted more than two decades ago that her team had found evidence in the form of charcoal from hearth fires that humans had lived here about 48,000 years ago.

A fireman who recently looked at charcoal in my backyard couldn't tell that it was from a fire eight months ago rather than half an hour ago. Yet Dr Guidon can date charcoal so accurately at 48,000 years old (sure it wasn't 46,000 years?), that she is willing to upend everything that evolutionary anthropoligists know about the migration of humans to the Americas on that basis. Is that how easy it is to in effect upend all existing evidence of human evolution in all of the Americas?
While scholars in the United States generally viewed Dr. Guidon’s work with skepticism, she pressed on, obtaining the permission of Brazilian authorities to preserve the archaeological sites near the town of São Raimundo Nonato in a national park that now gets thousands of visitors a year despite its remote location in Piauí, one of Brazil’s poorest states.
Dr. Guidon remains defiant about her findings. At her home on the grounds of a museum she founded to focus on the discoveries in Serra da Capivara, she said she believed that humans had reached these plateaus even earlier, around 100,000 years ago, and might have come not overland from Asia but by boat from Africa.

That's a huge difference to what was previously believed! How remarkable that scientists know so little with any certainty about humans in the Americas over a few thousand years, yet are so certain about humans in Africa, Asia or Europe to the point that they feel they have proved human descent all the way back to a single cell over a period of 2.1 billion years.
Professor Boëda, who succeeded Dr. Guidon in leading the excavations, said that such early dates may have been possible but that more research was needed. His team is using thermoluminescence, a technique that measures the exposure of sediments to sunlight, to determine their age.

Why did they not just use carbon-dating, seeing it's considered so reliable? Is this a suggestion that carbon-dating might not be reliable in this instance for some reason?
At the same time, discoveries elsewhere in Brazil are adding to the mystery of how the Americas were settled.
In what may be another blow to the Clovis model of humans’ coming from northeast Asia, molecular geneticists showed last year that the Botocudo indigenous people living in southeastern Brazil in the late 1800s shared gene sequences commonly found among Pacific Islanders from Polynesia.
How could Polynesians have made it to Brazil? Or aboriginal Australians? Or, if the archaeologists here are correct, how could a population arrive in this hinterland long before Clovis hunters began appearing in the Americas? The array of new discoveries has scholars on a quest for answers.

So now here is a third theory! And it has scholars on a quest for answers? The very fact that the issue is able to be disputed, shows that it had never been a concrete finding.

Like, if someone claims to have new research proving that the distance from Surfers Paradise to Burleigh Heads, Queensland is not 10km as has been believed, but is actually more like 16km or even 140km - it wouldn't have scholars on a quest for answers. We'd all know it was mad.

Similarly, if the original evidence about humans in the Americas had ever had any certainty about it in the first place at all, then no new 'evidence' could now have scholars on a such quest for answers.

So there's isn't certainty about how long humans have existed in the Americas. And therefore we can't source the continent of the Americas for evidence that human evolution has occurred.  
Reflecting how researchers are increasingly accepting older dates of human migration to the Americas, Michael R. Waters, a geoarchaeologist at Texas A&M University’s Center for the Study of the First Americans, said that a “single migration” into the Americas about 15,000 years ago may have given rise to the Clovis people. But he added that if the results obtained here in Serra da Capivara are accurate, they will raise even more questions about how the Americas were settled.
“If so, then whoever lived there never passed on their genetic material to living populations,” said Dr. Waters, explaining how the genetic history of indigenous peoples links them to the Clovis child found in Montana. “We must think long and hard about these early sites and how they fit into the picture of the peopling of the Americas.”

Long and hard. Yes, please. What a good idea!

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