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New Human Ancestor Discovered

The Case of the Missing Ancestor

DNA from a cave in Russia adds a mysterious new member to the human family.

by Jamie Shreeve

In the Altay Mountains of southern Siberia, some 200 miles from where Russia touches Mongolia, China, and Kazakhstan, nestled under a rock face about 30 yards above a little river called the Anuy, there is a cave called Denisova. It has long attracted visitors. The name comes from that of a hermit, Denis, who is said to have lived there in the 18th century. Long before that, Neolithic and later Turkic pastoralists took shelter in the cave, gathering their herds around them to ride out the Siberian winters. Thanks to them, the archaeologists who work in Denisova today, surrounded by walls spattered with recent graffiti, had to dig through deep layers of goat dung to get to the deposits that interested them. But the cave’s main chamber has a high, arched ceiling with a hole near the top that directs shimmering shafts of sunlight into the interior, so that the space feels holy, like a church.

In the back of the cave is a small side chamber, and it was there that a young Russian archaeologist named Alexander Tsybankov was digging one day in July 2008, in deposits believed to be 30,000 to 50,000 years old, when he came upon a tiny piece of bone. It was hardly promising: a rough nubbin about the size and shape of a pebble you might shake out of your shoe. Later, after news of the place had spread, a paleoanthropologist I met at Denisova described the bone to me as the “most unspectacular fossil I’ve ever seen. It’s practically depressing.” Still, it was a bone. Tsybankov bagged it and put it in his pocket to show a paleontologist back at camp.

The bone preserved just enough anatomy for the paleontologist to identify it as a chip from a primate fingertip—specifically the part that faces the last joint in the pinkie. Since there is no evidence for primates other than humans in Siberia 30,000 to 50,000 years ago—no apes or monkeys—the fossil was presumably from some kind of human. Judging by the incompletely fused joint surface, the human in question had died young, perhaps as young as eight years old.

Anatoly Derevianko, leader of the Altay excavations and director of the Institute of Archaeology and Ethnography in Novosibirsk, thought the bone might belong to a member of our own species, Homo sapiens. Sophisticated artifacts that could only be the work of modern humans, including a beautiful bracelet of polished green stone, had previously been found in the same deposits. But DNA from a fossil found earlier in a nearby cave had proved to be Neanderthal, so it was possible this bone was Neanderthal as well.

Derevianko decided to cut the bone in two. He sent one half to a genetics laboratory in California; so far he has not heard from that half again. He slipped the other half into an envelope and had it hand-delivered to Svante Pääbo, an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. It was there that the case of the Denisovan pinkie bone took a startling turn.

Pääbo, a transplanted Swede, is arguably the world’s leading expert in ancient DNA, especially human DNA. His milestones are many. In 1984 he became the first person to isolate DNA from an Egyptian mummy. In 1997 he accomplished the same feat for the first time with a Neanderthal, a kind of human that vanished more than 25,000 years before the Egyptian pharaohs. That secured his scientific reputation.

When Pääbo received the package from Derevianko, his team was hard at work producing the first sequence of the entire Neanderthal genome—another feat that had once seemed impossible and that was occupying most of his attention. His lab also had a backlog of other fossils to test from all parts of the globe. So it wasn’t until late 2009 that the little Russian finger bone drew the attention of Johannes Krause, at the time a senior member of Pääbo’s team. (He’s now at the University of Tübingen.) Like everyone else, Krause assumed the bone was from an early modern human. He had developed a method for distinguishing the DNA of such a fossil from that of the archaeologists, museum workers, and anyone else who might have handled and therefore contaminated it.

Krause and his student Qiaomei Fu extracted the finger bone’s mitochondrial DNA (mtDNA), a small bit of the genome that living cells have hundreds of copies of and that is therefore easier to find in ancient bone. They compared the DNA sequence with those of living humans and Neanderthals. Then they repeated the analysis, because they couldn’t believe the results they’d gotten the first time around.

On a Friday afternoon, with Pääbo away at a meeting at Cold Spring Harbor Laboratory on Long Island, Krause called a meeting of the lab staff and challenged anyone to come up with a different explanation for what he was seeing. No one could. Then he dialed Pääbo’s cell. “Johannes asked me if I was sitting down,” Pääbo remembers. “I said I wasn’t, and he replied that I had better find a chair.”

Krause himself recalls that Friday as “scientifically the most exciting day of my life.” The tiny chip of a finger bone, it seemed, was not from a modern human at all. But it wasn’t from a Neanderthal either. It belonged to a new kind of human being, never before seen.

In July 2011, three years after Tsybankov unearthed the bone chip, Anatoly Derevianko organized a scientific symposium at the archaeological camp a few hundred yards from Denisova cave. At an opening night dinner punctuated with frequent toasts of vodka, Derevianko welcomed the 50 researchers, including Pääbo, who had come to see the cave and share their views on how the mysterious new human fit into the fossil and archaeological record for human evolution in Asia.

The year before, two other fossils had been found to contain DNA similar to that of the finger bone, both of them molars. The first tooth had turned up among the specimens from Denisova housed at Derevianko’s institute in Novosibirsk. It was bigger than either a modern human or a Neanderthal tooth, in size and shape resembling the teeth of much more primitive members of the genus Homo who lived in Africa millions of years ago. The second molar had been found in 2010 in the same cave chamber that had yielded the finger bone—indeed, near the bottom of the same 30,000-to-50,000-year-old deposits, called Layer 11.

Remarkably, that tooth was even bigger than the first, with a chewing surface twice that of a typical human molar. It was so large that Max Planck paleoanthropologist Bence Viola mistook it for a cave bear tooth. Only when its DNA was tested was it confirmed to be human—specifically, Denisovan, as the scientists had taken to calling the new ancestors. “It shows you how weird these guys are,” Viola told me at the symposium. “At least their teeth are just very strange.”

Pääbo’s team could extract only a tiny amount of DNA from the teeth—just enough to prove they came from the same population as the finger, though not from the same individual. But the finger bone had been spectacularly generous.

DNA degrades over time, so usually very little remains in a bone tens of thousands of years old. Moreover, the DNA from the bone itself—called endogenous DNA—is typically just a tiny fraction of the total DNA in a specimen, most of which comes from soil bacteria and other contaminants. None of the Neanderthal fossils Pääbo and his colleagues had ever tested contained even 5 percent endogenous DNA, and most had less than one percent. To their amazement, the DNA in the finger bone was some 70 percent endogenous. Apparently, the cold cave had preserved it well.

Given so much DNA, the scientists easily ascertained that there was no sign of a male Y chromosome in the specimen. The fingertip had belonged to a little girl who had died in or near Denisova cave tens of thousands of years before. The scientists had no idea, at first, what she looked like—just that she was radically different from anything else they had ever seen.

For a while they thought they might have her toe too. In the summer of 2010 a human toe bone had emerged, along with the enormous tooth, from Layer 11. In Leipzig a graduate student named Susanna Sawyer analyzed its DNA. At the symposium in 2011 she presented her results for the first time. To everyone’s shock, the toe bone had turned out to be Neanderthal, deepening the mystery of the place.

The green stone bracelet found earlier in Layer 11 had almost surely been made by modern humans. The toe bone was Neanderthal. And the finger bone was something else entirely. One cave, three kinds of human being. “Denisova is magical,” said Pääbo. “It’s the one spot on Earth that we know of where Neanderthals, Denisovans, and modern humans all lived.” All week, during breaks in the conference, he kept returning alone to the cave. It was as if he thought he might find clues by standing where the little girl may have stood and touching the cool stone walls she too may have touched.

Pääbo grew up in Stockholm with his single mother, a chemist, and on certain days with his father, a biochemist named Sune Bergström, who had another, legitimate family and would later win a Nobel Prize. Pääbo’s own first passion was Egyptology, but he switched to molecular biology, then fused the two interests in 1984 with his work on mummy DNA. Once anchored in the study of the past, he never let go. He is 58 now, tall and lanky, with large ears, a long, narrow head, and pronounced eyebrows that arch up and down animatedly when he’s excited—about Denisova, for instance.

How had all three kinds of human ended up there? How were Neanderthals and Denisovans related to each other and to the sole kind of human that inhabits the planet today? Did their ancestors have sex with ours? Pääbo had a history with that kind of question.

The Neanderthal DNA he had made headlines with in 1997 was utterly different from that of any person now alive on Earth. It seemed to suggest that Neanderthals had been a separate species from us that had gone extinct—suspiciously soon after our ancestors first migrated out of Africa into the Neanderthals’ range in western Asia and Europe. But that DNA, like Krause’s first extract from the Denisovan finger, was mtDNA: It came from the mitochondria, the energy-producing organelles inside the cell, and not from the cell nucleus, where the vast bulk of our genome resides. Mitochondrial DNA includes only 37 genes, and it’s inherited only from the mother. It’s a limited record of a population’s history, like a single page torn from a book.

By the time of the Denisova symposium, Pääbo and his colleagues had published first drafts of the entire Neanderthal and Denisovan genomes. Reading so many more pages allowed Pääbo and his colleagues, including David Reich at Harvard University and Montgomery Slatkin at the University of California, Berkeley, to discover that human genomes today actually contain a small but significant amount of Neanderthal code—on average about 2.5 percent. The Neanderthals still may have been swept into extinction by the strange, high-browed new people who followed them out of Africa, but not before some commingling that left a little Neanderthal in most of us, 50,000 years later. Only one group of modern humans escaped that influence: Africans, because the commingling happened outside that continent.

Although the Denisovans’ genome showed that they were more closely related to the Neanderthals, they too had left their mark on us. But the geographic pattern of that legacy was odd. When the researchers compared the Denisovan genome with those of various modern human populations, they found no trace of it in Russia or nearby China, or anywhere else, for that matter—except in the genomes of New Guineans, other people from islands in Melanesia, and Australian Aborigines. On average their genomes are about 5 percent Denisovan. Negritos in the Philippines have as much as 2.5 percent.

Putting all the data together, Pääbo and his colleagues came up with a scenario to explain what might have occurred. Sometime before 500,000 years ago, probably in Africa, the ancestors of modern humans split off from the lineage that would give rise to Neanderthals and Denisovans. (The most likely progenitor of all three types was a species called Homo heidelbergensis.) While our ancestors stayed in Africa, the common ancestor of Neanderthals and Denisovans migrated out. Those two lineages later diverged, with the Neanderthals initially moving west into Europe and the Denisovans spreading east, perhaps eventually populating large parts of the Asian continent.

Later still, when modern humans ventured out of Africa themselves, they encountered Neanderthals in the Middle East and Central Asia, and to a limited extent interbred with them. According to evidence presented by David Reich at the Denisova symposium, this mixing most likely occurred between 67,000 and 46,000 years ago. One population of modern humans then continued east into Southeast Asia, where, sometime around 40,000 years ago, they encountered Denisovans. The moderns interbred with them as well and then moved into Australasia, carrying Denisovan DNA.

This scenario might explain why the only evidence so far that the Denisovans even existed is three fossils from a cave in Siberia and a 5 percent stake in the genomes of people living today thousands of miles to the southeast. But it left a lot of questions unanswered. If the Denisovans were so widespread, why was there no trace of them in the genomes of Han Chinese or of any other Asian people between Siberia and Melanesia? Why had they left no mark in the archaeological record—no distinctive tools, say? Who were they really? What did they look like? “Clearly we need much more work,” Pääbo acknowledged at the Denisova symposium.

The best of all possible developments would be to find Denisovan DNA in a skull or other fossil with distinctive morphological features, one that could serve as a Rosetta stone for reexamining the whole fossil record of Asia. There are some intriguing candidates, most from China, and three skulls in particular, dated between 250,000 and 100,000 years ago. Pääbo is working closely with scientists at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing and has set up a DNA testing lab there. Unfortunately DNA does not preserve well in warmer climates. To date, no other fossil has been identified as Denisovan by the only way Denisovans can be known: their DNA.

In 2012 Pääbo’s group published a new version of the finger bone’s genome—astonishingly, one that in accuracy and completeness rivals any living human’s genome that has been sequenced. The breakthrough came from a German postdoc in Pääbo’s lab named Matthias Meyer. DNA consists of two interlocking strands—the familiar double helix. Previous methods for retrieving DNA from fossil bone could read out sequences only when both strands were preserved. Meyer had developed a technique for recovering short, single-stranded fragments of DNA as well, greatly increasing the amount of raw material to work with. The method produced a version of the Denisovan girl’s genome so precise that the team could discriminate between genetic information inherited from her mother and that from her father. In effect, they now had two highly accurate Denisovan genomes, one from each parent. These in turn opened a window on the entire history of their population.

One immediate revelation was how little variation there was between the parents’ genomes—about a third as much as there is between any two living humans. The differences were sprinkled across the genomes, which ruled out inbreeding: If the girl’s parents had simply been closely related, they would have had huge chunks of exactly matched DNA. The pattern indicated instead that the Denisovan population represented by the fossil had never been large enough to have developed much genetic diversity. Worse, it seemed to have suffered a drastic decline sometime before 125,000 years ago—the little girl in the cave may have been among the last of her kind.

Meanwhile the ancestral population of modern humans was expanding. Myriad fossils, libraries full of books, and the DNA of seven billion people are available to document our subsequent population history. Pääbo’s team discovered a completely different one inside a single bone chip. The thought tickles him. “It’s incredibly cool that there is no one walking around today with a population history like that,” Pääbo told me, his eyebrows shooting up.

And yet the Denisovans also have something to say about our own kind. With virtually every letter of the Denisovan genetic code in hand, Pääbo and his colleagues were able to take aim at one of the profoundest mysteries: In our own genomes, what is it that makes us us? What defining changes in the genetic code took place after we separated from our most recent ancestor? Looking at the places where all living humans share a novel genetic signature but the Denisovan genome retains a primitive, more apelike pattern, the researchers came up with a surprisingly short list. Pääbo has called it the “genetic recipe for being a modern human.” The list includes just 25 changes that would alter the function of a particular protein.

Intriguingly, five of these proteins are known to affect brain function and development of the nervous system. Among them are two genes where mutations have been implicated in autism and another that’s involved in language and speech. Just what those genes actually do to make us think, act, or talk differently than Denisovans, or any other creature that has walked the Earth, remains to be seen. The lasting contribution of studying Denisovan DNA, Pääbo says, “will be in finding what is exclusively human.”

But what of the little girl herself? The tiny bit of bone that is all we ever had of her—or at least the half that went to Leipzig—is gone now. In pulling DNA from it, Johannes Krause and Qiaomei Fu eventually used it all up. The little girl has been reduced to a “library” of DNA fragments that can be exactly copied again and again forever. In the scientific paper discussing the history of her population, Pääbo and his colleagues did mention, almost in passing, a few facts about her that they had gleaned from that library: She probably had dark hair, dark eyes, and dark skin. It isn’t much, but at least it sketches in broad strokes what she looked like. Just so we know whom to thank.

Ancient Roman Road Found

Ancient Roman Road Found

The worn-down flat stones of the ancient road date to around 1,800 years ago.

Chinese Space Station Silhouetted against the Sun

French astrophotographer Thierry Legault had perfect timing. He captured an image of the Chinese space station Tiangong-1 crossing the path of the sun. At Bad Astronomy, Phil Plait writes:

In this picture, you can see the station silhouetted against the Sun’s face; it’s the H-shaped object between the sunspots. Right now, the Shenzou-10 spacecraft is docked to Tiangong-1; each is one half of the H.
Perspective is funny; the two spacecraft together are about 20 meters across but don’t look much smaller than the sunspots … which are as large as our entire planet! But, of course, they’re a wee bit farther away. Like, 500,000 times farther.

More

Daily Comic Relief

Stray dog comes to the rescue of woman in car crash

Hero was a stray when he came to the rescue of a woman in a car crash Shannon Lorio crashed her car on a rural road in Georgia. Her life was in danger, but she received help from an unlikely hero. As she lay in her wrecked vehicle, a stray dog approached from out of the woods and came to her aid. The dog kept her awake and pulled her out of the car, dragging her over 100 feet back to the road. She was able to flag down a passing car before she collapsed unconscious. After saving Shannon's life in 2010, the stray dog was taken to the Humane Society where he was adopted by canine search and rescue trainer Heidy Drawdy. He was appropriately named Hero. In the video below, Shannon recounts the events around her rescue by Hero that fateful day.

Woman called 911 about brawling squirrel and snake on her patio

A Gold Canyon, Arizona, woman called 911 and told the dispatcher there was brawl on her back patio between a gopher snake and a ground squirrel.
When firefighters arrived the two had been going at it for a half hour with no plans of stopping. The squirrel took every opportunity to gnaw on the snake's body. Tangled in the arm of the chair the snake only managed to get in a couple of strikes.

YouTube link.

Firefighters had to step in and break up the brawl. The snake had a few nicks when it was released back into the desert but firefighters said it looked like it would be just fine.

"Typically the ground squirrel is food for a snake so it was kind of interesting to see the tables turned a little bit," said Firefighter Ryan Philips. Philips said he believed the squirrel had a nest nearby.

A History Of Daring Red Panda Escapes

Don't be fooled by its fluffy, clumsy amble. The red panda is a master escape artist. Red pandas may look like terrestrial animals but they're arboreal - they're awkward and clumsy on the ground, which is misleading. They're designed for life in the trees, with super-sharp claws for climbing.

They might not be great jumpers, but that's about their only weakness as far as escaping goes; they're excellent swimmers as well as climbers. That plus an energetic, curious, and playful personality and metabolism makes them one of the best jailbreakers at the zoo.

Loud, Red-Headed Bird Species Discovered

Loud, Red-Headed Bird Species Discovered

A red-headed bird with a call that sounds like a cell phone ringing has just been discovered in a Cambodian jungle. 

Animal Pictures

 

*****

The Daily Drift

Nature's Beauty

Carolina Naturally is read in 192 countries around the world daily.

Paddling along ...

Today is National Canoe Day 

Don't forget to visit our sister blog: It Is What It Is

Today in History

1096   Peter the Hermit's crusaders force their way across Sava, Hungary.  
1243   The Seljuk Turkish army in Asia Minor is wiped out by the Mongols.  
1541   Former followers murder Francisco Pizarro, the Spanish Conqueror of Peru.
1794   The French defeat an Austrian army at the Battle of Fleurus.  
1804   The Lewis and Clark Expedition reaches the mouth of the Kansas River after completing a westward trek of nearly 400 river miles.  
1844   Julia Gardiner and President John Tyler are married in New York City.  
1862   General Robert E. Lee attacks McClellen's line at Mechanicsville during the Seven Days' campaign. 1863   Jubal Early and his Confederate forces move into Gettysburg, Pennsylvania.  
1900   The United States announces it will send troops to fight against the Boxer Rebellion in China.  
1907   Russia's nobility demands drastic measures to be taken against revolutionaries.  
1908   Shah Muhammad Ali's forces squelch the reform elements of Parliament in Persia.  
1916   Russian General Aleksei Brusilov renews his offensive against the Germans.  
1917   General Pershing arrives in France with the American Expeditionary Force.  
1918   The Germans begin firing their huge 420 mm howitzer, "Big Bertha," at Paris.  
1926   A memorial to the first U.S. troops in France is unveiled at St. Nazaire.  
1924   After eight years of occupation, American troops leave the Dominican Republic.  
1942   The Grumman F6F Hellcat fighter flies for the first time.  
1945   The U.N. Charter is signed by 50 nations in San Francisco, California.  
1951   The Soviet Union proposes a cease-fire in the Korean War.  
1961   A Kuwaiti vote opposes Iraq's annexation plans. 1
963   President John Kennedy announces "Ich bin ein Berliner" at the Berlin Wall.  
1971   The U.S. Justice Department issues a warrant for Daniel Ellsberg, accusing him of giving away the Pentagon Papers.  
1975   Indian Prime Minister Indira Gandhi is convicted of election fraud.  
1993   Roy Campanella, legendary catcher for the Negro Leagues and the Los Angeles Dodgers, dies.

Non Sequitur

Fishing Tops List of Lightning Death Causes

Fishing Tops List of Lightning Death Causes

Most lightning deaths in the United States occur while people are enjoying outdoor activities, with fishing the most deadly.

Did you know ...

About the .001%

Spoiler alert! Ken Jennings tells us pirates never drew treasure maps

That ancient networks of secret underground tunnels found everywhere in Europe

The truth hurts

John Boehner Is Bug Eyed and Terrified as The Senate Unleashes His Worst Nightmare

Speaker John Boehner (r-OH) spends most of his time stuck between the tea party caucus and the political needs of his cabal, and then justifying the resulting dearth of legislation to the press by waving around a pamphlet ironically marked “jobs bill” in large print, which contains nothing related to actual jobs. But this week marks the beginning of Boehner’s worst nightmare, as the Senate advances immigration reform.

The Speaker must eventually be able to move some kind of immigration reform through the House if he is to do his job for the cabal; that is, if he is to do the bare minimum necessary to keep them from losing Hispanics for the next generation.
However, the tea party caucus is already freaking out about the alleged “amnesty” offered in any immigration reform bill that is remotely pragmatic. In other words, the tea party caucus of novices are not in the House to legislate; they are there to appease the base of wingnut extremists that put them there (aka, running for re-election instead of legislating). To this end, they are insisting on changes to immigration reform that render it unacceptable to Democrats.
Minority Leader Nancy Pelosi warned Boehner last week that given the civil war dividing the repugican cabal, he needed Democratic votes to move any legislation. She also informed Boehner that he wasn’t going to get Democratic votes by appeasing the crazy, fringe, parasitic extremists in his cabal.
Pelosi told Greg Sargent at the Washington Post that the recent farm bill debacle (aka, “amateur hour” as Pelosi called the debacle at Netroots Nation) in which House repugicans tried to go too far to the right and hence lost Democratic votes should be a warning to Boehner, “They were asking us to abandon our values, because they couldn’t get their act together. Hopefully they learned a lesson that you cannot go too far.”
John Boehner knows that if he wants to move any legislation forward in the House that can actually help elect repugicans in the future, he needs Democrats on board, because the tea party caucus will not budge.
Sargent further explained the position Boehner finds himself in:

Pelosi’s remarks are a reminder of the dilemma Boehner faces. There really may be nothing that a majority of repugicans could support that can also win over Democrats in any significant numbers. Anything that can pass the House with almost entirely repugican votes — whatever that would be — won’t get the support of Senate Democrats or President Obama. Which means, as Brian Beutler put it, that the only way Boehner can get reform through the House that has a chance of becoming law is if he accepts the need to “dispense with the member management theatrics and throw in with Democrats.”
Pelosi seems eager to use the farm bill debacle to sharpen the reality of the choice Boehner faces. “He’s going to have to work with us,” Pelosi says. “Hopefully they’ve learned something about legislating.”

The fact that John Boehner’s fumbling, petulant ineptitude is the best of the modern day repugican cabal speaks volumes about the electoral challenges facing the repugican cabal. It’s all downhill from Speaker Boehner, and he can’t even do the most basic job as Speaker without Nancy Pelosi doing all of the heavy lifting via the Democratic Party behind the scenes.
Without Pelosi quietly doing his job on the rare occasion that the House is actually allowed to vote on something that doesn’t offend most Americans, Boehner’s legislative record would be even more humiliating than it is now. Boehner can either “dispense with the member management theatrics and throw in with Democrats” or face certain legislative and repugican cabal electoral failure.
Instead of making a firm decision to either save his career or save his party, Boehner will spend the hours leading up to the inevitably ugly immigration face off in bug-eyed terror, barely suppressing frightened squeaks of EEP! even as he remains frozen in place, unable even to run from the looming shadow of inevitable demise.
Only the beltway media remains satiated by Boehner’s lurching pivots and red meat distractions. At some point soon, he will realize that even his well worn, sniveling, Obama-hate shuffle pivot won’t save him from the impending shadow of immigration reform doom. That might work on the media, but in spite of their best efforts, the media won’t manage to sell bigotry as a big tent idea for the repugican cabal.

The truth be told

Arizona repugicans Propose Bill That Would Not Allow Atheists To Graduate High School

by Hemant Mehta 

A group of Arizona politicians — all repugicans, of course — have proposed a law (House Bill 2467) requiring public high school students to recite the following oath in order to graduate:

I, _______, do solemnly swear that I will support and defend the Constitution of the United States against all enemies, foreign and domestic, that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge these duties; So help me god.

To quote Comedy Central’s Ilya Gerner: “Nothing says ‘I take this obligation freely’ quite like a state law that withholds your diploma unless you swear an oath.”
Kevin Bondelli adds:

… graduating high school is not the same thing as voluntarily accepting the responsibility of a public office or admission to the legal bar. A high school diploma is, with extremely few exceptions, required to have a chance to live above the poverty level. It is the culmination of an education that up until that point was compulsory.

It’s bad enough the repugicans are demanding loyalty of the kind normally reserved for members of Congress and beyond — but there’s also no way I would say those last four words, and the current text of the legislation does not allow for any alternatives.
In other words, if this bill were to become a law, atheists would either not be allowed to graduate… or they would be forced to lie so they could graduate. Neither option is acceptable.
Mike Sunnucks of the Phoenix Business Journal points out another problem:

The Arizona bill could also face legal challenges if it is approved.
jehovah’s witnesses, some muslims and pacifist quakers have in the past challenged loyalty oaths imposed by the federal government and other agencies, saying they conflict with their beliefs and religious professions. Similarly, some Arizona students could challenge the proposed high school oath as a violation of their religious liberties and freedom of expression.

This bill is the work of Representatives Bob Thorpe, Sonny Borrelli, Carl Seel, T.J. Shope, Jeff Dial, David Livingston, Chester Crandell, and Steve Smith.
Smith and Shope have also introduced legislation demanding that all students in grades 1-12 recite the Pledge of Allegiance (with “under god”) every day. At least in that bill, students can get out of saying it with their parents’ permission.
No such exemption exists in the Loyalty Oath.
Keep in mind that in both cases, the bills do not help children get a better education. That’s the saddest thing about all this. The people who are in charge of fixing the education crisis are proposing solutions that would only waste more classroom time and exclude many students from graduating despite fulfilling their current requirements.
***Update***: While the bill still includes the god language, Think Progress reports that it may be revised:

As written, the bill does not exempt atheist students or those of different faiths from the requirement, though Thorpe has pledged to amend the measure. “In that we had a tight deadline for dropping our bills, I was not able to update the language,” he wrote in an e-mail to the Arizona Republic. “Even though I want to encourage all of our students to understand and respect our Constitution and constitutional form of government, I do not want to create a requirement that students or parents may feel uncomfortable with.”

So it’s possible alternative language may solve the atheist problem, but *requiring* students to take the oath still poses a host of constitutional issues. Another option would be to make the oath optional, but that would make this bill completely irrelevant.
Which would be fine by me.

Tom the Dancing Bug