Sorry, your patent on yoga has run out Washington Post (blog) Those trappings have always been incidental to the deeper aim of enlightenment. Secondly, yoga did not originate in Hinduism as Prof. Shukla claims. ... |
Leggo my ego – Winnipeg Free Press
Leggo my ego Winnipeg Free Press O, The Oprah Magazine, celebrates its tenth anniversary this month with practical advice, spiritual enlightenment, an exhortation to "Live Your Best Life," ... |
When False Flags Don’t Fly
Happy Birthday Hubble!!
A star forming region in the Carina Nebula called Mystic Mountain. Click for larger. Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI).
Twenty years ago tomorrow the Hubble Space Telescope was launched. I can hardly believe the telescope has been in space twenty years already. Along with this remarkable image, the Hubble folks have a whole series of other things lined up to mark the occasion. Be SURE to read the press release below OR just click the link and read it on Hubblesite and see more images!
The press release from Hubblesite:
NASA’s best-recognized, longest-lived, and most prolific space observatory zooms past a threshold of 20 years of operation this month. On April 24, 1990, the space shuttle and crew of STS-31 were launched to deploy the Hubble Space Telescope into a low Earth orbit. What followed was one of the most remarkable sagas of the space age. Hubble’s unprecedented capabilities made it one of the most powerful science instruments ever conceived by humans, and certainly the one most embraced by the public. Hubble discoveries revolutionized nearly all areas of current astronomical research, from planetary science to cosmology. And, its pictures were unmistakably out of this world.
At times Hubble’s starry odyssey played out like a space soap opera, with broken equipment, a bleary-eyed primary mirror, and even a space shuttle rescue/repair mission cancellation. But the ingenuity and dedication of Hubble scientists, engineers, and NASA astronauts have allowed the observatory to rebound time and time again. Its crisp vision continues to challenge scientists with exciting new surprises and to enthrall the public with ever more evocative color images.
NASA, the European Space Agency (ESA), and the Space Telescope Science Institute (STScI) are celebrating Hubble’s journey of exploration with a stunning new picture, online educational activities, an opportunity for people to explore galaxies as armchair scientists, and an opportunity for astronomy enthusiasts to send in their own personal greetings to Hubble for posterity.
NASA is releasing today a brand new Hubble photo of a small portion of one of the largest seen star-birth regions in the galaxy, the Carina Nebula. Towers of cool hydrogen laced with dust rise from the wall of the nebula. The scene is reminiscent of Hubble’s classic “Pillars of Creation” photo from 1995, but is even more striking in appearance. The image captures the top of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby bright stars. The pillar is also being pushed apart from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks like arrows sailing through the air.
Hubble fans worldwide are being invited to share the ways the telescope has affected them. They can send an e-mail, post a Facebook message, use the Twitter hashtag #hst20, or send a cell phone text message. Or, they can visit the “Messages to Hubble” page on http://hubblesite.org, type in their entry, and read selections from other messages that have been received. Fan messages will be stored in the Hubble data archive along with the telescope’s many terabytes of science data. Someday, future researchers will be able to read these messages and understand how Hubble had such an impact on the world.
The public will also have an opportunity to be at-home scientists by helping astronomers sort out the thousands of galaxies seen in a deep Hubble observation. STScI is partnering with the Galaxy Zoo consortium of scientists to launch an Internet-based astronomy project (http://hubble.galaxyzoo.org) where amateur astronomers can peruse and sort galaxies from Hubble’s deepest view of the universe into their classic shapes: spiral, elliptical, and irregular. Dividing the galaxies into categories will allow astronomers to study how they relate to one another and provide clues that might help scientists understand how they formed.
For students, STScI is opening an education portal called “Celebrating Hubble’s 20th Anniversary” (http://amazing-space.stsci.edu/hubble_20/). It offers links to “fun facts” and trivia about Hubble, a news story that chronicles the Earth-orbiting observatory’s life and discoveries, and the IMAX “Hubble 3D” educator guide. An anniversary poster containing Hubble’s “hall-of-fame” images, including the Eagle Nebula and Saturn, is also being offered with downloadable classroom activity information.
To date, Hubble has looked at over 30,000 celestial objects and amassed over one-half million pictures in its archive. The last heroic astronaut servicing mission to Hubble in May 2009 made it 100 times more powerful than when it was launched. In addition to its irreplaceable scientific importance, Hubble brings cosmic wonders into millions of homes and schools every day. For the past 20 years the public has become co-explorers with this wondrous observatory.
Do Asphalt-Loving Microbes Point the Way to Life on Titan? | 80beats
Extremophiles microbes: They’re tougher than you. Scientists have found microorganisms living in the ultra-dry Atacama desert, Antarctica, volcanic hot springs, and now, lakes of asphalt.
Trinidad, the larger island of the Caribbean duo Trinidad and Tobago, is home to Pitch Lake. This 100-acre pool of hot liquid asphalt is the largest of its kind on our planet, but microbiologist Steven Hallam thought it could tell us something about another world: the Saturnian moon of Titan. If anything could live in the toxic stew of Lake Pitch, he thought, perhaps there’s hope for the hydrocarbon lakes and rivers of that distant moon. He found that the earthly lake teems with life. “Water is scarce in the lake and certainly below the levels normally thought of as a threshold for life to exist,” he says. “Yet on average, each gram of ‘goo’ in the lake contains tens of millions of living cells” [Australian Broadcasting Corporation].
As you might imagine, studying samples of an asphalt lake is, well, unpleasant. The molasses-like goop got all over the lab, Hallam says, and because oil and water don’t mix, water couldn’t wash it off. “It’s somewhat nasty,” says astrobiologist Dirk Schulze-Makuch of Washington State University in Pullman, who led the field study. If the thick gunk gets on your clothes, he says, you might as well just toss them out [Science News]. Yet the team slogged through it, and submitted the findings to the journal Astrobiology. The researchers say that 30 percent of the organisms they found in Lake Pitch were previously unknown.
However, not all the mysteries around these microbes have been solved. The issue of unexpectedly low water activity still remains a question mark, Schulze-Makuch acknowledges. It is possible that the organisms whose genetic material they recovered could inhabit tiny reservoirs of water trapped in the asphalt samples [Christian Science Monitor]. For some scientists, then, the Lake Pitch inhabitants may not have as much to say about Titan as Hallam hopes. If the organisms feed on the hydrocarbons but live in tiny amounts of water, that would appear to be a much different situation than hypothetical life on Titan. There, presumably, life would have no water in which to reside.
Related Content:
DISCOVER: A Moon Full of Smust (Smust being the smog/dust combo that covers Titan)
DISCOVER: The Search For Aliens Gets Harder—But More Encouraging
80beats: New Evidence for Ice-Spewing Volcanoes on Saturn’s Moon Titan
80beats: Hydrocarbon Lake on Saturnian Moon May Be a Hotspot for Alien Life
80beats: New Takes on Titan Hints at More Fuel for Potential Life
80beats: Antarctica’s “Blood Falls” Shows How Aliens Might Live on Ice Worlds
Image: Dirk Schulze-Makuch,Washington State University
Fast Food News: It Boosts Impatience, and What Trumps KFC’s Double Down? | Discoblog
It's a common nutritional fail--you pledge to make a nice, fresh home-cooked meal, but get impatient and opt for fast food instead. Now, new research suggests that 'we are how we eat' and that the mere thought of fast food can result in general impatience. Researchers from the University of Toronto conducted a series of experiments in which they showed volunteers logos from several fast-food chains or asked them to recall the last time they'd visited, writes Scientific American.
And they found that folks who had thought about fast food would then read faster, even though no one told them to hurry. And they also expressed a preference for time-saving products, like shampoo plus conditioner. And they tended to opt for immediate rewards, like getting a small cash payment right away rather than waiting a week for a larger sum.
Looking at the results, the researchers conclude that a fast-food lifestyle may not only impacts people's waistlines, but may also have a far-reaching and often unconscious impact on their behavior. In other fast-food news, over the last couple of days the American people have been simultaneously horrified and fascinated by KFCs new Double Down sandwich--which is two pieces of fried chicken sandwiching a bunch ...
Daily Data Dump (Friday) | Gene Expression
What is the impact of strict population control? Unintended consequences. Note the convergence in fertility between South Korea and the People’s Republic of China. Coercion or no, some things are inevitable.
Beating Obesity. Marc Ambinder went from 235 to 150 in a year after surgery.
For ancient hominids, thumbs up on precision grip. Many things which we perceive to be derived may be more ancestral than we’d thought.
New Genetic Framework Could Help Explain Drug Side Effects. Medicine is a crap shoot, so you want to load the die in your favor as much as you can.
Chimpanzees Prefer Fair Play To Reaping An Unjust Reward. Not too surprising, but there’s a lot of “complex behavior” whose building blocks are probably pretty ancient. The fact that humans can “socialize” with dogs and cats are somewhat suggestive to me of common mammalian cognitive furniture.
NCBI ROFL: Friday flashback: A woman’s history of vaginal orgasm is discernible from her walk. | Discoblog
"AIM: The objective was to determine if appropriately trained sexologists could infer women's history of vaginal orgasm from observing only their gait. METHODS: Women with known histories of either vaginal orgasm or vaginal anorgasmia were videotaped walking on the street, and their orgasmic status was judged by sexologists blind to their history... ...RESULTS: In the sample of healthy young Belgian women (half of whom were vaginally orgasmic), history of vaginal orgasm (triggered solely by penile-vaginal intercourse) was diagnosable at far better than chance level (81.25% correct, Fisher's Exact Test P < 0.05) by appropriately trained sexologists... ...CONCLUSIONS: The discerning observer may infer women's experience of vaginal orgasm from a gait that comprises fluidity, energy, sensuality, freedom, and absence of both flaccid and locked muscles." [Originally posted 9/1/09] Photo: flickr/loop_oh Related content:
Discoblog: NCBI ROFL: Distinguishing between new and slightly worn underwear: a case study.
Discoblog: NCBI ROFL: Is that a ruthenium polypyridine complex in your pocket or are you just happy to see me?
Discoblog: NCBI ROFL: Does this outfit make me look like I want to get laid? WTF is NCBI ROFL? Read our FAQ!
A Tropical, Fatal Fungus Gains a Foothold in the Pacific Northwest | 80beats
A rare but potentially life-threatening tropical fungus is spreading through the Pacific Northwest, researchers have reported.
The culprit is a new strain of the Cryptococcus gatti fungus, and is known to have been lethal in 25 percent of the reported human infections. C. gatti usually only infects transplant and AIDS patients and people with otherwise compromised immune systems, but the new strain is genetically different, the researchers said. “This novel fungus is worrisome because it appears to be a threat to otherwise healthy people” [Reuters], says lead researcher Edmond Byrnes.
However, scientists aren’t sounding a public health alert because the death toll is still very small–in the United States, five of the 21 people who contracted the fungus in the have died.
The new strain of the C. gatti fungus has been found in both humans and animals like cats, dogs, and sheep, researchers write in the journal PLoS Pathogens. Because its such a rare infection, researchers warn that physicians could potentially miss diagnosing it.
C. gatti is a tropical fungus, normally found in Southeast Asia, Australia, and South America; it arrived on our continent in 1999 via imported plants or trees. In the past five years it migrated from Canada’s British Columbia province into the United States. The fungus is thought to live on the bark of about 10 species of trees, including Douglas fir and western hemlock. Epidemiologist Julie Harris of the Centers for Disease Control says the primary victims of infection have been people who spend a lot of time outdoors, often in contact with soil, and those who do woodwork and construction [Los Angeles Times].
Infection occurs when someone inhales the floating spores given off by the fungus. The spores are known to lodge in the lungs and cause a persistent cough and breathing difficulties, and have also been linked to meningitis and weight loss. But unlike bacterial or viral infections, this fungal infection isn’t transferable and can’t be passed from person to person.
Treatment for the infection includes a long course of anti-fungal medication. While the new strain is “highly virulent,” lead researcher Byrnes says there’s no cause for panic–just for vigilance. “Overall it’s a pretty low threat, and it’s still uncommon in the area, but as the range of the organism expands and the number of cases increases accordingly, it’s becoming more of a concern,” he says [CNN]. Epidemiologist Philip Alcabes, Ph.D told CNN that the emergence of a new, mutant C. gatti strain is “pretty normal” and that “it is an expectable evolutionary event in nature that has a slight amount of human fallout.” He adds that if this fungus follows previous patterns, its virulence should diminish eventually.
Related Content:
80beats: Spores in Mastodon Dung Suggest Humans Didn’t Kill Off Ancient Mammals
80beats: How the Frog-Killing Fungus Does Its Dirty Work
80beats: Fungus Behind the Irish Potato Famine Strikes the U.S.
Image: Duke University
(WW)^n | Bad Astronomy
First Full Face Transplant–Jaw, Nose, Teeth, Etc–Declared a Success | 80beats
A hospital in Barcelona has announced that it has successfully carried out the world’s first full face transplant.
A team of 30 doctors conducted a 24-hour surgery on the patient who had lost most of his face in an accident; in the end the surgeons gave him new jaws, cheekbones, nose, teeth, skin, and other features.
The patient now has a completely new face from his hairline down and only one visible scar, which looks like a wrinkle running across his neck, said Dr. Joan Pere Barret, the surgeon who led the team [Associated Press]. She added that if you ran into the patient at the hospital now, you would not notice anything unusual.
This is the first time that doctors have performed a total facial transplant. Over the past few years, partial facial reconstructions have been performed on ten patients, including on an American woman who suffered an unspecified trauma and a Chinese farmer whose face was mauled by a bear. All the patients were put on a strict regime of immunosuppressant drugs after surgery to ensure that their bodies didn’t reject the transplanted bones, muscles, and skin, and were also given psychiatric counseling.
The current Spanish patient is reportedly a farmer in his 30s who accidentally shot himself in the face in 2005. Prior to the face transplant, he had to breathe and be fed through tubes. After looking at himself in the mirror, post-surgery, he is said to be happy with his new visage.
Related Content:
80beats:First American Face Transplant Is Successful (So Far)
80beats: Bear Attack Victim Gets Successful Face Transplant
80beats: Woman Gets Transplanted Windpipe That Was Grown in Her Arm
Discoblog: Organ Transplants Gone Horribly Awry
DISCOVER: How Do Transplant Patients Wind Up With Killer Organs?
Image: Valle d’hebron Hospital
Where no meat has gone before | Bad Astronomy
Now I know why watching Trek made my blood pressure rise.
Hey, y’know what would go well with this? Antipasto. HAHAHAHAHA!
Anyway, this one certainly looks like more of a meal than the Tiny-E. And it’s weird: the secondary hull looks like a Shuttle external tank. Life imitates art imitates life.
Tip o’ the meat grinder to BABloggee cturner301 and MyFoodLooksFunny.
Hubble’s 20th Birthday Pic: “Eagle Nebula on Steroids” | 80beats
Happy birthday, old friend.
Tomorrow marks 20 years since the space shuttle Discovery carried the Hubble Space Telescope into orbit. And to mark the occasion, NASA released the latest in a long line of incredibly gorgeous images of nebulae and star birth. This is the Carina nebula, which the telescope first shot in 2007. “We wanted to have an image that will be at least as spectacular as the iconic ‘pillars of creation,’ says Mario Livio of the Space Telescope Science Institute in Baltimore, referring to a widely reproduced 1995 Hubble image of the Eagle Nebula. “This particular image can arguably be called ‘Eagle Nebula on steroids’” [Science News]. This sweeping view comes thanks to the Wide Field Camera 3, installed during a Hubble upgrade last summer.
There’s plenty more Hubble love to go around. DISCOVER blogger Phil Plait promises a few surprises in his “Ten Things You Don’t Know About Hubble.” And if you’ve already seen the Eagle Nebula more times than you can count, check out our gallery of the most underrated Hubble images.
Related Content:
DISCOVER: Happy Birthday, Hubble: The Telescope’s Most Underrated Images
Bad Astronomy: Ten Things You Don’t Know About Hubble
80beats: Prepare To Be Amazed: First Images from the Repaired Hubble Are Stunning
80beats: Hubble Spies Galaxies That Formed Just After the Big Bang
Image: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team (STScI)
Redefining Humanity | The Intersection
'What is it, exactly, that distinguishes us from other species?' So begins a recent article by UT professor Michael Webber, who offers an interesting take on a subject that's long been debated. He suggests that what makes us human is the way we manipulate energy:
I contend that what really separates humans from all the other species is that we are the only ones to manipulate energy. The First Law of Thermodynamics tells us that energy has many forms (for example, chemical, thermal, kinetic, electrical, atomic, radiant) and that we can convert from one form to another. And though all species benefit from the natural conversion of radiant energy (for example, sunlight) into chemical energy (derived from, for example, photosynthesis), humans are the only species that will specifically manipulate energy from one form to another — for example converting chemical energy (fuels) to thermal energy (heat) or mechanical energy (motion).
And, thus, a new definition of humanity is born: Humans intentionally manipulate energy.
With this in mind, Webber argues that we ought to accept responsibility for its negative effects. In other words, his definition implores us to be better stewards of this pale blue dot. It's a perspective I like very much. Go read ...
A Novel Geoengineering Idea: Increase the Ocean’s Quotient of Whale Poop | Discoblog
The fight against global warming has a brand new weapon: whale poop. Scientists from the Australian Antarctic Division have found that whale poop contains huge amounts of iron and when it is released into the waters, the iron-rich feces become food for phytoplankton. Phytoplankton absorbs carbon dioxide from the air, the algae is in turn eaten by Antarctic krill, and baleen whales eat the krill. Through this neat cycle, globe-warming CO2 is kept sequestered in the ocean. Scientists have long known that iron is necessary to sustain phytoplankton growth in the oceans, which is why one geoengineering scheme calls for adding soluble iron to ocean waters to encourage the growth of carbon-trapping algae blooms. While environmentalists have fretted over the possible consequences of meddling with ocean chemistry that way, this new study on whale poop suggests an all-natural way to get the same carbon-trapping effect: Increase the number of whales in the ocean. When Stephen Nicol of the Australian Antarctic Division analyzed the feces of baleen whales, he found an astounding amount of iron in it. New Scientist reports:
Nicol's team analyzed 27 samples of faeces from four species of baleen whales. He found that on average whale faeces had 10 million times as much ...
Ships Race to Contain the Gulf of Mexico Oil Spill | 80beats
The oil rig fire in the Gulf of Mexico is finally out, as the Deepwater Horizon sank into the sea yesterday and hope for finding 11 missing workers began to fade. The damage assessment for the oil spill, however, has just begun.
Oil from an undersea pocket that was ruptured by the rig, which was leased by the energy company BP, has begun to spread outward. The spill measures 10 miles (16 kilometers) by 10 miles, about four times the area of Manhattan, and is comprised of a “light sheen with a few patches of thicker crude,” U.S. Coast Guard Lieutenant Commander Cheri Ben-Iesau said today [BusinessWeek]. Whether or not the 700,000 gallons of diesel on board Deepwater Horizon is part of the spill remains unknown. Transocean, the company that owns the rig, admitted that it failed to “to stem the flow of hydrocarbons” before the rig sank.
The biggest concern this morning is that the spill could be headed for the coast of Louisiana, less than 50 miles away, which would maximize the environmental damage. Ed Overton, an LSU environmental sciences professor, said he expects some of the light crude oil to evaporate while much of it turns into a pasty mess called a “chocolate mousse” that ultimately breaks apart into “tar balls,” small chunks of oily residue that can wash ashore. “It’s going to be a god-awful mess for a while,” he said. “I’m not crying doomsday or saying the sky is falling, but that is the potential” [AP]. Once oil hits land it’s far more difficult to clean up; even 21 years after the Exxon Valdez accident, its oil can still be found in Alaska beaches.
Now the task is to stem the tide. Fearing a potential environmental disaster, BP announced Thursday that it was dispatching a flotilla of more than 30 vessels capable of skimming more than 170,000 barrels of oil a day to protect sea lanes and wildlife in the area of the sunken platform [The New York Times]. According to the AP, BP had put down 6,000 feet of containment boom by last night, with 500,000 more feet en route. The company is also preparing to dig a secondary well to try to plug the ruptured oil deposit with concrete and mud.
The scale of disaster remains to be seen. Energy experts at first estimated a worst-case scenario of more than 300,000 gallons of oil leaking into the sea per day. However, the size of the oil pocket remains unknown. If it’s a small one, the containment would be far easier. And in a bit of hopeful news, the Coast Guard said it found no new leakage yesterday.
If you’re a fan of DISCOVER, check us out on Facebook.
Related Content:
80beats: Obama Proposes Oil & Gas Drilling in Vast Swaths of U.S. Waters
80beats: 21 Years After Spill, Exxon Valdez Oil Is *Still* Stuck in Alaska’s Beaches
80beats: 20 Years After Valdez Spill, Eagles Are Healthy; 7 Other Species Still Hurting
80beats: “Nanosponge” Could Soak Up Oil Spills
Images: United States Coast Guard
Happy 20th anniversary, Hubble! | Bad Astronomy
Tomorrow marks the 20th anniversary of the launch of the Hubble Space Telescope. I spent ten years of my life working on that magnificent machine, from using observations of a supernova for my PhD, all the way to helping test, calibrate, and eventually use STIS, a camera put on Hubble in 1997.
Last year, I published Ten Things You Don’t Know About Hubble, and I don’t think I can really add much to it here. I also have a lot of new readers since then, so I’ll simply repost it now as my tip o’ the dew shield to the world’s most famous observatory.
Introduction
On April 24, 1990, the Space Shuttle Discovery roared into space, carrying on board a revolution: The Hubble Space Telescope. It was the largest and most sensitive optical-light telescope ever launched into space, and while it suffered initially from a focusing problem, it would soon return some of the most amazing and beautiful astronomical images anyone had ever seen.
Hubble was designed to be periodically upgraded, and even as I write this, astronauts are in the Space Shuttle Atlantis installing two new cameras, fixing two others, and replacing a whole slew of Hubble’s parts. This is the last planned mission, ever, to service the venerable ’scope, so what better time to talk about it?
Plus, it’s arguably the world’s most famous telescope (it’s probably the only one people know by name), and yet I suspect that there are lots of things about it that might surprise you. So I present to you Ten Things You Don’t Know About the Hubble Space Telescope, part of my Ten Things series. I know, my readers are smart, savvy, exceptionally good-looking, and well-versed in things astronomical. Whenever I do a Ten Things post some goofball always claims they knew all ten. But I am extremely close to being 100% positive that no one who reads this blog will know all ten things here (unless they’ve used Hubble themselves). I have one or two big surprises in this one, including some of my own personal interactions with the great observatory!
Ten Things You Don’t Know About Hubble
Life and Love in the Uncanny Valley | Visual Science
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David Hanson’s robots are by now somewhat familiar faces, including his Einstein robot currently being used as a research tool at Javier Movellan’s Machine Perception Lab at UCSD, and the punk rock conversationalist Joey Chaos. A less familiar face is that of Bina Rothblatt, the blonde at the end of the table in the above photograph. Bina is a robot commissioned by Sirius Satellite Radio inventor Martine Rothblatt to look like her beloved wife. Take that, uncanny valley!
Photographer Timothy Archibald and I worked closely on this project with the idea of creating portraits, and maybe a kind of family portrait, of the Hanson robots. After flying to Texas to shoot Hanson and robots at his home and workshop in Dallas, Texas, Archibald wrote to me.
“Here is a big house in a Texas suburb that looks normal on the outside. On the inside it is robot making company made up of a floating array of 9-12 employees sculpting things, working on the electrical stuff and writing code for software…taking over the living room, den, kitchen, etc. On the upstairs level is where Hanson, his wife and 3 year old live. They they are in month three of this arrangement. There is no down time. People trickle in at 11:00 AM and stay until 1-3 AM everyday including weekends. They are cranking right now, trying to hit deadlines with The Android Portrait of Bina Rothblatt as well as a potential consumer robot called ZENO. Curiously, Hanson’s son is also named Zeno. There is a story on how that came to be, of course…”
To see more photography from this story, check out DISCOVER magazine’s May 2010 issue on newsstands now.
Katherine Batiste of Hanson Robotics working on a computer with “An Android Portrait Of Bina Rothblatt” sits on the table.
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Steven Johnson on Big Business Semiotics | The Loom
Here’s a lecture Steven Johnson gave last night at Columbia about the future of text. (Steven has a transcript here.) Lo and behold, that degree in semiotics twenty years ago makes a lot of sense now!
[Update: I embedded the video here this morning, but it starts on its own, and sometimes it shows a lecture by someone else. Future of journalism, indeed--c'mon, Columbia! Here's the place where I think you can find the video.]
Nearly 100% Out-of-Africa in the past 100,000 years | Gene Expression
Since I’ve been talking about the possibility of admixture with “archaics” (I’m starting to think the term is a bit too H. sapiens sapiens-centric, is the Neandertal genome turning out to have more ancestral alleles?) I thought I’d point to a paper out in PLoS ONE which reiterates the basic fact that the overwhelming genetic evidence today suggests a massive demographic expansion from an African population within the last 100,000 years. Study after study has supported this contention since the mid-1980s. The question is whether this is the exclusive component of modern human genetic ancestry, which is a somewhat more extreme scenario. In any case, the paper is Formulating a Historical and Demographic Model of Recent Human Evolution Based on Resequencing Data from Noncoding Regions:
Our results support a model in which modern humans left Africa through a single major dispersal event occurring ~60,000 years ago, corresponding to a drastic reduction of ~5 times the effective population size of the ancestral African population of ~13,800 individuals. Subsequently, the ancestors of modern Europeans and East Asians diverged much later, ~22,500 years ago, from the population of ancestral migrants. This late diversification of Eurasians after the African exodus points to the occurrence of a long maturation phase in which the ancestral Eurasian population was not yet diversified.
They took 213 individuals, a little over half from diverse African groups, and the other half split evenly between Europeans and East Asians, and sequenced 20 distinct noncoding autosomal regions of the genome. ~27 kilobases per person. The noncoding part is important because they are trying to look at neutral regions of the genome, not subject to natural selection (this is obviously an approximation, as there is some evidence that even noncoding regions may have some selective value). The variation is what you’d expect, Africans more varied than non-Africans, and the two Eurasian populations are distinct from each other, but less so than either is from the Africans. Lots of statistics ensue, and an “Approximate Bayesian Computation (ABC) analysis.” I’ll cut to the chase, the highest probability model is illustrated in panel A of figure 4. Expansion out of Africa ~60,000 years ago, major bottleneck, a ~40,000 year interregnum where there was a relatively unified Eurasian population genetically, and then a separation between East and West Eurasians ~20,000 years ago.
I’ll stipulate that I haven’t dug deep into the statistics, nor would I really comprehend all the details if I did spend a weekend on it. But I’m rather skeptical of the 40,000 year period of a common Eurasian population. Reading the text where they discuss this finding it seems clear that it was surprising to the authors, and I’m not sure how convinced they are about it either. It is interesting that the second most probable scenario, B, is a simultaneous expansion out of Africa by two different groups which lead to East and West Eurasians. That makes me a little less confident about the details on Eurasian demographic history overall than I’d already been. They do note that some Y chromosomal data imply that all Eurasian populations may have derived from a Central Asian group, and the settlement of Europe ~35,000 years ago may actually indicate population replacement (though it’s pretty clear that many Central Asian groups have been recently heavily admixed with the incursion of Turks from Mongolia in historical time overlain upon a Iranian substrate, and some sequencing of ancient Cro-Magnon mtDNA shows that their haplgroup is still found in many Eurasian, and even New World, populations). Perhaps there is a more complicated story to be told about the replacement of early modern H. sapiens sapiens by later H. sapiens sapiens. I wouldn’t discount it, but one analysis does not push me to consider this at all likely. Additionally, they obviously couldn’t test the “two wave” model Out-of-Africa whereby there was a southern migration which skirted the Indian ocean along with a north wave which pushed into Central Asia; they didn’t have any “southern” Eurasian samples. Also, I do want to make a note of the fact that they had a lot more parameters in their model than I’m mentioning, including migration between the two Eurasian groups.
But let’s jump to the conclusion and highlight a portion which is relevant to what I’ve been discussing on this weblog over the past few days. As I observe above they constructed scenarios with different parameters to see which fit the data best, and one of those parameters was interbreeding with older hominin groups in Eurasia. Here’s what they say in the discussion:
For those historical and demographic parameters that have been previously studied, our co-estimations are in agreement with previous reports, highlighting the general accuracy of our estimates. For example, our estimation of the replacement rate of archaic hominids by modern humans, although indicating that the introgression of archaic material into the gene pool of modern humans has been minimal, did not rule out the presence of minor archaic admixture of other hominids in modern humans in agreement with previous observations…However, it is important to emphasize that our inferences are based on non-coding neutral regions of the genome and that adaptive introgression from archaic to modern humans may have occurred to a greater extent…Indeed, in contrast to neutral alleles, adaptive variants may attain high frequencies by natural selection after minimal genetic introgression. Future studies comparing coding-sequence variation in modern humans and extinct hominids (e.g. Neanderthals) should help to answer this question.
Their models don’t offer any plausible scenarios where more than 1% of the sequence which they analyzed was derived from populations which were not from the recent Out-of-Africa movement. But, they do specifically say that they lose power to ascertain whether there was admixture at levels below 1%. At some point in the medium term future when we have a fair amount of ancient DNA from Neandertals sequenced, as well as a lot of genomes of modern human beings, if we still don’t find any evidence for alleles which have introgressed from other lineages which had long been separated, the time for hedging may be over. But at this point there’s still some wiggle room. What I’m wondering though is how the University of New Mexico group found lots of evidence of introgressed lineages when other groups have not. Granted, they had 10 times as many individuals and more diverse populations, but presumably far less of the genome. If there was admixture which we could detect, in light of the nearly two decades of this sort of stuff, I assumed it would be cases of adaptive introgression. Here a very low level of admixture could still lead to the increase in frequency of a haplotype which bears the hallmarks of having been in a distinct population from H. sapiens sapiens for long periods of time (like haplogroup D for the microcephalin gene). In other words, I assumed that evidence of introgression would be a story of genetics & natural selection and not genomics & admixture. For instance, particular metabolism genes and the like which new Africa populations might have picked up just like they’d eventually develop their own adaptations from mutation or extant variation if they didn’t admix. I guess 614 microsatellites may not count as genomics, but if adaptive introgression on a few select genes was how we’d detect interbreeding between native Eurasian groups and the Africans this not a way I’d assume you could find any evidence of that.
Citation:Laval G, Patin E, Barreiro LB, Quintana-Murci (201). Formulating a Historical and Demographic Model of Recent Human Evolution Based on Resequencing Data from Noncoding Regions PLoS One : 10.1371/journal.pone.0010284
