Genes of Extinct Ancestor Survive in Modern Humans

Genes inherited from long-extinct human ancestors may be more common than thought, suggesting a Homo sapiens origin story with more than a few evolutionary one-night stands.

The latest findings involve genes from Denisovans, a recently-discovered member of the Homo genus who lived in central and eastern Asia until 40,000 years ago. Denisovans, humans and neanderthals last shared a common ancestor about 1 million years ago.

Earlier research found lingering Denisovan traces in genomes of people from Oceania. Now they’ve been found in southeast Asia, too.

“We haven’t been a very exclusive species, with a very narrow origin,” said Martin Jacobsson. Interbreeding with other members of the human family tree “is not a unique event. It’s a more complex story than we thought before.”



In a study published Oct. 31 in the Proceedings of the National Academy of Sciences, Jacobsson and co-author Pontus Skoglund searched through 1,500 human genome scans from around the world for genes found in Denisovans but not chimpanzees or Neanderthals.

While the previous finding of Denisovan inheritance involved analysis of ultra-high-resolution human genome scans, of which only a few exist, Jacobsson used low-resolution scans. These are more commonly available and allowed the researchers to detect Denisovan signals in genomes from mainland southeast Asia. A signal also appeared in South America, but Jacobsson said that’s probably a false positive.

The 40,000 year-old tooth from which Denisovans were first identified in 2010. Image: David Reich et al./Nature.

Beyond the fun of knowing that Denisovan genomes live on, the findings add to a growing sense of the richness of the human evolutionary story.

Until relatively recently, it was thought that human ancestors trekked out of Africa about 100,000 years ago in a single straight shot, descending without diversion into modernity. But what’s emerged from fossil findings in recent years is a picture of Homo sapiens and its near relatives flowing out of Africa again and again, with some populations vanishing and others surviving, often living side-by-side.

Now, thanks to well-preserved ancient genomes, it’s possible to look at mixing: Evidence of interbreeding with Neanderthals in northern Europe was found, followed by the Denisovan studies. Critically, the new findings fit a genetic pattern suggesting multiple episodes of interbreeding with Denisovans.

“We were evolving for a little while, then isolated, then mixed again,” said Jacobsson. “It’s not so simple that you can say, there’s only been one admixture.”

“I find it really cool that people use the archaic genomes we produced to try to arrive at new insights,” said geneticist Svante Paabo of Germany’s Max Planck Institute, who originally sequenced the Denisovan genome from 40,000-year-old fingerbones found in a Siberian cave. “Of course one will have to see which of them hold up.”

As for what Denisovan genes do for people who have them, it’s hard to say. Unlike Neanderthal genes, which seem to have given human immune systems a boost, Denisovan gene function isn’t yet understood.

“It might take a little longer, until we get better-quality ancient genomes,” said Jacobsson. “But I’m guessing there are people out there trying to do this now.”

Image: Global map of Denisovan gene frequency in modern human genomes. (Jacobsson and Skoglund/Proceedings of the National Academy of Sciences)

Citation: “Archaic human ancestry in East Asia.” By Pontus Skoglund and Mattias Jakobsson. Proceedings of the National Academy of Sciences, Vol. 108 No. 44, Oct. 31, 2011.

See Also:

• Fossil Finger DNA Points to New Type of Human
• Neanderthals Mated With Humans Outside of Africa
• Neanderthal Genome Shows Most Humans Are Cavemen
• Neanderthals Had Feelings, Too

The paradox of expectations

by Seth Godin

Low expectations are often a self-fulfilling prophecy. We insulate ourselves from failure, don't try as hard, brace for the worst and often get it.

High expectations, on the other hand, will inevitably lead to disappointment. Keep raising what you expect and sooner or later (probably sooner) it's not going to happen. And we know that a good outcome that's less than the great one we hoped for actually feels like failure.

Perhaps it's worth considering no expectations. Intense effort followed by an acceptance of what you get in return. It doesn't make good TV, but it's a discipline that can turn you into a professional.

Restore Your Near Vision -- Without Reading Glasses

Cornea Inlay Improves Near Vision in People With Presbyopia

By Charlene Laino
WebMD Health News

Reviewed by Laura J. Martin, MD

Oct. 24, 2011 (Orlando, Fla.) -- A Lifesaver-shaped micro-disc about the size of a pinpoint can help restore normal reading vision in the millions of baby boomers who have trouble making out newspaper print, cell phone text messages, and other small print, researchers say.

In a study, the Kamra cornea inlay improved near vision in all of about 2,000 people with presbyopia, says Minoru Tomita, MD, PhD, executive director of the Shinagawa LASIK Center in Tokyo.

He presented the findings here at the annual meeting of the American Academy of Ophthalmology.

Correcting Presbyopia

Presbyopia refers to the gradual loss of the eye's ability to focus, making it difficult to see objects up close. It's a natural, albeit annoying, part of the aging process that most people begin to notice in their 40s.

The Kamra corneal inlay is designed to restore near vision without affecting distance vision. It does so by taking advantage of the "pinhole effect," which blocks peripheral rays and only allows focused light to reach the retina. (You can try this at home: Just roll up a piece of paper to create a pinhole-sized opening at one end and a larger opening at the other, and look through it.)

The inlay weighs less than a grain of salt and patients will not feel it, Tomita tells WebMD.

During the 15- to 20-minute procedure, the same type of laser employed in LASIK eye surgery is used to create a flap in the non-dominant eye. The inlay is placed on the cornea layer and centered over the pupil, and the flap is repositioned.

For people who have trouble seeing objects that are far away, simultaneous LASIK laser eye surgery can be used to restore distance vision.

The inlay is not available in the U.S., although maker AcuFocus hopes to gain FDA approval next year. It is available in Europe, Asia, and South America.

The cornea inlay costs about $5,000 to $7,000, "about the same as LASIK," Tomita says.

The Study

The new study, funded by AcuFocus, involved people in their 40s, 50s, and 60s who had problems with near and distance vision. LASIK was performed to correct distance vision, and the microscopic ring was implanted to correct near vision.

Of the approximately 450 people who have been followed for six months to date:

• Those in their 40s could read four additional lines on a 13- to 15-line eye chart, on average. People in their 50s could read five more lines, and those in their 60s could read seven additional lines.

"Basically, they could only read headlines before the procedure," says AAO spokesman James Salz, MD, clinical professor of ophthalmology at the University of Southern California in Los Angeles.

"Afterward, they could read most things, except the very small print on a medicine bottle," he says. Salz reviewed the results for WebMD.

• About 90% of people in all three age groups said they were satisfied or very satisfied with the results.
• About 95% said they were less dependent on reading glasses.
• Long distance vision was 20/20 or better in people in all age groups.

Tomita says the most common side effect was dry eye, which affected about 10% of patients and was treatable.

In general, the most common side effects include ocular surface changes, glare,halos, and night vision disturbances, according to AcuFocus' web site. Over time, these conditions are expected to lessen or go away.

Results 'Impressive'

Salz tells WebMD that he's generally impressed with the inlay. "It's very safe and reversible. If we put it in and you don't like it, we can take it out," he says.

Salz notes that some people with presbyopia opt for LASIK to deliberately under-correct one eye to let them see close objects, even though it's at the slight expense of distance vision.

"This inlay changes focus so you can read and it doesn't affect distance," he says.

But "this doesn’t mean you will never need glasses," Salz says. "It’s primarily for what I call social vision -- taking a quick look at a menu, at the GPS in the car, and so on," he says.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.

Making Solar Panels As Ubiquitous And Efficient As Leaves

Leaves are the ultimate solar panel. If we're going to power more of the world with the sun, we're going to need to imitate plants, one way or another.
Enough solar energy strikes the earth in one hour to power our civilization for a year, and futurists like Ray Kurzweil see us moving to an all-solar civilization in the span of a single human lifetime.


But getting to a civilization powered entirely by renewables isn't going to happen with current technology. Traditional solar panels might become cheaper, but the laws of physics say they can't become that much more efficient. Not to mention that the resources required to build the kind of desert-spanning solar farms that would be required to replace even a percentage point or two of our current energy mix boggle the mind.


But there is another way, and it borrows directly from nature: "solar leaves." They've become a shorthand for the idea that if we can only make solar panels cheap enough, no one will bother to use anything else ever again.


There are a number of competing visions for how a solar leaf will work and what it might be made from. Daniel Nocera at MIT is working on a combination of catalysts that use sunlight to--like a leaf--directly convert water into hydrogen . (Which can then be burned or used in a fuel cell.) Another group of MIT researchers have successfully printed solar cells onto paper, conjuring visions of a future in which solar cells are as cheap as the morning paper.

But making these kinds of solar cells into a true replacement for our current energy system will require technology that isn't merely cheap; in some sense, it needs to be disposable. (Obviously, a closed production cycle where 100 percent of its recyclable components are reclaimed would be optimal.)


In addition to price, disposability respects the fact that all energy infrastructure, and especially parts of it that are continually exposed to the sun's powerful radiation, has to be periodically replaced. And while Nocera's vision of a water-bathed, hydrogen-spewing lozenge is tempting, this may be a case where it's more important to imitate the form of nature rather than its exact mechanism.


This is the vision of researchers at Germany's University of Technology Chemnitz, who have just published work on durable solar cells that could be printed with traditional processes. Imagine a copy shop in Nairobi spooling out a continuous ribbon of "solar leaves" at up to 15 meters per second on a single machine and you've got the idea. These solar leaves could be cut to whatever length the user prefers, then connected to a battery or home with simple alligator clips.


Printed solar cells still require some kind of substrate (usually metallic) whose widespread adoption might deplete world reserves. But what if we could make solar leaves out of nothing but carbon?


Jiaxing Huang and colleagues at Northwestern University are working on a solar cell that is made out of nothing but three different forms of carbon: balls (fullerenes), sheets (graphene), and tubes (carbon nanotubes). Best of all, all three can be mixed up in a test tube full of water. It's what chemists call aqueous chemistry. This makes the production of these solar cells biomimetic from start to finish, and implies that some day we'll be making solar panels on paper with little more than graphite as a feedstock.




Of course, we don't have to wait decades to see what effect solar leaves will have on the success of solar power. Already, solar panels known as thin film solar, which are produced by something like a traditional printing process, are a $3 billion business. One research firm projects that this market could explode to $44 billion by 2017.


Thin film isn't as efficient as silicion solar cells, but the world's abundance of sunshine makes that irrelevant. These days, it's all about finding an patch of ground and throwing up inexpensive panels. Plants have been covering every inch of earth's surface with what are essentially solar panels for billions of years--now it's our turn.

Animal Production Practices Create Antibiotic Resistance

“We produce nine billion food animals in the United States every year. And most of these animals are fed antibiotics throughout their life. And it’s the single greatest use of antibiotics in the United States.” Lance Price, director of the TGen North Center for Microbiomics and Human Health in Flagstaff, at the ScienceWriters2011 conference on October 16th.

“And then this is the thing that just drives public health people crazy: most antibiotics are fed to healthy animals to promote growth or to prevent diseases that may be just occurring because of the way we’re raising them. Overcrowding and unsanitary conditions—we call them production diseases. And so we’re using these lifesaving drugs as production tools. It’s pretty amazing.

“So most animals are raised in concentrated animal feeding operations, or CAPOs. I could not honestly engineer a better system for creating antibiotic-resistant bacteria than to introduce antibiotics to this setting. And that’s exactly what we do every day in the United States. If we all recognize that antibiotic resistance is one of the greatest threats to public health that we face today, we have to do something about this.”

—Steve Mirsky