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Notable Developments

Science  20 Dec 2013:
Vol. 342, Issue 6165, pp. 1444
DOI: 10.1126/science.342.6165.1444

Find out what Science staff considered the top breakup, breakdowns, breakout, and genomes of the year, as well as 2013's top fossil, politico, vertebrate, and invertebrate.

Fossil of the Year: Dmanisi Skull Gives New Face to Early Human Ancestors

CREDIT: GURAM BUMBIASHVILI/GEORGIAN NATIONAL MUSEUM

Researchers unveiled the most complete skull of an early human ancestor this past November—and proved once again that a single fossil can transform our picture of human ancestors. The stunning 1.8-million-year-old remains of a mature male had a remarkably small brain and a large, jutting jaw. That's just the opposite of what researchers expected to find for members of our genus Homo at this time. Four skulls of our direct ancestor, Homo erectus, found in the same sliver of time and place—at Dmanisi in Georgia—had bigger brains and less conspicuous mugs. As a result, the latest Dmanisi skull, which even includes the fragile midface bones, has given early Homo a new visage.

If it, too, is a member of H. erectus, as the researchers think, that species had more diversity in brain size and facial traits than previously believed. New dating of the skull and its four companions also suggests that H. erectus left Africa soon after it appeared there 1.9 million years ago.

But some paleoanthropologists suggest the skull could belong to Homo habilis, a more distant earlier human ancestor that lived in Africa about 2.3 million to 1.4 million years ago. Or it could belong to a new species. Regardless of the skull's precise identity, its remarkable preservation will make it an icon for the face of early Homo for decades, if not centuries, to come.

Vertebrate of the Year: The Rat That Ages Beautifully

CREDIT: ROMAN KLEMENTSCHITZ, WIEN (OWN WORK) [GFDL (HTTP://WWW.GNU.ORG/COPYLEFT/FDL.HTML) OR CC-BY-SA-3.0 (HTTP://CREATIVECOMMONS.ORG/LICENSES/BY-SA/3.0/)], VIA WIKIMEDIA COMMONS

They will never win a beauty contest, but naked mole rats (Heterocephalus glaber) may hold a lesson or two for humans. Two studies this year, for instance, found clues to why these rodents can live 30 years, cancer-free. One secret may be a ribosome that excels at producing error-free proteins; misformed proteins can clog up the body's systems and accelerate aging. Another could be a supersized version of a complex sugar that seems to protect against cancer. Naked mole rats don't break this compound down as fast as other animals, so it builds up in the spaces between cells and may keep the cells from clumping together and forming tumors.

Invertebrate of the Year: Top-Gear Planthopper

Turns out humans weren't the first organism to gear up to gain a powerful mechanical advantage. In September, high-speed videos revealed that immature Issus coleoptratus planthoppers are such great leapers because of toothy interacting gears on their rear legs. By meshing together, the gears cock and coordinate the legs prior to and during each explosive hop.

CREDIT: BURROWS ET AL., SCIENCE 341 (13 SEPTEMBER 2013)

Breakout of the Year: Voyager Is Really Out There, Somewhere

Thirty-six years out from Earth, its power dwindling and several instruments dead, the Voyager 1 spacecraft has left the invisible cocoon spun by the sun and entered interstellar space. So concluded Voyager team leaders and most space physicists in September. But it had taken them a year to realize Voyager had broken out of the heliosphere—the bubble inflated by the sun's wind of charged particles. That is a testament to just how weird the outer "edge" of the solar system proved to be.

Going, gone.

Voyager 1 (top) has exited the heliosphere in this artist's conception, while Voyager 2 (bottom) is getting close.

CREDIT: NASA/JPL-CALTECH

Team members had a checklist of indicators that would confirm that Voyager 1 had crossed into interstellar space. The density of plasma—the soup of low-energy charged and neutral particles pervading space—should jump, cosmic rays produced within the heliosphere should drop while those of interstellar space should increase sharply, and the direction of the magnetic field that pervades all space should switch. Voyager couldn't detect any change in plasma density, because its plasma instrument failed shortly after passing by Saturn. It did measure the expected changes in cosmic rays, in August 2012. But it never saw the magnetic field switch. So the official team line had Voyager in a "depletion region" still within the heliosphere.

There, Voyager would have remained if not for a little help from the sun. Twice it sent a solar blast out Voyager's way, setting off oscillations in the plasma that the spacecraft's plasma wave instrument could detect, giving team members a proxy for plasma density. Extrapolating back, they could see that the plasma density had shifted in August 2012, just when cosmic rays had switched. Team leaders concluded that Voyager 1 had actually entered interstellar space at that time, even though the magnetic field did not shift.

That interpretation will be tested as Voyager 2, a few years behind its sibling, brings its operating plasma instrument to bear on the same region.

Politico of the Year: Chairman Smith Versus the Scientists

U.S. Representative Lamar Smith (R–TX) likes to recall how a "D" in a freshman physics class at Yale University taught by a former presidential science adviser, D. Allan Bromley, caused him to switch his major to American studies—and started him on the road to a career in politics. Now, the tables have turned: This year, Smith gave a failing grade to the National Science Foundation (NSF) as part of a controversial attempt to reshape U.S. science policy that has scientists talking.

CREDIT: NASA

As the new chair of the House of Representatives science committee, Smith has drafted legislation that would alter how NSF manages peer review. He says the proposed changes would make the system more transparent and ensure that tax dollars are being spent wisely. But science leaders view the bill as a threat to a system that has fueled 60 years of innovation—and that other nations are trying to copy.

In a bid to preempt the draft legislation, this month NSF announced plans to sharpen its descriptions of funded grants to emphasize their relevance to important societal goals. Will it be enough?

Breakup of the Year: Siberian Meteor Blast Delivers a Warning Shot

February's window-shattering explosion over Chelyabinsk, Russia, terrified thousands and caused hundreds of injuries, mostly minor. It also provided a windfall for scientists and a public relations bonanza for asteroid hunters.

CREDIT: RIA NOVOSTI/SCIENCE PHOTO LIBRARY

For scientists, the midair self-destruction of a 19-meter-diameter rock provided a key benchmark for reevaluating the threat from such relatively small visitors from the asteroid belt. Researchers had plenty of observations to work with. Data came from 400 public and private video cameras, seismographs, ground-based sensors that record ultra-low-frequency sound, and satellites intended to catch clandestine nuclear tests.

The Chelyabinsk blast had an energy equivalent of about 500 kilotons of TNT, researchers estimate, or about 23 times the energy of the nuclear bomb dropped on Nagasaki. Initially, that output appeared to make the airburst a rarity, far larger than expected by astronomers who use telescopic surveys to gauge asteroid hazards. But after researchers compared the sound and brightness of Chelyabinsk with other meteor airbursts over a 20-year period, they found that big airbursts are at least three times—and perhaps 10 times—more frequent than astronomers thought.

The incident energized those eager to find other small asteroids, whether heading for Earth or passing nearby. NASA is cranking up its search effort because it wants to find an asteroid smaller than 10 meters for an astronaut rendezvous. The nonprofit B612 Foundation wants to fly a spacecraft-borne telescope to help with that mission and search for hazardous asteroids, if someone will provide the funding.

Ruling of the Year: U.S. High Court Bars Human Gene Patents

In June, the U.S. Supreme Court reversed three decades of policy—and rattled the biotech world—when it ruled that human genes cannot be patented. The case, Association for Molecular Pathology v. Myriad Genetics, pitted a Utah company that owns patents on the human breast cancer genes BRCA1 and BRCA2 against doctors and researchers who argued that the patents were invalid and stifling research. The court agreed unanimously, finding that human genes are a "product of nature" and so not patentable.

CREDIT: CQ ROLL CALL/NEWSCOM

It will take years for the full consequences of this revolution in legal thinking to become clear. But the decision is already making waves. It spurred several companies to offer breast cancer diagnostic tests that competed with Myriad's—sparking a contentious new legal battle. And in October, federal Judge Susan Illston in San Francisco cited the Supreme Court's reasoning in striking down another DNA patent, involving a Down syndrome test developed by Sequenom of San Diego, California. Sequenom plans to appeal, and it is likely that many companies will be asking judges to clarify exactly how the law defines a product of nature.

Breakdowns of the Year

CREDIT: NASA

In May, for the first time in recorded history, atmospheric concentrations of carbon dioxide rose above 400 parts per million, dramatizing the failure of governments to limit greenhouse gas emissions. • The same month, a second reaction wheel failed on the Kepler planet-hunting spacecraft, dooming its ability to point accurately and collect precise data. • In October, congressional gridlock on spending issues forced the U.S. government to partially shut down for 16 days, paralyzing science funding agencies, disrupting research projects, and canceling many Antarctic field studies. • More than one-half of 304 free open-access journals accepted a bogus paper submitted by Science journalist John Bohannon, who sparked fierce debate over the quality of peer review when he reported his sting. • By year's end, disgraced Dutch social psychologist Diederik Stapel had retracted at least 54 papers based on made-up data, but was giving a TED talk about his misconduct.

Genomes of the Year

CREDIT: COURTESY OF BORIS MICHEL

Notable sequences of 2013: The oldest human mitochondrial DNA, which comes from a 400,000-year-old Neandertal ancestor found in Spain but mysteriously resembles that of a different extinct human • The oldest organismal genome, from a 700,000-year-old frozen horse hoof • Other complete genomes came from the comb jelly, changing views of the animal tree of life • Minke whale, revealing how marine mammals cope with deep dives • Amborella, sister to all flowering plants, explaining the early days of angiosperms • Tiger, lion, and snow leopard, capturing the genomic essence of big cats • The scorpion Mesobuthus martensii (at right), which has 10,000 more genes than humans do • Norway spruce (Picea abies), white spruce (Picea glauca), and, soon, loblolly pine (Pinus taeda), each with genomes about seven times the size of a human's—a sequencing tour de force • The invaluable HeLa cancer research cell line, requiring permission from the family of Henrietta Lacks • King cobra and Burmese python, telling an evolutionary tale of extreme adaptations • Four bats which, when compared to dolphins, highlight a common core of echolocation genes • Pigeon, revealing the gene for crests • Irish famine potato blight, showing that this historic strain is extinct.

Also Noted: Ribosome Robot

CREDIT: BY JÁ (OWN WORK) [GFDL (HTTP://WWW.GNU.ORG/COPYLEFT/FDL.HTML) OR CC-BY-SA-3.0-2.5-2.0-1.0 (HTTP://CREATIVECOMMONS.ORG/LICENSES/BY-SA/3.0)], VIA WIKIMEDIA COMMONS

In January, one of the world's first nanofactories made its debut. Researchers built a molecular machine that mimics the cell's protein-building factory, the ribosome, but is one-tenth the size. This ribosome robot includes a molecular axle track with a ring around it. When heated, the ring's sulfur-containing amino acid sequentially grabs each of three amino acids from the track to build a short peptide chain. The machine has been hailed as ingenious, but it won't replace ribosomes anytime soon. It takes days to do what the real ribosome can do in tenths of a second.

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