The year saw many developments that will have far-reaching and long-lasting implications, both practically and intellectually. Start the countdown below and go to the end to see some of the other important stories that didn’t quite make the cut.

Image: Wim Lustenhouwer, VU University Amsterdam

Symbolic Thought Shown to Exist in Other Human Species

What distinguished Homo sapiens from other members of the human family and fueled our extraordinary success as a species? One popular notion holds that our propensity for symbolic thought, which underlies language, was key. But mounting evidence indicates that Neandertals shared this talent. And now comes news that an even older, more primitive human ancestor—Homo erectus from Asia—showed signs of symbolic thought, too.

Researchers have discovered a shell engraved with a geometric pattern at a H. erectus site known as Trinil, on the Indonesian island of Java, that dates to between 540,000 and 430,000 years ago. The find is at least 300,000 years older than the oldest previously known engravings, which come from South Africa.

Analysis of the engraving, made on a freshwater mussel shell, suggests that its maker used a shark tooth or another hard, pointed object to create the zigzag design. “The engraving was probably made on a fresh shell specimen still retaining its brown [skin], which would have produced a striking pattern of white lines on a dark ‘canvas,’” Josephine C. A. Joordens of Leiden University in the Netherlands and her colleagues surmise in their report, published online December 3 in Nature. (Scientific American is part of Nature Publishing Group.)

The find hints that many more such items—300,000 years’ worth, in fact—are out there awaiting discovery, and it raises the question of just how much farther back in the human lineage such behaviors might have originated.—Kate Wong

World’s Oldest Engraving Upends Theory of Homo sapiens Uniqueness

Ancient Engraving Strengthens Case for Sophisticated Neandertals

When the Sea Saved Humanity [for subscribers]


Cyber Attacks Spell the End of Magnetic-Stripe Credit Cards

The Home Depot this year became the victim of one of the largest data breaches in history. Cyber thieves in September stole about 56 million records from the company’s retail credit card processing systems, far surpassing the 40 million records Target reported stolen in December 2013 but short of the 2007 theft of 90 million records from TJX Cos., the largest in history. Although cyber theft occurs with alarming regularity, The Home Depot’s breach stands out for its sheer size and its potential impact to relegate the magnetic-stripe credit cards so many rely on to the dustbin of obsolete technologies.

This is because mobile payment systems now exist to effectively replace conventional credit and debit cards. October saw the debut of Apple Pay, for example, a system that lets users make purchases with their iPhones without revealing customer payment information to the retailer. Google has offered a similar digital wallet for years and certain retailers, including Walmart and Best Buy, say they are likewise working on a rival smartphone payment app called CurrentC.

The Home Depot, Target and TJX thefts represent a systemic failure of businesses to protect their customers’ personal information. In fact, The Home Depot was likely victimized by the same hacking group that hit point-of-sale systems at Target, Michaels, Neiman Marcus and restaurant chain P. F. Chang's.

Customers are realizing that they can either trust these businesses to improve their cybersecurity or they can explore new technologies to protect themselves. —Larry Greenemeier

A Guardian “Agent” to Protect You from Digital Fraud

Crime Ring Revelation Reveals Cybersecurity Conflict of Interest

Squiggly Lines Secure Smartphones

Credit: Svisio/Getty Images/iStockphoto

First Synthetic Chromosome of Yeast Made [Video]

What does it take to build the first chromosome of complex cellular life from scratch? Hundreds of college kids. In March undergraduate students in Johns Hopkins University's Build a Genome course announced success in re-creating yeast's chromosome 3, which controls sexual reproduction.

The students synthesized the bases—the A, C, T and G molecules—in sequence and inserted them into yeast in chunks. The yeast’s own DNA repair system then knit the DNA into the existing genome; over time the natural chromosome was thus replaced with the human-made one. The hope is that such manipulation will lead to tests of specific genes and a better understanding of "junk" DNA, cell division and evolution itself. And it marks the first time in history such a chromosome has been synthesized by humans and adopted by yeast, which serves as one of biotechnology’s model organisms.

Some day, perhaps, all 16 yeast chromosomes will be human-made—at least, that’s the goal of the Synthetic Yeast 2.0 project. So that's some 12 million working pairs of DNA to go. Better get more college kids.—David Biello

Baker's Yeast Gets a Genetic Makeover

Is the Gene-Editing Revolution Finally Here?

DNA with Man-Made Bases Functions Just Fine

PhotoDisc/ Getty Images

Botched Handling of Deadly Germs at U.S. Labs

A spate of safety mishaps at federal labs in 2014 sparked congressional hearings and renewed lawmakers’ calls for better oversight at high-containment research facilities.

In June a U.S. Centers for Disease Control and Prevention lab prepped anthrax samples for shipment but failed to properly inactivate the bacterium. The following month U.S. Food and Drug Administration researchers discovered six long-forgotten vials of smallpox tucked away in an unsecured cold room at the National Institutes of Health campus in Bethesda, Md. And back in March researchers at the U.S. Department of Agriculture received a shipment of animal flu virus from a well-respected CDC lab but only later discovered that the samples had been inadvertently contaminated with pathogenic H5N1 flu virus. Such sloppiness, alongside earlier events, revealed a troubling pattern of mistakes. CDC Director Tom Frieden called the series of incidents a “wake-up call” that raises “serious and troubling questions.” Nobody was hurt as a result of the lapses with those deadly agents but they did prompt a temporary freeze on shipments in and out of high-security labs and a comprehensive review of biosecurity procedures. The two CDC flu and anthrax laboratories involved with the bungled samples were also shuttered.

In the months that followed the reported lapses the CDC deployed cameras and tablets in high-level biosafety spaces as part of its effort to avoid future infectious disease botch-ups.—Dina Fine Maron

CDC Botched Handling of Deadly Flu Virus

Poor Oversight Catches Up with High-Security Infectious Agent and Disease Labs

Bio-Unsafety Level 3: Could the Next Lab Accident Result in a Pandemic?

New Tracking Technologies Aim to Prevent Sloppy Handling at U.S. Biolabs

The doomed Antares rocket explodes after take-off. Credit: NASA

Catastrophes Tarnish Commercial Spaceflight

Two disastrous accidents this year, occurring only days apart, dealt a heavy blow to the burgeoning “New Space” industry, a loose collective of private companies, often backed by eccentric billionaires, that are competing to make access to space more economical and routine.

On October 28 an unpiloted Antares rocket operated by Orbital Sciences Corp. exploded shortly after launch, most likely because of troubles with its Russian-built main engines, which, though refurbished, are a half-century old. The failed rocket launch was part of a $1.9-billion NASA contract to ferry cargo to the International Space Station. No one was hurt but Orbital Sciences’s stock price plunged and NASA was left looking sheepish when, only hours after the fiery crash, a long-planned Russian Soyuz rocket flawlessly launched another resupply mission to the space station.

Only three days later a test flight of Virgin Galactic’s SpaceShipTwo suborbital spacecraft ended in tragedy when the vehicle crashed in the Mojave Desert, killing one pilot and seriously injuring the other. Subsequent analyses suggested that SpaceShipTwo broke apart in midair from aerodynamic stresses after two stabilizers at the rear of the vehicle somehow moved into a high-drag “feathered” position as the engine was still firing. Typically, SpaceShipTwo’s stabilizers would only be deployed when the spacecraft was past the apex of a suborbital flight and preparing to reenter the atmosphere.

Orbital Sciences’s next Antares launch to the International Space Station is slated for 2016 and will rely on a yet-to-be-announced newer main engine. Virgin Galactic’s future plans are somewhat murkier. Hundreds of wealthy private individuals had agreed to pay $250,000 apiece for suborbital rides on SpaceShipTwo but some spooked “space tourists” are asking for refunds. The company, already far behind schedule before the destruction of its premiere spacecraft, can’t hope to recoup its losses until commercial flights are regular and ongoing, a prospect that now seems far away indeed. For these and other New Space ventures to ultimately succeed, market forces may need to be more forgiving than the harsh physics of rocketry.—Lee Billings

Unmanned Supply Rocket Explodes Seconds after Liftoff

Virgin Galactic's Passenger Spacecraft Crash Kills Pilot

Crash Analysis: How SpaceShipTwo’s Feathered Tails Work

Failure Is Always an Option

California’s Folsom Lake, outside Sacramento, in 2011 (top) and 2014 Ibottom). Photo Credits: CA Dept. of Water Resources

Worst Drought in Millennium Hits California

Low precipitation and record high temperatures have combined to make California's ongoing drought the worst in the past 1,200 years. The current water scarcity stands out in the ordinarily arid state’s history because temperatures have been higher compared with past droughts, although a number of previous events have actually been drier than the current one, according to research findings to be published in Geophysical Research Letters.

Meanwhile around the world the average temperature this year will likely be the hottest on record, making 2014 the 38th consecutive year with an “anomalously high” reading, according to a World Meteorological Organization report released in December during the United Nations climate talks in Lima, Peru.

Despite this assessment, a recent National Oceanic and Atmospheric Administration–sponsored study points to natural oceanic and atmospheric patterns as the “primary drivers” behind the Golden State's water woes, finding “no conclusive evidence” linking human-caused climate change and the drought.

Regardless of the cause, droughts also hit parts of Texas, Oklahoma, Kansas, Colorado and New Mexico. None are as bad as California’s, which stretched into its third year and received little relief during its supposed rainy season early in the year. By the end of April the entire state was experiencing at least some form of drought, a catastrophe expected to cost California’s economy $2.2 billion in lost crops, jobs and other damages, Reuters reported in August. That month, heavy rains actually exacerbated the problem—creating deadly mudslides and flash floods near Los Angeles—without making a dent in the state’s water deficit.

In November state voters approved Proposition 1—also known as the Water Quality, Supply, and Infrastructure Improvement Act of 2014—authorizing $7.1 billion in bonds to upgrade California's water system to help provide some relief in the form of new storage facilities, conservation, recycled water, desalination and general drought preparedness. —Larry Greenemeier

The Past and Future of California's Water

Drought, Water and the Rise of California [Special e-publication]

California's Drought May Be Worst in a Millennium

Caliornia Drought Could Wipe Out Southernmost Coho Salmon Group

2014 to Be Hottest Year Ever Measured

The sun sets behind BICEP2 (foreground) and the South Pole Telescope (background). Credit: Steffen Richter, Harvard University

Big Bang Gravitational Waves—or Not

If the universe ballooned exponentially just after it was born, as predicted by so-called “inflation” theory, it could have created spacetime ripples called gravitational waves. When scientists announced in March that they had found evidence of just such ripples, the report was hailed as “one of the greatest discoveries in the history of science” because it seemed to provide the first direct proof of inflation.

But then doubt set in. Had the researchers, working at the BICEP2 experiment near the South Pole, really ruled out more mundane explanations for their data? Over the ensuing months physicists argued back and forth; dozens of papers analyzed the BICEP2 findings and their potential implications. The latest measurements now suggest BICEP2’s data could just as easily result from boring old dust as from gravitational waves.

BICEP2 looked at the cosmic microwave background—the oldest light in the universe, which pervades the sky in all directions. In this light the experimenters saw a special kind of polarization—a curling pattern in the orientation of the light waves—that they deduced was caused by gravitational waves’ expansion and contraction of spacetime. Yet data published in September by the European Planck satellite suggest that the polarization BICEP2 saw could be a product of thicker-than-expected galactic dust in the region of the Milky Way that the South Pole experiment observed.

These findings deflated many physicists’ excitement but they are far from conclusive proof against gravitational waves. Either way, the hubbub has illustrated not just the trial and error that is at the heart of the scientific method but also the way the universe keeps finding new ways to throw curve balls at those who try to figure it out. —Clara Moskowitz

In-Depth Report: Cosmic Inflation and Big Bang Ripples

Feature Article: How Big Bang Gravitational Waves Could Revolutionize Physics

Multiverse Controversy Heats Up over Gravitational Waves

Video: 5 Essential Facts about Gravitational Waves from the Big Bang

Video: Shocked Physicist Learns His Big Bang Theory Is True

President Obama's visit to Beijing has yielded a major climate pact. Credit: Official White House Photo by Chuck Kennedy

U.S. and China in Historic Climate Deal

This was a big year for action on climate change. The United Nations Intergovernmental Panel on Climate Change wrapped up its fifth review of the state of climate science finding that, yes, humans are still to blame and that the problem is getting worse. The U.S. Environmental Protection Agency released a plan to curb carbon dioxide pollution from power plants. The U.N. secretary general held an international summit on global warming that involved more than 100 heads of state, including U.S. Pres. Barack Obama. And more than 100,000 people marched through the streets of New York City to demand that those world leaders do something about climate change. Even NASA got in on the act, finally getting the Orbiting Carbon Observatory into orbit on the agency's second try.

But nothing was bigger than the historic agreement between the world's two largest polluters—the U.S. and China. China agreed to halt the growth in its greenhouse gas pollution around 2030 as well as source 20 percent of its power from nonpolluting sources such as dams, nuclear, solar and wind by the same year. The U.S. pledged to cut its greenhouse gas pollution at least 26 percent below 2005 levels by 2025.

Add in an effort by the 28 countries of the European Union to cut CO2 pollution 40 percent below 1990 levels by 2030 and the nations responsible for more than half of the world's global warming pollution problem have now committed to curbs. That means, as the Climate Action Tracker noted, the world is on pace for a "discernibly lower temperature increase than previously estimated." More and faster is what matters now but the era of action to avoid catastrophic climate change started in 2014. —David Biello

Everything You Need to Know about the U.S.–China Climate Change Agreement

Can China Cut Coal?

400 PPM: What's Next for a Warming Planet

Philae bounces along the comet’s surface. ESA / Rosetta / DLR / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA / annotated by Emily Lakdawalla

First Touchdown on a Comet

In space science 2014 was the year of the comet—Comet 67P/Churyumov–Gerasimenko, to be exact, a chunk of dusty ice that spends most of its time drifting between Mars and Jupiter. Like all comets this one is a relatively pristine remnant from our solar system’s infancy, filled with secrets that could help scientists solve lingering mysteries of how the sun’s planets formed.

During late summer the European Space Agency’s Rosetta spacecraft reached the comet after a decade-long deep-space journey, entering into orbit for a year to study the icy body as it plunges sunward. The nail-biting climax of Rosetta’s mission, however, came with the deployment of Philae, a dishwasher-size probe that aimed to make humanity’s first soft landing on a comet and perform months of surface operations. In mid-November the world watched spellbound as Philae fell for seven hours in an unpowered descent to the tumbling comet.

Soon after the landing it became clear that Philae was in trouble. A stabilizing thruster and harpoons meant to anchor the probe had failed to fire, sending Philae bouncing in the comet’s feeble gravity, as if it had landed on a trampoline. It came to rest off-course and tilted at an angle, in shadow where its solar-powered batteries could not fully recharge. Although mission scientists worked to save the probe, less than three days after landing Philae’s batteries drained and it fell silent, but not before delivering unprecedented data and images that are still being analyzed.

Scientists may attempt to reawaken Philae in August 2015, when the comet’s close approach to the sun should boost sunlight falling on the little lander’s solar panels. In the meantime Rosetta still orbits overhead, its mission ongoing. Late in December the spacecraft’s observations of the icy body found that the comet’s ratio of hydrogen isotopes do not match that of Earth’s oceans, suggesting that wherever our planet’s water came from, most of it was not from water-rich comets. Despite Philae’s woes, overall civilization’s first mission to orbit and land on a comet was a meteoric success. —Lee Billings

Rosetta Spacecraft Makes Historic Comet Rendezvous [Video]

Lander Stable on Comet, for Now

Never Mind Philae’s Topsy-Turvy Touchdown, Its Brief Mission Advances Comet Science

A health worker gets cleaned off after visiting an Ebola patient in Liberia. Credit: USAID

The Ebola Outbreak

Ebola catapulted into public consciousness this year with an epidemic in west Africa that dwarfs all prior Ebola outbreaks combined. The virus has devastated communities in Sierra Leone, Liberia and Guinea and sent ripples across the world. The outbreak made its public debut in March in Guinea and by mid-December the virus had infected more than 17,000 people and killed 6,000. Ebola has left an indelible mark on the economy, health care systems and governments in the most affected nations and forced communities to upend traditional rituals—including washing the dead, shaking hands and kissing on meeting—to tamp down the spread.

Travelers from west Africa sometimes took the virus to other countries—Thomas Duncan, for instance, became the first person to die of Ebola in the U.S. after becoming infected in his home country of Liberia. But health care workers and those tending to ill Ebola patients have borne the brunt of the disease, including two U.S. nurses who became infected while caring for Duncan. Globally, more than 620 health care workers have contracted Ebola, roughly half of whom have died. Rare cases of Ebola in the U.S. have ignited pubic debate about mandatory quarantines for returning aid workers.

The virus is transmitted via direct contact with the blood, feces or bodily fluids of symptomatic patients and the disease is particularly contagious during its victims’ final throes or directly after death, when the viral load is high. The disease is not transmitted via air like the flu.

Eliminating Ebola’s global threat hinges on stamping it out in west Africa through tried-and-true health care response methods. In recent months the U.S. has poured millions of dollars into the response. Patients must be identified and isolated and all people who may have come into direct contact with them must be tracked for the appearance of symptoms.

Although researchers have learned a great deal about Ebola in the past year, there is still no proven vaccine or treatment for the virus other than rehydration and careful clinical management of symptoms. Several potential therapies and vaccines are currently in clinical trials. —Dina Fine Maron

Ebola: What You Need to Know [In-Depth Report]

Fact or Fiction?: The Ebola Virus Will Go Airborne

How Did Nigeria Quash Its Ebola Outbreak So Quickly?

Ebola’s Relentless Tide: A Timeline

Aedes albopictus mosquito can spread chikungunya.Credit: Centers for Disease Control and Prevention

Other important stories of 2014

  • The disappearance of Malaysia Airlines Flight 370 in March, which among other issues, highlighted flaws in aircraft tracking and tested the limits undersea search technology.

  • An outbreak of a rare enterovirus that can cause a deadly respiratory illness swept through North America, affecting mostly children.

  • The weakening of the polar vortex, which ordinarily swirls around the Arctic and bottles up frigid air, brought near-record cold to North America this past winter. In somewhat related news, an EF-5 sharknado reportedly pummeled Manhattan.

—Philip Yam