Biggest Scientific Breakthroughs of 2013

From intergalactic neutrinos and invisible brains, to the creation of miniature human "organoids," 2013 was an remarkable year for scientific discovery. Here are 17 of the biggest scientific breakthroughs, innovations and advances of 2013.

Voyager I Leaves the Solar System

Escaping the solar system is no mean feat. For 36 years, NASA's Voyager 1 spacecraft has putting distance between itself and the Sun at speeds approaching 11 miles per second. At a pace like that, scientists knew Voyager was approaching the fringes of the heliosphere that surrounds and defines our solar neighborhood – but when would it break that barrier? When would it make the leap to interstellar space? After months of uncertainty, NASA finally made the news official this September. "Voyager 1 is the first human-made object to make it into interstellar space," said Don Gurnett, lead author of the paper announcing Voyager's departure; "we're actually out there."

The CRISPR Craze Takes Off

Bacteria have their own version of an adaptive immune system; but "CRISPR," as the system is known, does not target protein antigens they way your immune system does. Instead, CRISPR works by targeting and eliminating specific DNA sequences with matching strands of RNA. What's more, the system is easily manipulated – since researchers first reported harnessing the system in January,writes Elizabeth Pennisi in a perspective piece for Science, "various groups have used it to delete, add, activate or suppress targeted genes in human cells, mice, rats, zebrafish, bacteria, fruit flies, yeast, nematodes and crops, demonstrating broad utility for the technique." For scientists in search of new tools, few qualities are more important than versatility and ease of use. CRISPR has both – and, some say, the potential to revolutionize the field of molecular biology.

The Milky Way is Brimming with Habitable Worlds

Planet-hunting scientists announced in November that 22% of sunlike stars in the Milky Way are orbited by potentially habitable, Earth-size worlds. This remarkable finding suggests there could be as many as two-billion planets in our galaxy suitable for life — and that the nearest such planet may be only 12 light-years away. Is Earth 2.0 out there? With figures like that, it's hard to imagine otherwise. Who knows – with all the Kepler data we've got to sift through, there's a chance we've already found it. [Image Credit M. Kornmesser/ESO]

Brain-to-Brain Interfaces Have Arrived

Back in February, researchers announced that they had successfully established an electronic link between the brains of two rats, and demonstrated that signals from the mind of one could help the second solve basic puzzles in real time — even when those animals were separated by thousands of miles. A few months later, a similar connection was established between the brain of a human and a rat. Just one month later, researchers published the results of the first successful human-to-human brain interface. The age of the mind-meld, it seems, is near at hand.

There is Life at the End of the World

There is life in Lake Whillans. For millions of years, the small body of liquid water has lurked hundreds of meters below Antarctica's Ross Ice Shelf, sealed off from the outside world and the scientists who would explore its subglacial depths. Earlier this year, a team of researchers led by Montana State University glaciologist John Priscu successfully bored a tunnel to Whillans and encountered life, making Priscu and his colleagues the first people in history to discover living organisms in the alien lakes at the bottom of the world. [Photo by Alberto Behar, JPL/ASUM]

Doctors Cure HIV in a Baby Born With the Disease

In a monumental first for medicine, doctors announced in March that a baby had been cured of an HIV infection. Dr. Deborah Persaud, who presented the child's case at the 20th annual Conference on Retroviruses and Opportunistic Infection, called it "definitely a game-changer."

Newly Discovered Skulls Could Prune Humans' Evolutionary Tree

An incredibly well-preserved, 1.8-million-year-old skull from Dmanisi, Georgia suggests the evolutionary tree of the genus Homo may have fewer branches than previously believed. In a report published in October, a team led by Georgian anthropologist David Lordkipanidze writes that it is "the world's first completely preserved hominid skull." And what a skull it is. When considered alongside four other skulls discovered nearby, it suggests that the earliest known members of the Homo genus (H. habilis, H.rudolfensis and H. erectus) may not have been distinct, coexisting species, at all. Instead, they may have been part of a single, evolving lineage that eventually gave rise to modern humans.

Curiosity Confirms Mars Was Once Capable of Harboring Life

In March, NASA scientists released perhaps the most compelling evidence to date that the Red Planet was once capable of harboring life. Earlier this year, Curiosity drilled some samples out of a sedimentary rock near an old river bed in Gale Crater. This geological area used to feature a series of stream channels, leaving behind finely grained bedrock indicative of previously wet conditions. Using the rover's onboard instrumentation, NASA scientists analyzed these samples to detect some of the critical elements required for life, including sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon. The rover is currently on a trek to its primary scientific target – a three-mile-high peak at the center of Gale Crater named Mount Sharp – where it will attempt to further reinforce its findings.

Neuroscientists Turn Brains Invisible

Gaze upon the stunning effects of CLARITY, a new technique that enables scientists to turn brain matter and other tissues completely transparent. It's been hailed as one of the most important advances for neuroanatomy in decades, and it's not hard to see why.

The Death of Genomic Anonymity

Few things in this world are more personal than your DNA. For this reason, databases like the Human Genome Project have always respected the privacy of their participants. By separating individuals' identities from their donated DNA samples, researchers have upheld a standard of "genomic anonymity." Those days are now officially over. In January, researchers at MIT demonstrate that the identities of volunteers who donate personal genome sequence data can be revealed using only publicly available information. In an interview with io9, lead researcher Yaniv Erlich discussed how the team's search method works, the implications of the method's discovery, and why this could change the way we deal with genetic data.

Researchers Detect Neutrinos from Another Galaxy

By drilling a 1.5 mile hole deep into an Antarctic glacier, physicists working at the IceCube South Pole Observatory this year captured 28 neutrinos, those mysterious and extremely powerful subatomic particles that can pass straight through solid matter. And here's the real kicker: the particles likely originated from beyond our solar system – and possibly even our galaxy. "This is a landmark discovery," said Alexander Kusenko, a UCLA astroparticle physicist who was not involved in the investigation, "possibly a Nobel Prize in the making."

400,000-Year-Old DNA Muddles Humanity's Origin Story

DNA recovered from a 400,000-year-old thigh bone has complicated our view of human evolution. The oldest-known human DNA discovered to date, the genetic material preserved within the bone – which anatomists first identified as Neanderthal-like – is thought to belong not to a forerunner to Neanderthals, but that of a little-understood branch of hominins known as Denisovans. The discordant findings are leading anthropologists to reconsider the last several hundred thousand years of human evolution. "It is possible," writes Carl Zimmer, in his coverage of the discovery for the New York Times, "that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA." [Image Credit: Javier Trueba, Madrid Scientific Films]

Dawn of the Mini-Organ

SEXPAND

Lab-grown organs-in-miniature are providing scientists with new ways to study therapies and diseases as they play out in human tissues. The so called "organoids" are generated by coaxing pluripotent stem cells into a variety of specialized tissues, giving rise to "liver buds," "mini-kidneys," and itty-bitty human brains like the one pictured above, which grow no bigger than an apple seed.

A Long-lost Continent is Discovered Beneath the Indian Ocean

For ages, Mauritia has been hiding. The small, precambrian continent once resided between Madagascar and India, before splitting off and disappearing beneath the ocean waves in a multi-million-year breakup spurred by tectonic rifts and a yawning sea-floor. But now, volcanic activity has driven remnants of the long-lost continent right through to the Earth's surface.After millions of years, and some incredible geologic sleuthing, it seems Mauritia has been found, as researchers reported in Nature Geoscience back in February.

Giant "Pandoravirus" Could Redefine Life as we Know it

Scientists in July announced the discovery of a pair of viruses that defy classification. Bigger and more genetically complex than any viral genus known to science, these so-called "pandoraviruses" could reignite a longstanding debate over the classification of life itself.

NASA Discovers "A Previously Unknown Surprise Circling Earth"

NASA's recently deployed Van Allen probes — a pair of robotic spacecraft launched in August 2012 to investigate Earth's eponymous pair of radiation belts — turned out out some very unexpected findings in February, when they spotted an ephemeral third ring of radiation, previously unknown to science, surrounding our planet.

Human Cloning Becomes a Reality

A scientific milestone 17 years in the making, researchers announced in May that they had derived stem cells from cloned human embryos.The controversial technology could lead to new treatments for diseases like Parkinson's and diabetes — while bringing us one step closer to human reproductive cloning.

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