The Top 11 Science and Health Stories of 2016

The global population of tigers is on the up again. Rupak De Chowdhuri/Reuters

In a year when the U.S. presidential campaign dominated the headlines (who won?), you might have missed some of the most interesting and important science and health stories. Here are a few of Newsweek's favorites.

Zika Goes Global

Ten-month-old Allan Miguel dos Santos of Cabo de Santo Agostinho, Brazil appears healthy, but his parents were informed that the child had acquired microcephaly 5 months later. Zika, the mosquito-borne illness, can cause the brain malformation microcephaly in infants born to mothers infected during pregnancy. Diego Herculano/NurPhoto via Getty

In a little over a year, the Zika virus spread to more than 50 countries and territories in Latin America, Pacific and the Caribbean—and Florida. In July, for the first time, officials identified several cases of the virus in Miami-Dade County. Scientists have confirmed the mosquito-borne illness can cause the brain malformation microcephaly in infants born to mothers infected during pregnancy. Brazil reported at least 4,000 such cases. In the U.S., delayed funding slowed efforts to develop vaccines and drugs. —Jessica Firger

Albert's Black Holes

Einstein's theory of gravitational waves was given more merit in 2016, when gravitational waves were detected for the first time through their ripples through space-time 1.3 billion years ago after two black holes collided. NASA

In February, physicists confirmed they had detected gravitational waves—100 years after Albert Einstein first predicted their existence. The source? Two massive black holes crashing together 1.3 billion years ago in a collision so strong it sent ripples through the space-time fabric—perturbations also known as gravitational waves. After the Big Bang, it's the most powerful explosion ever detected. The waves were picked up by a pair of instruments at the Laser Interferometer Gravitational-Wave Observatory, in Washington state and Louisiana. —Sandy Ong

Running Out of the Wild

The Amazon Basin's wilderness areas declined by 30 percent. Paulo Whitaker/Reuters

In the past two decades, humans have destroyed 10 percent of the world's wilderness, an area more than twice the size of Alaska. The Amazon Basin and central Africa have been particularly hard hit, with their wilderness areas declining by 30 percent and 14 percent, respectively. Although the amount of protected land has doubled since the 1990s, much more needs to be done to offset the destruction. Wilderness is vital for preserving biodiversity and limiting climate change, and it's home to many indigenous peoples. —Douglas Main

Trekking Through the Cortex

A new, detailed map of the cerebral cortex should enable neuroscientists to better understand how creativity and intelligence are reflected in the folds of the cortex. BSIP/UIG/Getty

Researchers have unveiled the most detailed map yet of the cerebral cortex, the outermost layer of the brain, responsible for language, tool use and abstract thinking. The map confirmed the boundaries of 180 regions in the brain, 97 of them new to science. The map should enable neuroscientists to better understand how creativity and intelligence are reflected in the folds of the cortex. One intriguing discovery: The size of these regions varies from one individual to another, perhaps providing insight into our individual intellects and mental health. —Paul Raeburn

Crisp Gene Edits

The first use of CRISPR-Cas9, an experimental gene-editing tool, can be used to correct misspellings in a human genome. National Human Genome Research Institute/Reuters

In November, scientists in China reported the first use of an experimental—and controversial—gene-editing tool, known as CRISPR-Cas9, to treat lung cancer. The idea is to use a patient's modified white blood cells to attack the disease. CRISPR can also be used to correct misspellings in a genome to fix mutations or to insert new genes. Many fear that its arrival marks the beginning of the age of designer babies. —Jessica Firger

Weed Backers

People gather for an election results watch party put on by supporters of Arizona Proposition 205, a legal marijuana initiative, in Phoenix, Arizona, November 8. Although voters did not approve the initiative in Arizona, many other states, including California, approved similar propositions. Nancy Wiechec/Reuters

On November 8, voters in four states chose to legalize recreational marijuana, bringing the number of states with such laws to eight (plus Washington, D.C.). Another 20 states allow medical use of marijuana. Activists were ecstatic that California approved recreational use—with its huge economy, the legal cannabis market is projected to grow to $22 billion by 2020. Marijuana's growing acceptance will make it easier to study conditions for which it could be helpful, such as epilepsy, glaucoma and cancer. —Sandy Ong

Planet Nine, Planet Nine...

This artistic rendering shows the distant view from Planet Nine back toward the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. R. Hurt/Caltech

In January, two astronomers reported new evidence of a massive, shadowy Planet Nine tracing the outer limits of the solar system. It has a mass 10 times that of the Earth, and its orbit takes it 20 times farther from the sun, on average, than Neptune. The catch? Konstantin Batygin and Mike Brown of Caltech haven't seen it—they inferred its existence from the behavior of smaller objects nearby that appear to be subject to its gravitational pull. Now the search is on. Brown predicts astronomers will find it by 2018. —Paul Raeburn

Not All Fat Is Bad

Red-meat enthusiasts weren't too pleased with two federal health agencies' endorsement of vegetables in their new dietary guidelines. Joshua Lott/Reuters

In early 2016, two federal health agencies released Dietary Guidelines for Americans 2015-2020, Eighth Edition. It turned out to be unpopular with red-meat-loving lawmakers, who claimed its endorsement of vegetables was not based on current science. The sugar lobby complained the advice sullies their image by recommending that Americans limit sugar intake to just 10 percent of daily calorie intake. But there was one pleasant surprise: The panel of experts concluded that not all fat is bad. —Jessica Firger

Pity the Drowning Rats

The Bramble Cay melomys has become the first mammal believed to go extinct entirely due to climate change impacts. Queensland Government

The Bramble Cay melomys, a small Australian rodent, was declared extinct by researchers in June. The atoll where it lived is lower than 10 feet in elevation, and rising sea levels were blamed for destroying the melomys' habitat, making it the first mammalian casualty of climate change. Its numbers dwindled to 12 in 2004. Researchers from the University of Queensland had planned an emergency captive breeding program to increase their numbers but found upon returning in 2016 that none were left. —Sandy Ong

Magic Mushrooms Help Cancer Patients

Psilocybe cubensis, or "magic mushrooms." Getty

There is an alarming dearth of new psychiatric treatments, and truly novel pharmaceuticals haven't been developed in a generation. However, research on psychedelics, such as psilocybin, the active ingredient in psychoactive or "magic" mushrooms, has the potential to change that. Two studies published December 1 in the Journal of Psychopharmacology show that 80 percent of cancer patients facing extreme distress were significantly less depressed and anxious six months after a single session in which they ingested the medication. Another 2016 study suggests psilocybin could ease treatment-resistant depression. These results haven't been demonstrated with any other class of drugs. —Douglas Main

Cat Claws Back

For the first time in a century, the global population of tigers has increased. In 1900, there were approximately 100,000 tigers throughout Asia, a number that plummeted to 3,200 by 2010. Scientists now say the trend has changed. They estimate that the population has climbed to just under 3,900. The increases have been seen in India, Russia, Nepal and Bhutan. Countries with tigers set a goal of doubling tiger populations by 2022, and research suggests there is enough habitat left to accommodate this growth, if the animals are properly protected. The increase is due in part to improved protections against poaching in some areas, although that remains an ever-present threat. —Douglas Main

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- Psilocybin greatly reduces anxiety in cancer patients
- Inside the battle to prevent a Zika epidemic in the U.S.
- Gravitational waves have been detected for the first time