(Left to right): Chad Ehlers/Stock Connection/Aurora Photos; ESO/M. Kornmesser; Mark Dixon

Top stories: Earliest images of dogs, contemplating a meatless United States, and candidates for life on alien worlds

A human has been injected with gene-editing tools to cure his disabling disease. Here’s what you need to know

For the first time, researchers have infused a person’s blood with gene-editing tools, aiming to treat his severe inherited disease. The 44-year-old patient has a rare metabolic disorder called Hunter syndrome. The idea for the therapy is to turn modified liver cells into a factory for making the enzyme missing in the disease.

What would happen if all Americans went vegan?

Although animals now make up some 49% of agricultural emissions in the United States, a nation of 320 million vegans would only reduce greenhouse gas emissions from agriculture by some 28%, according to a new study. The authors claim the switch could also lead to deficiencies in key nutrients—including calcium and several vitamins.

This exoplanet could be a better candidate for life than Proxima b

Proxima b, discovered last year, may be our nearest Earth-size exoplanet, but its star, Proxima Centauri, regularly blasts the planet with deadly ultraviolet light and x-rays. Now, astronomers have found a potentially more hospitable destination, and not much farther away. The planet’s closeness makes it a prime candidate in searches for alien life, scientists say.

These mussels could be key to decontaminating New York City’s dirty waters

A team of scientists has found a possible solution for New York City’s famously dirty waterways: tens of thousands of mussels. A floating raft stocked with the marine bivalves could remove about 60 kilograms of nitrogen from the water each year, researchers suggest, and a flotilla of hundreds of rafts could make meaningful improvements to water quality in urban areas.

New California telescope aims to catch quickly moving celestial events

Astronomers have converted a decades-old telescope into a new instrument that will enable it to snap single images covering an area more than 200 times the size of the full moon. Now, the new Zwicky Transient Facility can survey the whole northern sky visible from the Palomar Observatory near San Diego, California, every night, empowering astronomers to spot anything that changes from one day to the next.

These may be the world’s first images of dogs—and they’re wearing leashes

Engravings of a hunter and his dogs carved into a sandstone cliff suggest humans mastered the art of training and controlling dogs thousands of years earlier than previously thought. The carvings, which date back more than 8000 years, according to a new study, show lines running from two animals’ necks to the hunter’s waist and are likely the earliest depictions of leashes.