Life

Microbes

Slimming germs

In the gut, the right microbe mix can help keep off extra weight — at least in mice.

Health & Medicine

Explainer: Where and when did HIV begin?

The virus that causes AIDS may have evolved in monkeys or apes more than a century ago.

Brain

The upside of cheating

Many people assume that cheaters and thieves will secretly feel shame or guilt. A new study challenges that. It finds that people who cheat without causing anyone much harm actually enjoy a little buzz afterward.

Microbes

Mystery microbes of the sea

Biologists find archaea a true curiosity. They make up one of life’s three main branches. The two better known branches are bacteria and eukaryotes (u KARE ee oatz). That last branch includes animals, plants and fungi. But archaea have remained mysterious. Very little is known about them. In fact, their unique status wasn’t even recognized until relatively recently, in 1977.

Brain

Age-old fears perk up baby’s ears

Kids start paying attention to scary sounds when only a few months old.

Life

Building an almost-brain

Special cells can weave themselves together into blobs that, under a microscope, look a lot like the brain tissue in a developing fetus. You might think of these cellular masses as “brains-under-development.” Madeline Lancaster and Jürgen Knoblich offer a more technical name for them: “cerebral organoids.”

Brain

Learning words in the womb

Fetuses are listening. And they’ll remember what they heard. Studies had shown they can hear songs and learn sounds while in the womb. Now scientists show that fetuses can learn specific words, too. And for at least a few days after they’re born, babies can still recall commonly repeated words.

Animals

Alien carp leap onto the scene

Last summer, Alison Coulter got a big surprise as she piloted a boat along the Wabash River in Indiana. Startled by her boat’s motor, a 60-centimeter (24-inch) carp leaped out of the river. In some cases, jumping Asian carp have broken a boater’s nose, jaw or arm.

Brain

Video games: When granddad wins

With some practice, people over 60 bested untrained 20-year-olds.

Health & Medicine

Meet the new meat

Scientists made a hamburger without harming animals; but it cost as much as a house.

Animals

Mud worth more than gold

Reed Scherer and Ross Powell have studied mud from all over the world. It is different in each place. Mud from the Sulu Sea near Borneo is as smooth as cream cheese. Mud from Chesapeake Bay, in the mid-Atlantic United States, clings to your skin like peanut butter.

Brain

Putting the brakes on overeating

Restoring a chemical in the gut sends a message to mouse brains to stop overeating.