Tattoos may have staying power because of a hand off between generations of immune cells known as macrophages, say a group of French researchers. If true, this would overturn notions that tattoo ink persists in connective tissue or in long-lasting macrophages. Immunologist Sandrine Henri of the Immunology Center of Marseille-Luminy, in France, and colleagues tattooed […]

“Pop” goes the knuckle — but why? Scientists disagree over why cracking your knuckles makes noise. Now, a new mathematical explanation suggests the sound results from the partial collapse of tiny gas bubbles in the joints’ fluid. Most explanations of knuckle noise involve bubbles, which form under the low pressures induced by finger manipulations that […]

Shimmering, gelatinous comb jellies wouldn’t appear to have much to hide. But their mostly see-through bodies cloak a nervous system unlike that of any other known animal, researchers report in the April 21 Science. In the nervous systems of everything from anemones to aardvarks, electrical impulses pass between nerve cells, allowing for signals to move […]

Northern elephant seals are the true masters of the power nap. On long trips out to sea, the seals snooze less than 20 minutes at a time, researchers report in the April 21 Science. The animals average just two hours of shut-eye per day while swimming offshore for months — rivaling African elephants for the […]

MINNEAPOLIS — Bubbles of radiation billowing from the galactic center may have started as a stream of electrons and their antimatter counterparts, positrons, new observations suggest. An excess of positrons zipping past Earth suggests that the bubbles are the result of a burp from our galaxy’s supermassive black hole after a meal millions of years […]

Since early 2022, sea urchins have been mysteriously dying off across the Caribbean. Now scientists say they have identified the main culprit: a type of relatively large, single-celled marine microorganism called a scuticociliate. The discovery is a little surprising given that “ciliates are not normally seen as agents of mass mortality,” says Ian Hewson, a […]

The classical view of how the human brain controls voluntary movement might not tell the whole story. That map of the primary motor cortex — the motor homunculus — shows how this brain region is divided into sections assigned to each body part that can be controlled voluntarily (SN: 6/16/15). It puts your toes next […]

An animal bone fragment full of human-made pits hints at how prehistoric people in Western Europe may have crafted clothing. The nearly 40,000-year-old artifact probably served as a punch board for leatherwork, researchers report April 12 in Science Advances. They suggest that the bone fragment rested beneath animal hide while an artisan pricked holes in […]

Methane is a greenhouse gas with dual personalities. It heats Earth’s atmosphere 28 times as potently as carbon dioxide, gram for gram. But its absorption of the sun’s radiation high in the atmosphere also alters cloud patterns — casting a bit of shadow on its warming effect. So rather than adding even more thermal energy […]

People have different tastes. It turns out that octopuses, squid and cuttlefish do too. These soft-bodied cephalopods have proteins on suckers along their tentacles that allow them to “taste” by touching objects. But the species have evolved to detect different compounds, researchers report in two studies published in the April 13 Nature. And the differing […]