New research suggests that some age-related changes in our immune cells may be reversible. Every day, microscopic cells move through our bodies, searching for infections, damaged cells, and other threats. They squeeze between the cells lining blood vessels, maneuver through tightly packed tissues, and navigate a maze of fibers that hold our organs together. These immune cells are extraordinarily agile. They stretch, bend, and change shape to pass through openings narrower t

The Science Behind October's Picture-Perfect Days Every autumn, there comes a stretch of days when the world seems to have acquired a better pair of glasses. The trees stand against the sky with outlines so sharp they might have been cut from paper. Clouds seem to acquire an extra dimension, their brilliant white peaks and soft gray folds sculpted by the afternoon sun. Distant hills, which spent the summer fading politely into the background, suddenly come into focus. E

There is something almost irresistible about a fire. We pull our chairs closer, watch the flames rise and fall, and find ourselves staring into the embers long after the flames have flickered out. Scientists have found that our fascination with fire goes beyond its warmth and beauty. Watching and listening to crackling flames can lower our blood pressure. And the ancient custom of gathering around flames may have helped shape how humans share stories, exchange ideas and build

In 1432, centuries before photography existed, a Flemish artist painted the reflection of a real window inside a tiny blue gemstone. Detail from The Singing Angels panel of the Ghent Altarpiece | Jan van Eyck, 1432 The window belonged to the Vijd Chapel, where the finished work would hang. Nearly 600 years later, the illusion is still convincing. The artist was Jan van Eyck, and the jewel appears in the Ghent Altarpiece, one of the great masterpieces of European art. Think ab

“Mine.” It is one of those words toddlers discover with impressive enthusiasm. By around age two, children are beginning to understand that some things belong to them and other things belong to someone else. A toy can be mine. A cup can be yours. Remove the wrong object from the wrong two-year-old and the distinction can become very clear. What is interesting is how much follows from that simple idea. Once we think something belongs to us, we begin to treat it differently. Ps

A building goes up. A road is repaved. A delivery truck pulls away from another doorstep. Together, the things we build and buy are becoming one of the heaviest features of the planet. By 2020, the world’s buildings, roads, vehicles and other human-made objects still in use weighed an estimated 1.1 trillion metric tons, about equal to the weight of every living thing on Earth. Researchers pinpointed 2020, give or take six years, as the year the two lines crossed. The comparis

What makes you want to get up in the morning? Depending on the day, the answer might be family, absorbing work, a garden that needs tending or a morning on the water. It might also be a shaggy dog hopefully waiting for breakfast and the first walk of the day. The Japanese have a word for it: ikigai. Commonly translated as “a reason for being” or “that which makes life worth living,” ikigai can sound like a single defining purpose. In ordinary Japanese usage, the word

Before vaccines, injectable drugs and certain medical devices reach patients, they are tested for dangerous bacterial toxins. For decades, that safety check has depended on an unlikely source: the bright blue blood of the horseshoe crab. Few contributors to modern medicine look less reassuring. With its domed shell, ten legs and long, pointed tail, a horseshoe crab at the water’s edge resembles a small armored vehicle abandoned by an alien army. The tail, in particular, looks

How Much of Your Personality is Really You? Before children can talk, they are already developing reputations. One is cautious. Another is fearless. One reaches eagerly for a stranger; another treats every unfamiliar face as a possible security breach. Some toddlers recover quickly when frustrated. For others, a sandwich cut into triangles rather than squares is evidence that civilization has failed. Developmental psychologists use the word temperament to describe these e

Every fall, broad-winged hawks begin leaving the forests of New England and eastern North America. Some will travel thousands of miles to wintering grounds in Central and South America. And for much of the journey, they barely need to flap their wings. Their secret starts on the ground. The sun heats patches of earth, warming the air just above it. This movement of warm and cool air also helps create a familiar summer sea breeze. Land heats faster than water, warm air over t

The United States now owes roughly $40 trillion, which is the sort of number that makes $1 million seem like something you might find between the sofa cushions. $40,000,000,000,000. The zeros are worth displaying because otherwise the word trillion slips past all too easily. But what exactly is this $40 trillion? It is the result of decades of borrowing to cover federal deficits. Whenever Washington spends more than it collects, the Treasury borrows the difference. A bi

When was the last time something made you stop and simply take it in? Maybe it was an enormous night sky, a piece of music, a newborn baby, or learning something about the universe that was almost impossible to comprehend. We know what awe feels like. What scientists are beginning to understand is what it does to us. Research suggests that awe can shift our attention away from everyday concerns, strengthen our sense of connection to others, and change the way we perceive ours