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

One of the year's best celestial events is almost here. The Perseid meteor shower will peak on the nights of August 12 and 13, and this year should provide excellent viewing thanks to a thin crescent Moon that won't wash out the display. Under dark skies, observers may see up to one hundred meteors per hour, including the occasional brilliant fireball. One of those brilliant streaks may be created by a particle no larger than a grain of sand. That tiny speck may have spent bi

Something is missing from summer. Not dramatically missing. Quietly missing. The kind of absence you notice before you can name it. Fewer moths circling the porch light. A garden that seems a little too still. An evening that once hummed and now, mostly, doesn’t. If you have lived in the same place long enough, you may remember the difference: the hum, the flutter, the sense of summer as something alive and moving. Children growing up today may not. To them, this is sim

I Thought I Understood Color. I Didn't. I thought I understood why an apple is red. Like most people, I learned that white light contains all the wavelengths we perceive as different colors and that apples absorb some wavelengths while reflecting others. I understood the science up to that point. What I hadn't really grasped was how those reflected wavelengths became the experience of the color red. I first encountered this idea through a classroom prism, which spread white l

The story of your life began earlier than most people realize. Long before you were born, your mother was developing inside your grandmother's womb. As she grew, her ovaries were already forming millions of immature egg cells. One of those tiny cells would eventually become the egg that, years later, helped create you. That same egg cell remained inside your mother's ovary throughout her childhood. Years later, as part of her monthly cycle, it began the final stage of its

Goosebumps appear in some strange situations. Walking alone down a dark street can bring them on. So can the soaring chorus of a favorite song. One feels like fear. The other feels like joy. Yet both begin with exactly the same ancient reflex. When the hairs on the back of your neck seem to stand up, researchers believe the response is part of an ancient threat-detection system. For our distant ancestors, something approaching unseen from behind could mean immediate danger.

Your Brain on Flow If you've been watching the World Cup, you've seen it without knowing what to call it. The player who seems to move a half-second ahead of everyone else. The striker who scores before anyone can react. The goalkeeper who is just there. Psychologists call it flow. The rest of us call it being in the zone. A moment when the work stopped feeling like work. When the right words arrived without argument or effort. When the hands, or the voice, or the body knew

Here is something worth sitting with for a moment A study published this June found that every animal lives inside its own version of time. Not faster or slower, exactly, but differently organized. Scientists have called it a “timescape.” The fly’s timescape is finely grained, tuned by millions of years of evolution to detect the exact moment a threat is moving toward it. Every creature has one, shaped by biology, built for survival. The fly you cannot swat is not being diffi