The fairy tales and stories we love often begin with someone asking questions. Sleeping Beauty has a princess exploring a castle just to see what’s inside. Jack climbs his beanstalk because he wants to know what’s at the top. All these happen because of curiosity.

Curiosity may be the driving force of all science and experiments, encouraging us to explore the highest mountains and deepest oceans. But it’s also our biggest downfall. It’s the voice that says “push the button”, and it’s what burnt Icarus’ waxen wings.

When it comes to curiosity, we are not born equal. Some people can’t help but question, or examine something, while others are quite happy with what they have and what they see. So why isn’t curiosity distributed evenly among people?

Our brain rewards us for good behavior. When we satisfy our desire, our brain says to us, “Yes, well done on looking after the body—have some endorphins(内啡肽).”The seeking system is the thing that encourages us to explore and go beyond our comfort zone. It has various reward systems set up for the satisfaction of our goal. Without the seeking system, we’d just sit still and satisfy ourselves with whatever we have.

For the curiosity differences between men and women, research suggests that men are more likely to do risky behavior, from going on financial investments to swimming in the sea. Perhaps it is because of some kind of “hunter-gatherer” society behavior, where men are regarded as needing to be more risk-seeking and curious to help feed, protect, and care for “the whole group”.

And children are born with great curiosity. The success that teenagers will have in satisfying their curiosity, or how far they are allowed to devote themselves to it, will determine how efficient those curiosity pathways are in later life. If children are given new environments to explore, the room to play and experiment, and the freedom to ask questions and examine them, then they will do so more later in life as well.

A smile is the key to a thousand doors, but deploying it in every situation without mastery of its use is dangerous, says a new social science study.

Scientists say it takes a great many muscles to smile; scientists at Queen’s University Belfast in a recent study found that subtle differences in the way in which a person smiled had not-so-subtle impacts on the opinions which the test participants had about the smiler. “Smiling at another person does not always lead to trust and cooperation,” said Dr. Stephanie Carpenter from the University of Michigan, a co-author of the study. “Subtle differences in a smile can definitely have a real impact on whether people trust each other and choose to cooperate. In fact, the way you smile in a good or bad situation can impact whether people trust you.

“Think about movie villains, for example in James Bond films,” said Dr. Magdalena Rychlowska from Queen’s University, who led the research published in Cognition and Emotion journal. “They often make happy smiles when something bad has happened or is about to happen. This context makes these otherwise happy and normal smiles feel threatening and unpleasant.” She adds, “The findings of this study show the power of subtle facial expressions and the positive consequences that an affiliation smile can have in difficult situations. It also highlights the importance of social context — a happy smile that could be read as a signal of trustworthiness in one setting can, but in another setting, it can be seen as the evidence of bad intentions.”

Mastery of the smile then, can be an excellent way of getting out of difficult social situations, while the lack thereof can be an excellent way of getting into one.

The peak of Mount Everest is the highest point in the world, which extends 29,029 feet (8,840 meters) above sea level. On Earth, mountains can’t grow much higher than Mount Everest. So what stops our planet’s mountains from growing forever?

“There are two major reasons for that,” said Nadine McQuarrie, a professor in the department of geology at the University of Pittsburgh.

The first reason is gravity. Many mountains form because of movements in Earth’s surface layer known as plate tectonics (板块构造论). This theory describes the Earth’s crust (壳) as mobile and dynamic, divided into large pieces that move around with time. When two plates crash, the impact forces materials on their touching edges to move upward. This is how the Himalayas mountain range, which includes Mount Everest, formed.

“The plates keep pushing together and the mountain keeps growing, until it becomes too hard to do that work against gravity,” McQuarrie told Live Science. At some point the mountain becomes too heavy, and its own weight stops the upward growth caused by the crash of those two plates.

But mountains can also form in other ways. Volcanic mountains, like those on the Hawaiian Islands, for example, form from boiling rock that erupts through the planet’s crust and begins piling up. “But no matter how mountains are formed, they eventually become too heavy and succumb to gravity,” McQuarrie said.

In other words, if Earth had less gravity, its mountains would grow higher. That is indeed what happened on Mars. Mars’ Olympus Mons, the tallest known volcano in the solar system, extends 82,020 feet (25,000 meters) high, nearly three times taller than Mount Everest.

The second reason relates to rivers. At first, rivers make mountains appear taller — they carve into the edge of the mountains and create deep cracks near a mountain’s base. But as rivers gradually destroy materials, their channels may become too steep. This can cause landslides (滑坡) that carry materials away from the mountain and limit its growth.