Scientists have been experimenting with playing sounds to plants since at least the 1960s, during which time they have been exposed to everything from Beethoven to Michael Jackson. Over the years, evidence that this sort of thing can have an effect has been growing. One paper, published in 2018, claimed that an Asian shrub known as the telegraph plant grew substantially larger leaves when exposed to 56 days of Buddhist music—but not if it was exposed to Western pop music or silence. Another, published last year, found that marigolds and sage plants exposed to the noise of traffic from a busy motorway suffered growth difficulty.

Plants have been evolving（进化） alongside the insects that eat them for hundreds of millions of years. With that in mind, Heidi Appel, a botanist now at the University of Houston, and Reginald Cocroft, a biologist at the University of Missouri, wondered if plants might be sensitive to the sounds made by the animals with which they most often interact. They recorded the vibrations made by certain species of caterpillars（毛毛虫） as they chewed on leaves. These vibrations are not powerful enough to produce sound waves in the air. But they are able to travel across leaves and branches, and even to neighbouring plants if their leaves touch.

They then exposed tobacco plant—the plant biologist's version of the laboratory mouse—to the recorded vibrations while no caterpillars were actually present. Later, they put real caterpillars on the plants to see if exposure had led them to prepare for an insect attack. The results were striking. Leaves that had been exposed had significantly higher levels of defensive chemicals, making them much harder for the caterpillars to eat. Leaves that had not been exposed to vibrations showed no such response. Other sorts of vibration—caused by the wind, for instance, or other insects that do not eat leaves—had no effect.

"Now speakers with the right audio files are more often being used to warn crops to act when insects are detected but not yet widespread," says Dr. Cocroft. "Unlike chemical pesticides, sound waves leave no dangerous chemicals."

The new radio programme from self-help expert Glennon Doyle unexpectedly disturbed me. In a session of We Can Do Hard Things, she focuses on boundaries and their importance to our mental happiness. I heartily agree with her, because saying a polite but firm "no" is one of the basics for a happy life. I was, however, interested when she raised the idea that perhaps, as well as learning when to confirm our boundaries, we also need to stretch them. When does a boundary become a cage that locks us away?

Isn't it always the case that just as you think you've got an area of life nailed; somebody comes along to show you that that's not the case? As I listened, I started to see boundaries that might cause more problems than they were solving.

There was the work boundary that said that unless a project fell exactly into my topics, I wouldn't take it—which meant that I turned down work that was otherwise interesting and rewarding.

There was the boundary that said I wasn't to buy anything until I'd reached my savings goal—which resulted in me having to restart my laptop 20 times a day.

And then there was a boundary around relationships that set out exactly how I should be treated and what I wanted in them. Helpful to some extent, it blocked me from allowing someone to express their love for me, even if it wasn't quite what I had predicted.

Had I been doing boundaries wrong all the time? Did I need to figure them all out again? I've spent the past few weeks looking at the boundaries I've secretly put in place, and I've let myself lower some that have been my protection over the years. Then I've come to the conclusion that, when it comes to boundaries, I'm a beginner again, and that's fine. In fact, being back at the beginning is a blessing because it means there are still lessons to be learned and adventures to be had and that is something for which I can only be grateful.

The English language has many expressions that describe a fast-moving event. Some expressions relate to body movements. We say something happens in the blink of an eye or in a heartbeat. Other expressions are related to the world of nature.

For example, there is an expression related to velocity involving an animal. You might think the creature will be a big cat, such as a lion or maybe even a small but speedy animal, such as a hare（野兔）. But it is none of them. The expression today involves sheep-baby lambs to be exact.

Lambs are cute, but they are not really known for their lightning speed. Our expression is about a specific part of the animal—its tail. Lambs can shake their tails very fast. And when something happens quickly, we say it happens in "two shakes of a lamb's tail". Here is an example, "I'm going to the store. I'll be back in two shakes of a lamb's tail!" This expression is a cuter and more descriptive way of saying "quickly". Maybe instead of sending a text message with the letters BRB （be right back）, we could use the image of a lamb shaking its tail.

Being cute like a lamb may be fun, but it has its shortcomings. Cute things are often not taken seriously. And that is why Americans rarely use "two shakes of a lamb's tail" in a serious situation. For example, if a person gets hit by a car, people would say something like "Help is on the way!" Generally speaking, an emergency is not a good time to use cute animal expressions.