The places in this book are all unique in their own ways.

Pig Beach. Around 15 lovely swimming pigs hang out on a lonely island in the Bahamas known as Pig Beach. In 2017, local people were sad to see that several of the pigs had died. It’s thought that they died from eating too much sand. And the local government also puts stricter rules in place to stop people from feeding the pigs. The question is how a group of pigs got to a lonely island? One guess is that a group of sailors left them there, with plans to come back and eat them later on. Nobody really knows.

Living Root Bridges. Villagers in India came up with a clever way to cross fast-flowing rivers and streams in the rainy season — living root bridges. One of the most famous root bridges is the Umshiang Double — Decker, which is actually two bridges on top of each other. It is 180 years old. Villagers helps special kinds of tree roots on the opposite sides of streams to join and make a bridge. You have to be patient when you are making a root bridge — they take 15 to 20 years to grow.

Chocolate Hills. They may look like something out of a chocolate factory, but don’t try eating anything from these hills — despite the name, they are made of mud, stone and grass! The green grass on the hills turns brown like chocolate in the summer. There are more than a thousand mounds (土堆) that range from 30—120 meters high. Locals say the mounds were made by a giant water buffalo (水牛) that stole villagers’ crops. To solve the problem, they left out bad food for the beast to eat, which made him poo (排便) out the hills! Another story says the hills are formed from the dried tears of a sad god.

With all the traditional media channels, including newspapers, magazines and television shows, shrinking (缩水), advertisers are worrying about how they can reach customers. Banner (横幅) ads for our devices are ugly and disturbing. To overcome various digital problems, the ad industry has been serving up a sneaky solution-making ads look less like ads and more like the articles, videos and posts.

This trend, called native advertising, has taken over the Internet; even the websites such as www.nytimes.com and Wall-Street.com are using it. On Facebook and Twitter, one in ten items is an ad; only the small subtitle “Sponsored (赞助的)” appearing in light grey type tells you which posts are ads.

Won’t these ads made to look like reported articles mislead people? Sometimes, yes. A study from the Interactive Advertising Bureau found that only 41 percent of general news readers could tell such ads from real news stories. And it’s getting worse. Advertisers worry that the “Sponsored” label discourages readers from clicking, so some websites are makíng the labels smaller and less noticeable. Sometimes the labels disappear entirely.

At a recent talk about the difficulty of advertising in the new, small-screen world, I heard an ad manager tell an impressive story. She had gotten a musical performance-paid for by her soft drink customer-perfectly inserted (插入) into a TV award show, without any moment of blackness before or after. “It looked just like part of the real show!” She said happily.

Look, it is great that native advertising works. But if advertisers truly believe in their material, they should have no problem labeling it as advertising.

For now native ads continue to be a fashion-with no laws governing them and no labeling standards. But that could change-the Federal Trade Commission has begun considering regulations. If the now generation of digital advertisers clean up their act according to the regulations, native ads might become more acceptable.

Unless you don’t like cookies, you’ll pick the plate with three cookies instead of two.

Being able to tell more from less is one of the most basic math talents. And it’s one that a surprising number of animals have. A robin（知更鸟）will pick the piece of wood with more mealworms. A salamander（蝾螈）will pick the box with more fruit flies.

Animals will even pick more of something when it means they get less in all. Horses, for example, will go for three tiny apples over two much larger ones.

But animals do not have math class - why would they need to count?

Being able to know the larger of two groups is useful to animals in lots of ways. It helps them pick the tree with more food, or run to the larger group of friends for protection. For example, if a shark comes, a fish in a group of 40 is less likely to become lunch than a fish in a group of 10. So if a fish makes a decision between two groups, it’s better to join the larger one.

Many animals can also do a simple form of counting, finding out how many of something there is. Even animals we don’t usually think of as smart can tell the difference between one, two, and three. Fish and honeybees can be trained to get through a maze（迷宫） by choosing turns marked by a certain number of dots（点）-to find the way out, they have to count.

Some animals, including pigeons, parrots, crows, and mice, can count much higher than three. A pigeon（鸽子）can learn to peck（啄）a piece of wood 24 times -no more, no less-to get a treat. It can even remember its place and continue counting if stopped.