【推荐3】Over years, there’s one thing I’ve collected more than any other: books. They slowly piled up (堆积) around until I made a decision—to clear away some of them.    1     But with the possibility for an international move, it seemed unreasonable to keep ones that I wouldn’t be able to carry.

Then what was left were my favorites. Instead of taking over every corner in my home, my collection now includes two organized shelves.     2    

I have some books set in New York. They take me back to the rush of early morning rides or of summer weekends. My San Francisco collection mainly includes Armistead Maupin’s Tales of the City. I pull them off the shelf when I feel disappointed in the place I now call home, and I let them take me to a happier view of this city.    3     When I lived there, I never found myself reading books set there. But since I moved away, they’ve become my favorites.

    4     That’s what my pile of library books mainly have. I enjoy reading about places that I’d hardly want to call home, and I often try to read a novel or two ‘set in a location I’m going to. After all, the point of reading is exploration; it is a form of travel, a way to go somewhere new through written words.

The books that have earned their place on my shelf, however, are those I share a history with.     5     While you can’t always go home, a book can bring you there.

【推荐1】What does your dog do if you lie down on the floor and put your arms or legs out straight to exercise? Does your dog come to your rescue in the same way as if you fell down, or realize you mean to do that? Researchers in Germany carried out a series of experiments to see whether dogs understand if humans do things on purpose.

For their study, they had 51 dog owners drop off their pets to the laboratory. First, the dogs learned that a human experimenter would feed them treats through a gap in a glass partition (隔断). And the researchers designed two situations, which were known as “unwillingness vs. inability”. In the “unwillingness” situation, the experimenter held the food in front of the dogs but didn’t give it to them on purpose, often teasing (戏弄) them before pulling it away. For the “inability” situation, they had two conditions, one where the person seemed clumsy (笨拙的) and he appeared as if he were trying to give the treat to the dogs, but it fell down. In the other, the gap was enveloped and the pet couldn’t get the treat.

In all of these experiments, the experimenter left the treat on the floor in front of the dogs, and the dogs were easily able to get to the treat. How quickly they got back the food depended on the specific situation. The researchers predicted correctly that the dogs would wait longer to go to get the treat if they thought the experimenter didn’t want them to have it, while they went to get it quickly when the treat was meant for them. “They probably understood that -This guy is not very skilled but he wants to give the food to me.” Bräuer suggests.

Bräuer says that there could be other factors that led to the dogs’ such performance in the experiments. Although she thinks the findings are important, Bräuer says she is looking forward to what other scientists around the world will say.

【推荐2】If you ever get the impression that your dog can “tell” whether you look content or annoyed, you may be onto something. Dogs may indeed be able to distinguish between happy and angry human faces, according to a new study.

Researchers trained a group of 11 dogs to distinguish between images (图像) of the same person making either a happy or an angry face. During the training stage, each dog was shown only the upper half or the lower half of the person’s face. The researchers then tested the dogs’ ability to distinguish between human facial expressions by showing them the other half of the person’s face on images totally different from the ones used in training. The researchers found that the dogs were able to pick the angry or happy face by touching a picture of it with their noses more often than one would expect by random chance.

The study showed the animals had figured out how to apply what they learned about human faces during training to new faces in the testing stage. “We can rule out that the dogs simply distinguish between the pictures based on a simple cue, such as the sight of teeth,” said study author Corsin Muller. “Instead, our results suggest that the successful dogs realized that a smiling mouth means the same thing as smiling eyes, and the same rule applies to an angry mouth having the same meaning as angry eyes.”

“With our study, we think we can now confidently conclude that at least some dogs can distinguish human facial expressions,” Muller told Live Science.

At this point, it is not clear why dogs seem to be equipped with the ability to recognize different facial expressions in humans. “To us, the most likely explanation appears to be that the basis lies in their living with humans, which gives them a lot of exposure to human facial expressions, and this exposure has provided them with many chances to learn to distinguish between them,” Muller said.