【推荐1】The words “protect animals” appear everywhere in books and on screens, because some animals are even in danger of dying out. But sometimes the reality can be a little different from what people read or watch.

About 300 black bears were killed in Florida, the US, in October, 2015. It’s been the first bear hunt in the state since 1994. Local officers explained that the black bear population (族群) had grown to 3,500 and become a menace to local people. In the past two years, bears have hurt at least four people in Florida.

Months ago, the Swiss government allowed the locals to kill a wolf. This was because the wolf killed 38 sheep, and it was a great loss to some local farmers. Days ago in China, three old men were caught by the police for killing a sorrow (鬣羚), a kind of protected animal. They said they killed the animal because it ate the plants they grew.

However, these stories don’t always mean that animal protection stops because of human interests especially when it is related to economic (经济的) development. A man named Zhou Weisen set up a wild animal base in Guilin, Guangxi. He saved over 170 tigers and about 300 bears. His base also offered jobs to local people.

“There may never be a standard answer to the question of whether we should give more attention to the environment or human development,” said Robert May, a British expert at Oxford University. “But we shouldn’t put either one to one side, as the future is uncertain.”

【推荐2】Many animals move from one place to another at certain times of the year. This yearly movement is called migration (迁徙). They migrate to find food, a partner or warmer climate. One of the most wonderful migration in nature is that of the North American monarch butterfly (帝王蝴蝶).

Every autumn, millions of these beautiful insects with fine black and orange wings begin a long and difficult journey. Somehow they manage to travel around 4,000 kilometers south and find their way to California or Mexico. However, until recently no one knew how they did this.

A team of scientists led by Professor Eli Shlizerman at the university of Washington has now found the answer. They have found out that the monarch is able to tell the time of day. It uses its eyes to measure the position of the sun. These two pieces of information—the time of day and the point where the sun is in the sky—allow the butterfly to determine the way to go. Finally, it manages to reach the places where it will spend the winter.

The solution to the mystery of the monarch’s amazing ability comes at a time when it is in serious trouble. Its population has crashed by as much as 90 percent in the last few years. Sadly, human activity is the main reason why the number of monarch butterflies is decreasing. In many of the places where the butterfly can be spotted, people are destroying the natural environment. They cut down trees and use chemicals that kill the plants that monarch caterpillars (幼虫) feed on.

The research on the monarch’s behavior has however led to a greater awareness of this creature. People have been working together to record its migration and make sure that there are enough plants for it to eat. If this works, there may come a time when the number of monarch butterflies increases once again. The more we know about this lovely creature, the greater the chance it will survive to keep its place in the natural world for a long time to come.

【推荐3】Birds rely on their keen sense of hearing to detect prey(猎物) and identify other birds on the basis of their songs. In fact, birds have better hearing than humans, so they hear with much more detail. So how do birds hear?

Birds and humans both have an inner ear and a middle ear. However, birds differ from humans in that they lack an external ear structure. Where humans have an outer ear organ, birds have a funnel-shaped(漏斗状的) opening that functions as their outer ear, located on each side of their head. These openings are usually positioned behind and slightly below a bird’s eyes and are protected by soft feathers.

The position of a bird’s head also plays a role in its hearing abilities. Scientists have determined that noises register(显示) at different frequencies on each side of the bird’s head. Depending on the angle from which the noise originates, it registers with a certain frequency in the left eardrum(耳膜) but with a different frequency in the right eardrum. This allows the bird to locate a sound’s origin.

Let’s take a look at owls. They are known for their extremely accurate hearing, which helps them locate prey at night. This hearing ability is partly due to the unbalanced arrangement of the ear openings, with one opening being lower than the other. Sounds register in these openings at slightly different times. Owls can use this time difference, which is only 30 millionths of a second, to determine whether the sounds are coming from their left or their right. Other birds of prey have small covers in front of their ears that help them determine whether sounds are coming from above them or below them. Some owls do appear to have ears on the top of their head, but those are actually feathers controlled by small muscles under the skin that do not affect their hearing at all.

【推荐1】A pretty face is never forgotten. Do you believe so? But maybe it is untrue! Psychologists believe beautiful people are less likely to be recognized. A new study suggests that attractiveness can actually prevent the recognition of faces, unless a pretty face has particularly distinctive features, such as Angelina Jolie’s.

German psychologists think the recognition of pretty faces is distorted (扭曲) by emotions. Researchers Holger Wiese, Carolin Altmann and Stefan Schweinberger at the University of Jena, Germany, discovered in a study that photos of unattractive people were more easily remembered than pretty ones when they showed them to a group of people.

For the study, which was published in science magazine Neuropsychologia, the psychologists showed photos of faces to test subjects. Half of the faces were considered to be more attractive and the other half as less attractive, but all of them were being thought of as similarly distinctive looking. The test subjects were shown the faces for just a few seconds to memorize them and were shown them again during the test so that they could decide if they recognized them or not.

The researchers were surprised by the result. “Until now we assumed that it was generally easier to memorize faces which are being considered as attractive, just because we prefer looking at beautiful faces,” Dr. Wiese said. But the study showed that such a connection cannot be easily proven. He assumes that remembering pretty faces is distorted by emotional influences, which enhance the sense of recognition at a later time. The researchers’ idea is backed up by evidence from EEG-recordings (脑电图记录) they used during their experiment which show the brains’ electric activity.

The study also revealed that in the case of attractive faces, considerably more false positive results were detected. In other words, people thought they recognized a face without having seen it before. “We obviously tend to believe that we recognize a face just because we find it attractive.” Dr. Wiese said.

【推荐1】It took Sheperd Doeleman nearly a decade to pull off the impossible. As the director of the Event Horizon Telescope(EHT), a project involving hundreds of international researchers, he spent years flying suitcases full of hard drives around the globe to coordinate(协调) observations between radio telescopes on four continents(大洲). On April 9, 2019, the coordination at last released the fruits of their labors and the world got the first image of a black hole.

The feat-which pioneering black hole theorist James Bardeen called hopeless in 1973-represented a towering achievement of astronomical technology. “It took everyone a little by surprise that they got such a good image so fast,” says Andrew Strominger, a theoretical physicist at Harvard University.

Now Strominger and other researchers are back with a wild answer, which appeared last week in Science Advances. With a distance enough telescope, the EHT coordination could see multiple reflections(反射) of light streaming from around the black hole. By sorting through the precise pattern in these rays, astronomers could study black holes and test Einstein’s theory of gravity like never before. Basically, they hope black holes will become more like stars and planets: not just objects to think about, but to directly observe.

The team did pencil-and-paper calculations using Einstein’s theory of General Relativity and some simulations(模拟) to analyze what black holes do to light. “Black holes, they’re just kind of the best at everything they do,” Lupsasca says. “And that includes bending light rays into loops(圈、环).”