"Over the years the unthinkable hasbecome thinkable and today we sense we are close to being able to alter humanheredity œ#)." These were the words of David Baltimore of the CaliforniaInstitute of Technology, on December 1st, when he opened a three-day meeting inWashington to discuss the morality and use of human gene editing. Dr Baltimoreis an old hand at these sorts of discussions, for he was also a participant inthe Asilomar conference, in 1975, which brought scientists together to discussa safe way of using the then-new tcchnology of recombinant DNA, and whoserecommendations influenced a generation of biotechnology researchers.

Four decades on, the need for a similarsort of chin-wag has arisen. The InternationalSummit on Human Gene Editing has been held by the national scientific academiesof three countries — America, Britain and China. They are particularlyconcerned about whether gene editing should be used to make heritable changesto the human germ line, something Dr Baltimore described as a deep andtroubling question. Like those of Asilomar, the conclusions of this meetingwill not be binding. But the hope is that, again like Asilomar, a mixture ofcommon sense and peer pressure will create a world in which scientists aretrusted to regulate themselves, rather than having politicians and civilservants do it for them. The meeting is being held against a backdrop of rapidscientific advance, Since 2012 research into a new, easy-to-use editing tool calledCRISPR-Cas9 has blossomed. This technique involves a piece of RNA (a chemicalmessenger, which can be used to recognise a target section of DNA) and anenzyme (酶)called a nuclease that can snip unwanted genes out and paste new ones in.

Public interest was aroused in April,when Chinese scientists announced they had edited genes in non-viable ( 无活力的) humanembryos, and again in November when British researchers said they hadsuccessfully treated a one-year-old girl who had leukaemia ( 白血病),using gene-edited T-cells. T-cells are part of the immune system that attack,among other things, tumour cells. The researchers altered T-cells from ahealthy donor to encourage them to recognise and kill the patient's cancer, tomake them immune to her leukaemia drug, and to ensure they did not attack herhealthy cells.

In another recent development, a firmcalled Edit as Medicine, which is based in Cambridge, Massachusetts, has saidit hopes, in 2017, to start human clinical trials of CRISPR-Cas9 as a treatmentfor a rare genetic form of blindness known as Leber congenital amaurosis (伯氏先天性黑蒙).Though other companies are already testing gene-editing therapies, these employolder, clunkier forms of the technology that seem likely to have lesscommercial potential. Moreover, researchers at the Broad Institute, also inCambridge, said this week that they had made changes to CRISPR-Cas9 whichgreatly reduce the rate of editing errors — one of the main obstacles to thetechnique's medical use.

On the subject of germ-line editing,Eric Lander, the Broad's head, told the meeting it would be useful only in rarecases and said it might be a good idea to "exercise caution? before makingpermanent changes to the gene pool. The need for caution is advice that mightalso be heeded by those pursuing work in animals other than people, and inplants — subjects not being covered by the summit.

    Frigatebirds seagoing fliers with a 6-foot wingspan, can stay aloft(up in the air) for weeks at a time, a new study has found.

Since the frigatebird spends most of its life at sea, its habits outside of when it reproduces on land aren't well-known-until researchers started tracking them around the Indian Ocean. What the researchers discovered is that the bird's flying ability is unbelievable.

    Ornithologist(鸟类学家) Henri Weimerskirch put satellite tage(标签) on a couple of dozen frigatebirds. When the data started to come in, he could hardly believe how high the birds flew.

    "First, we found, 'Whoa, 1,500 meters. Excellent,' " says Weimerskirch, "And after 2,000, after 3,000, after 4,000 meters-OK, at this altitude they are in freezing conditions, especially surprising for a tropical bird."

"There is no other bird flying so high relative to the sea surface," he says. "It's the only bird that is known to intentionally enter into a cloud," Weimerskirch says. And not just any cloud—a soft, white cumulus cloud(积云). Over the ocean, these clouds tend to form in places where warm air rises from the sea surface. The birds take a ride on the current of rising air, all the way up to the top of the cloud.

    Frigatebirds have to find ways to stay aloft because they can't land on the water. Since their feathers aren't waterproof, the birds would drown in short order. They feed by harassing other birds in flight until they bring whatever fish they've swallowed back into their mouth and the frigatebird takes it.

So in between meals, frigatebirds fly higher... and higher.

    In one case, for two months-continuously aloft.

    One of the tagged birds flew 40 miles without a wing-flap. Several covered more than 300 miles a day on average, and flew continuously for weeks. They are blessed with an unusual body. No bird has a larger wing surface area compared with body weight.

    With only about 1,000 pandas left in the world, China is desperately trying to clone (克隆) the animal and save the endangered species (物种). That's a move similar to what a Texas A & M University researchers have been undertaking for the past five years in a project called "Noah's Ark".

    Noah's Ark is aimed at collecting eggs, embryos(胚胎), semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A& M's College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.

    It is estimated that as many as 2,000 species of mammals, birds reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.

    This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal.

    The entire procedure could take from three to five years to complete.

    "The nuclear transfer (核子移植) of one species to another is not easy, and the lack of available (capable of being used) panda eggs could be a major problem," Kraemer believes. "They will probably have to do several hundred transfers to result in one pregnancy (having a baby). It takes a long time and ifs difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort, adds Kraemer, who is one of the leaders of the Project at Texas A& M, the first-ever attempt at cloning a dog.

    "They are trying to do something that's never been done, and this is very similar to our work in Noah's Ark. We're both trying to save animals that face extinction. I certainly appreciate their effort and there's a lot we can learn from what they are attempting to do. It's a research that is very much needed."

    While we all try to find happiness, sometimes we still end up feeling low. While most people can control this feeling, low moods can stay with some, leading to depression. About 322 million people suffered from depression in 2015, according to a report by the World Health Organization in February. This is more than 4 percent of the world's population.

    Depression is described by the WHO as a mental disorder. It has several symptoms including sadness, loss of interest and feelings of low self-worth. In severe cases, depression may even lead to suicide.

    The number of people living with depression is increasing. The WHO reported a rise of 18.4 percent between 2005 and 2015. Young people are a group known to suffer with depression. “The pressures on today's youth are like no other generation, perhaps," Dan Chisholm, an official of WHO, told Reuters.

    In China, depression among young people is on the rise, Zhu Zhuohong, a psychology professor with the Chinese Academy of Sciences, told Xinhua News Agency. Competition to outperform others, especially in education, can cause a lot of pressure for Chinese youth.

    Almost 1.2 million Chinese people aged 15 to 24 suffer from depression, according to a report released by British science journal The Lancet in May.

    Luckily, more and more efforts are being made to deal with this problem. This year's World Health Day, held on April 7, will focus on depression. The day will highlight the “Depression: let's talk" campaign. The campaign aims to make sure that people with depression both seek and get help.

    Researchers have discovered the first Earth-sized planet. It was first marked by scientists' using NASA's Kepler telescope (望远镜), so it's called Kepler﹣186f. It lies about 500 light years from Earth and goes around its star. The planet is the right distance from its star for water: not too close or not too far. Water is one important condition that scientists guess is necessary for life. So it could have water and possible life. It's called a true Earth cousin.

    "This planet is an Earth cousin, not an Earth twin," said Barclay, who is among a team of scientists reporting on the discovery in the magazine Science this week.

    "It's very exciting to find a planet similar to the Earth," Barclay said. "It's not easy work because things change as we get more measurements."

    Scientists don't know anything about the air of Kepler-186f, but it will be a task for future telescopes which can study for chemicals that have something to do with life.

    "It's possible for life to live in this planet, but that doesn't mean there is life in it," Barclay said.

    So far, scientists have found nearly 1,800 planets in the universe.

    "The past year has seen a lot of progress in the search for Earthlike planets. Kepler﹣186f is very important because it is the first planet that is the same temperature and is almost the same size as Earth," scientist David Charbonneau wrote in an email.

The Stanford marshmallow（棉花糖）test was originally conducted by psychologist Walter Mischel in the late 1960s. Children aged four to six at a nursery school were placed in a room. A single sugary treat, selected by the child, was placed on a table. Each child was told if they waited for 15 minutes before eating the treat, they would be given a second treat. Then they were left alone in the room. Follow-up studies with the children later in life showed a connection between an ability to wait long enough to obtain a second treat and various forms of success. 

As adults we face a version of the marshmallow test every day. We're not tempted（诱惑）by sugary treats, but by our computers, phones, and tablets — all the devices that connect us to the global delivery system for various types of information that do to us what marshmallows do to preschoolers. 

We are tempted by sugary treats because our ancestors lived in a calorie-poor world, and our brains developed a response mechanism to these treats that reflected their value — a feeling of reward and satisfaction. But as we've reshaped the world around us, dramatically reducing the cost and effort involved in obtaining calories, we still have the same brains we had thousands of years ago, and this mismatch is at the heart of why so many of us struggle to resist tempting foods that we know we shouldn't eat. 

A similar process is at work in our response to information. Our formative environment as a species was information-poor, so our brains developed a mechanism that prized new information. But global connectivity has greatly changed our information environment. We are now ceaselessly bombed（轰炸）with new information. Therefore, just as we need to be more thoughtful about our caloric consumption, we also need to be more thoughtful about our information consumption, resisting the temptation of the mental "junk food" in order to manage our time most effectively.