The World Meat Free Day for 2017 falls on 12, June, but what would actually happen if the whole world suddenly went vegetarian(素食的) permanently?

     If vegetarianism were accepted by everyone by 2050, the world would have about seven million fewer deaths every year. No meat would lower the chances of some diseases or even some cancers and so save the world 2-3% global GDP in medical bills. Food-related emissions would drop by around 60%. This would be due to getting rid of red meat which come from methane (甲烷) producing livestock (家畜) — from people's diets. Turning former pastures (牧场) into native habitats and forests would slow climate change and bring back lost biodiversity, including some animals which were previously pushed out or killed in order to keep cattle.

    However, farmers in the developing world could really suffer. Arid and semi-arid lands can only be used to raise animals as there's no or little water in these places, such as the Sahel land strip in Africa next to the Sahara; nomadic (游牧的) groups that keep livestock there would be forced to settle permanently and lose their cultural identities if there were no more meat. Losing meat also means that we also lose traditions. There's no more Christmas turkey. We would need to replace meat with nutritional substitutes, in particular for the world's estimated two billion-plus unhealthy or weak people for lack of nutrients. Animal products contain more nutrients per calorie than staples like grains and rice.

    Everybody currently engaged in the livestock industry would need to be retrained for a new career. This could be in agriculture, reforestation or producing bioenergy. Failing to provide career alternatives could lead to mass unemployment and social problems, particularly in traditionally rural communities.

    Billionaire Bill Gates has offered the many thousands of graduates some career and life advice. Over a series of 14 tweets in his Tweeter posted last Monday, the world's richest man used the words “impact”, “happiness” and “progress”. He did not mention money. Instead, he told the graduates what jobs he would be looking for if he started out today.

“AI (artificial intelligence), energy and bio-sciences are promising fields where you can make a huge influence”, he wrote. Earlier this year, Gates—who famously dropped out of Harvard to found Microsoft—said that artificial intelligence had “ phenomenal” potential, and “anything connected with that would be an exciting lifetime career.” In the same speech at Columbia University, he said there is a huge growing demand in the energy field to develop reliable, cheap and clean energy.

    As well as urging new graduates to surround themselves with people who challenge you, teach you, and push you to be your best self, Gates reminded them to think of others, especially the less fortunate.

    He wrote that it had taken him decades to learn about the world's worst unfairness and described this lack of early understanding as his one big regret. “You know more than I did when I was your age,” he wrote, “ You can start fighting unfairness, whether down the street or around the world sooner.”

    He finished by asking graduates to consider the progress human has already made, saying that he believe the world is getting better. “ That matters because if you think the world is getting better, you want to spread the progress to more people and places.”

    The health of millions could be at risk because supplies of medicinal plants are being used up. These plants are used to make traditional medicine, including drugs to fight cancer. “The loss of medicinal plants is a quiet disaster,” says Sara Oldfield, secretary general of the NGO Botanic Gardens Conservation International.

    Most people worldwide rely on herbal (药草制的) medicines which are got mostly from wild plants. But some 15,000 of the 50,000 medicinal species are under threat of dying out, according to report from the international conservation group Plantlife. Shortages have been reported in China, India, Kenya, Nepal, Tanzania and Uganda.

    Over-harvesting does the most harm, though pollution and competition from invasive species (入侵物种) and habitat destruction all contribute. Businessmen generally harvest medicinal plants, not caring about sustainability (可持续性),” the Plantlife report says, “damage is serious partly because they have no idea about it. but it is mainly because such collection is unorganized” Medicinal trees at risk include the Himalayan yew (紫衫) and the African cherry, which are used to treat some cancers.

    The solution, says the report's author, Alan Hamilton, is to encourage local people to protect these plants. Ten projects studied by Plantlife in India, Pakistan, China, Nepal, Uganda and Kenya showed this method can succeed. In Uganda, the project has kept a sustainable supply of low-cost cancer treatments, and in China a public-run medicinal plant project has been created for the first time.”

    “Improving health, earning an income and keeping cultural traditions are important in encouraging people to protect medicinal plants,” says Hamilton, “You have to pay attention to what people are interested in.”

    Ghillean Prance, the former director of the Royal Botanic Gardens at Kew in London, agrees that medicinal plants are in need of protection. “Not nearly enough is being done,” he told New Scientist. “We are destroying the very plants that are of most use to us.”

    It's hard to talk to Dad sometimes. His silence about his feelings and thoughts made him mysterious and hard to see through. You could never break his hard shell and get to know him. And he seemed to want to stay that way too.

    But a year ago when my relationship with my wife and career took a hit, I needed my dad to pull back the curtain so I could see him as real and accessible. I was facing serious problems, and I wanted to know whether he had faced them before and how he had found his way, because I felt like I had lost mine. In desperation, it occurred to me that sending an email might be the key, so I wrote him one, telling him about my regrets and fears, and I asked him to answer, if he felt like it.

    Two weeks later, it showed up in my inbox: a much thought, three page letter. Dad, a 68­year­old retired technologist and grandfather of four, had carefully considered my message, and crafted a response. He mentioned his lost love, the foolish mistake he made in career and the stupid pride he had between him and his parents. He comforted me that “life will still find its right track despite many of its twists and turns”.

    I closed the email and started to cry, because I wished I had opened it up earlier but was grateful it wasn't too late. I cried because at first, in the midst of my own struggles, his letter instantly put me at ease. And I cried because in the end, it was so simple: I just had to hit “Send”.

    We've since had many email exchanges. This increasing communication opened a door into his world. My problems haven't been magically solved, but getting to know my dad better has made the tough stuff more manageable and life sweeter. It's hard to talk to Dad sometimes, but I'm glad I found a way to talk to mine.

    A lifetime of active exercise will let you keep the body of a 20-year-old well into your 70s, scientists have found.

    The physical decline (衰退) thought to be an unavoidable part of ageing is actually the result of not exercising enough, according to the research, which found that regular cyclists kept the muscles, lungs, and even the immune system (免疫系统) of people years younger. Besides, many serious health problems could be prevented if people became more active, researchers insist.

    Janet Lord, a leading researcher, said, “Our findings prove the false belief that ageing automatically makes us weaker. We now have strong evidence that encouraging people to do regular exercise throughout their lives can solve the problem that we are living longer but not healthier.”

    She looked at 125 cyclists aged 55 to 79 who had been exercising regularly for 25 years and compared them with 75 ordinary people of a similar age and 55 people aged 20 to 36. On a series of physical measures, the cyclists showed no difference from people much younger in their immune systems and making T cells.

    Now Professor Lord aims to discover how much exercise people need to do to stay young. “You needn't work out a lot. It may be intensity (强度) that helps—like going up and down the stairs ten times a day.”

    While there is no magic method of staying mentally and physically fit in later life, the benefits of keeping active can never be ignored, whatever your age or state of health.

    Shop with Your Doc is part of a broader and still growing movement in US medicine to shift the focus away from simply treating disease toward caring for the whole person. It is meant to help people make educated, healthy choices one grocery cart at a time. Across the country, hospitals are setting up food banks and medical schools are putting cooking classes on the curriculum. Nonprofits are connecting medical centers with community resources to ensure that low-income Americans have access to fresh fruits and vegetables.

    For centuries, Western medicine's mission was to cure disease. But over the past generation, two generation, two significant trends are of concern to the medical community, says Timothy Harlan, executive director of Goldring Center for Culinary Medicine at Tulane University in New Orleans. Healthcare costs began to soar (激增), and relatively inexpensive, poor-quality food became more common. "There's a very straightforward link between people improving their diets and improving the condition that they have," Dr. Harlan says.

    The connection drove the medical and nonprofit communities to rethink their approach to health. What emerged was the concept of the "social determinants of health"—the notion of taking into account the biological, physical, and socioeconomic circumstances surrounding a patient. A healthy person isn't just someone who is free from disease, the theory goes; he or she also enjoys "a state of complete mental, physical and social well-being."

    The question the medical community now faces is how to get patients—especially low-income families—to recognize these determinants and make it possible for them to eat and live healthier. In Boston, medical experts responded by creating an on-site pantry (食品室) at Boston Medical Center. Since its founding in 2002, the pantry has evolved into a kind of nutrition center where primary care providers at BMC send patients for food. Today the pantry, which gets 95 percent of its stock from the Greater Boston Food bank, hosts free cooking classes and serves about 7,000 people a month. The Greater Boston Food Bank has also launched its own initiatives, striking partnerships with four community health centers across the state to offer free mobile produce markets. The organization also helped develop toolkits (软件包) that map local pantries, markets that accept government food vouchers, and other resources.

    At Tulane in New Orleans, Harlan is leading the development of a curriculum that combines medicine with the art of food preparation. His philosophy: Doctors who know their way around a kitchen are better at helping their patients. And empowering patients to take charge of their own diets is one way to help them deal with the incredible costs of health care, Harlan says. The curriculum has since been adopted at 35 medical schools around the United States. Chipping away at bad habits is a good place to start getting patients to think about the choices they make for themselves and their families, say Dr Maureen Villasenor, the Orange County pediatrician (儿科医生).