Scientists are debating how to limit their newly-discovered power to change genetic structure (结构). Scientists already modify the genes (基因) of farm animals and agricultural plants to make them more productive or stronger. But now they can also change genes in wild animals and plants. These genes would continue into later generations. For example, it may be possible for scientists to remove from existence the kind of mosquitoes, small flying insects, that carry the Zika virus. They might also be able to permanently remove species (物种) of plants and animals that are damaging to other species.

    In a report published last week, the U. S. National Academies of Sciences, Engineering and Medicine (NAS) said it supports continued research on this kind of gene control. But it warned that it is not possible to know what will happen when these changed plants and animals are released (释放) into the wild.

    Sixteen biologists, ethicists (伦理学家) and policymakers are on an NAS committee that is examining the issue. They say that there is value to the new technology. But, they say, there is not enough evidence to support the release of modified organisms (生物体) from the laboratory into nature.

    Many people would support stopping mosquitoes and rats from carrying diseases. But scientists say we must understand the possible scientific, ethical, legal and social results of such action before we decide whether to take it. Gene modification is spread through reproduction (繁殖).

    Changed genes will continue to spread as long as an animal or plant continues to reproduce. They cannot be limited to a farm or kept within a country's borders. Scientists are wondering what may happen if a modified organism mates with another species. They are not yet sure how the modified genes would affect the other species. It is possible that those genes could harm those creatures or even lead to their disappearance from our planet.

    Are you sick of going to bed late and waking up tired? Then grab your hiking boots and a tent. A new study suggests that camping in the great outdoors for a couple of days can reset your body clock and help you get more sleep.

    The body clock is an internal system that tells our bodies when it's time to go to sleep and when it's time to wake up. Scientists track this clock by measuring the amount of melatonin (褪黑激素) circulating in a person's blood at any given time.

    In a healthy sleeper, melatonin levels rise a few hours before bedtime, stay high through the night, and then settle back down when it's time to wake up.

    In our modern society, however, most of us stay up many hours past sunset and would probably sleep in many hours after sunrise if we could. And the trouble is, your melatonin levels may still be high when your alarm clock goes off in the morning, which leads to fatigue. It may also have other health consequences as well, such as diabetes (糖尿病), overweight and heart disease.

    Professor Kenneth Wright of the University of Colorado in the US wanted to see if our body clocks can be reset by a short stay in nature. His team recruited (招募) fourteen physically active volunteers in their 20s and 30s. Nine went on a weekend camping trip, while the other five stayed home. At the end of the weekend, the researchers reported that in just two days, the campers' body clocks had shifted so that their melatonin levels began to rise more than an hour earlier than they did before they left on the trip. By contrast, the body clocks of the group that stayed home shifted even later over the course of the weekend.

    “This tells us we can reset our clocks fast,” Wright said.

    Therefore, if you want to change your sleep patterns you could try to increase your exposure to natural light during the day and decrease the amount of artificial light you see at night. And if that doesn't work，there's always camping.

    You eat food and drink water, right? Skipping Rocks Lab is changing how you and your future generations will have water. Have you ever thought you could eat water? Think again, this is actually happening somewhere in the world.

    The group at Skipping Rocks Lab has made a water bottle you can eat. The product is called Ooho. Unlike plastic bottles, Oohos are neither tall nor hard. They look more like bubbles, or small, round, clear balls. They can hold liquid inside. People who drink Oohos can be surprised: the outside bursts in the mouth.

    Rodrigo Garcia Gonzalez is with Skipping Rocks Lab. He explains that the outside, or the membrane, of Ooho is made of seaweed, a plant that grows in the ocean. “It's a membrane made of seaweed that can contain water or any kind of liquid. It's made from an extract (汁) of the brown seaweed.”

    The Ooho membrane is tasteless, and you can eat it. The company says even if you throw away the membrane, it will break down in about four weeks. Gonzalez says the membrane is strong, and good for the environment.

Every year, billions of plastic water bottles are thrown away, polluting land and waterways around the world. The typical water bottle made of plastic can take hundreds of years to degrade.

    Lise Honsinger is also with Skipping Rocks Lab. “Most people just grab a bottle of water, hold it for five minutes, drink it, and throw it away. How can that then exist for 700 years? So, yeah, this is absolutely a solution to that. We are very purist: we don't want to see this packaged in plastic.”

    There are limits to the Ooho. It cannot be refilled. Each bottle is small. And Oohos do not store for more than a few days. The Skipping Rocks Lab is working on those issues. “We're still working on things like extending the shelf life, looking at different options in terms of thickness, if we want to make one that stands up more, or more flexible for marathons where people just want to eat it whole.”

    Right now, Skipping Rocks Lab can make only a few thousand Oohos a day. But it is developing new technology that could increase that number to hundreds of thousands.

    I'm Caty Weaver. Kevin Enochs wrote this story. Anne Ball adapted it for Learning English. Kelly Jean Kelly was the editor.

    Increasingly, over the past ten years, people-especially young people have become aware of the need to change their eating habits, because much of the food they eat, particularly processed food, is not good for the health. Consequently, there has been a growing interest in natural foods: foods which do not contain chemical additives and which have not been affected by chemical fertilizers（化肥）widely used in farming today.

    Natural foods, for example, are vegetables, fruit and grain which have been grown in soil that is rich in organic matter. In simple terms, this means that the soil has been nourished by unused vegetable matter, which provides it with essential vitamins and minerals. This in itself is a natural process compared with the use of chemicals and fertilizers, the main purpose of which is to increase the amount but not the quality of foods grown in commercial farming areas.

    Natural foods also include animals which have been allowed to feed and move freely in healthy pastures（生活状况）. Compare this with what happens in the mass production of poultry（家禽）: there are battery farms, for example, where thousands of chickens live crowded together in one building and are fed on food which is little than rubbish. Chickens kept in this way are not only tasteless as food; they also produce eggs which lack important vitamins.

    There are other aspects of healthy eating which are now receiving increasing attention from experts in diet. Take, for example, the question of sugar. This is actually a nonessential food! It is not that sugar is harmful in itself. But it does seem to be additive: the quantity we use has grown steadily and in Britain today each person consumes an average of 200 pounds a year! Yet all it does is provide us with energy, in the form of calories. There are no vitamins in it, no minerals and no fibre.

    Road trip

    Motorhome delivery offers great family holidays. For just $1 a day, you can hire a fully﹣equipped motorhome, which you deliver to a specific destination within some days and kilometers. You then hire another one to get home or take a bus or train. Your only other expense will be fuel and about﹩20 a day for parking fees. To learn more, visit apollocamper.com.

    Plan ahead

    For a comfortable break, flexibility with times, dates and places helps lower the cost. Find a few hotels you like, ask about their vacant rooms, then wait a few weeks and call again. If they still have rooms, you're at an advantage to ask for a better price. Lots of last﹣minute deals are online. Watif （watif.com.au） has deals on hotels that have dropped their prices so slow. You don't know where you're staying until it's booked, but anywhere with four or five stars has to be fairly good.

    Back to nature

    Wild camping appeals to nature lovers and costs nothing. This is forbidden on beaches and parks in most urban areas, but you can turn up in more distant area as long as nobody owns the land. You'll need to take everything with you and may need to shop on eBuy （ebuy.com.au）.If you're a camping beginner, be aware of safety measures and get your questions answered on the Internet.

    Swap meet

    How about a home swap？For a $250 yearly joining cost, you can stay in someone's home in an international place of your choice while they or someone else stays in yours. Find out more at familylink.com.au.

    Finding fruits and vegetables at your typical grocery store that have been grown without the extensive use of pesticides can be difficult. Fortunately, The Environmental Working Group(EWG) has done all of the work for you in finding healthy and pesticide－free produce.

    EWG has created the 2018 Shopper's Guide to Pesticides in Produce, which helps shoppers to find uncontaminated produce. Many consumers do not realize that pesticide residues(残留) are very common on conventionally grown produce products, even after they have been washed or peeled. Because of this, EWG has created their series of guides to lead consumers to safer food choices.

    In order to create these guides, EWG analyzed the USDA pesticides tests, which found a total of 230 different pesticides and pesticides breakdown products on thousands of produce samples. Analyzing this information, EWG observed the big differences of the amount of pesticides found from product to product.

    The guide's two main components are two compiled lists highlighting the cleanest and dirtiest produce concerning pesticides. These two lists, Dirty Dozen and Clean Fifteen, show consumers how certain foods continue to carry trace amounts of pesticides with them all the way to the grocery store shelves, while others make it to your kitchen virtually pesticide－free.

    Some of the highlights from their analyses included the following findings：

    More than one－third of strawberry samples analyzed in 2016 contained 10 or more pesticide residues and breakdown products.

    Spinach(菠菜) samples had, on average, almost twice as much pesticide residue by weight compared to any other crop.

    No single fruit sample from the Clean Fifteen tested positive for more than four pesticides.

    “With EWG's guide, consumers can fill their fridges and fruit bowls with plenty of healthy conventional and organic produce that isn't contaminated with multiple pesticide residue," said Sonya Lunder, a senior analyst in EWG.

    Only 25 years ago, the National Academy of Sciences raised concerns about exposure to poisonous pesticides in our food, yet consumers still consume a mixture of pesticides every day in America.