Mountaineers have noted that as they climb, for example, up to the 12,633­foot Humphreys Peak in Arizona, plant life changes greatly. In the Sonoran Desert, one climbs into a pine forest at 7,000 feet and a treeless tundra(冻土带) on the top of the mountain. It may seem that plants at a given altitude are associated in what can be called “communities” －groupings of species. The idea is that over time, plants that require particular climate and soil conditions come to live in the same places, and are frequently to be found together. Scientists study the history of plant life and build up a picture of how groups of plants have responded to climate changes and how ecosystems develop. But are these associations, which are real in the present, permanent?

    A great natural experiment took place on this planet between 25,000 and 10,000 years ago, when small changes in the earth's orbit caused great sheets of ice to spread from poles. These glaciers(冰川) covered much of North America and Europe to depths of up to two miles, and then, as the climate warmed, they retreated. During this retreat, they left behind newly uncovered land for living things to occupy, and as those living things moved in they laid down a record we can read now. As the ice retreated and plants started to grow near a lake, they release pollen(花粉). Some would fall into the lake, sink to the bottom and mix with the sand. By drilling into the lake bottom it is possible to read the record of the plant life around the lake. The fossil record seems clear; there is little or no evidence that entire groups of plants moved north together. Things that lived together in the past don't live together now, and things that live together now didn't live together in the past. Each individual living things moved at its own pace. The fossil record seems to be telling us that we should be thinking about preserving species by giving them room to move about－to respond to environmental changes.

    Scientists have found living organisms trapped in crystals (晶体) that could be 50,000 years old.

    The organisms were found in a hot, but beautiful cave system in Naica, Mexico. These ancient life forms can be seen only with a microscope. Penelope Boston, who leads the Astrobiology Institute at NASA, the space agency of the United States, says the ancient microbes were able to live by eating minerals such as iron.

    She spoke about the discovery recently at a meeting of the American Association for the Advancement of Science. If the findings are confirmed, they will show how microbes can survive in extreme conditions. Forty different kinds of microbes and some viruses were found in the underground area. The genetic structures of these organisms are 10 percent different from those of their nearest relatives.

    The caves in Naica are 800 kilometers deep. They were once used for mining lead. Before the miners began working in the caves, the area was separated from the surface and the outside world. Some of the caves are as big as the large religious centers built during Europe's Middle Ages. There are crystals covering the walls. The caves are so hot that scientists must wear special clothing to keep cool. The clothing keeps the crystals safe from human germs (病菌) or other damage. Boston said the researchers could only work for about 20 minutes at a time before they had to go to a room that was 38 degrees Celsius to cool down.

    NASA officials would not let Boston share her findings with scientific experts before last week's announcement. So scientists could not say much about the findings. But Norine Noonan, a biologist with the University of South Florida, said she believed them. “Why are we surprised?”Noonan asked. “ As a biologist, I would say life on Earth is extremely tough and extremely colorful.”

    Boston is also studying microbes commonly found inside caves in other countries, such as Ukraine and the United States. These microbes appear to be impossible to kill. Boston said they show how difficult life on Earth can be.

    Kumiko And The Dragon

    Author: Briony Stewart

    Price: $16.95

    Kumiko is a little girl, who likes to listen to her obasaan's stories before going to bed. But she hates sleeping alone at night. She often begs to sleep with her mother but her mother won't hew(坚持)of it. Each day, bedtime is hard for little Kumiko as she walks upstairs with heavy steps and her frightened heart beats wildly.

    Roti Rolled Away

    Author: Anti Utarid   Price: S9. 10

    It takes place in India. Asha of about nine visits her Nard(grandmother)on top of a hill Her Nani has just made hot fresh Rotis and the Roti is given to Asha to eat. However, the Rot escapes Nannis hands and begins to roll out into the great big hills.

    The Alchemist

    Author: Paulo Coeho   Price: $8.83

    This book is about a Spaniard shepherd boy. Santiago has a dream about hidden treasure at the Egyptian Pyramids.

    The Cay

    Author: Theodore Taylor    Price:UK 5.9 pounds

    Set during the Second World War. The Cay is about the adventures of Philip who set off from the island of Curacao off the Venezuelan coast, with his mother, bound for Virginia. First published in 1969, this book has won eleven literary award and has been translated into fifteen.

    In a paper published in the journey Science Advance, researchers describe how Matabele ants, a species of large ant known for attacking termite colonies (白蚁群落), will, after the battle, pick up injured fellow soldiers and carry them back to the nest where they can recover.

    The paper is the latest in a growing body of research that this form of helping behavior, previously observed in some mammals and birds, may not require complex emotion, and may, therefore, be far more widespread in nature than previously thought.

    “Here we have an example of an individual saving another individual,” says lead researcher Erik Frank who conducted the research. “We can be quite certain that the ants don't know why they are doing what they are doing.”

    It's a behavior that pays off for the colony. Our classic conception of worker ants is that they are essentially abandoned, but Mr. Frank and his colleagues calculated that the practice of rescuing nest mates results in a colony size that is a 28.7 percent larger than it would be had the ants left their fellow soldiers for dead.

    “These injured ants are able to recover from their injuries, ” says Frank. “They are essential for the safety and the betterment of the colony. ”

    When a Matabele ant is injured, as often happens during battles with termites, its body will give off two smelly chemicals that tell other ants to carry it back to the nest. Indeed, the researchers found that using these chemicals to seek help from uninjured ants will effectively activate the rescue behavior, supporting their theory that the ants were acting on pure instinct(本能), not more complex emotions.

    “The more we study rescue behavior in ants and other animals, the more we are going to realize that it's not just limited to the species we've observed so far, ” says Karen Hollis, a professor at Mount Holyoke College, mentioning studies that found that dolphins help other injured dolphins to the surface for air, capuchin monkeys defend each other during intergroup battles, and rats free other rats that are trapped.

    Now, more than ever before, people are wondering what life is all about, and what it is for. Seeking material success is beginning to trouble large numbers of people around the world. They feel that the long-hours work culture to make more money to buy more things is eating up their lives, leaving them very little time or energy for family or pastimes. Many are turning to other ways of living and downshifting is one of them.

    Six percent of workers in Britain took the decision to downshift last year. One couple who downshifted is Daniel and Liz. They used to work in central London. He was a newspaper reporter and she used to work for an international bank. They would go to work by train every day from their large house in the suburbs, leaving their two children with a nanny(保姆). Most evenings Daniel wouldn't get home until eight or nine o'clock, and nearly twice a month he would have to fly to New York for meetings

    They both earned a large amount of money but began to feel that life was passing them by.

    Nowadays, they run a farm in the mountains of Wales, I always wanted to have a farm here, says Daniel, "and we took almost a year to make the decision to downshift. It's taken some getting used to, but it's been worth it. We have to think twice now about spending money in car repairs and we no longer have any holidays. However, I think it's made us stronger as a family, and the children are a lot happier."

    Liz, however, is not quite sure. "I used to enjoy my job, even though it was hard work and long hours. I'm not really a country girl, but I suppose I'm gradually getting used to looking after the animals. One thing I do like, though, is being able to see more of my children. My advice for other people wanting to do the same is not to think about it too much or you might not do it at all."

In summer holiday, the kids are out of school, so it is a good time to plan for a family travel. However, it's not easy to prepare for a family travel. Here are four travel apps(应用程序) to make your trip more relaxing.

Yuggler

Search nearby for family-friendly activities, from free events to worthwhile attractions. Use Yuggler to plan for what to do each day, based on the weather or the type of entertainment your kids want or need, and look through reviews written by parents who've been there. So instead of paying $20 per person for entrance to the big museum, you can locate just-as-fun spots with zero admission, saving a family of $80.

Sit or Squat

Held by Charmin, this app uses your phone's built-in location finder to find out the closest public restrooms. Perhaps more importantly, Sit or Squat provides the restrooms'cleanliness scores, which are made by the users who have been there. It is quite convenient.

My Disney Experience

The official Walt Disney World app's interactive map(互动地图), which uses your tool's GPS, helps you find restaurants, restrooms, and attractions nearby. You can also access real-time wait times for popular rides and character appearances, meaning you're making the most of your time.

Wi-Fi Finder

Find free Internet near your current location in a minute. Wi-Fi Finder works offline too. Before you head out, download the offline database(数据库) to your phone, so you won't waste data while searching for a hotspot, which is key during an international trip. You'll save as much as $15 off the hotel Wi-Fi cost.