Coffee drink is widespread. When people argue about whether coffee is good for health, they're usually thinking of the health of the coffee drinker. Is it good for your heart? Does it increase blood pressure? Does it help you concentrate? However, coffee affects the health of the human population in other ways, too.

    Traditionally, coffee bushes were planted under the shade of taller trees. However, more and more farmers in Latin America are deforesting the land to grow full sun coffees. At first, this increases production because more coffee bushes can be planted if there aren't any trees. With increased production come increased profits.

    Unfortunately, deforesting for coffee production immediately decreases the local wildlife habitat, because native birds nest and hide from predators（捕食者）in the tall trees and migrating birds rest there.

    Furthermore, in the long term, the full-sun method also damages the ecosystem because more chemical fertilizers and pesticides（杀虫剂）are needed to grow the coffee. The fertilizers and pesticides kill insects that eat coffee plant, and then the birds eat the poisoned insects and also die. The chemicals kill or sicken other animals as well, and can even enter the water that people will eventually drink.

    Fortunately, farmers in Central and South America are beginning to grow more coffee bushes in the shade. We can support these farmers by buying coffee with such labels as "shade-grown" and "bird-friendly".

    Sure, these varieties might cost a little more. But we're paying for the health of the birds, the land, ourselves, and the planet. I think it's worth it.

    How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.

    The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.

    The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. “It's kind of like having a dentist actually watch your brushing on a day-to-day basis,” says Thomas Serval, the French inventor.

    The toothbrush will also be able to talk to other applications on your phone, so developers could, for instance, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. “We try to make it smart but also  fun,” Several says.

    Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said “yes,” but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.

    The company says the Kolibree will go on sale this summer, for $99 to $199, developing on features. The U.S. is the first target market.

    Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

Holidays

    Many of us have had this experience: we lie down in a bed other than our own, perhaps at a friend's house or in a hotel room, and find it difficult or impossible to fall asleep. Is it because the bed is uncomfortable? Maybe, but perhaps there can be other reasons.

    According to a new study published in Current Biology, a significant reason is what the scientists call "first night effect". They believe that one side of the brain acts as a "night watch" to warn us about potential dangers. It forces us to stay awake on the first night in a new environments.

    For the study, 35 young volunteers were asked to sleep in a sleep lab for several days. Meanwhile, researchers watched their brain activities.

    According to the researchers, on their first night, the left brain was more active than the right brain and people had a hard time sleeping. However, left-brain activities decreased as days went by, falling even to the point of complete calm. In this process, the participants got an increasingly better sleep experience.

    The findings suggest that the different rhythms of the sides of the brain affect our sleep. When the two sides work differently, the balance between them is broken. Thus, the brain can't relax and is sensitive to anything strange in the surroundings, just as it is in the daytime.

    "At some level, the brain is continuing to analyze things, even though you are not aware of the analysis, " US professor Jerome Siegel told Smithsonian

    "If something unusual happens - if a door opens or you hear a key in a lock --you can be alert, even though the intensity of the stimulus (刺激强度) is quite low." More surprisingly, this phenomenon is similar to the way some animals sleep.

    The researchers think that it is the result of evolution (进化), and works to protect us in potentially dangerous environments.

    If you have ever had what you think is "first night effect", researchers suggest that you bring your own pillow or sleep in a room similar to your bedroom next time you sleep away from home.

    Is there a way to turn back the aging process in people? For centuries, people have been looking for a "fountain of youth." The idea is that if you find a magical fountain, and drink its water, you will not age.

    Researchers in New York did not find an actual fountain of youth, but they may have found a way to turn back the aging process. It appears that the answer may be called the hypothalamus, which is part of your brain. It controls important body activities, including growth, the way we process food and so on. Researchers found that hypothalamus neural stem cells (干细胞) also influence how fast aging takes place.

    Dongsheng Cai was the leading researcher in a study on aging in mice. He and his team reported their findings. "when the hypothalamus starts aging, particularly the loss of hypothalamus stem cells, so does the body." he said.

    Using this information, the researchers began trying to activate (激活) the hypothalamus in laboratory mice. The results show that the treatment slowed aging in the animals. "When we injected the hypothalamus stem cells to the middle-aged mice, the mice aged slowly and they could also live longer."

    But these results were just from studying mice in a laboratory. If the mice can live longer, does that mean people could have longer lives? The next step is to see if the anti-aging effects also work in human beings. If so, they say the findings could lead to new ways to help doctors identify and treat age-related health problems.

    MacDonald's will soon remove cheeseburgers and chocolate milk from its Happy Meal menu to set a good example in offering a healthy diet for kids at its restaurants.

    Customers can still ask for cheeseburgers or chocolate milk with kids' meal, but MacDonald's said that not listing them would make them less likely to be ordered. Since it removed soda from the menu four years ago, orders for it with the Happy Meal have fallen by 14%.

    As MacDonald's is known for getting more business from families with children, it is especially important for it to offer a healthy diet instead of junk food. And the Happy Meal is a key part of that. The Happy Meal has long been a target(目标) of health advocates(拥护) and parents who link it to childhood obesity(肥胖症). To get rid of its bad image, MacDonald's has made many changes on the Happy Meal over the years, including cutting the size of its fries and adding fruit.

    Recently, the company replaced its former apple juice with a new kind of juice that has less sugar. MacDonald's wants all its Happy Meal choices to have 600 calories or fewer. It also wants less than 10% of the meal calories to come from fat and added sugar. The cheeseburger and chocolate milk didn't meet those new standards. However, MacDonald's is trying to cut sugar from chocolate milk and believes it'll be back on the menu eventually.

    There will be other changes. For example, bottled water will be added as a choice to the menu, but it will cost extra. Currently, the Happy Meal menu lists milk, chocolate milk, and apple juice.

    For international restaurants, MacDonald's said that a least half of the Happy Meal choices available must meet the new standards. Some MacDonald's restaurants are adding new menu items to obey. For example, In Italy, a grilled chicken sandwich was added to the Happy Meal menu.