Of all nature's disasters, forest fires are often considered the most frightening. Moving at lightning speed, huge walls of flames can burn acres of land in just a few minutes. And although technology, including the use of fire-retardant chemicals, has greatly helped the fight against forest fires, they still do great damage.

    According to the National Interagency Fire Center, the fire season last year was the worst on record in terms of the number of fires and acres burned. There were 96. 385 fires and 9.873429 acres affected by fire in a year that was 125% more destructive(毁灭性的) than the10-year average. These fires cost the federal government $1.5 billion to fight, and this figure does not include the money spent by local and state governments as part of the effort.

    Fires in the southern states represented half of the national total last year with Texas, Oklahoma and Arkansas being home to a usually high amount of activity. Wildfire has also taken place in Western states such as California, Colorado and Alaska throughout the past 10 years.

    It is said that two-thirds of forest fires are started accidentally by people. Almost one quarter are purposely set, while lighting causes 10%.

    Forest fires can have advantageous effects. Charcoal(木炭) enriches soil and some plant species(种类) grow well after fire. The cones of the jack pine tree, for example, will not spread their seeds unless there is heat. Douglas fir trees grow best in open sunlight areas after fire.

    Most birds produce short, simple calls, but songbirds also have the ability of many complex vocal (发声的) patterns that help them attract mates, defend territory (领地), and strengthen their social bonds. Each songbird species has its own unique song patterns, some with characteristic regional dialects. Experienced listeners can even distinguish individual birds by their unique songs.

    A lot of what scientists know about bird song comes from studying zebra finches. A baby male zebra finch typically learns to sing from its father or other males, starting while it's still a baby bird in the nest. First comes the sensory learning stage, when the baby finch hears the songs sung around it and commits them to memory. The bird starts to vocalize during the motor learning stage, practicing until it can match the song it memorized. As the bird learns, hearing the tutor's song over and over again is helpful — up to a point. If it hears the song too many times, the imitation (模仿) becomes worse -- and the source matters. If the song is played through a loudspeaker, he can't pick it up as easily. But hide the same loudspeaker inside a toy painted to look like a zebra finch, and his learning improves.

    What if the baby never hears another zebra finch's song? Interestingly enough, it'll sing anyway. Isolated finches still produce what are called innate songs or isolate songs. A specific tune might be taught, but the instinct to sing seems to exist in a songbird's brain. Innate songs sound different from the “cultured” songs learned from other finches - at first. If isolate zebra finches start a new colony, the young birds pick up the isolate song from their fathers. But the song changes from generation to generation. And after a few generations, the melody actually starts to resemble the cultured songs sung by zebra finches in the wild.

    Scientists have been studying how people use money for long. Now they're finding some theories may apply to one group of monkeys.

    Researchers recently taught six monkeys how to use money. They gave the monkeys small metal disks(圆片) that could be used like cash and showed them some yummy apple pieces. The monkeys soon figured out that if they gave one of the disks to a scientist, they'd receive a piece of apple in return.

    If you think that is all the monkeys can figure out, you are wrong. Two researchers, Jake and Allison, acted as apple sellers in the experiments. The monkeys were tested one at a time and had 12 disks to spend in each experiment. Jake always showed the monkeys one apple piece, while Allison always showed two pieces. But that's not necessarily what they gave the monkeys. The number of apple pieces given for a disk was determined at random.

    Experiment One: Allison showed two pieces of apples but gave both pieces only half the time. The other half, she took one piece away and gave the monkey just the remaining piece. Jake, on the other hand, always gave exactly what he showed: one piece for each disk. The monkeys chose to trade more with Allison.

    Experiment Two: Allison continued to sometimes gave two pieces and sometimes one piece. But now, half the time, Jake gave the one apple piece he was showing, and half the time he added a bonus. Guess what? The monkeys chose to trade more with Jake.

    In the first experiment, the monkeys correctly figured out that if they traded with Allison, they'd end up with more treats. In the second one, when a monkey received two pieces from Jake, it seemed like again. When Allison gave the monkey only one piece instead of the two she showed, it seemed like a loss. The monkeys preferred trading with Jake because they'd rather take a chance of seeming to win than seeming to lose.

    We also sometimes make silly business decisions just to avoid the feeling that we're getting less, even when were not. Would you have made the same choices?

    The idea that you can use humor, laughter, and play to make you healthier probably seems too simple to be true. However, it is really true and simple. The sense of humor, laughter and play has an important part in keeping you healthy.

    Use "the best medicine" to treat the blues with a sense of humor, which is closely tied to laughter. Laughter is infectious. Have you ever heard a big laugh of a young child and been able to keep yourself from smiling? When laughter is shared between people, it makes them closer to each other and increases their happiness. Smiling is the beginning of laughter and a smile is also just as infectious as laughter is. You can experience something by smiling at everyone around you, and you will feel happier just by sharing a smile, even with a stranger.

    Play is an important part of making sure that we stay healthy. We are often encouraged to make sure our children play, and are told of the benefits of being out playing. However, what we often forget is that it is just as important for old people to make play be part of their life as it's for children. Physical play is important for the old and it certainly helps prevent illness. While the studies are still in the early stages, the studies that have been done have shown that physical play certainly plays a part in preventing cognitive (认知的) falling.

    Anyway, adding humor, laughter, and play to our life will influence us mentally, physically and socially and bring us many advantages. So we should make full use of humor, laughter and play to make our life more active, interesting and happier.

    Your house may have an effect on your figure. Experts say the way you design your home could play a role in whether you pack on the pounds or keep them off. You can make your environment work for you instead of against you. Here are some ways to turn your home into part of your diet plan.

    Open the curtains and turn up the lights. Dark environments are more likely to encourage overeating, for people are often less self­conscious (难为情) when they're in poorly lit places—and so more likely to eat lots of food. If your home doesn't have enough window light, get more lamps and flood the place with brightness.

    Mind the colors. Research suggests warm colors fuel our appetites. In one study, people who ate meals in a blue room consumed 33 percent less than those in a yellow or red room. Warm colors like yellow make food appear more appetizing, while cold colors make us feel less hungry. So when it's time to repaint, go blue.

    Don't forget the clock—or the radio. People who eat slowly tend to consume about 70 fewer calories (卡路里) per meal than those who rush through their meals. Begin keeping track of the time, and try to make dinner last at least 30 minutes. And while you're at it, actually sit down to eat. If you need some help slowing down, turn on relaxing music. It makes you less likely to rush through a meal.

    Downsize the dishes. Big serving bowls and plates can easily make us fat. We eat about 22 percent more when using a 12­inch plate instead of a 10­inch plate. When we choose a large spoon over a smaller one, total intake (摄入) jumps by 14 percent. And we'll pour about 30 percent more liquid into a short, wide glass than a tall, skinny glass.

    There is a very long list of rules for the New York City subway. Don't put your feet on a seat, don't carry open cups of coffee or soda, don't take more than one seat... Those are just a few of the rules. There are hundreds more.

    With so many rules, why is it still unpleasant to ride the subway?

    Some people think that the problem is that no one enforces the rules. Other passengers sometimes try to enforce rules. But you can't rely on them because New Yorkers have unwritten rules against talking to strangers and making eye contact with strangers. How can you tell someone to take her shopping bags off the seat and throw away her Coke without talking to her or looking at her? It is difficult.

    There are other New Yorkers who think that the subway is unpleasant because there are not enough rules. One rider wrote a letter to The New York Times a couple of weeks ago suggesting a few more subway rules. Here are some of the rules that she would like to see:

    —Don't lean on the poles. You prevent other people from holding on. They can fall down.

    —Talk quietly. The trains are already too noisy.

    —Give your seat to elderly passengers or to parents with small children.

    If those unwritten rules of etiquette are written down, will the rude people be more likely to follow them? It doesn't make sense to make more rules that no one will enforce.

    The real problem is that we are forgetting how to be nice to each other. It is embarrassing that we need a rule to tell us to give our seat to elderly passengers. Nobody should need to be reminded to do that.

    I say we stop talking about the rules and try to remember our manners. Let's be nice to each other not because a police officer might tell us to get off the train, but because it is the right thing to do. Then New York City would be more civilized —both above ground and below.