Ever wonder how much a cloud weighs? What about a hurricane? A meteorologist（气象学家） has done some estimates and the results might surprise you.

    Let's start with a very simple white puffy cloud—a cumulus cloud(积云). How much does the water in a cumulus cloud weigh? Peggy LeMone, senior scientist at the National Center for Atmospheric Research in Boulder, Colorado, did the numbers. “The water in the little cloud weighs about 550 tons,” she calculates. “Or if you want to convert it to something that might be a little more meaningful...think of elephants.” Assume（假设） an elephant weighs about six tons, she says, that would mean the water inside a typical cumulus cloud would weigh about one hundred elephants.

    The thought of a hundred elephants' worth of water floating in the sky begs another question—what keeps it up there?

    “First of all, the water isn't in elephant-sized particles(微粒); it's in tiny tiny tiny particles,” explains LeMone. And those particles float on the warmer air that's rising below. But still, the concept of so much water floating in the sky was surprising even to a meteorologist like LeMone. “I had no idea how much a cloud would weigh, actually, when I started the calculations（计算）,” she says.

    So how many elephant units of water are inside a big storm cloud—10 times bigger all the way around than the “puffy” cumulus cloud? Again, LeMone did the numbers: About 200,000 elephants.

    Now, come to the calculations for a hurricane about the size of Missouri and the figures get really massive. “What we're doing is weighing the water in one cubic meter theoretically pulled from a cloud and then multiplying by the number of meters in a whole hurricane,” she explains.

    The result? Forty million elephants. That means the water in one hurricane weighs more than all the elephants on the planet. Perhaps even more than all the elephants that have ever lived on the planet.

    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.”

    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?

    Believe it or not, the size of the human brain has become smaller over the past 20,000 years. Scientists argue over whether this means we are becoming more or less intelligent as a species.

    “I'd call that a major downsizing in an evolutionary eye blink (眨眼),” John Hawks told Discover magazine.

    Why is the brain becoming smaller?

    There are different theories to explain it. One is that tens of thousands of years ago, before the decline began, to survive in cold and dangerous conditions, humans needed a stronger and larger body and therefore, a larger head. Also they had to chew the tough meat of rabbits, foxes and horses. As conditions improved, the brain stopped growing, according to supporters of this theory.

    Another theory comes from a recent study by David Geary and Drew Bailey. They found that brain size decreased as population density(密度) increased.

    “As complex societies appeared, the brain became smaller because people did not have to be as smart to stay alive.” Geary told AFP.

    But smaller brain size does not necessarily mean that modern humans are less smart than their ancestors. “Modern humans simply developed different, more complex forms of intelligence,” said Brian Hare.

    Hare's studies focus on two types of great apes: chimpanzees and bonobos. Both are much like humans, but are physically quite different from one another. The bonobo has a smaller brain than the chimpanzee, and is also much less aggressive and more tolerant.

    “When it comes to working out a problem,” Hare said, “chimpanzees are much less likely to accomplish it if it involves working together. Not so with bonobos.”

The smaller brain in modern humans may be evidence that we can cooperate,” Hare told the US National Public Radio.

    Facebook says it is working on technology to allow us to control computers directly with our brains. It is developing "silent speech "software to allow people to type at a rate of 100 words per minute, it says. The project, in its early stages, will require new technology to detect brainwaves without needing invasive operation. "We are not talking about monitoring your random thoughts," assured Facebook's Regina Dugan. "You have many thoughts, and you choose to share some of them. We're talking about monitoring those words. A silent speech interface（界面）-one with all the speed and flexibility（灵活）of voice. "

    Ms Dugan is the company's head of Building 8, the firm's hardware research lab. The company said it intends to build both the hardware and software to achieve its goal, and has employed a team of more than 60 scientists and academics to work on the project.

    On his Facebook page, Mark Zuckerberg added, "Our brains produce enough data to stream four HD（高清）movies every second. The problem is that the best way we have to get information out into the world-speech-can only send about the same amount of data as a 1980s modem. We're working on a system that will let you type straight from your brain about five times faster than you can type on your phone today. Finally, we want to turn it into a wearable technology that can be produced in quantity. "

    Technology is going to have to get a lot more advanced before we can share a pure thought or feeling. but this is a first step. Other ideas detailed at the company's developers conference in San Jose included work to allow people to "hear" through skin. The system, comparable to Braille, uses pressure points on the skin to pass information. "One day, not so far away, it may be possible for me to think in Chinese, and you to feel it instantly in Spanish,"Ms Dugan said.

Throughout our daily lives, we have known plenty of people and will know more. But how can we tell if someone is worth our trust? In a paper published recently in the Journal of Personality and Social Psychology, researcher gave us the answer.

The researchers asked 401 adults from the United States to fill out a questionnaire measuring their guilt-proneness (内疚倾向) in different situations as well as several other qualities, and then play a short online game. In this game, Player 1 is given 1, which they can choose to give to Player 2. Any money given to Player 2 is then automatically increased to 2.50. Player 2 can then decide whether to keep all of the money or behave in a trustworthy way by returning a part of the money to Player 1. The researchers found more guilt-prone people were more likely to share the money with Player 1. Actually, in follow-up studies, guilt-proneness predicted trustworthiness better than other personality qualities the researchers measured.

Why might guilt lead to trustworthy behavior? The researchers found people who were guilt-prone also reported feeling a must to act in ethical (合乎道德的) and responsible ways while interacting (互动) with their partners in the game. People who are guilt-prone tend to avoid engaging in behavior that might harm or disappoint others. If they do something bad, guilt encourages them to try to make things right again.

Then, how can we use this research to ascertain whether someone is trustworthy? "One way to do this might be observe how they respond to experience regret," lead author Emma Levine, assistant professor at the University of Chicago Levine, explains. Another way is to ask them to describe a difficult dilemma they faced in the past, suggests co-author Taya Cohen, associate professor at Carnegie Mellon University. This is particularly effective, Cohen and her colleagues have found, because it allows us to see if they're concerted about the effects their actions have on others.