It's official. Denmark—as well as being the world's best country to live in for women with the second-happiest people and one of the best healthcare systems in Europe—has the most contented babies. Or, at least, the ones who cry the least. According to research published in the Journal of Pediatrics, Danish, German and Japanese babies cry the least, while British, Canadian and Italian babies cry the most.

    “I'm not surprised,” Danish parenting expert and co-author of The Danish Way of Parenting Jessica Alexander tells me. “The first year of a child's life is considered so important in Denmark. Danish parents are much less stressed because they get good maternity and paternity leave (孕产假). The atmosphere is much calmer and, if mothers are getting more time off, that goes hand in hand with less stress, more contact, more routines and less crying.” She pauses before throwing in a final tip: “Oh, and Danish babies sleep outdoors a lot.”

    In Denmark, a woman is given four weeks pregnancy leave followed by 52 weeks of paid leave that can be shared between parents. And Alexander thinks there is another important reason why Danish babies cry less: breastfeeding. “It's just the done thing in Denmark,” she says of a country that has the world's highest breastfeeding rates. “In other countries, there are continual discussions about whether you should or shouldn't breastfeed. In Denmark, breastfeeding has never gone out of style. And everyone does it for a year.”

    For Iben Sandahl, Alexander's co-author, it comes down to the Danish attitude to life in general. “We are an honest and pure people,” she tells me. “We are surrounded by social support and are less likely to become angry, sad or annoyed when our babies are crying. And we are good at embracing (拥抱) all kinds of feelings, so we aren't scared. Instead, we try to connect with the babies when they cry. It's how babies communicate and it's about trying to understand it.”

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    New mercury(汞) threat to oceans from climate change

    Rising temperatures could boost mercury levels in fish by up to seven times the current rates, said Swedish researchers in an article published in Science Journal. They've discovered warming increases levels of the toxin (毒素) in sea creatures. In experiments, they found that extra rainfall drives up the amount of organic material flowing into the seas. This alters the food chain, adding another layer of complex organisms which boosts the concentrations of mercury up the line.

    Mercury is one of the world's most toxic metals, and according to the World Health Organization, is one of the top ten threats to public health. The substance at high levels has been linked to damage to the nervous system, paralysis and mental impairment in children.

    The most common form of exposure to mercury is by eating fish containing methylmercury(甲基水银), an organic form of the chemical which forms when bacteria react with mercury in water, soil or plants. Levels of mercury in the world's ecosystems have increased by between 200% and 500%, since the industrial revolution say experts, driven up by the use of fossil fuels such as coal.

    In recent years there have been concentrated efforts to limit the amount of mercury entering the environment, with an international treaty, called the Minamata Convention, signed by 136 countries in place since 2013.

Researchers hope that the Minamata treaty will be successful and countries reduce the amount of mercury that is being produced. Otherwise this discovery of a previously unknown source could have impacts for human health.

    Other researchers in the field say that the new study highlights important issues that have previously been little known.

     “This work experimentally proves that climate change will have a significant effect of methylmercury budgets in coastal waters and its accumulation in fish,” said Milena Horvat from the Jozef Stefan Institute in Slovenia.

     “This work will also help us understand the formation of mercury in fish and help reduce mercury from emission sources (primarily industrial).”

    Only two countries in the advanced world provide no guarantee for paid leave from work to care for a newborn child. Last spring one of the two, Australia, gave up the bad distinction by setting up paid family leave starting in 2011. I wasn't surprised when this didn't make the news here in the United States — we're now the only wealthy country without such a policy.

    The United States does have one explicit family policy, the Family and Medical Leave Act, passed in 1993. It entitles workers to as much as 12 weeks' unpaid leave for care of a newborn or dealing with a family medical problem. Despite the modesty of the benefit, the Chamber of Commerce and other business groups fought it bitterly, describing it as “government-run personnel management” and a “dangerous precedent (先例).” In fact, every step of the way, as (usually) Democratic leaders have tried to introduce work-family balance measures into the law, business groups have been strongly opposed.

    As Yale law professor Anne Alstott argues, justifying parental support depends on defining(定义) the family as a social good that, in some sense, society must pay for. Parents are burdened in many ways in their lives: there is “no exit” when it comes to children. Society expects — and needs — parents to provide their children with continuity of care. And society expects — and needs — parents to persist in their roles for 18 years, or longer if needed.

    While most parents do this out of love, there are public punishments for not providing care. What parents do, in other words, is of deep concern to the state, for the obvious reason that caring for children is not only morally urgent but important to the future of society. To classify parenting as a personal choice for which there is no collective responsibility is not merely to ignore the social benefits of good parenting; really, it is to steal those benefits because they accrue (累积) to the whole of society as today's children become tomorrow's citizens. In fact, by some estimates, the value of parental investments in children, investments of time and money, is equal to 20-30% of GDP. If these investments bring huge social benefits — as they clearly do — the benefits of providing more social support for the family should be that much clearer.

                                        Do dogs understand us?

    Be careful what you say around your dog. It might understand more than you think.

    A border collie named Rico recognizes the names of about 200 objects, say researchers in Germany. The dog also appears to be able to learn new words as easily as a 3-year-old child. Its word-learning skills are as good as those of a parrot or chimpanzee(黑猩猩).

    In one experiment, the researchers took all 200 items that Rico is supposed to know and divided them into 20 groups of 10 objects. Then the owner told the dog to go and fetch one of the items and bring it back. In four tests, Rico got 37 out of 40 commands right. As the dog couldn't see anyone to get clues, the scientists believe Rico must understand the meanings of certain words.

    In another experiment, the scientists took one toy that Rico had never seen before and put it in a room with seven toys whose names the dog already knew. The owner then told Rico to fetch the object, using a word the dog had never heard before.

    The correct object was chosen in seven out of l0 tests, suggesting that the dog had worked out the answer by process of elimination(排除法). A month later, Rico remembered half of the new names, which is even more impressive.

    Rico is thought to be smarter than the average dog. For one thing, Rico is a border collie, a breed (品种)known for its mental abilities. In addition, the 9-year-old dog has been trained to fetch toys by their names since the age of nine months.

    It's hard to know if all dogs understand at least some of the words we say. Even if they do, they can't talk back. Still, it wouldn't hurt to sweet-talk your dog every now and then. You might just get a big, wet kiss in return!

    Have you ever spent an afternoon in the backyard, maybe grilling or enjoying a basketball game, when suddenly you notice that everything goes quiet? There is an old phrase "calm before the storm"， often used in a situation—a quiet period just before a great activity or excitement. According to our own experience, we know there is actually calm before the storm. But what causes this calm? And is it always calm before the storm? Let's hear what scientists have to say.

    A period of calm happens in a particular kind of storm, the simplest kind of storm—a single－cell thunderstorm. In this type of thunderstorm, there is usually only one main updraft, which is warm, damp air and drawn from places near the ground. Storms need warm and damp air as fuel, so they typically draw that air in from surrounding environment. Storms can draw in the air that fit their need from all directions—even from the direction in which the storm is traveling.

    As the warm, damp air is pulled into a storm system, it leaves a low－pressure vacuum(真空) coming after. The rising air meets the cold dry air that has already existed in the storm clouds, thus the temperature of the warm, damp air drops, and the water vapour (水蒸汽) in it changes into tiny drops that are a precondition of rain. These drops accumulate and build on larger particles like dust, until they grow large enough to form raindrops.

    This warm, damp air keeps moving upwards, but it becomes cooler and drier during its trip through cloud. When it reaches the top of the cloud, the air gets spit out(被挤出) at the top. This air is sent rolling out over the big thunderclouds. From there, the air goes down. Warm and dry air is relatively stable, and once it covers a region, that air, in turn, causes the calm before a storm.

    Most thunderstorms, though, don't start with calm. That's because most are actually groups of storms with complex wind patterns. There's so much air moving up and down storm groups that the calm before the storm never happens. Instead, before the storm, it might be really windy!

    People say that text messages and e-mails lack emotion compared to phone or face-to-face conversations. But one thing seems to improve it – the emoticon(表情符).

    These little symbols – whether it's a wink(眨眼); -), a smiley : -) or a sad face : -) - always add a little something to whatever you are sending out, making it more expressive than cold words on a screen.

    To be sure, emoticons have changed the way that we communicate with each other. But there is more: a new study found that they are even changing how our brains work – we now react to emoticons in the same way as we would to real human faces, reported Live Science.

    It's actually amazing when you start to think about it: what an emoticon consists of is simply three punctuation marks(标点符号) – on their own, they carry no meaning as a pair of eyes, a nose or a mouth, but after they were first put together as symbols for faces in 1982, they began to appear more and more in our written materials.

    Owen Churches, a scientist at Flinders University in Australia, wanted to find out what people see in emoticons that make them so popular. So he showed 20 participants images of real faces, a smiley emoticon and a series of meaningless characters while their brain activities were monitored.

    Previous studies have already shown that our brains process human faces differently than they do other objects – they analyze the position of the mouth relative to the nose and the eyes to “read” for emotions. As a result, certain parts of our brain, such as the occipital-temporal cortex, are activated(激活).

    When Churches compared participants' brain activities, he was surprised to find that the brain areas that were activated when people looked at smiley emoticons were the same as when they were shown pictures of real faces.

    According to Churches, this is a good example of how culture is shaping our brains. “Emoticons are a new form of language that we're producing,” Churches told ABC Science. “Before 1982 there would be no reason that ':-)' would activate face-sensitive areas of the cortex, but now it does because we've learnt that this represents a face.”

    Next time you chat with your friends online, try to use emoticons where they are needed. It'll be almost like you're smiling or winking at them yourself.