Human speech contains more than 2, 000 different sounds, from the common "m" and "a" to the rare clicks of some southern African languages. But why are certain sounds more common than others? A ground-breaking, five-year study shows that diet-related changes in human bite led to new speech sounds that are now found in half the world's languages.

More than 30 years ago, the scholar Charles Hockett noted that speech sounds called labiodentals, such as "f" and "v", were more common in the languages of societies that ate softer foods. Now a team of researchers led by Damián Blasi at the University of Zurich, Switzerland, has found how and why this trend arose.

They discovered that the upper and lower front teeth of ancient human adults were aligned (对齐), making it hard to produce labiodentals, which are formed by touching the lower lip to the upper teeth. Later, our jaws changed to an overbite structure(结构), making it easier to produce such sounds.

The team showed that this change in bite was connected with the development of agriculture in the Neolithic period. Food became easier to chew at this point. The jawbone didn't have to do as much work and so didn't grow to be so large.

Analyses of a language database also confirmed that there was a global change in the sound of world languages after the Neolithic age, with the use of "f" and "v" increasing remarkably during the last few thousand years. These sounds are still not found in the languages of many hunter-gatherer people today.

This research overturns the popular view that all human speech sounds were present when human beings evolved around 300, 000 years ago. "The set of speech sounds we use has not necessarily remained stable since the appearance of human beings, but rather the huge variety of speech sounds that we find today is the product of a complex interplay of things like biological change and cultural evolution," said Steven Moran, a member of the research team.

    Most damagingly, anger weakens a person's ability to think clearly and keep control over his behaviour. The angry person loses objectivity in evaluating the emotional significance of the person or situation that arouses his anger.

    Not everyone experiences anger in the same way; what angers one person may amuse another. The specific expression of anger also differs from person to person based on biological and cultural forces. In contemporary culture, physical expressions of anger are generally considered too socially harmful to be tolerated. We no longer regard duels (决斗) as an appropriate expression of anger resulting from one person's awareness of insulting behaviour on the part of another.

    Anger can be identified in the brain, where the electrical activity changes. Under most conditions EEG (脑电图) measures of electrical activity show balanced activity between the right and left prefrontal (额叶前部) areas. Behaviourally this corresponds to the general even-handed disposition (意向) that most of us possess most of the time. But when we are angry the EEG of the right and left prefrontal areas aren't balanced and, as a result of this, we're likely to react. And our behavioural response to anger is different from our response to other emotions, whether positive or negative.

    Most positive emotions are associated with approach behaviour: we move closer to people we like. Most negative emotions, in contrast, are associated with avoidance behaviour: we move away from people and things that we dislike or that make us anxious. But anger is an exception to this pattern. The angrier we are, the more likely we are to move towards the object of our anger. This corresponds to what psychologists refer to as of ensive anger: the angry person moves closer in order to influence and control the person or situation causing his anger. This approach-and-confront behaviour is accompanied by a leftward prefrontal asymmetry (不对称) of EEG activity. Interestingly, this asymmetry lessens if the angry person can experience empathy (同感) towards the individual who is bringing forth the angry response. In defensive anger, in contrast, the EEG asymmetry is directed to the right and the angry person feels helpless in the face of the anger-inspiring situation.

You can't always predict a heavy rain or remember your umbrella. But designer Mikhail Belyaev doesn't think that forgetting to check the weather forecast before heading out should result in you getting wet. That's why he created lampbrella, a lamp post with its own rain- sensing umbrella.

    The designer says he come up with the idea after watching people get wet on streets in Russia. “once, I was driving on a central Saint Petersburg street and saw the street lamps lighting up people trying to hide from the rain. I thought it would be appropriate to have a canopy (伞蓬) built into a street lamp.” he said.

    The lampbrella is a standard-looking street lamp fitted with an umbrella canopy. It has a built-in electric motor which can open or close the umbrella on demand. Sensors (传感器) then ensure that the umbrella offers pedestrians shelter whenever it starts raining.

In addition to the rain sensor, there's also a 360° motion sensor on the fiberglass street lamp which detects whether anyone is using the lampbrella. After three minutes of not being used the canopy is closed.

     According to the designer, the lampbrella would move at a relatively low speed, so as not to cause harm to the pedestrians. Besides, it would be grounded to protect from possible lighting strike. Each lampbrella would offer enough shelter for several people. Being installed (安装) at 2 meters off the ground, it would only be a danger for the tallest of pedestrians.

      While there are no plans to take lampbrella into production, Belyaev says he recently introduced his creation to one Moscow Department, and insists his creation could be installed on any street where a lot of people walk but there are no canopies to provide shelter.