【推荐2】Bees are unimaginably territorial (有地盘意识的), fighting to death to defend their home with painful stings (螫刺). But killer bees are particularly fierce. They appeared after African bees were imported to Brazil in the 1950s. By the 1980s, they had spread north to the United States, outgunning native bees along the way. Their massive attacks have killed more than 1,000 people.

Mario Palma, a biochemist at Sao Paulo State University in Rio Claro, Brazil, who studies social behavior in bees, wanted to understand the basis of this aggression. So he and his colleagues swung a black leather ball in front of some killer bees and collected the bees whose stingers got stuck in the ball during the attack. They also collected killer bees that remained in the cell. The analysis suggested that killer bee brains have two proteins that—in the aggressive bees—quickly break into pieces to form a so-called “neuropeptide (神经肽)”, they reported this week in the Journal of Proteome Research.

Palma and his colleagues already knew that bee brains have these two proteins. “We were astonished when we identified some very simple neuropeptides, which were produced in a few seconds,” Palma said. Killer bees that remained in the cell did not make these neuropeptides, he reported. And when his team put these neuropeptides into young, less aggressive bees, they “became aggressive like older individuals”.

Palma added that these neuropeptides also increase the production of   energy   and alarm chemicals. They could also encourage the nerve cells in killer bees needed to make the stinging attack. “There is a fine biochemical regulation in the killer bee brain,” he said. Researchers have found these neuropeptides in other insects, but few had associated them with “fight” behavior.

【推荐3】Walk through the Amazon rainforest today and you will find it is steamy, warm, damp and thick. But if you had been around 15,000 years ago, during the last ice age, would it have been the same? For more than 30 years, scientists have been arguing about how rainforests like the Amazon might have reacted to the cold, dry climates of the ice ages, but until now, no one has reached a satisfying answer.

Rainforests like the Amazon are important for mopping up CO₂ from the atmosphere and helping to slow global warming. Currently the trees in the Amazon take in around 500 million tons of CO₂ each year: equal to the total amount of CO₂ giving off in the UK each year. But how will the Amazon react to future climate change? If it gets drier, will it still survive and continue to draw down CO₂ ?

Scientists hope that they will be able to learn in advance how the rainforest will manage in the future by understanding how rainforests reacted to climate change in the past. Unfortunately, getting into the Amazon rainforest and collecting information are very difficult. To study past climate, scientists need to look at fossilized pollen, kept in lake mud. Going back to the last ice age means drilling deep down into lake sediments （沉淀物）which requires specialized equipment and heavy machinery. There are very few roads and paths, or places to land helicopters and aeroplanes. Rivers tend to be the easiest way to enter the forest, but this still leaves vast areas between the rivers completely unsampled（未取样）.So far, only a handful of cores have been drilled that go back to the last ice age and none of them provide enough information to prove how the Amazon rainforest reacts to climate change.

【推荐1】It’s not just adults who have a thing or two to discuss with other people, babies too have their own social lives and enjoy group interaction, according to a world-first study.

The breakthrough study conducted by psychologist Professor Ben Bradley, at Charles Sturt University, could completely transform the way child-care centres are set up. In their study, the researchers examined groups of nine-month-old babies in New South Wales and Britain.

And they came across astounding(令人吃惊的) results. It was found that infants had “social brains” and focused not just on their mothers but on social life in groups as well.

“They communicate with more than one baby at once, and show jealousy and generousness,” said Professor Bradley.

He added, “They develop their own meanings through group interaction, they notice if a group member is behaving differently and they take on roles, such as leaders and followers.”

“A baby who has a depressed mother tends to be withdrawn ( 内 向 的 ), but put that same baby in a group of its peers (同龄人) and they behave and interact like any other baby.”

It was the first all-baby group study ever to be conducted. “Most studies of babies concentrate on the infant-mother relationship, assuming that is the single foundation for mental health, but babies are constantly involved with groups of people other than their mothers, fathers, siblings, grandparents and those taking care. Therefore, the mother-baby approach needs to be combined with a group approach,” said Bradley.

Phoebe Christison, a child-care worker at Camperdown Sunshine Bubs in Sydney’s inner west, said she often noticed what appeared to be emotional attachments developed between toddlers.

She said, “Joel （     1     ） months ) and Isabella （     2     ） months ) always like to hold hands when they sit in their high chairs and eat. And babies definitely show jealousy. They push and touch each other, and copy what the other is doing.”

【推荐2】The brain has a powerful ability to remember and connect events separated in time. And now, in that new study in mice published in Neuron, scientists at Columbia’s Zuckerman Institute have cast light on how the brain can form lasting links.

The hippocampus-a small, seahorse-shaped region buried deep in the brain-is an important headquarters for learning and memory. Previous experiments in mice showed that disruption (中断) to the hippocampus leaves the animals with trouble learning to associate two events separated by tens of seconds.

“The traditional view has been that cells in the hippocampus keep up a level of continuous activity to associate such events,” said Dr. Ahmed, co-first author of the study. “Turning these cells off would thus disrupt learning.”

To test this view, the researchers imaged parts of the hippocampus of mice as the animals were exposed to two different stimuli (刺激物): a neutral (神经的) sound followed by a small but unpleasant puff of air. A fifteen-second delay separated the two events. The scientists repeated this experiment across several trials. Over time, the mice learned to associate the sound with the soon-to-follow puff of air. Using advanced microscopy, they recorded the activity of thousands of neurons (神经元) , a type of brain cell, in the animals’ hippocampus over the course of each trial for many days.

“We expected to see continuous neural activity that lasted during the fifteen-second gap, an indication of the hippocampus at work linking the auditory sound and the air puff,” said computational neuroscientist Stefano Fusi, PhD. “But when we began to analyze the data, we saw no such activity.” Instead, the neural activity recorded during the fifteen-second time gap was sparse (稀少的). Only a small number of neurons worked, and they did so seemingly at random.

To understand activity, they had to shift the way they analyzed data and use tools designed to make sense of random processes. Finally, the researchers discovered a complex pattern in the randomness: a style of mental computing that seems to be a remarkably efficient way that neurons store information.

“We were happy to see that the brain doesn’t maintain ongoing activity over all these seconds because that’s not the most efficient way to store information,” said Dr. Ahmed. “The brain seems to have a more efficient way to build this bridge.”

In addition to helping to map the circuitry involved in associative learning, these findings also provide a starting point to more deeply explore disorders, such as panic and post-traumatic stress disorder.

【推荐3】Language as a System of Symbols (符号)

Of all systems of symbols, language is the most highly developed. It has been pointed out that human beings, by agreement, can make anything stand for anything. Human beings have agreed, in the course of centuries of mutual dependency, to let the various noises that they can produce with their lungs, throats, tongues, teeth, and lips systematically stand for certain happenings in their nervous systems. We call that system of agreements language.

There is no necessary connection between the symbol and that which it stands for. Just as social positions can be symbolized by feathers worn on the head, by gold on the watch chain, or by a thousand other things according to the culture we live in, so the fact of being hungry can be symbolized by a thousand different noises according to the culture we live in.

However obvious these facts may appear at first glance, they are actually not so obvious as they seem except when we take special pains to think about the subject. Symbols and the things they stand for are independent of each other, yet we all have a way of feeling as if, and sometimes acting as if, there were necessary connections. For example, there are people who feel that foreign languages are unreasonable by nature; foreigners have such funny names for things, and why can’t they call things by their right names? This feeling exhibits itself most strongly in those English and American tourists who seem to believe that they can make the natives of any country understand English if they shout loud enough. Like the little boy who is reported to have said, “Pigs are called pigs because they are such dirty animals, ” they feel that the symbol is inherently connected in some way with the things symbolized.

【推荐3】Going to university is supposed to be a mind-broadening experience. That statement is probably made in comparison to training for work straight after school. But is it actually true? Jessika Golle of the University of Tubingen, in Germany reports in Psychological Science this week that those who have been to university indeed seem to leave with broader and more curious minds than those who have spent their immediate post-school years in vocational (职业的) training for work. However, it was not the case that university broadened minds. Rather, vocational training for work seemed to have narrowed them. The result is not quite what might be expected.

Dr. Golle came to this conclusion after she and a team of colleagues studied the early careers of 2,095 German youngsters. The team used two standardized tests to assess their volunteers’ personality traits (特点) including openness, conscientiousness (认真) and so on, and attitudes such as realistic, investigative and enterprising twice, once towards the end of each volunteer’s time at high school, and then again six years later. Of the original group, 382 had to make a choice between the academic and vocational routes, and it was on these that the researchers focused. University beckoned for 212 of them. The remaining 170 chose vocational training and a job.

When it came to the second round of tests, Dr. Golle found that the personalities of both groups had not changed significantly. As for changes in altitude, again, none were noticeable in the university group. However, those who had chosen the vocational route showed marked drops in interest in tasks that are investigative and enterprising in nature. And that might restrict their choice of careers.

The changes in attitude that the researchers recorded were more worrying. Vocational training has always been what Germany prides itself on. If Dr Golle is correct, and changes in attitude brought about by the very training are narrowing people’s choices that is indeed a matter worthy of serious consideration.