Sound travels very well through water-much better, in fact, than it does through air. So it shouldn't be surprising that many ocean animals make noise. They use sound to communicate and hunt. As biologist Brandon Southall says, “Their whole world is related to sound.”

    Dolphins whistle, organizing hunts. Lovesick whales sing so loudly they can be heard hundreds of miles away. But these days they aren't the only ones sounding off. They have more and more competition from human machines.

    Every day, thousands of huge container ships sail across the world's oceans. On top of the engine noise, the ships' propeller (螺旋桨) make a loud noise all the time. All that can make it hard for ocean animals trying to listen out for friends, or dinner. Animals swimming nearby a ship can be deafened or even killed.

    Underwater construction can also be dangerously loud. When construction machines called pile drivers were used during repairs to the San Francisco-Oakland Bay Bridge, dead fish appeared.

    Geologist (地质学家) pound on the seafloor too, trying to find oil wells and map Earth's surface. The results are useful lo science, but all that hammering probably gives ocean animal a headache.

    As people realize how important sound is to ocean animals, they are looking for ways to reduce human noise. Ships could get quieter just by slowing down. Engineers are also trying to find quieter propeller ships.

    Now some companies are using a simple invention called a bubble curtain, which makes sound waves passing through it lose energy and gel quieter. It seems to work - when bubble curtains were fixed on the San Francisco bridge project fish deaths dropped.

    We still have a lot to learn about sound in the oceans, but together we can help keep the sea a quieter place.

    Ever order a drink, and feel cheated on the pour? Before you trouble the waiter, take a closer look at the size of your glass. “People will generally think there being less in larger containers, than in smaller ones.” Says Theresa Marteau, a behavioral scientist at the University of Cambridge, in England.

    She and her workmates had analyzed（分析）how larger amounts—and larger plates—trick us into eating more food. And they wondered: could the same be true for alcohol?

    So the researchers convinced the employees at a local bar to run an experiment: every two weeks, for four months, they'd change the bars wine glasses from the standard 300 milliliter size, to either slightly larger—370 milliliters, or slightly smaller—250 milliliters. They saw how the size of the glass affected customers' drinking habits, even though the pour, the amount of alcoholic drinks, was unchanged.

    It turned out that serving wine in smaller glasses had no measurable effect. But the large glasses increased wine sales 10 percent-even after controlling for day of the week, temperature, holidays and so on. The reason? “When the wine, the same amount, is being served in a larger glass, people are probably thinking they've got less in there.” Which, she says, means they might drink more, believing they haven't hit their nightly limit. Or, they might just feel less satisfied with the pour, and buy another round. The study appears in the journal BMC Public Health.

    Marteau says that, if later studies confirm this effect, public health officials might consider directing a certain average glass size. “Stating clearly the largest size in which wine can be sold could be a measure to reduce the overconsumption（过度消耗）of alcohol that seems to be shown by the glass size.” Until that happens, the bar in the study now always serves its wine in the larger glasses.

    Chimps will cooperate in certain ways, like gathering in war parties to protect their territory. But beyond the minimum requirements as social beings, they have little instinct to help one another. Chimps in the wild seek food for themselves. Even chimp mothers regularly decline to share food with their children, who are able from a young age to gather their own food.

In the laboratory, chimps don't naturally share food either. If a chimp is put in a cage where he can pull in one plate of food for himself or, with no great effort, a plate that also provides food for a neighbor to the next cage, he will pull at random —he just doesn't care whether his neighbor gets fed or not. Chimps are truly selfish.

    Human children, on the other hand are extremely cooperative. From the earliest ages, they decide to help others, to share information and to participate in achieving common goals. The psychologist Michael Tomasello has studied this cooperativeness in a series of experiments with very young children. He finds that if babies aged 18 months see an unrelated adult with hands full trying to open a door, almost all will immediately try to help.

    There are several reasons to believe that the urges to help, inform and share are not taught .but naturally possessed in young children. One is that these instincts appear at a very young age before most parents have started to train children to behave socially. Another is that the helping behaviors are not improved if the children are rewarded. A third reason is that social intelligence develops in children before their general cognitive (认知的) skills, at least when compared with chimps. In tests conducted by Tomasello, the children did no better than the chimps on the physical world tests, but were considerably better at understanding the social world.

    The core of what children's minds have and chimps' don't is what Tomasello calls shared intentionality. Part of this ability is that they can infer what others know or are thinking. But beyond that, even very young children want to be part of a shared purpose. They actively seek to be part of a “we”, a group that intends to work toward a shared goal.

    Their beautiful call suggests the arrival of spring, but the routes taken by cuckoos(杜鹃) during their annual migration(迁徙) have remained a mystery. Now, though, scientists from the British Trust for Omithology(BTO) have revealed the details of their remarkable 10,000-mile journey, with the help of tracking devices.

    Five male birds were caught in Norfolk last May and fitted with satellite-tagged "backpacks" before being released. The scientists then monitored their progress over 12 months as they flew to Africa in the autumn, and returned in the spring.

    The project was carried out to discover why every year fewer of the birds return to Britain. Between 1995 and 2010，the population of cuckoos spending summer here fell by almost half, and the number is continuing to decline. Previously, the lack of information about the cuckoos' long migration has hampered the understanding of how to help conserve the birds.

    Earlier this year, it was reported that cuckoos arrived in the UK much earlier than normal. Their call was recorded by ornithologists(鸟类专家) as early as February, a month ahead of their usual arrival.

    Like all migrating animals, cuckoos respond to the changing seasons. They depend on lush plants to provide the fruit and food for insects that they feed on. This reliance on seasonal patterns means that a changing climate could make an already challenging journey impossible for them.

Photographic self-portraits have existed for as long as cameras have been in human hands. But what about selfies in space? On Twitter last year, NASA astronaut Edwin Aldrin, who famously became the second man to walk on the moon in July 1969, laid claim to a spaceflight first: taking the first selfie in space during the Gemini XII mission in 1966.

"For me, it needs to be digital to be selfie," argues Jennifer Levasseur, a director at the Smithsonian National Air and Space Museum. According to Levasseur, the concept of a selfie is directly linked to internet culture. "The thing that makes a selfie is sharing it," she says.

Still, astronauts have been carrying cameras aboard space vehicles since the 1960s. In 1966, Aldrin used a Hasselblad camera designed specifically for space. Hasselblad also painted the first camera in space a matte(磨砂) black to reduce reflections in the orbiter window. But cameras used in space need to survive extreme conditions, like temperature swings from -149° to 248°F, so Hasselblad painted later model silver.

Astronauts visiting the moon then had to take out the film and leave their camera bodies behind when they returned to Earth, because early space missions were limited by a weight limit on the returned trip. Then a big change in space camera technology came after the space shuttle Columbia broke apart on its return to Earth in 2003, Levasseur notes. "Fear that they'd never be able to bring film back from space and lose all that hard work accelerated the push for digital," she says.

Today, astronauts also have access to internet and social platforms in space and can post true space selfies made using digital cameras. Similarly, space robots are participating in selfie culture, capturing remote pictures of themselves in space or on other planets and sending them back to Earth.