【推荐1】Bird eggs come in a variety of colors, but new research shows that diversity follows a simple pattern — the colder the climate, the darker the egg. Darker eggs take in more heat than lighter ones. This could help developing chicks stay warm while their parents look for food. That's the conclusion of the study．

Biologists have long tried to understand why birds' eggs come in so many shapes and colors. There could be many reasons. The color may help make eggs less likely to be discovered by their natural enemies. The egg shape or color might also somehow protect eggs against bacteria or signal their quality. The shape or color might even help keep an egg warm. “Scientists have discovered some evidence to support all of these assumptions(假设),” says Phillip Wisocki, who worked on the research．

Wisocki and his colleagues turned to collections of birds' eggs in museums. They compiled (汇编) data from 634 species. These represented all but four of the 40 living orders of birds. Then they plotted the data on a global map. The brightness and color of eggshells were closely related to a region's temperature, they showed. That was true even after considering that closely related species can have similarly colored eggs. Birds in the far north — which tends to be colder — had darker, browner eggs. Eggs became lighter and slightly bluer for birds closer to the equator. Egg colors, however, tended to be more varied in the tropics．

Darker eggs may be an adaptation to the cold, the research now suggests. Like a dark car parked in the sun, a dark egg should take in more heat from the sun than a lighter egg. To test this theory, Wisocki's group exposed chicken eggs to direct sunlight and tracked how well they assimilated heat. Some were white. Others were brown or blue. Sure enough, brown eggs warmed faster and cooled more slowly than the lighter eggs．

【推荐2】According to a new study, human noise is a “major global pollutant” that harms a wider range of animal life than we tend to think. Published in the journal Biology Letters, the study suggests noise pollution not only harms lots of animals, but also threatens the survival of more than 100 different species.

Lots of species rely on sound for communication, for example, including many amphibians, birds, insects and mammals which use sound for vital business like finding mates or warning about predators (捕猎者). If noise pollution drowns out enough of these messages. it can threaten survival and the stability of their populations.

On the other hand, noise pollution can make it harder for some predators to find food Bats and owls rely on sound to hunt, for instance, which may not work if noise pollution drowns out the sounds of their prey like insects and mice. Even if noise pollution is mild, it might still force them to spend more time and energy searching for food, which could be enough to cause a decline.

Noise pollution is a well-known risk for whales and dolphins, but it threatens other sea animals, too. The researchers cite fish larvae, which are easily drawn to the sounds of coral reefs (珊瑚礁). This is how they find suitable habitats, but if their journey features too much noise from ships and other human sources, more fish larvae may get lost or move into wrong reefs, potentially reducing their lifespan.

Similarly, noise pollution influences the way animals migrate (迁徙), which in turn can have chain effects for ecosystems along migration routes. Some migrating birds avoid areas with noise pollution, the researchers note, which may change not only where they travel, but also where they establish long-term homes and raise their young. Many ecosystems and non-migrating species have come to depend on the arrival of migrating birds, and many others may be unprepared for their sudden absence, so this could cause a series of ecological changes.

“Noise must be considered as a global pollutant and we need to develop strategies to protect animals from noise for their livelihoods,” says Kunc, the lead author of the study.

【推荐3】Spiders are master builders, expertly turning silk into complex 3D webs that serve as their home and hunting ground. To gain a deeper understanding of their world, scientists have translated the structure of a spider’s web into music.

“The spider lives in an environment of vibrating (振动的) strings,” says Markus Buehler, the project’s principal investigator. “They don’t see very well, so they perceive their surroundings by detecting vibrations, which have different frequencies.” Such vibrations occur, for example, when the spider stretches a strand of silk during construction or when the wind or a trapped fly moves the web.

The researchers scanned a natural spider web to capture 2D cross-sections and reconstructed its 3D network using a mathematical model. They assigned different frequencies of sound to strands of the web, creating musical “notes” that they combined in patterns based on the web’s 3D structure to generate music. Then they made a harp-like (像竖琴的) virtual instrument and played the spider web music in several live performances around the world, creating an inspiring harmony of art and science.

To gain insights into how spiders build webs, the researchers also scanned a web during construction, transforming each stage into music with different sounds. “The spider’s way of ‘printing’ the web is remarkable because no support material is used, as is often needed in current 3D printing methods,” Buehler says. This knowledge could help develop new 3D printers that work like spiders, enabling them to construct complex structures without using additional materials for support.

The team is also interested in learning how to communicate with spiders in their own language. They recorded web vibrations produced when spiders performed different activities, such as building a web, communicating with other spiders or sending signals to admirers. “Now we’re trying to generate signals to basically speak the language of the spider,” Buehler says. “If we expose them to certain patterns of vibrations, can we affect what they do or can we begin to communicate with them? Those are really thrilling ideas, and I believe they could be achieved in the near future.”

【推荐2】Prosthetic limbs (义肢) have been around for a long time. The oldest known dates back more than 3,000 years. But prosthetics which behave like the real thing, as well as looking like it, are still very much a work in progress. And a group at Shanghai Jiao Tong University, in China, have just come up with a significant advance — an affordable prosthetic hand that not only responds like a real one to signals from the wearer’s brain, but is also able to signal back to the brain what it is touching and doing.

Gu Guoying and his colleagues describe their invention in Nature Biomedical Engineering. Its fingers are made of rigid tubes, connected to a 3D-printed plastic palm. In contrast to current models, which are electrically powered, Dr Gu’s hand is powered pneumatically by a pump held in a waist bag. This reduces its weight below 300 grams — half that of some current models, and less, indeed, than the weight of a real hand.

The big advance is that it does not require invasive surgery or electronic implants into the residual limb to communicate with the user’s brain. Sensors on the skin record electrical activity from the remaining arm muscles. In an intact arm, this activity would tell those muscles how to operate the hand.

Dr Gu and his colleagues compared the efficacy of their invention with that of existing models using tests including writing, grasping and lifting objects, lifting food to the mouth. Normally, they found, it worked better — particularly for delicate tasks like handling fragile objects, petting a cat and shaking hands.

The other attraction of Dr Gu’s invention is that it is cheap. The components it is made from cost about $500. Existing models may sell for $10,000 or more. If it, or something similar, goes into production, that will permit the transformation of many more of the lives of the 5 million people who have lost a hand, or were born without one, than is possible at the moment.