【推荐1】Winter begins in the north on December 22^nd. People and animals have been doing what they always do to prepare for the colder months. Squirrels(松鼠), for example, have been busy gathering nuts from trees. Well, scientists have been busy gathering information about what the squirrels do with the food they collect.

They examined differences between red squirrels and gray squirrels in the American state of Indiana. The scientists wanted to show how these differences could affect the growth of black walnut(黑胡桃) trees. The black walnuts is the nut of choice for both kinds of squirrels. The black walnut tree is also a central part of some hardwood forests.

Rob Swihart of Purdue University did the study with Jake Goheen, a former Purdue student now at the University of New Mexico. The two researches estimate(估计) that several times as many walnuts grow when gathered by gray squirrels as compared to red squirrels. Gray squirrels and red squirrels do not store nuts and seeds in the same way. Gray squirrels bury nuts one at a time in a number of places. But they seldom remember where they buried every nut. So some nuts remain in the ground. Conditions are right for them to develop and grow the following spring. Red squirrels, however, store large groups of nuts above ground. Professor Swihart calls “death traps for seeds”.

Gray squirrels are native to Indiana. But Professor Swihart says their numbers began to decrease as more forests were cut for agriculture. Red squirrels began to spread through the state during the past century.

The researchers say red squirrels are native to forests that stay green all year, unlike walnut trees. They say the cleaning of forest land for agriculture has helped red squirrels invade Indiana. Jake Goheen calls them a sign of an environmental problem more than a cause.

【推荐2】Dyeing eggs has long been an Easter tradition, but it’s the dyeing of baby chicks that is upsetting in some states.

The dye, which is often ordinary food coloring, is either injected into eggs being hatched or sprayed onto newly hatched chicks. Although hatchery owners say the practice is harmless, critics argue that spraying the birds with color is stressful and that dyeing the animals transforms them into something attractive that can be thrown away when their colorful feathers disappear.

“These are living creature and dyeing them sends out a message saying that they are more of a new and unusual object than a living animal,” said Dr. Marc Copper, senior scientific manager for the Royal Society for the Prevention of Cruelty to Animals.

Dyed chicks --- and sometimes rabbits --- have been a traditional part of the Easter holiday in some parts of the world, but the practice has gone largely underground in the U.S. because many people view it as cruel.

Today, about half of U.S. states ban the dyeing of animals, but last month the Florida Legislature passed a bill to remove the state’s 45-year-old ban. The drive to end the law wasn’t related to Easter chicks; it was done at the request of a dog groomer(美容师) who wanted to enter pet beauty contests.

Florida governor Rick Scott must agree to remove the ban, which would be lifted July 1, but the Animal Rights Foundation of Florida(ARFF) has asked him not to remove the ban. In addition to allowing animals dyeing, the law would also lift a ban on selling baby animals as pets, and the organization fears that next year the state could see hundreds of dyed baby chicks on the market.

As long as the dye is not poisonous, experts say the birds’ health isn’t affected, and there are scientific reasons to dye animals. Wildlife researchers often inject eggs with dye to track birds in the wild, and teachers have dyed chicks for educational purposes. However, animal advocates are quick to point out that dyeing baby chicks for Easter isn’t educational --- it’s done simply to earn profits.

【推荐2】In the movie Jurassic Park (1993) a billionaire creates a theme park filled with dinosaurs, brought back from extinction through cloning by a team of scientists.

Although the film is of course fictional, the methods used in it to bring animals back from the dead may soon become reality.

Scientists from Harvard University in the US are currently working on resurrecting the woolly mammoth, a mammal that became extinct around 4,000 years ago.

However, it wouldn't be an exact copy of the hairy beast. "Our aim is to produce a hybrid elephant-mammoth embryo,” Professor George Church, head of the team of scientists, told The Guardian.

“Actually, it would be more like an elephant with a number of mammoth traits. We're not there yet, but it could happen in a couple of years."

The team is hoping to make a “mammophant”- a mix between an elephant and a mammoth. It would be like a regular elephant but have features from the mammoth that would make it more adaptable to cold weather.

Small ears, a thick layer of body fat and, of course, long hair are what helped the mammoth live in freezing temperatures.

So why go through all the effort and expense to bring back an animal that died out thousands of years ago? The answer lies in climate change.

It's hoped that the creatures will stop frost in the world's tundra from melting and releasing huge amounts of harmful greenhouse gases into the atmosphere.

Mammoths used to keep the tundra from thawing by punching through snow and allowing cold air to come in," said Church. In the summer, they knocked down trees and helped the grass grow."Church and his team are attempting to mix mammoth DNA, recovered from frozen samples of the animal found in Siberia, with that of the Asian elephant, which is its closest relative.

There are critics who believe that the media has got carried away with the story though, after several websites ran headlines such as Woolly mammoths will be roaming Earth again within two years.

“So far, scientists have managed to incorporate traits of the mammoth into elephant DNA. In a few years, they hope to make an embryo, but that's a long way from creating a viable embryo, "Popular Science magazine wrote.

Some have even gone so far as to call the story “fake news". Paleoanthropologist(古人类学家)John Hawks wrote on blog platform Medium: Is this just another case of the media sensationalizing(大肆渲染) what is otherwise a good science story?"

Although we may not be seeing woolly mammoths at the zoo any time in the near future, it's still exciting to know that there is still the possibility of a real Jurassic Park someday, however tiny that possibility may be.

【推荐3】As people age, the body changes in all sorts of predictable ways. Brains can slow. Wounds take longer to recover. And sleep patterns(模式) shift, too. This can come as news to many, says Michael V. Vitiello, a psychologist at the University of Washington who is expert in sleep in aging.

The most noticeable---and often most annoying---changes are how sleep and wake-up times change and sleep gets lighter, often beginning in middle age. Gone are weekend sleep to 11 a.m. and the ability to sleep through a noisy garbage truck down the block.

But not every restless night can be ignored. Studies have found that poor sleep can create a particular threat to older adults---Falls, depression and anxiety, problems with memory, and increased suicide(自杀) risk are among the effects of sleep issues in this population group that researchers have found. But scientists are still unsure why those risk connections exist.

What is clear is the connection between good sleep and psychological well-being in older adults. A 2010 study showed us that connection when it came to sleep quality, but sleep quantity didn't show the same effects. And that, experts say, may be the key to understanding sleep as you age. If you're sleeping less, but don't feel negative effects out of bed, the changes you notice may just be normal age-related.

Over time, Vitiello says, sleep patterns simply change. "A lot of older adults recognize that they don't sleep the same as they did when they were 18, but they can still function and they're OK. And all is well with the universe."