A new study suggests that people who drank a certain amount of alcohol（酒）had a lower risk of cancer and death than those who drank more or none during a nine-year period. And with each additional drink a week, the risk of cancer and death from any cause increased, the scientists reported.

    However, the study found only an association between alcohol and cancer and death, and did not prove cause and effect, the researches said. What sets the new study apart, said lead study author Andrew Kunzmann, is that previous studies looked at cancer and death separately. “What our study does is combine the two outcomes together and we find that lighter drinking is associated with the lowest risk of cancer or death,” Kunzmann said.

    But Kunzmann noted that the participants（参与者）were all older adults. That means that “we're not really showing what happens in younger people if they drink,” he said. Also, it's difficult to account for other lifestyles that could have affected the results. “These could also influence health. But the results did take into consideration differences in diet, smoking and education among participants,” Kunzmann noted.

    The researchers said that they hope their study sparks conversation about reducing the suggested alcohol intake in countries' guidelines. “We're not telling people what they can or can't do or what they can or can't drink,” Kunzmann said. “We're just trying to give them reliable evidence so that they can make their own informed, healthy decisions.”

    Languages have been coming and going for thousands of years, but in recent times there has been less coming and a lot more going. When the world was still populated by hunter-gatherers , small tightly knit (联系) groups developed their own patterns of speech independent of each other. Some language experts believe that 10,000 years ago, when the world had just five to ten million people, they spoke perhaps 1,200 languages between them.

    Soon afterwards, many of those people started settling down to become farmers, and their languages too became more settled and fewer in number. In recent centuries, trade, industrialization, the development of the nation-state and the spread of universal compulsory education, especially globalization and better communications in the past few decades, all have caused many languages to disappear, and dominant languages such as English, Spanish and Chinese are increasingly taking over.

    At present, the world has about 6,800 languages. The distribution of these languages is hugely uneven. The general rule is that mild zones have relatively few languages, often spoken by many people, while hot, wet zones have lots, often spoken by small numbers. Europe has only around 200 languages; the Americas about 1,000; Africa 2,400; and Asia and the Pacific perhaps 3200, of which Papua New Guinea alone accounts for well over 800. The median number (中位数) of speakers is a mere 6,000, which means that half the world's languages are spoken by fewer people than that.

    Already well over 400 of the total of 6,800 languages are close to extinction (消亡), with only a few elderly speakers left. Pick, at random, Busum in Cameroon (eight remaining Speaker), Chiapaneco in Mexico (150), Lipan Apache in the United States (two or three) or Wadjigu in Australia (one, with a question-mark) none of these seems to have much chance of survival.

    If your dog looks pleased to see you—it is probably because it loves the particular way you smell.

    The scent (气味)of a familiar human apparently lingers like perfumein the animal's brain—where it causes an instinctive emotional response, research reveals.

    Our scent acts on a part of the canine (犬科的) brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.

    Gregory Bern, of Emory University in Atlanta, said, “While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the 'reward response' is reserved for their humans. When humans smell the perfume of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive (认识的). So is it in dogs. But since dogs have a more sensitive smell than humans, their responses would likely be even more powerful than the ones we might have. In our experiment, however, the owners of the dog were not physically present. The canine brain responses were being caused by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.”

    The experiment involved 12 dogs of various kinds by brain scans while five different scents were placed in front of them. The scent samples (样本)came from the subject (接受试险者) itself, a dog the subject had never met, a dog living in the subject's household. The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.

    The results showed all five scents gained a similar response in parts of the dogs brains involved in detecting smells. Responses were significantly stronger for the scent of familiar humans, followed by that of familiar dogs. The findings showed dogs reacted strongest to the scent of familiar humans even when they were not there. Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.

    Researchers say the findings could improve the way to select animals helping wounded old soldiers or disabled people.

    Shyness May Be Partly Inherited(遗传)

    About 92 million Americans are shy, and according to recent research about half of them inherited the trait.

    The studies were discussed at the American Psychological Convention.

    One study, by Harvard University, was of babies 21- 48 months old. It concluded that these babies had a high heart rate when shown unfamiliar people or different toys.

    Although shyness is not new, it has only recently become of interest to researchers. The first study on the genetic connection was in 1979.

    According to Warren Jones of the University of Tulsa, social relations these days are more complex. "With less ritual(仪式) and more complex situations," he said, "shyness is a national concern."

    Not all shy people are anxious and fearful, according to another study. Evidence shows that only half of shy people are tense, worried, and fearful in social situations.

    Many men use shyness as an excuse for failing in social situations, according to C.R. Snyder of the University of Kansas. "This is not true of females. Perhaps, American men are pressured to be assertive(自信的) and successful. So they would rather say they're shy than admit they're incompetent."

    Shy people may do very well socially after the first meeting with someone. In fact, shy people tend to be more stable.

    The psychologists said shyness seems to be cultural. Japan has the highest rating. China and Israel have the lowest rating. The United States rated in the middle.

    A new study suggests climate conditions in the Sahara Desert, one of hottest, driest and most deserted areas in the world, have changed from wet to dry a about every 20,000 years.

    But previous evidence has suggested the Sahara did not always experience such extreme heat and dry conditions. At times, the Sahara Ranged to a very wet climate. This permitted plants and animals to develop and grow and led to the creation of human settlements. Now, they have discovered more evidence, which, the lead researcher David Mc Gee says, supports the idea that the Sahara's climate kept changing between wet and dry about every 20,000, years.

    McGee reported these climate changes were mainly driven by changes in the Earth's(地轴)as the planet travels round the sun .This process affects the amount of sunlight between seasons. Every 20,000 years the Earth receives more strong summer sunlight. When the Earth's axis changes again, the amount of sunlight is reduced. This season change happened continuously every 20,000 years. The other part of the season produced rainy conditions, resulting in a wetter, greener, plant-rich environment. When the rainy activity weakens, the climate becomes hot and dry, like the Sahara remains today.

    The scientists based their research on dust collected from ocean sediment(沉积物)in the Atlantic Ocean bottom off the coast of West Africa. The dust contained layers (层)of ancient sediment built up over millions of years. Each layer could contain traces of Saharan dust as well as the remains of life forms. This information was used to assess over what time period the dust had built up. This led to the overall finding that the Saharan changes from wet to dry climates happened every 20,000 years.

David McGee said that today we only see the Sahara Desert as an extremely deserted and "inhospitable" place. The new study suggests that the area's climate has changes between grasslands and a much wetter environment, and back to dry climates, even over the last quarter million years. McGee says he thinks the latest research can be valuable in studying the Sahara's history as it relates to human settlement.

Bees (蜜蜂) touch our lives in ways we may not realize. They are responsible for as much as one third of the food that we eat, and even play a role in growing the cotton (棉花) used in much of our clothing. {#blank#}1{#/blank#} Here's how you can help:

1. Plant more flowers

Bees depend on garden flowers to ensure they have different kinds of diet. By planting flowers in your garden you can create a pleasant place for bees. {#blank#}2{#/blank#} Another idea is to add hanging baskets of flowers next to your front door.

2. Find a space for a beehive (蜂窝) in your garden

Many would-be beekeepers find it difficult to find a safe space for their bees. If you have some space, contact your local beekeeping organization. {#blank#}3{#/blank#} You will be surprised what a difference a beehive will make to your garden.

3. Give bees water

{#blank#}4{#/blank#} They use water to produce food for their bee families and control the temperature in their hives. Bees look for a clean source of water. Leave out containers filled with clean water in your outdoor spaces and refresh them often.

4. Be bee friendly

Bees are good neighbors, and only sting (蜇) when they feel threatened. Beekeepers wear protective clothing when they are dealing with bees. If a bee flies in front of you when unprotected, do not flap (拍打) your hands. {#blank#}5{#/blank#} The bee will soon lose interest.