The Maya loved cacao so much that they used the beans as currency. They also believed it is good for you — which many people still say today about cacao’s most famous byproduct, chocolate. 【小题1】. While some have suggested that less than an ounce of dark chocolate might improve heart health, much of the research doesn’t involve eating actual chocolate but rather its components-flavanol, especially.

【小题2】. In a clinical trial of 21,000 adults, they found that the half of the group that took500mg of. cocoa flavanol supplements daily had a significantly lower risk of death from cardiovascular disease than those who had taken a placebo (安慰剂).

Flavanols may also boost insulin sensitivity, according to some studies, which might be helpful in reducing the risk of type 2 diabetes (糖尿病). 【小题3】. Those at risk of diabetes might be wise to choose a cacao-inspired supplement instead of eating chocolate — and the sugar it contains. Other research suggests that the flavanols found in cacao (also present in fruits, vegetables, and tea) could slow cognitive decline during aging, or even boost brain performance by improving blood flow to the cerebral cortex.

What these findings mean for chocolate is limited, however. Participants would have had to eat multiple fat and sugar filled chocolate bars a day to source 500mg of flavanols. 【小题4】. So understanding why certain types of chocolate are healthier than the rest is the focus of further research.

Rising Seas Will Erase More Cities by 2050, New Research Shows

Rising seas could affect three times more people by 2050 than previously thought, according to new research, threatening to all but erase some of the world's great coastal cities.

The authors of a paper published on Tuesday developed a more accurate way of calculating land elevation based on satellite readings, and found that the previous numbers were far too optimistic. The new research shows that some 150 million people are now living on the land that will be below the high-tide line by mid-century. In Thailand, more than 10 percent of citizens now live on the land that is likely to be covered with water by 2050, compared with just 1 percent according to the earlier technique. The political and commercial capital, Bangkok, is particularly dangerous.

In other places, the migration caused by rising seas could cause or worsen regional conflicts. Basra, the second largest city in Iraq, could be mostly underwater by 2050. If that happens, the effects could be felt well beyond Iraq's borders, according to John Castellaw, a retired Marine Corps general.

“Further loss of land owing to rising waters there threatens to drive further social and political instability in the region, which could lead to armed conflicts again and increase the likelihood of terrorism,” said Castellaw, who is now on the advisory board of the Center for Climate and Security, a research and advocacy group in Washington. “So, this is far more than an environmental problem,” he said. “It's a humanitarian, security and possibly military problem too.”

Bats are the only mammals(哺乳动物) that can fly a great distance, but they have another ability. Many bats live a very long time for an animal of their size. European researchers are studying bats to understand why they live so long. They hope to make discoveries aimed at fighting the aging process in human beings.

Last week, the group of scientists said they had identified important biological qualities in some bat species. The group studied bat chromosomes(染色体), a line of genes found in the nucleus(细胞核) of cells. The scientists were most interested in structures connected to the ends of the chromosomes. They are called telomeres(端粒), which protect the ends of chromosomes and shorten each time a cell divides. Scientists believe this shortening process causes cells to breakdown. They say this is what causes aging.

The European researchers studied 493 bats from four bat species. The group used information that had been gathered over more than 60 years. Of these animals ，the greater mouse-eared bat generally lived the longest, an average of 37 years. The scientists said this and a related species, which are grouped together under the name Myotis, had telomeres that did not shorten with age. Another Myotis bat holds the record for oldest age, reaching 41years. The scientists’ findings suggest that these bats cells have the ability to maintain and repair their telomeres. This, they said, helps guard against the aging process.

Based on its body size, a bat like the greater mouse-eared bat would be expected to live four years. But, these mammals have been found to live nearly 10 times longer than that. The scientists found that only 19 species of mammals live longer than humans when their body size is considered. Eighteen of these are bats.