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大家好，先看完文章再看标题哈！第三和第四篇是一篇文章~ [Time 1] Article 1 ( Check the title later ) Monkey Smiles Are Contagious
Believe it or not, the gelada monkeys (Theropithecus gelada) on the right may be sharing a good laugh—and possibly the emotions that go along with it. Previously, only humans and orangutans had been shown to quickly and involuntarily mimic the facial expressions of their companions, an ability that seems to be linked to empathy. After spending months observing every playful interaction among the gelada population at Germany's NaturZoo, scientists are ready to add another, more distantly related species to that list. Geladas of all ages were more likely to mimic the play faces of their companions within 1 second of seeing them than they were to respond with a different kind of expression, according to a paper published by the team this week in Scientific Reports. What's more, the fastest and most frequent mimicry responses occurred between mothers and their infant offspring, like the pair pictured on the left. More research is required to determine if geladas are sharing emotional states in addition to facial expressions, but the team suggests that studying the quantity and quality of these mother-child interactions could provide a way forward. [字数：186] [Time 2] Article 2 Sexual Partner Status Affects A Woman's, But Not A Man's, Interest In The Opposite Sex
A study by Indiana University neuroscientist Heather Rupp found that a woman's partner status influenced her interest in the opposite sex. In the study, women both with and without sexual partners showed little difference in their subjective ratings of photos of men when considering such measures as masculinity and attractiveness. However, the women who did not have sexual partners spent more time evaluating photos of men, demonstrating a greater interest in the photos. No such difference was found between men who had sexual partners and those who did not. "These findings may reflect sex differences in reproductive strategies that may act early in the cognitive processing of potential partners and contribute to sex differences in sexual attraction and behavior," said Rupp, assistant scientist at The Kinsey Institute for Research in Sex, Gender and Reproduction. For the study, 59 men and 56 women rated 510 photos of opposite-sex faces for realism, masculinity/femininity, attractiveness, or affect. Participants were instructed to give their "gut" reaction and to rate the pictures as quickly as possible. The men and women ranged in age from 17 to 26, were heterosexual, from a variety of ethnic backgrounds and were not using hormonal contraception. Of the women, 21 reported they had a current sexual partner; 25 of the men reported having a sexual partner. This is the first study to report whether having a current sexual partner influences interest in the opposite sex. Other studies have demonstrated that hormones, relationship goals and social context influence such interest. "That there were no detectable effects of sexual partner status on women's subjective ratings of male faces, but there were on response times, which emphasizes the subtlety of this effect and introduces the possibility that sexual partner status impacts women's cognitive processing of novel male faces but not necessarily their conscious subjective appraisal," the authors wrote in the journal article. The researchers also note that influence of partner status in women could reflect that women, on average, are relatively committed in their romantic relationships, "which possibly suppresses their attention to and appraisal of alternative partners." [字数：344]
[Time 3]
Article 3 DNA study links indigenous Brazilians to Polynesians
Indigenous people that lived in southeastern Brazil in the late 1800s shared some genetic sequences with Polynesians, an analysis of their remains shows. The finding offers some support for the possibility that Pacific islanders traded with South America thousands of years ago, but researchers say that the distinctive DNA sequences, or haplogroups, may have entered the genomes of the native Brazilians through the slave trade during the nineteenth century. Most scientists agree that humans arrived in the Americas between 15,000 and 20,000 years ago, probably via the Bering land bridge linking northeastern Asia with what is now Alaska. But the precise timing and the number of ‘migration waves’ is unclear, owing largely to variations in early Americans’ physical features, says Sérgio Pena, a molecular geneticist at the Federal University of Minas Gerais in Belo Horizonte, Brazil. One broad group of these Palaeoamericans — the Botocudo people, who lived in inland regions of southeastern Brazil — stands out, having skull shapes that were intermediate between those of other Palaeoamericans and a presumed ancestral population in eastern Asia. Now, a genetic analysis sheds light on the possible heritage of the Botocudo. Pena and his colleagues studied short stretches of mitochondrial DNA (mtDNA) in samples drilled from teeth in 14 Botocudo skulls kept in a museum collection in Rio de Janeiro. By analysing material from inside the teeth, the team minimized the possibility of contamination with DNA from the numerous people who have probably handled the skulls since they arrived at the museum in the late 1800s. The mtDNA from 12 of the skulls matched a well-known Palaeoamerican haplogroup. But mtDNA from two of the skulls included a haplogroup commonly found in Polynesia, Easter Island and other Pacific island archipelagos, the researchers report today in Proceedings of the National Academy of Sciences. A separate lab confirmed the result with samples from one of the skulls, indicating that the ‘Polynesian haplogroup’ did not result from contamination, the researchers contend. [字数：323]
[Time 4]
“But to call that haplogroup Polynesian is a bit of a misnomer,” says Lisa Matisoo-Smith, a molecular anthropologist at the University of Otago in Dunedin, New Zealand. The haplogroup is also found — albeit at a lower frequency — in populations living as far west as Madagascar. Nevertheless, says Pena, it is a mystery how DNA from Palaeoamericans living in southeastern Brazil could include gene sequences typically found in Pacific islanders. “We have this finding,” he says. “Now we have to explain it.” The researchers say that it is possible — but unlikely — that the DNA could have come from Polynesians who voyaged from remote islands to the western coast of South America. Those traders or their progeny would then have made their way to southeastern Brazil and settled or interbred with natives. But that, too, is improbable, says Pena, because the Andes are a formidable barrier that west coast residents typically did not climb or cross. Although researchers have suggested that ancestors of some species of chickens made their way to Chile through trade with pre-Columbian seafarers from Polynesia, a subsequent study3 poked holes in that conclusion. The researchers also entertain scenarios in which the haplogroup arrived in South America via the slave trade. Around 2,000 Polynesians were brought to Peru in the 1860s, and some could have ended up in Brazil, although the researchers say that they are not aware of any evidence that this occurred. And between 1817 and 1843, approximately 120,000 slaves were shipped from Madagascar to Brazil — and some of them were probably transported to areas where the Botocudo also lived. Although the researchers consider the latter scenario to be the most probable, Pena says: “We currently don’t have enough evidence to definitively reject any of these scenarios.” “This is a pretty exciting initial result,” says Alice Storey, an archaeologist at the University of New England in Armidale, Australia. Further studies of genetic material from the skulls, including detailed analyses of nuclear DNA (which contains much longer genetic sequences than mtDNA), could offer more insight into the mysterious ancestry of the Botocudo, she says. [字数：346]
[Time 5]
Article 4
A Medical Renaissance?
With the completion of sequencing of the human genome in 2001, many researchers immediately set their sights on using this information to better understand the genetics and, more recently, epigenetic effects identified during the initiation, development, and progression of cancer. Moving from the pre–genome-era identification of single gene variants associated with hereditary cancers, advances in sequencing technology have enabled the use of a whole-genome approach to examine the differences between the genomes, and epigenetic regulation, of tumor and patient DNA. This issue of Scienceexamines how these advances are shaping our current understanding of cancer at the genomic level.
Unfortunately, there is no magic bullet, as no single genetic variant or epigenetic effect has been identified as a target in the fight against all cancers. In a comprehensive Review, Vogelstein et al. distill information derived from more than 100 cancer genome sequencing projects into a series of clear principles about tumor biology and then discuss the projected clinical impact of cancer genome analysis on early detection and treatment of the disease. Kilpivaara and Aaltonen call for standards for cases in which whole-genome sequencing reveals clinically relevant mutations in individual patients to bridge differences between the laboratory and the clinic. McLeod reviews how best to apply pharmacogenomic information in identifying and tailoring drugs to target cancers. Finally, Suvà, Riggi, and Bernstein examine how cell fates are controlled by epigenetic regulation and identify parallels between cancer and cellular differentiation. In addition, Science Signaling presents related content on 26 March and 6 April, highlighting how cancer-associated alterations in the genome or proteome can result in altered signaling that contributes to tumorigenesis, metastasis, and drug resistance. Our Science News department profiles Elaine Mardis, whose expertise in developing DNA sequencing technology led her to become a pioneer in cancer genomic research, and explores how the heterogeneity of individual tumors, revealed by sequencing studies, poses treatment problems. Science Careers profiles Fátima Al-Shahrour, a bioinformaticist who works on interpreting the genome to help select more effective drugs for cancer patients. Technological breakthroughs, coupled with the greatly reduced costs of sequencing, suggest that in our not-too-distant future, routine cancer treatment will not focus on the organ of origin but rather on the genomic profile of the cancer. This fundamental goal, to be able to read the complex code embedded in our bodies to identify the best therapies for each individual over the course of their treatment, portends a medical enlightenment. [字数：402]
[越障]
Article 5Why is this Northern Hemisphere spring so cool?Scientists are beginning to offer explanations as to how global warming can lead to a longer winter.
Several media organizations are reporting this week on a story that’s been talked about quietly in climate and science media circles for some years now. It’s the idea that, as Earth warms, the Arctic will “release” its cold to lower latitudes. Arctic sea ice reached its maximum for this northern winter on March 15, 2013, and it was the 6th-smallest sea ice maximum on record, according to the National Snow and Ice Date Center (NSIDC). Surprised? It seemed like a cold winter, didn’t it? But, in fact, although the winter of 2012-2013 was cooler than last year, this winter ranked as the 20th-warmest winter since record-keeping began. And now, strangely, although we’re past the vernal equinox, the unofficial beginning of northern springtime, many parts of the Northern Hemisphere are still experiencing unseasonably cool temperatures. What’s going on? It appears we’re experiencing climate’s complexity, and some climate scientists are now beginning to speak out about mechanisms by which a decrease in Arctic sea ice could, in some years, drive a longer winter and chilly springtime. The root cause is atmospheric circulation. Global warming may be altering the way air circulates around the globe, in a way that in some years leads to more snow and ice at the more populated latitudes of Earth’s globe. In National Geographic on March 26, 2013, Daniel Stone wrote: Without a substantial ice cover, Arctic wind is less constrained. The jet stream — the belt of cool air that regulates weather around most of the Northern Hemisphere — then dips farther and farther south, bringing cold air from the Arctic closer to the equator. The result is much colder weather dipping into the spring much longer, and more forcefully, than normal. A second mechanism for global warming’s leading to a cool springtime is explained in yesterday’s Discovery News in an article by Larry O’Hanlon. He spoke to climate researcher Steve Vavrus of the University of Wisconsin, who uses computers to model the effects of decreased Arctic sea ice on global weather. Vavrus said that slowing westerly winds, due to global warming, could in some years keep winter weather around longer. Those winds keep weather systems moving from west to east. So if a snow storm (or heat wave) strikes your area, it simply won’t move out as quickly, according to Vavrus. Meanwhile, in the Arctic itself, 2013 has been a year of massive springtime cracking of the sea ice. After sea ice maximum each year, scientists begin to see what they call leads, which are long cracks in the Arctic ice. As springtime progresses, and sunlight brings warmth to the Arctic, the cracks in Arctic ice will begin to open up, and the ice cover starts to melt. This year, scientists at NSIDC are reporting “remarkable” mid-winter cracking of the Arctic ice. Walter Meier of NSIDC told Discovery News: There is cracking every year when the ice is pushed by the winds and currents. But this was particularly extreme. Qualitatively, this seems like the biggest. He said that powerful winter storms this year led to many large cracks, hundreds of meters wide, stretching all across the Arctic. The cracks quickly froze again, but this refrozen ice is thinner and weaker than the older, multi-year ice that used to make up much of Arctic sea ice. Recall that autumn 2012 brought a record year for Arctic sea ice minimum, meaning that much of the ice in the Arctic is relatively fresh now, having only this year begun to build after the September minimum. Thus, in the Arctic this year, the ice that in some years is relatively old and strong is now relatively young and weak. That will make the ice all-the-more vulnerable to melting when summer arrives, a few months from now. What is difficult about local weather and global climate is its complexity. Year-to-year changes are always occurring, due to a multitude of factors unrelated to global warming. For example, the northern winter of 2011-2012 was mild, and that warmth was credited to unexpected oscillations of the North Atlantic and Arctic weather patterns. There can be short-term ups and downs, in other words, that may or may not follow the longer-term trend, caused by all sorts of factors. But, overall, global warming leading to a cold spring? I can see my friend Ben, who is devout believer that Earth is not warming, rolling his eyes now. And yet if you know, or at least believe, in climate’s complexity, the strangeness of this year’s chilly spring doesn’t seem surprising. One last thought. Arctic sea ice stayed nice and solid and created a relatively stable weather pattern throughout my lifetime at least, in the last half of the 20th century. Now it melts a bit more each year, and the weather patterns have become less stable, and I wonder … what’s next? Bottom line: This past winter was the 20th-warmest winter since record-keeping began. Arctic sea ice maximum was on March 15, 2013, and it was the 6th-smallest maximum on record. Meanwhile, winter just keeps hanging on in the Northern Hemisphere. Scientists are beginning to offer explanations as to how global warming can lead to a longer winter. [字数：859]
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发表于 2013-4-2 19:37:51
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