摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
后 记
2008北京奥运会是世界送给中国的最珍贵礼物。如何充分“享受”这个千载难逢的历史时刻，每个人心中都有自己的盘算。打从申奥成功的那天起，我便萌生了制作一部科普系列片的想法并开始准备资料。但“好事多磨”，三波九折，直到2007年7月才最后确定由中央电视台体育节目中心和交通银行、武汉电视台《科技之光》联合摄制。这本集子里收进的35篇作品便是我为系列电视片《科技与奥运》撰写的文字稿。
摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
“计算机的应用使体育训练真正从传统的经验型转为定量的科学型，大大缩短了优秀运动员‘脱颖而出’的周期。”
奥运金牌之路
人类自古用金子来体现不朽的价值。奥运会把黄金制成奖牌授予每一届力拔头筹的冠军，于是金牌便标记了一个时代人类自身能力的“疆界”。夺取奥运金牌是每个运动员毕生的追求和梦想，而奥运金牌得主照例被尊为国家和民族的英雄。这些奥运赛场上啸傲风云的体坛翘楚从哪里来？一百年间，各国体育界和科学界都在不遗余力地探索和追寻，希望解读他们成功背后的种种奥秘。
摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
“也许我们总有一天能建造更多‘环球同此凉热’的人工冰雪场，但作为奥运会的‘半边天’，冬奥会大概永远只会在地球高纬度地区的冬季举行。”
冰雪盛会
比起赤日炎炎、热力四射的夏季奥运会，冰天雪地、银装素裹的冬季奥运会别有一番韵致和风光。这里是洁白如玉的征途，晶莹如镜的赛场，“断桥危立”的跳台，陡峻盘曲的滑道。脚踩冰刀和滑雪板的健儿们驰骋如风、将飞欲翔；驾驭雪橇的勇敢者则创造了陆地极限速度，被誉为“冰上一级方程式”。1908年伦敦奥运会便首次设立了花样滑冰项目，但早期奥运会“夏行冬令”的确勉为其难。1924年巴黎奥运会将冰雪项目的比赛提前半年在夏蒙尼举行并称之为“第八届奥林匹亚国际体育周”，此后被国际奥委会“追认”为第1届冬季奥运会。当“白色奥运”从“附庸地位”到另立门户，五环旗交替飘扬在地球上寒暑分明的两个季节时，奥运会就更加色彩绚烂和充实完整了。
摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
“历届奥运会曾经使用过火药、硫磺、树脂、萘、橄榄油、四氮六甲圜做火炬的燃料。”
圣火不灭
历届奥运会最宏大的格局和最壮阔的场景，莫过于举世瞩目的开幕仪式了。这是一个时代人类社会组织能力和文明水准的标志。而点燃圣火则是开幕式的“点睛之笔”。随着主体育场美丽的火焰冲天而起，“奥运之龙”便“破壁而飞”了。
原文链接：
West versus east: individualistic versus holistic?
Your culture may shape the way you think, but beware simplistic stereotypes, warns Ed Yong
AS A SPECIES, we possess remarkably little genetic variation, yet we tend to overlook this homogeneity and focus instead on differences between groups and individuals. At its darkest, this tendency generates xenophobia and racism, but it also has a more benign manifestation – a fascination with the exotic.
Nowhere is our love affair with otherness more romanticised than in our attitudes towards the cultures of east and west. Artists and travellers have long marvelled that on opposite sides of the globe, the world’s most ancient civilisations have developed distinct forms of language, writing, art, literature, music, cuisine and fashion. As advances in communications, transport and the internet shrink the modern world, some of these distinctions are breaking down. But one difference is getting more attention than ever: the notion that easterners and westerners have distinct world views.
Psychologists have conducted a wealth of experiments that seem to support popular notions that easterners have a holistic world view, rooted in philosophical and religious traditions such as Taoism and Confucianism, while westerners tend to think more analytically, as befits their philosophical heritage of reductionism, utilitarianism and so on. However, the most recent research suggests that these popular stereotypes are far too simplistic. It is becoming apparent that we are all capable of thinking both holistically and analytically – and we are starting to understand what makes individuals flip between the two modes of thought.
One of the pioneers of this research is Richard Nisbett from the University of Michigan, Ann Arbor. In his book The Geography of Thought, he recounts a study done in 2001 in which he asked American and Japanese students to describe animated videos of underwater scenes. As befits the stereotype, the Americans were more likely to start by mentioning prominent objects such as brightly coloured moving fish or aquatic plants, while the vast majority of the Japanese students started by saying something about the context – the scene looked like a stream, or the water was green. They also mentioned more relationships between the objects and their environment. In another experiment, using eye-tracking equipment and a picture of a tiger in a jungle, Nisbett found that Americans tended to look at the tiger more quickly and focus on it for longer than did Chinese people, whose gaze flicked more often between the animal and the background.
“Cultural differences may even extend to the way people view causality and wield logic”
Over the years, Nisbett and others have amassed evidence to suggest that such differences in visual attention influence the way in which people from east and west think about the world. For a start, they affect how people categorise objects, with east Asians tending to group things according to how they relate to each other and Americans tending to rely on shared features. When shown pictures of a chicken, a cow and some grass, and asked to decide which two objects belong most closely together, for example, most American kids choose the chicken and cow, since they are both animals, while Taiwanese children tend to group the cow and the grass together because one eats the other (International Journal of Psychology, vol 7, p 235). Likewise, Nisbett found that American students usually group “monkey” with “panda”, while Chinese students see “banana” as a better fit for “monkey” (Journal of Personality and Social Psychology, vol 87, p 57).
There also seem to be distinctly eastern and western views of causality. Americans are more likely to explain murders and sports events by invoking the traits and abilities of individuals, while Chinese tend to refer to historical factors. One study compared English-language newspaper accounts of a recent killing in the US, in which a postal worker shot his boss along with several bystanders, with Chinese newspaper reports of a graduate student who shot his adviser and bystanders. The English-language papers speculated heavily on the killer’s state of mind, while the Chinese papers emphasised his relationships with his superiors and the wider societal factors that could have led to the killings, such as the lack of religion in China or recent massacres elsewhere in the world (Journal of Personality and Social Psychology, vol 67, p 949).
Cultural differences may even extend to the way people wield logic. Chinese people are happier with contradictions and try to find a middle ground between two opposing positions, while Americans are more inclined to reject one proposition for the other. For example, Nisbett found that when faced with a brief vignette of daughters rebelling against their mothers, three-quarters of Americans suggested that one party was at fault. By contrast, three-quarters of Chinese students assessed the situation from both sides and tried to reconcile the differences between mothers and daughters (American Psychologist, vol 54, p 741).
Time and again, studies like these seem to support the same basic, contrasting pattern of thought. Westerners appear to perceive the world in an analytic way, narrowing their focus onto prominent objects, lumping them into categories and examining them through logic. Easterners take a more holistic view: they are more likely to consider an object’s context and analyse it through its changing relationships with its environment.
Nisbett has suggested that historical cultural factors are the key to understanding these differences. The intensive, large-scale agriculture of ancient China involved complex cooperation among farmers and strict hierarchies from emperor down to peasant. “You had to pay attention to what other people were doing and you had to obey orders,” he explains. “These kinds of strong social constraints on behaviour have been characteristic of east Asian life ever since.” The situation in ancient Greece, often thought of as the fount of western culture, was very different: agriculture on such a scale was impossible and most occupations did not require interactions with large numbers of people. The Greeks led independent lives and valued individualism. That allowed them to focus better on objects and goals in isolation, without being overly constrained by the needs of others – traits that persist to this day in western culture. “If that story is all correct, it’s not east versus west, it’s interdependence versus independence,” says Nisbett.
False dichotomy?
Certainly it is appealing to think that a single dimension – individualism/collectivism – can account for much of the difference in people’s behaviour around the world. That might explain why many psychologists have been happy to go along with it. However, recently it has become apparent that the east-west dichotomy is not as clear-cut as this.
For a start, the simplistic notion of individualistic westerners and collectivist easterners is undermined by studies designed to assess how people see themselves, which suggest that there is a continuum of these traits across the globe. In terms of individualism, for example, western Europeans seem to lie about midway between people in the US and those in east Asia.
So it’s not all that surprising, perhaps, that other studies find that local and current social factors rather than the broad sweeps of history or geography tend to shape the way a particular society thinks. For example, Nisbett’s group recently compared three communities living in Turkey’s Black Sea region who share the same language, ethnicity and geography but have different social lives: farmers and fishers live in fixed communities and their trades require extensive cooperation, while herders are more mobile and independent. He found that the farmers and fishers were more holistic in their psychology than herders, being more likely to group objects based on their relationships rather than their categories: they preferred to link gloves with hands rather than with scarves, for instance (Proceedings of the National Academy of Sciences, vol 105, p 8552). A similar mosaic pattern of thought can be found in the east. “Hokkaido is seen as the Wild West of Japan,” says Nisbett. “The citizens are regarded as cowboys – highly independent and individualistic – and sure enough, they’re more analytic in their cognitive style than mainland Japanese.”
Is it time we moved beyond simplistic notions of eastern and western psychology? Daphna Oyserman from the University of Michigan in Ann Arbor certainly thinks so. She is not happy invoking history to explain modern human behaviour. “We can’t test if history mattered,” she says. “But we can test how contexts can evoke one or other mindset.”
Isolation and conformity
Take social isolation. It has been suggested that the stereotypical eastern world view stems partly from a greater concern about being isolated from social groups, which makes people more likely to conform and attend to interpersonal relationships. Art Markman and his then colleague Kyungil Kim at the University of Texas in Austin wanted to see how isolation would affect the mindset of American students, so they asked them to remember occasions either when they had been ostracised from a group or when they had excluded others (Journal of Experimental Social Psychology, vol 42, p 350). The students then studied photos of different cows against various backgrounds and later had to pick out the animals they had seen from a larger set. For students who recalled shunning others, it made little difference to their performance whether the cows appeared against new backdrops. However, students who had recalled being socially snubbed were better at spotting cows they had seen before against the same background, indicating that they paid more attention to the relationship between the cows and their environment. In fact, they behaved much as you might expect east Asians to do when given the same task..
This experiment suggests that while the psychology of westerners may be superficially distinct from easterners, when social isolation is an issue there is little difference between the two. In fact, Oyserman’s analysis of 67 similar studies reveals just how easily social context can change the way people think. For example, psychologists have “primed” east Asian volunteers to adopt an individualistic mode of thought simply by getting them to imagine playing singles tennis, circling single-person pronouns or unscrambling sentences containing words such as “unique”, “independence” and “solitude”. In many of the experiments volunteers from a single cultural background – be it eastern or western – show differences in behaviour as large as those you normally get when comparing people from traditionally collectivist and individualist cultures.
The ease with which priming can alter our modes of thought makes it very unlikely that a penchant for either analytic or holistic thinking stems from deep-seated differences in the brains of westerners and easterners. Instead, it seems that the cultural context in which we grow up simply gives us more practice in thinking about the world in a particular way. “Everyone can think both ways, but on average, people tend to do more of one than the other,” says Oyserman.
“Instead of dividing the world along cultural lines we should recognise and cultivate our cognitive flexibility”
Brain imaging supports this. In an experiment that involved subjects looking at a series of squares with lines in them, Trey Hedden from the Massachusetts Institute of Technology found that in east Asians the areas of the brain involved in focusing attention worked harder if they had to identify lines of the same length regardless of the surrounding squares – an “absolute” task that requires you to focus on an object regardless of its context. But with Americans the same brain areas were working harder to identify lines whose sizes varied proportionally with their squares – a “relative” judgement where context is key (Psychological Sciences, vol 19, p 12). In other words, people had to think harder to perform tasks outside their cultural comfort zone. The brain uses the same mental machinery to solve complex tasks, but cultural differences can affect how well trained these areas are.
Intriguingly, Hedden also discovered that in both groups, people who identified more strongly with American culture found the absolute task easier. Such ease of transition between different modes of thinking is even more pronounced in people with roots in more than one culture. Verónica Benet-Martínez from the University of California, Riverside, found that it takes very little to prime the perception of people who have grown up with cultural influences from both east and west. When she asked a group of Chinese students in Hong Kong to watch a video of a single fish swimming in front of a shoal, those who had previously seen American symbols such as the US flag were more likely to claim that the solitary fish was leading the others. However, subjects primed with Asian symbols, including a Chinese dragon, perceived the event’s context as more important and were more likely to describe the scenario as a shoal chasing after a renegade (Journal of Cross- Cultural Psychology, vol 33, p 492).
Clearly, the dichotomy between holistic eastern and analytical western thinking is more blurred than the stereotypes suggest. If we all flip between different modes of thought depending on social context, says Oyserman, psychologists should be trying to find out which contexts provoke the holistic and which the analytical mindset, rather than perpetuating a false divide.
Are the descendants of herders more likely to be individualistic thinkers?
This approach is all the more important, she says, because the supposed dichotomy is based on limited evidence, with China and Japan representing the east in most studies and the US and Canada flying the flag for the west. In many regions, from southern Asia to Latin America, studies are extremely scarce, and even better-studied Europe is mostly embodied by the unrepresentative duo of Germany and the Netherlands. “The kind of things that cue analytic or holistic thought may be very different in these [neglected] societies,” Oyserman says. “Honour, for example, is a hugely important issue in areas that haven’t been studied very thoroughly, like the Middle East, Africa or Latin America.”
What is clear is that the minds of east Asians, Americans or any other group are not wired differently. We are all capable of both analytic and holistic thought. “Different societies make one option seem to make the most sense at any given moment,” says Oyserman. But instead of dividing the world along cultural lines, we might be better off recognising and cultivating our cognitive flexibility. “There are a lot of advantages to both holistic and analytic perception,” says Nisbett. In our multicultural world it would benefit us all if we could learn to adopt the most appropriate mode of thought for the situation in which we find ourselves. ■
—————————————————————
Ed Yong is a science writer based in London and author of Not Exactly Rocket Science (Lulu, 2008)
原文链接：
http://www.newscientist.com/article/mg20126981.900-jellyfish-sushi-seafoods-slimy-future.html
Can we maintain a seafood industry by focusing on creatures such as squid?
With many seafood species exploited beyond their ability to bounce back, it’s time to look for tasty alternatives. Anyone for squid, algae or jellyfish, asks Caroline Williams
It’s a Friday night in 2050. It’s been a long week at work and even if you could be bothered to cook, there’s nothing in the fridge. So what fast food will you pick up on your way home? How about some squid and chips? Perhaps an algae burger? And don’t forget the crunchy fried jellyfish rings on the side.
One thing’s for sure: unless something changes soon, familiar favourites such as cod, haddock, hake and plaice will be off the menu. In fact, if we’re not careful, an assortment of exotic alternatives will be all the ocean has left to offer us.
This may seem an extreme vision of the future, but marine biologists are alarmed by the imbalances that are appearing in marine ecosystems. The ocean is changing fast – too fast, it seems, for us to reliably predict the combined effects of overfishing, pollution and climate change. What is clear is that the changes, by and large, are not good news for our bellies. “We are entering a time of great uncertainty,” says Boris Worm, of Dalhousie University in Halifax, Nova Scotia, Canada, and the Census of Marine Life project. “If we continue as we have been, in 50 years there may not be much left to take from the ocean.”
Worm and an international team of ecologists have taken a comprehensive look at the state of the world’s fisheries. Their results, published in the journal Science in 2006 (vol 314, p 787), make grim reading. In short, catches of wild fish are plummeting and the researchers predict that without steps to protect biodiversity, all current commercial fish and seafood species will collapse by 2050 (see graph, right). If we do empty the oceans of fish, it will leave a gaping hole in our diet. Fish provide around 20 per cent of our intake of animal proteins, according to a 2007 estimate of the UN’s Food and Agriculture Organization (FAO). That means each of us wolfs down an average of 16.4 kilograms of fish per year. National figures vary widely, from virtually none in some landlocked nations like Afghanistan, to about 20 kilograms per person per year in the UK and US and a whopping 180 kilograms in the Maldives.
This demand is increasing rapidly, as a result of the rising global population and increasing prosperity in the developing world. Maintaining catches at current levels is becoming difficult, let alone increasing them. According to the FAO, more than 75 per cent of the world’s fish stocks are either fully exploited, over-exploited, or recovering from past depletion.
Overfishing is not only affecting those whose diets depend on fish, of course. It is also creating huge gaps in marine ecosystems that are quickly exploited by opportunistic species. The shrimp and crab fisheries off the coast of Nova Scotia and Newfoundland are the direct result of the removal of large cod and haddock stocks through fishing.
While replacing one tasty marine food may not seem like much of a hardship, not all of the replacements for fish will be as delicious. In recent years, the fishing industry has shifted its focus down the food chain, taking larger numbers of small, plankton- eating fish like sardine and anchovy. This could be a dangerous strategy. Small fish are not only crucial to the survival of larger predatory fish such as hake, as well as birds and marine mammals – they also help to maintain balance in the species below them in the food chain. “If you remove small fish there is every possibility that other species in the food chain, like jellyfish, will have a good time of it,” says Tom Anderson, a marine ecologist at the National Oceanography Centre in Southampton, UK.
This is already happening in one of the world’s most productive fisheries, the Benguela current off the coast of Namibia in southern Africa. When Christopher Lynam of the University of St Andrews in the UK and his colleagues surveyed the area in 2003, they found that the ecosystem, which once supported large populations of sardines and anchovies, had been taken over by two species of jellyfish. The study estimated the biomass of jellyfish in the region at 12.2 million tonnes, more than three times that of mackerel, hake, sardine and anchovies combined (Current Biology, vol 16, p R492).
The reasons for these changes are complex. Shifts in climate, currents and sea temperature will have played a part, but a major factor is the collapse of the once abundant sardine and anchovy fisheries. In the late 1970s, the total fish catch was around 17 million tonnes per year. Now it is closer to 1 million tonnes. And since jellyfish eat fish eggs and larvae, as well as compete with young fish for food, the shift to a jellyfish-dominated ecosystem rather than a fish-dominated one may be irreversible, say the team.
Blooms of jellyfish have also appeared in the overfished waters of the Black Sea, Alaska, the Mediterranean and the Gulf of Mexico. In the Sea of Japan, overfishing of sardines and anchovies, plus blooms of phytoplankton caused by nutrient-rich coastal run-off, have led to a jellyfish problem of epic proportions: autumn blooms of the giant jellyfish Nemopilema nomurai, which can grow to more than 2 metres in diameter. In 2003 alone this jellyfish cost the Japanese fishing industry over $100 million, “clogging and bursting nets, causing high mortality of the catch due to venom, increasing the risk of capsizing trawlers and giving fishermen painful stings”, says Masato Kawahara, a marine ecologist at Hiroshima University in Japan.
Removing fish from an ecosystem may also have other consequences. In the Benguela current, the crash in phytoplankton-eating fish has also been linked to more frequent phytoplankton blooms (Ecology Letters, vol 7, p 1015). That can spell bad news: when the blooms die off, bacteria gobble them up, along with most of the oxygen in the water.
“The Aztecs are said to have eaten a kind of ‘cake’ made from the dried froth of blue-green algae”
Even overfishing large predatory fish could encourage these blooms. Zooplankton-eating fish thrive once their predators are gone, leading to a decline in their own prey. With fewer zooplankton to feed on phytoplankton, the latter can bloom unchecked.
The collapse of cod, haddock, hake, pollock, plaice and flounder fisheries off Nova Scotia have all coincided with an increase in phytoplankton. So has a reduction in the number of salmon in the north Pacific. And last year, Michele Casini of the Swedish Board of Fisheries in Lysekil, and colleagues, found a strong link between the collapse of cod stocks in the Baltic Sea in the early 1980s and phytoplankton blooms.
Squid, too, are increasingly thriving throughout the oceans. While changes in water temperatures may play a part, the main reason is the removal of their predators “Almost everything eats squid in the ocean – tuna, marlin and swordfish hardly eat anything else – so if you remove the squid’s predators, how can it not have an impact?” says George Jackson of the University of Tasmania in Hobart, Australia. And as squid grow quickly and live for less than a year, their numbers can rise rapidly if the conditions are right. “They’re the weeds of the sea,” he says.
The best-documented example is the Gulf of Thailand, which has been heavily overfished in recent decades. Here the Indo-Pacific squid Sepioteuthis lessoniana has moved in to fill the gaps in the ecosystem, forcing the fishing industry to adapt. “You see fishermen walking down the beach in Thailand with baskets of squid,” says Jackson.
Off the US coast, the Humboldt squid, Dosidicus gigas, has begun to expand its territory north from the east Pacific equatorial waters to the seas off central California. This has happened before, during El Niño years, when the water warmed enough for them to spread their range. The last time
this happened, in 1997-98, predation and competition from tuna and billfish sent most of them back south when the waters cooled. In the past five years, though, they have stayed put despite cooler seas, and seem to be thriving. Now they even threaten the Californian Pacific hake fishery.
If the outlook for today’s fisheries is as bleak as some suggest, we can expect to see growing numbers of gelatinous, rubbery and slimy creatures swimming or drifting through the oceans. So what will that leave us to eat with our fries?
Shrimp and crab aside, squid are likely to be the most palatable bet since they are already well established on menus worldwide. Larger species like the Humboldt squid are also commercially fished in Mexico, Peru and northern Chile. They yield a decent-sized steak and, as long as they are tenderised with lemon juice and not overcooked, they need not be tough or rubbery (see recipe online*). Nutritionally, squid are high in protein – about 16 per cent – low in fat and a good source of zinc, vitamins B2, B3 and B12, as well as some trace elements such as phosphorus, copper and selenium. On the downside, they are very high in cholesterol.
Jellyfish crunch
Compared to jellyfish, though, squid are positively nutritious and delicious. A common ingredient in Asian cuisine, jellyfish have been eaten for more than 1000 years in China, where they are often added to salads (Hydrobiologia, vol 451, p 11). In Japan they are served as sushi and in Thailand they are turned into a kind of crunchy noodle (see recipe online*). For those with a western palate, though, the taste and texture may take some getting used to. “I wouldn’t describe it as a sensation that would sweep the globe,” says Kevin Raskoff of Monterey Peninsula College in California. “It’s reminiscent of slightly tough strips of cucumber.”
Jellyfish are low in fat and high in copper, iron and selenium, but they are only about 5 per cent protein. Furthermore, they are typically prepared by being dried and salted so, unless a new approach is taken, jellyfish products could end up too high in sodium to become dietary staples (see table, left).
Each year, around a quarter of a million tonnes of jellyfish are landed worldwide. As well as China and Japan, there are small fisheries in Australia, India and the US. Cost remains a challenge: once caught, jellyfish have to go through a multistage treatment to reduce water content, decrease pH and firm the flesh – a process that can take up to 40 days. This, together with its unpredictable population and low nutritional value, makes further commercialisation a challenge.
Dried and salted, jellyfish can be added to salads or made into crunchy noodles
So while inventive locals in Obama, Japan, coped with a bloom of giant jellyfish in 2006 by turning them into sushi, soup and even novelty cookies, it is unlikely that they will replace fish as a major food source for the world. “If it’s a question of could we eat jellyfish, then yes we could, but the nutritional value is quite low,” say Raskoff. “I’d be concerned if they were the last things left on the menu.”
This leaves plankton as a possible fish replacement. The idea is not as odd as it first seems. After all, the Aztecs are said to have eaten a kind of “cake” made from the dried froth of blue-green algae, probably spirulina, that grew on the surface of Lake Texcoco. According to the accounts of Spanish conquistadores, it was highly nutritious and tasted like cheese. It is still eaten in a number of countries, including several in central Africa, where it is harvested from Lake Chad.
Marine phytoplankton, too, are packed with omega-3 fatty acids and trace minerals. Since their blooms tend to consist of mostly one species they could, in theory, be scooped up and turned into food. Even so, converting fishing trawlers to fish for algae would be unlikely to work in practice, says Peter Franks, a plankton ecologist at Scripps Institution of Oceanography in La Jolla, California. “Plankton blooms are dense – with up to a million cells in a litre of water. But a million cells would hardly make a phytoplankton cracker,” he says.
Besides, adds Franks, the practicalities of predicting where a bloom will occur and ensuring that the catch is not contaminated by the handful of species that are toxic would make it financially unfeasible. “I would not want to be running a business based on filtering plankton from the ocean as human food. You would be better off growing spinach,” he says.
Even squid, which look like a good option on paper, could be a risky bet as a major fishery, warns Jackson. “Squid are very much boom and bust,” he says, a characteristic that makes fisheries tricky to manage. “If there is a lot of food, they grow fast and reproduce early. But if conditions change, the population crashes.” He adds that “if you put pressure on squid populations, you’ll just create the same problem as we have with fish”.
Worm, though, dismisses talk of converting the global fishing fleet to seek out alternatives to fish. He points out that our fisheries are not quite finished, and says there are several instances where creating “no take” zones next to fisheries has allowed them to recover, making them more profitable than others where no such measures have been taken. And, he says, we are beginning to learn from our mistakes. Proposals to fish for krill off Nova Scotia have not yet been acted on because krill is such an important food source for other organisms, says Worm. “I think people are drawing a line in the sand. Doing this to a predator is one thing, but taking away the foundation of the ecosystem? That’s too risky.”
Worm is so confident we can turn the situation around that he is willing to bet
on the oceans of the future having more fish than we have today. “In 2048 I’ll be 80 years old and I hope I’ll be able to host a fish supper to celebrate,” he says. It is certainly not impossible, but it will take a seismic shift
in the way we manage the oceans. Without some serious changes, Worm’s seafood supper could be nutritious, it might even be delicious, but it probably won’t be fish. ■
Caroline Williams is a life sciences editor for New Scientist and based in Boston
MORE ONLINE
*See recipes and add your comments at www.newscientist.com/article/dn16654
摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
“可以预言，100年后的人类社会仍将“马照跑”。但人和马的关系大约还得调整。”
五环旗下的马蹄声（下）
英国利物浦安翠赛马场旁边的花丛中，长眠着一匹屡建奇勋的冠军马“红朗姆”。它从1973年到1977年，曾连续在全世界难度最大的英国国家大赛中夺得三次冠军和两次亚军。中国中央电视台记者蔡猛在采访“红朗姆”的驯马师金基尔.麦肯时问道，听说“红朗姆”去世后你像失去妻子一样难过？这位70岁的老人含着热泪回答，英国有2500万妇女，而“红朗姆”却只有一个。此言虽然值得非议，但却道出了骑师对赛马刻骨铭心的感情。1979年英国国家大赛前身患癌症的鲍勃.钱皮恩和受伤后被“判了死刑”的赛马阿尔丹提尼“相濡以沫”，人马同心，终于赢得1981年英国国家大赛的冠军。历史上留下了多少美丽、凄婉、悲壮的故事，记述了人和马的生死之交。作为最有灵性的动物，马可以在极限状态时仍然绝对忠于主人的命令，“知其不可为而为之”，奋不顾身，死而后已。好的骑手对马的感情如同亲子、密友和恋人。
摘自《奥运中的科技之光》，赵致真著。经赵致真先生授权，科学松鼠会网络发布，转载请注明。
“在所有哺乳动物中，马的眼睛是最大的，虽然看去炯炯有神，但视力却只有0.6左右并且对颜色十分迟钝。”
五环旗下的马蹄声（上）
马术是奥运会上唯一由人和动物共同参与的竞赛项目。当全世界的名马、上驷、良骏、神驹荟萃一堂，五环旗下震响着清脆激越的马蹄声时，奥运会便因此平添了磅礴气势和“龙马精神”。那些垂直障碍、伸展障碍、水坑障碍、组合障碍挑战着人与马的技巧、力量和勇气；典雅而华贵的盛装舞步被誉为“马的芭蕾”，展示了人马之间的神悟默契和灵犀相通；而“三日赛”是马术的全能项目，考验着人和马的“综合素质”与“绝对实力”。现代赛马运动起源于英国，1900年马术就在巴黎奥运会上占据了一席之地，不过早期只允许职业军官参加。直到1952年赫尔辛基奥运会，马术才对平民开放，并逐渐形成了“人不分男女，马不分公母”的竞赛模式。一百多年来，奥运会始终“马不停蹄”，著名的美国骑师迈克.普拉姆32年间参加过8届奥运会并接连“披金戴银”；德国“盛装舞步之王”让纳.克利姆克52岁上第6次在奥运上夺得金牌；法国驭手多里奥拉在两届奥运会上摘取桂冠。今天的赛马已经发展成为风靡全球、长盛不衰的娱乐和博彩产业链，每年创造价值数千亿美元。
原文链接：
http://www.newscientist.com/article/mg20126971.900-why-do-some-people-kill-themselves.html
A grand theory of suicide promises to answer this question once and for all, says Robert Pool
FOR a few months in late 2006 and early 2007, the woman who called herself kristi4 was one of the best-known members of the pro-anorexia community. As the administrator of a blog on LiveJournal.com, she dispensed advice, encouraged others and wrote candidly about her own struggles. Then, late one Friday night, after a series of entries describing what she was planning to do, kristi4 killed herself with an overdose of prescription sleeping pills, muscle relaxants and painkillers.
Her death was just one tragic data point in one of the most striking statistics in all of psychology. It has long been known that anorexia has the highest death rate of any mental illness: one out of every five people with anorexia eventually die of causes related to the disease. What has only now been recognised, however, is that a huge number of those deaths are from suicide rather than starvation. Someone who develops anorexia is 50 to 60 times more likely to kill themselves than people in the general population. No other group has a suicide rate anywhere near as high (Archives of General Psychiatry, vol 60, p 179).
Recently, psychologists have tried to explain why anorexia and suicide are so intimately connected, something which is helping to answer the wider question of why anyone would commit suicide. If this explanation holds up, it will give psychiatrists a new tool for screening patients and determining which of them are most likely to kill themselves, perhaps saving lives.
Suicide has always been a conundrum for psychologists and other researchers interested in human behaviour. Self-preservation is one of the strongest human instincts, so the drive to commit suicide must be even more powerful. But what causes it?
1 million
Approximate number of suicides worldwide each year
A century ago, both the sociologist Emile Durkheim and the psychoanalyst Sigmund Freud came up with sweeping explanations. Durkheim, not surprisingly, saw the roots of suicide in social factors, such as a failure to integrate into society, while Freud rooted his explanation in instinctual drives, particularly what he called the death instinct. More recent explanations have tended to focus on factors such as depression, hopelessness and emotional pain, but none of them have had much success in answering the fundamental question about suicide: why do some people kill themselves while others in seemingly identical circumstances do not?
Some progress has been made by crunching large amounts of data on suicide, says Harvard University psychologist Matthew Nock, who studies suicide and self- harm. Researchers have learned, for example, that suicide rates are rising and now account for 1.5 per cent of all deaths worldwide。
Suicide is the second leading cause of death among people aged 15 to 24, after vehicle accidents. Women are more likely than men to attempt suicide, while men are much more likely to succeed.
Most people who commit suicide have a mental disorder – anorexia, major depressive disorder, bipolar disorder, schizophrenia and borderline personality disorder are the most common, but an elevated suicide risk is part and parcel of many of the others, too. People who kill themselves also generally feel deeply depressed and hopeless at the time.
What the statistics do not tell us – and what psychologists most want to know – is exactly which people are most at risk. The vast majority of depressed, hopeless people do not commit suicide, so why do some do it?
In 2005, psychologist Thomas Joiner, a suicide specialist at Florida State University in Tallahassee whose own father committed suicide, set out to answer that question. By studying suicide statistics and paying particular attention to the groups with above average rates, Joiner believes he has found a common thread others have missed. “It was the first grand theory of suicide in quite a while,” says Nock..
In essence, Joiner proposed that people who kill themselves must meet two sets of conditions on top of feeling depressed and hopeless. First, they must have a serious desire to die. This usually comes about when people feel they are an intolerable burden on others, while also feeling isolated from people who might provide a sense of belonging.
Second, and most important, people who succeed in killing themselves must be capable of doing the deed. This may sound obvious, but until Joiner pointed it out, no one had tried to figure out why some people are able to go through with it when most are not. No matter how seriously you want to die, Joiner says, it is not an easy thing to do.The self-preservation instinct is too strong.
There are two ways people who want to die develop the ability to override the self- preservation instinct, Joiner argues. One is by working up to it. In many cases a first suicide attempt is tentative, with shallow cuts or a mild overdose. It is only after multiple attempts that the actions are fatal.
The other is to become accustomed to painful or scary experiences. Soldiers and police who have been shot at or seen their colleagues injured or killed are known to become inured to the idea of their own death. Both groups also have a higher-than-normal suicide rate. Similarly, doctors and surgeons who witness pain, injury and death are more likely to be able to contemplate it for themselves – the suicide rate for doctors is significantly higher than for the general population. Joiner describes this as a “steeliness” in the face of things that would intimidate most people.
Another group that displays steeliness are people with anorexia. Joiner had noted their heightened suicide rate in his original work, Why people die by suicide (Harvard University Press, 2005), but it wasn’t until later that he grasped the importance of the connection.
That realisation began to dawn in 2006, during a seminar in which two of Joiner’s graduate students, Jill Holm-Denoma and Tracy Witte, were listening to him describe the risk of suicide among people with anorexia. Witte observed that the high suicide rate had two possible explanations. Perhaps people with anorexia were no more likely to attempt suicide than people with other mental disorders, but the anorexia had so weakened their bodies that their suicide attempts were more likely to succeed. Alternatively, perhaps anorexia had so inured them to pain that they were more capable than others of doing what was necessary to kill themselves.
According to Joiner’s hypothesis, the second explanation should be correct. So Holm-Denoma set out to test the prediction. She examined nine suicides chosen randomly, and what she found told a very clear story.
“These people would have died regardless of their body weight,” she says. “We were just astounded by the lengths to which they went to make sure they were successful.” Three jumped in front of trains. Two hung themselves. Two took large drug overdoses. One poisoned herself with sleeping pills and toilet bowl cleaner. And one locked herself in a gas station restroom and set fire to a trash can that produced enough carbon monoxide to asphyxiate her. Nine cases, of course, are not enough to prove the point, but the fact that all took such drastic measures to kill themselves says something (Journal of Affective Disorders, vol 107, p 231).
Anorexia offers a “perfect storm” of the factors laid out in Joiner’s hypothesis, Holm-Denoma says. Social isolation is likely because people with anorexia avoid any interactions that might involve food – so that means not going out for a meal, no movies (the popcorn might be too tempting) and no stopping by a friend’s house. The result is the “thwarted belongingness” that Joiner describes as a key factor in suicide.
Then there is the feeling that they have become an intolerable burden to their family and friends. One popular approach to treating anorexia in children, for example, involves having a parent oversee their child full-time.
Most importantly, anorexia means becoming inured to pain. Merciless starvation leads to intense and painful hunger pangs and major headaches. Osteoporosis is common, making fractures more likely, not to mention the chest pains caused by heart damage. Kristi4’s blogs in the month leading up to her suicide show this perfect storm at work.
It is one of the strengths of Joiner’s explanation, says Nock, that it makes testable predictions such as the one spotted by Witte. For example, it should be possible to develop psychological tests to measure how much of a burden people feel, or how thwarted, and then use them to predict who will commit suicide. It should also be possible to examine rates of suicide among various groups with the characteristics Joiner is talking about.
Those tests are slowly taking shape. Recent work by some of Joiner’s students has shown that people who feel they are a burden and also experience thwarted belongingness are more likely to have suicidal thoughts (Journal of Consulting and Clinical Psychology, vol 76, p 72). A second study found that “painful and provocative events”, such as shooting a gun or getting into a fight, tend to increase something Joiner calls “acquired capability” – a written test that measures someone’s ability to hurt or kill themselves.
Meanwhile, University of Minnesota psychiatrist Scott Crow has studied suicide that they, too, kill themselves at a much higher rate than the general population. Crow has found a four to six-fold increase in suicides in this group. Bulimia starves the body at some level, as indicated by various biochemical markers, so people with bulimia may well be inured to pain in much the same way as those with anorexia.
Even though the evidence is all pointing in the same direction, Joiner says many more tests will be needed before his ideas can be accepted as a general explanation for suicide. “It’s a start,” he says of the evidence assembled to date. “But we need something much more systematic.”
Ultimately, he says, a better understanding of why people commit suicide should help clinicians better assess who is most at risk, and find new ways of preventing people from killing themselves. Long-term psychotherapy, for instance, could help chip away at a person’s fearlessness and lessen the likelihood that they will commit suicide.
But as long as people steel themselves to pain, as long as they feel isolated and a burden to others, Joiner’s theory predicts that suicide will be with us as well. ■
Robert Pool is a writer based in Tallahassee, Florida
原文链接： http://www.newscientist.com/article/mg20126971.800-rise-of-the-robogeeks.html
Human brains don’t work by magic, so whatever it is they do should be doable by machine
Forget the likes of Terminator and Wall·E – the first intelligent robot
to stalk this earth could be seriously square, says Michael Brooks
IN December, philosopher and artificial intelligence expert Aaron Sloman announced his intention to create nothing less than a robot mathematician. He reckons he has identified a key component of how humans develop mathematical talent. If he’s right, it should be possible to program a machine to be as good as us at mathematics, and possibly better.
This is no mad quest, insists Sloman, of the University of Birmingham in the UK. “Human brains don’t work by magic, so whatever it is they do should be doable in suitably designed machines,” he says.
Sloman’s creature is not meant to be a mathematical genius capable of advancing the frontiers of mathematical knowledge: his
primary aim, outlined in the journal Artifical Intelligence (vol 172, p2015), is to use such a machine to improve our understanding of where our mathematical ability comes from. Nevertheless, it is possible that such a robot could take us beyond what mathematicians have achieved so far. Forget robot vacuum cleaners and android waitresses; we’re talking about a machine that could spawn a race of cyber-nerds capable of creating entirely new forms of mathematics.
The field of artificial intelligence has promised much before, of course. Early researchers thought it might open a fast-track to understanding consciousness, and there were claims that artificially intelligent computers and robots would change the
world. The truth has been more prosaic. AI has done some clever things, such as give us great chess players and voice recognition software, but it hasn’t delivered a revolution.
But when it comes to mathematics, we can’t rule one out yet, says Alison Pease, who researches the philosophy of mathematics at the University of Edinburgh, UK. Pease teaches computers to do mathematics using AI programs, and thinks a computer really could astonish its programmer with a new mathematical insight. “Ours hasn’t yet, but there is no reason why one shouldn’t in the future,” she says.
The first concrete step towards this scenario came with a program written by Simon Colton, now at Imperial College London. The program was named HR, in honour of the mathematicians Godfrey Harold Hardy and Srinivasa Ramanujan. It looked for “interesting” sequences of numbers (New Scientist, 24 February 2001, p 13).
Some of HR’s discoveries have even been published – and HR, rather than Colton, got the credit. Though they might not look like cutting-edge advances, they could yet prove important. “I always refer to HR’s work in number theory as recreational mathematics, but things that look insignificant can end up being hugely significant and interesting,” Colton says.
Pease and her colleagues Alan Smaille and Markus Guhe have recently taken things further. In their Edinburgh computing laboratory they have been running virtual mathematics conferences, populated entirely by digital mathematicians (see “Reinventing the conjecture”, page 36). So where might that lead?
All the way to significant new mathematics, Sloman hopes. His idea is that our key mathematical capabilities are formed in childhood. So rather than engineering a fully fledged mathematician’s brain, Sloman thinks we should build a robot with a child-like brain and let it grow into its mathematical destiny.
There’s just one problem. How do we know which of our childhood capabilities equip us for a life of juggling numbers?
Sloman is busy gathering clues. The answer, he reckons, lies in the spatial awareness skills that children must acquire in order to negotiate their world: skills such as knowing that a toy train pushed into a tunnel will come out the other side. Or that a jigsaw puzzle piece fits its gap only when correctly oriented. Or that the number of toys on the sofa does not depend on the order in which you count them.
From the minds of babes
You might be surprised to learn, for instance, that you grasped the topological concept called “the transitivity of containment” when you were still a toddler. Stacking cups, one inside the other, you learned that the small cup would fit not only in the medium-sized cup, but also inside the big one.
Transitivity of containment, like other geometrical and topological concepts, is learned through experience. “There are hundreds, if not thousands more examples of things a child learns empirically, that are later seen to be theorems in topology, geometry and arithmetic,” Sloman says.
At some point, children make that jump for themselves. As toddlers, we soon translate our experiences into general theorems which we use to make predictions.
Take the train-through-a-tunnel example. By repeated experiences like this, toddlers
learn the basic properties of rigid rods. That’s why a 3-year-old carrying a long broom handle can negotiate a narrow corridor, turn a corner at the end without getting the broom handle caught in the vertical bars of a stair-gate, then make adjustments so that the handle will go through the next doorway. “There is a switch from learning empirically to realising it has ‘simply got to be like that’,” Sloman says.
And here is the key to the emergence of the mathematical mind. “The mechanisms that make that possible in a child are related to what makes it possible for them to go on to become a mathematician,” Sloman says.“A lot of abstract maths has its roots in our ability to think about space and time, processes, and interactions between processes and structures.”
Sloman has gone back to basics, to watch how children learn to navigate the world around them. He is building an archive of observations of children performing pseudo-mathematical tasks. These navigational and object manipulation skills – or at least the ability to acquire them quickly – must be encoded in the genome, Sloman reckons. And that means they could be encoded in a machine.
Sloman is still a long way from designing his robot toddler. Once he has catalogued the abilities of children at various stages of development, he still has to work out how to understand the mathematical implications of those abilities, then represent them in some form of computer code. “Information needs to be encoded in some form in order to be usable,” he says. The gargantuan scale of the task means his aims are necessarily modest: at this stage he is simply trying to show a link between spatial manipulations and the basics of mathematics. Anything more would be a bonus. But just how big could that bonus be? Could a robot mathematician really do something interesting?
“In principle, yes, absolutely,” Pease says. But, she adds, the story-so-far tempers her optimism. “Of all the scientific and mathematical discovery programs I’ve looked at, nothing has yet made a big discovery.” At the very least, she says, that means there is a long way to go.
Colton thinks there is every reason to believe computers could produce something interesting to mathematicians. “Software is already producing theorems of value to maths,” he points out. “Not of huge value, I admit – but then the average student or mathematician isn’t producing anything of huge value either.”
He and his team are convinced that computers can be genuinely creative. “Creativity is a very loaded word: people like to think it’s a uniquely human attribute,” he says. “The fact is, computers doing maths are more likely to be creative than, say, an undergraduate student, in many ways.”
Others are sceptical of this view. Computers are a useful tool, says Rafael Núñez an expert on mathematical cognition at the University of California, San Diego, but the sense that computers can invent mathematics is an illusion. Though it looks like we can make progress by programming machines to do mathematics, he reckons there can be nothing in these machines that isn’t pre-ordained by human mathematical concepts. “For me, it’s like computing the decimal places of pi,” Núñez says. “Once we have decided what the right rules are, we’re just using the computer to crunch numbers.”
Sloman thinks Núñez’s view is too narrow. He points to “evolutionary algorithms” as a reason for optimism. This innovation allows a computer to evolve its own programs by producing lots of them, testing them against a goal criteria, and then selecting and “interbreeding” the best ones. It has allowed computers do things that nobody programmed them to do. “In some cases no human even knows how they do what they do,” Sloman says. Aerospace and automobile designers have been using evolutionary algorithms since the late 1980s to optimise aircraft parts and streamline their designs. Even city traders are using them to buy and sell shares ( New Scientist, 28 July 2007, p 26).
Evolution has a few million years head start on us in developing brilliant mathematicians, of course, but at least we’re now in the race. “Our big discovery would be how do we do mathematics, rather than how do we write a program that can generate really new mathematics,” says Pease. “But hopefully one would lead on from the other.” ■
Michael Brooks is writer based in Lewes, UK, and author of 13 Things That Don’t Make Sense (Profile)
