科学的运动

Irregular bedtimes in young children may be associated with reduced academic performance, a UK study has shown.

Professor Yvonne Kelly, from University College London, followed the progress of over 11,000 British children born between September 2000 and January 2002. The regularity of each child's bedtime was recorded at ages 3, 5 and 7, with the exact bedtimes logged at ages 5 and 7. At age 7, each child also took reading, maths and spatial-skills tests.

Boys and girls without regular bedtimes, the team found, performed less well in academic tests than individuals who had a more regular schedule. Girls who experienced unusually late or unusually early bedtimes - after 9pm or before 7.30pm - also had reduced academic performance which was on par with children with irregular bedtimes.

The critical age for this effect appears to be three years.

Both girls and boys who lacked a regular bedtime at this age had impaired performance in cognitive tests at age 7, while children who had a regular bedtime at age 3 but an irregular bedtime at a later stage did not show a subsequent dip in academic performance at age 7

The effects of an irregular bedtime also appear to be cumulative, with girls who consistently had an irregular bedtime at ages 3, 5 and 7 performing worse academically than their peers who only experienced irregular bedtimes at two of those ages.

The reason an irregular bedtime at an early age leads to reduced academic performance in young children is not clear. Disrupted sleep may, Kelly and her colleagues speculate, result in less optimal brain development at an early age. They also suggest that children who lack sleep at an early age may have reduced acquisition of academic skills on which they can build in later years, thus leading to impaired performance.

However, there are several other factors which, the group propose, might also have an effect on the quantity and quality a child's sleep, including overcrowding, extracurricular activities or whether they had any siblings. The discipline of a regular bedtime might also reflect on the parental input to a child's upbringing.

Once the group took these factors in to account, they found that the negative impact of an irregular sleep pattern appeared to be greater in girls than in boys.

We all find ourselves having a chat to our cats and dogs at home sometimes, but they don't normally talk back. This week however, a paper in PNAS looks at communications between dolphins that suggests that they used learned names to address one another. Kate Lamble spoke to Vincent Janik from the University of St. Andrews.

Kate - So Vincent, what have you discovered?

Vincent - We've studied signature whistles of bottlenose dolphins for a while now and these are very unusual signals, in that every animal develops its own specific sound early in life and then uses that to broadcast where it is and who it is. These sounds also are occasionally copied by other dolphins and when we first found that, we thought that this might be a kind of labelling system or as has been discussed as a kind of naming system perhaps. In subsequent studies, we looked at who copies who and it turned out that it's mainly animals that are very close to each other like mothers and calves or also close associates.

In this a new study now, we've put this to the test by going out into the wild and playing back signature whistles to animal's here off the east coast of Scotland. What we really wanted to do was to find out whether we can address one animal just with a copy of its signature whistle. So, for that to be the case, we had treatment calls which were the signature of animals, but also other whistles from their repertoire and signature whistles from other animals. The result of the study was that the animals really only responded when we copied their own signature whistle, but did not to all the control sounds.

Kate - And you sent us a few of those signature whistles over. (CLIP) Those two whistles were obviously very different. How do we know that those are signature whistles as opposed to any other sort of random collection of clicks?

Vincent - This is an interesting question because indeed when you have an animal in captivity for example and you can isolate it from the group then the signature whistle is the most common whistle that the animal makes, it is producing it almost constantly. Now in the wild, this is a little trickier. We do know that about half of the whistles they produce are signatures, but the other half, other kinds of whistles, the way we found out what the signatures were in these wild animals here was using a study that we published earlier this year, showing that you can find out what signature whistles are by looking at the specific temporal patterns of whistles. So, if dolphins repeat whistles then the interval between these whistles for signature whistles have very specific values and you can look for those and you can identify then which of the whistles are signature whistles and which ones are not.

Kate - You mentioned that these whistles are learned by the animal when it's quite young. So, does each dolphin create its own nickname in a way?

Vincent - Yes, so one of the big differences we called as names to humans is that the animals develop them themselves, so they're not given to them. The way it happens is it is kind of a creative process in that the animal listens to other whistles in its environment and then maybe chooses one of the model, but then starts to change their whistles efficiently so that it becomes a new signal. So, the animals really do label themselves first in a way and then produce that whistle repeatedly when they are trying to contact the group. And only through this repetition do other members of the group of course learn that this new signal stands for a particular individual.

Kate - How do we know what these whistles are used for? Are they just being used to say hi and let other animals know that they're there or they're used as a warning like we hear other animals sort of scream warnings? Baboons tell other baboons that leopards are near for example.

Vincent - These whistles really just label the identity of the animal, so there isn't any additional information in the shape of the whistle. Now, there is of course additional information always in the voice of an animal, also of a human when we communicate. So, if an animal is afraid for example, then certain parameters change and those can also be extracted from receivera and they can recognise what state the animal is in. And so, through that, the animal can also convey for example whether there is danger eminent.

However, these signature whistles do not function the same way as alarm calls where they label particular predators for example. These whistles really just kind of stand for the individual that's producing them. For other calls that the animals might have, there are food calls that we found as well which kind of seem to be standing for food. But we need further research to see to what extent they really are labels rather than just a kind of excitement call by animals who encounter large schools of fish.

Kate - Is this naming unique to dolphins?

Vincent - The only other animal in which we find something comparable perhaps - apart from humans - are perhaps parrots. There's various studies from parrots that suggests that they may also have a signature call system that works in a similar way. But there's only very few studies so far and this is one of the rare cases where we actually have more information about dolphins than we have about birds even though birds as a group are studied much more extensively than dolphins.

Kate - Why does dolphin communication in particular fascinate us so much?

Vincent - I think there's different reasons for this fascination. On the one hand, people are fascinated with dolphins because they are beautiful animals and you encounter them in the wild.

The other fascination is the scientific one which really comes more from the fact that these animals have these advanced cognitive skills which really rival those of the non human primates. It is a puzzle to find this in an animal that clearly evolved in a completely different environment from ours. So, to have similarities in communication skills between humans and dolphins, like vocal learning for example, or also in other skills like social memory and recognition tasks is kind of a surprise in such a uniform environment.

What it really tells us and one of the interesting aspects about this is probably, a lot of these skills actually evolved primarily in social contexts rather than in perhaps tool manufacturing or tool use context which is one of the other possible origins of advanced cognition that we find in primates.

凯特——所以,你认为我们的理解how dolphins communicate can help us understand how our own language evolved?

Vincent - Yes, I think these comparative studies with animals that are quite far away from our own lineage are very useful in highlighting what could perhaps be common reasons for the evolution of complexity. In this case in particular, in communication but I think also beyond this in cognition in general. The fact that dolphins don't have opposable thumbs, don't produce complex tools is something that kind of hints at the more dominant role of social aspects.

Kate - What are the next steps in your work, now that you understand the role of these signature whistles?

Vincent - One of the interesting observations we've made is that if you follow a group of dolphins, every so often, you hear signature whistles of animals that aren't present in the group and one of the next questions really is, whether these are attempts of the animals in the group to find these other individuals or whether they perhaps really use them as referential labels to exchange information about third parties.

We're quite a long way away still to kind of make that discovery I think if it's there, but I think it's a very interesting question to see to what extent perhaps these learned signals could serve as truly referential signals which could only be shown if we show that they are conveying information to a dolphin about another dolphin.

Close study of the genome of the oil palm tree could result in significantlyincreased palm oil yield, a paper published in the journalNaturethis week has revealed.

Palm oil is one of the most commonly used edible vegetable oils, accounting for 45% of worldwide consumption. There is also a growing market for palm oil as a biofuel.

However, recent years have seen an increasing pressure on oil palm growers to increase their palm oil yield without increasing the land on which the oil palm is grown. This is particularly apparent in countries such as Malaysia - the world's second biggest producer of palm oil - where the area of land available for agriculture has been restricted in order to conserve the country's rainforest.

这个问题的答案很可能躺在DNA of the oil palm itself. Using the recently elucidated full oil palm genome sequence, a multinational group, led by Professor Robert Martienssen and Dr. Ravigadevi Sambanthamurthi, have identified a gene in the plant which is responsible for the thickness of the shell of the oil palm fruit. Plants with two copies of this gene - which has been named SHELL - have a particularly thick outer coating. In contrast, plants which possess no copies of the gene lack any kind of outer layer.

Most importantly, it has been noted that plants that possess only one copy of the SHELL gene have a larger fruit with a thinner shell. These plants produce around 30% more palm oil per metre of farmed land than either their thick-shelled or shell-less siblings.

Previously, identification of these higher yielding plants took 6 years, as farmers had to wait until the plant had grown sufficiently to start producing fruit. This is clearly a slow process, and has resulted in oil palm plantations which contain a mixture of high and lower yielding plants.

The hope is that future growers will be able to genetically screen palm oil plants at an early stage and then select for those plants will have the highest palm oil yield. In this way, farmers would be able to see an up to 30% increase in their palm oil production without increasing the area on which they farm.

We put this question to Dr Phillip Broadwith, from the Royal Society of Chemistry...

Philip Broadwidth - Well David, that's a very good question.

Basically, there are two kinds of things that you could think of when you're talking about stickiness. When you're talking about things like glue, sort of a super glue, there's often a chemical reaction going on and when you're talking about things like honey, it's not an actual chemical reaction but just interactions between the molecules.

So, for example, super glue is made from something called methacrylate and in the bottle, that's fine, but when it comes into contact with water, either in the air or on your fingers, then it starts a chemical reaction which bonds all of the molecules together into big long chains which is what sticks everything together, then the chemical bonds hold everything together.

It's the same for lots of other kinds of glue. But things like sugar or honey, which just feel kind of sticky, that's generally down to forces that are not actually chemical bonds, but instead interactions between molecules.

Some of those are "hydrogen bonds", which are the same interactions as between water molecules. But a sugar has lots of sites that can hydrogen bond, which means that there's a more cooperative effect. It's like putting lots of hooks into a surface and then trying to pull on it. If you've only got one, it's relatively easy to pull away, but the more hooks you have all acting together, the more sticky something is.

另一个轮流的ative to that is something called Van der Waals forces, which are generally to do with the surface area; it's a charge interaction. Things like gecko's feet have exceptionally high surface area, which is what allows them to stick to glass for example.

That's also the same forces that are in play when you look at things like post-it notes. They have a material on the back which is in very small spheres. When you press it down, that increases the surface area and allows it to stick to the paper, but it's not such a strong interaction that when you peel away the post-it note, it leaves the paper that you'd stuck it to intact.

It's not just technology on the pitch that's helping athletes change their game.After a fantastic couple of years for sport in Britain, we've heard a lot about the nutritional requirements of high performance athletes. From Michael Phelps' 10,000 calories a day diet to criticisms that Chris Froome might not have been eating enough in the year preceding his Tour de France victory.

But what effect does what we eat have on our physical performance? Could changing our diet really make us run faster or jump higher? Kate Lamble spoke to Dr. Phil Watson from the University of Loughborough.

Kate - So Phil, what do athletes need to watch in their diet?

Phil W. - It's a difficult question to answer because athletes are so diverse. The nutritional requirements of a 50-kilo gymnast for instance would be considerably different to the nutritional requirements of a 100-kilo heavyweight rower or Mo Farah running the 10,000 meters. So, there's certainly no one-size fits all. There's certainly evidence that high level athlete's performance will be impacted by what they eat. But you're not going to make a mediocre athlete an Olympic champion by eating correctly, but certainly, you could lose that Olympic gold medal by eating poorly.

Kate - Is there anything in particular that will help most athletes perform on the day? What should you be eating just before your race?

Phil W. - Well, researchers over the past 100 years has supported the idea that carbohydrate is important to performance certainly in a more prolonged event. So, something like the Tour de France or a marathon or the 10,000 meters that I mentioned previously. Carbohydrate, we obtain that from a variety of foods, things like pasta or rice, potato and sugary type foods. Carbohydrate is important because it's the primary fuel for exercise. So certainly, the evidence suggests that carbohydrate is important.

The other dietary component that's kind of persisted over the years obviously, dietry fads come and go, and you see these fad diets, but the other staple of sports nutrition is fluid. We lose fluid as we exercise particularly when we exercise in the heat. We sweat, we perspire, we lose fluid from our body and it's important that we replace that.

Kate - As well as a dietary plan, professional athletes also often take supplements. Why do they do that?

Phil W. - Well, there's a number of reasons for that. The most apparent reason is to improve their performance. There's a little bit of evidence that some supplements do that. A substance called creatine for instance has consistently shown to improve strength and power in those sorts of athletes. Caffeine is another supplement that has consistently been shown to improve performance. There are a few 'new kids on the block' substances like beta alanine, beetroot juice which there's a bit of growing evidence now to support their use.

Kate - Talking about beetroot juice, one of our team members is a very keen rower and she's been bringing in these beetroot juice supplement drinks that they've been giving out. Why particularly do we think that that might be helpful to athletes?

Phil W. - Beetroot is rich in dietary nitrate. Nitric oxide is very important for the body for a number of reasons. It regulates blood flow and it's important in muscle metabolism as well. Research over the past 4 or 5 years coming out of the University of Exeter has really shown that by ingesting beetroot in these beetroot juice shots that have become popular, you increase dietary nitrites which is a product used to generate nitric oxide within the body and it does certainly seem to improve performance.

Kate - Some of these supplements you mentioned earlier as well like caffeine are obviously also drugs. Where is the difference between the supplements that we take to help our performance and the supplements which we now consider in certain sports to be prohibited aids that go beyond what we normally eat?

Phil W. - There actually a very fine line. Caffeine for instance was on the World Anti-doping Agency prohibited list up until 2004 and you were allowed a certain urinary level of caffeine. Above that, you would be banned for using too much. My PhD supervisor, Professor Ron Maughan used the adage that, if it works, it's probably banned and obviously, there are some exceptions. So, caffeine and creatine are two that have hung around and have persisted in terms of nutrition.

Kate - We hear a lot about athletes who were banned for doing illegal substances or substances that are prohibited in their sport and some of them say, "I didn't know it was in the supplement that I was taking. I didn't know it was within my diet." Why is that the case? Why are they so confused about what they're consuming?

Phil W. - It's an interesting one. So, the World Anti-doping Agency rules are very explicit and strict liability applies. So, if you test positive, you can't point a finger and say I don't know. That doesn't stand up in court. But there has been a number of cases over the last I'd say, 10 to 15 years of athletes testing positive and going through that exact same scenario. They say, "I didn't take anything. I'm innocent." And then a study conducted in Germany a few years ago now, almost 10 years ago analysed dietary supplements brought from all over the world and found that some of those supplements were actually contaminated with steroid prohormones - precursors of anabolic steroids. And these substances weren't included on the label.

So, the authors of that particular study concluded that there's cross contamination occurring and this contamination could lead to positive doping tests in athletes. Certainly, some of our research has demonstrate that very trace amounts of these pro-hormones substances added to a dietary supplement can cause an athlete to test positive. So perhaps there is some link there.

Kate - When you talk about precursors to steroids, is that something that is actually a steroid or is that something that later gets turned into it somehow?

Phil W. - Yeah, it's a substance that later gets metabolised into a steroid. So, some of the substances are made available as dietary supplements, particularly to the body building industry, to the guys who are trying to get massive and look good on the beach. There's actually very little evidence that they do enhance muscle growth, but the body builders like the idea that, "I'm going to take a steroid precursor and that will make me grow muscle faster." So, these supplements are on the market and yeah, there's some evidence that the company that are making these types of supplements, there's some degree of cross contamination occurring and that's probably what's led to some of these positive doping cases.

Kate - By this point, sports nutrition has become a very exact science and we all hear about how a sports nutritionist is embedded into almost every professional sports team. Where can we go next? What's the next stage in us, helping develop nutrition that can help our athletes?

Phil W. - I don't know if sports nutrition and sport science has been slightly slow to adopt other areas of science, but in the last 10 years, molecular biology has become a big explosion area within exercise, physiology and sports nutrition.

So, we're really starting to understand some of the molecular processes going on within the muscle. The signalling that tells the muscle to grow in a certain way and that's being used by sports nutritionists now to look at the interaction between diet and training to try and maximise the training games from the given bout of training.

So, something that has become popular in the last couple of years and some of your listeners may have heard of it is the idea of train low, compete high and that means you train with low carbohydrate availability and then you compete with high carbohydrate availability. That seems to be beneficial because training with low carbohydrate stimulates a greater adaptive process. So, your body is under more stress during the training session. Your body responds to that stress and you seem to get greater training gains. Now, you can't undertake all your training sessions in this low carbohydrate situation because eventually, you'll breakdown and it's difficult to maintain the intensity. So they'll perhaps do two sessions in one day, one session with high carbohydrate availability which allows them to really push hard and then one session with low carbohydrate availability which puts this additional stress in the body and seems to enhance the adaptive process to trainings.

Hawkeye claim that their system is accurate and reliable, but science journalistNic Fleming warns that definitive calls will always be an impossible goal. Ginny Smith asked him about his point of view.

Ginny- So Nic, Hawkeye seems like quite a good way of preventing arguments in sport. What is it that you think the problem is with the technology?

Nic - It can be used obviously to replace a human referee. However, all I'm really saying is that if we do that, when you screen recreations using Hawkeye, I think there should be something on the screen to acknowledge that it's not a 100% representation of reality that there is a level of uncertainty and there's always going to be some inaccuracy because it is just a re-creation, a measurement. I think it would be very useful for that to be an acknowledgement of that on screen.

Ginny - So, at the moment, we use human referees and that sort of thing and of course, they're not going to be accurate. So, Hawkeye is going to be an improvement on that, so why do we need to point out to people that it's not accurate?

Nic - Well, because as things stand, technology of these kinds are obviously playing a larger and larger role in our lives. I think it's important that we have a mature relationship with some of these technologies. There is a danger that if you watch a Hawkeye replay from tennis for example, when I saw that a couple of years ago, when I was watching those, I would assume that that was an accurate representation of reality and I believe that that's what most people think when in fact, that's not the case. There's always going to be inaccuracy there. I just think that it's important that we use technological tools in an adult way and we understand their limitations and we don't just bow down to them and assume that they are always going to be correct and accurate, that we just acknowledge that there is an uncertainty there.

Ginny - So, how accurate would something have to be for you to accept that it was accurate? So, Hawkeye claim that their tennis system can predict up to 3.6mm which is tiny compared to a tennis ball. Is there really any difference there?

Nic - That's right. Well obviously, I mean, in terms of football, the big controversy was in 2010 and the Frank Lampard goal that must've been close to a meter over the line, looking at the video footage and obviously Hawkeye would've done better than the referee there and would presumably in 19 out of 20 other cases.

But there's a danger as we go forward when we're going to be able to produce footage that looks like real video footage with computers. And for political economic usages, there's a danger that people are going to end up being fooled by some of that footage. So, when we have these representations, I think it's important that we know what is real footage and what isn't. Things are going to become more and more realistic. So, we can all agree that we're going to use the technology and that that could be more accurate than the referee, but let's not pretend that it's 100% accurate.

Ginny - I think the only problem with that is that as humans, we find it quite difficult to understand uncertainty. So, if someone tells you that this is the answer but we're not certain that it's the answer, people will tend to assume that that means that it's wrong. Could that not lead to meaning more arguments?

网卡——好吧,我的意思是,这真的使我的另外一些er point really which is that, in a lot of scientific debates, that are in the public eye, be that sort of nuclear power or genetic modification or climate change, the media is constantly trying to fit science into a yes/no equation. Science isn't about yes/no's it's generally about probabilities. It's scientists saying, "We've got a model and we're 98% sure that this is going to happen." But this is constantly simplified. So, I suppose the other argument is that, if we can be a bit more open and mature in the use of tools like Hawkeye, if we can say, "Look, this is going to be much better than a human referee. However, there is an uncertainty." Perhaps that would help to spread the message amongst lots more people that in science, there is uncertainty and we have to be able to cope with uncertainty. We shouldn't pretend it's not there. That's my concern. We're pretending that uncertainty isn't there. Let's not patronise people in that way. Let's be upfront with people.

Ginny - So, we can kind of use these sports as almost a training ground to help people understand uncertainty in bigger questions as well.

Nic - Absolutely, yeah.

Ginny - And the most important thing when it comes down to it in sport is not actually that the call is correct 100% of the time, but that it's unbiased. So, at least with these electronic judges, they're unlikely to have a leaning one way or another.

Nic - I guess that's the case, yes. But then I mean, there are other people who will oppose these technologies for other reasons. I mean, a lot of the interest in sport is the drama, the controversy, the argument, the discussion, maybe in the pub afterwards. That's another argument that some people make against the use of these sort of technologies.