QnA: Diabetes, Driving and Dodgems
The Naked Scientists tackle the medical musings and chemical queries you've been sending in. Joining Chris Smith was astrophysicist Matt Bothwell, chemist Peter Wothers, psychologist Helen Keyes and physiologist Sam Virtue.
In this episode
07:54 - Planetary Life: Does size matter?
Planetary Life: Does size matter?
Michalec got in touch on the forum, Chris Smith put this sizeable situation to Astrophysicist Matt Bothwell...
Matt - So I really like this question. I think we should start with the caveat right at the beginning which is that we only know of life on one planet, which is earth, so as much as we are going to be trying to make educated guesses they are still kind of hypothetical situations. That being said the laws of physics do let us make a pretty educated guess which is that size does matter. And that the direction it goes in is bigger planets should have smaller animals. The reason for that is just because of gravity, so the bigger animal is the more massive it is the more it has to fight against gravity to hold itself up and so on a big planet with really strong gravity a really massive animal is going to be doing really really badly. You can see an example right here on planet earth: the biggest land animals that ever existed were dinosaurs but in the ocean where the buoyancy of the water slightly counteracts the force of gravity. It kind of simulates a low gravity environment almost. And so ocean creatures like whales can be much much bigger than any land creatures so we would definitely expect big planets would have small animals and vice versa.
Chris - There's also another possible effect to superimpose on this isn't there which is you get this phenomenon here on Earth called island dwarfism. Not Ireland as in where Helen comes from, as in an island surrounded by ocean, which is where you have a small landmass where the resources are limited. You tend to have smaller animals that are better able at not exhausting those resources than say a big animal which would munch its way through all the vegetation very very quickly and so in the same way that we think certain other animals have shrunk over evolutionary time and they've been dwarfed in that way. There's evidence that humans or human ancestors; this has happened with the island of Flores where the Homo floresiensis - these hobbit people - actually were thought to have evolved and are in a limited area and therefore they may have been forced to become small.
Matt - That's really interesting I think I guess on a planetary scale a planet would have to be very very small indeed for that kind of effect to kick in and so I think a complete lack of gravity might be a problem before limited resources.
10:13 - Are motorcyclists more risk prone than car drivers?
Are motorcyclists more risk prone than car drivers?
Chris Smith put this risky question from Katy to Anglia Ruskin psychologist, Helen Keyes.
Helen - There is a bit of a misperception here. So motorcyclists are certainly more vulnerable road users than drivers, in fact, motorcyclists are ten times more likely to be involved in a fatal accident than car passengers are. But it's not necessarily motorcyclists that are at fault here. So there's two reasons that drivers tend to hit motorcycles and they're to do with what we call look but fail to see errors. So this is when a driver looks up the road, a motorcyclist is coming and they see it, but they fail to notice it or take the motorcyclist into account. It's two reasons this happens. One is just straightforward visual perception. We just call it conspicuity: how conspicuous the motorcyclist is, and it just doesn't stand out against its background in the same way a car does. There’s been a really nice solution to this problem which is the inclusion of daylight running lights on motorcycles, or DRLs, which are lights that are always on during the day and we know that this can increase their visibility by up to 40% so this is fantastic. But I’m much more interested in the other type of error, the other look-but-fail-to-see error, which is cognitive conspicuity error, which is when drivers see the motorcyclist but almost don’t register the motorcyclist. This only happens with experienced drivers, so an experienced driver is much more likely to fail to spot a motorcyclist than a novice and that's quite interesting.
Chris - That sounds paradoxical isn't it.
Helen - It does! And it's because our brains are so good at using heuristics or relying on patterns that have worked before and we get - it’s not really lazy it's economical! So the brain is a very clever thing, and experienced driver who are used to looking up the road, seeing cars, taking them into account, so it's almost like we are most cognitively sometimes don't see the motorcycle or the cyclist or pedestrian because we're not expecting to. So it would be quite good if we could maybe increase cognitive awareness of motorcycles, not just visual perception.
Sam - On that, does make cyclists safer in Cambridge than in an equivalently sized city because there are so many of them relative to another city that motorists are actually more aware that they're likely to be there.
Helen - It absolutely should, so if we’re going by the cognitive conspicuity theory. It absolutely should make them more visible cognitively to drivers.
Chris - Yes and if we go by the death rate an accident rate in everything else does it bear up?
Helen - It does absolutely. Statistics are better than other parts of the country.
12:49 - Why do we get tired after a big meal?
Why do we get tired after a big meal?
Chris Smith asks physiologist, Sam Virtue, to digest this question from Don.
Chris - We've all been there. As the Americans like to put it the effect you get with too much turkey at Thanksgiving. Why does this happen? Can you help Don out.
Sam - What happens when you eat a large meal is that you take on board a lot of nutrients and the sum of the nutrients directly but also indirectly by causing the production of hormones from the gut can signal to the brain. And for reasons which are slightly hard to understand how they are evolved, sleeping and eating are very closely related. When you've eaten a large meal it activates active neurons in the brain which are also associated with sleep. And you can think about this, if you've just eaten a large meal and you're out in the wild, you're already pretty fat and slow from all this food and now you can fall asleep? That might possibly make you really easy prey, but perhaps a more positive ways to think maybe you crawl off to a nice hole because you don't need to go looking for food.
Chris - Assuming you can still fit into it , like Winnie the Pooh got stuck into too much happening.
Sam - Oh yes yes I have small children so I've been reading that quite recently. So the neurons that everything seems to converge on in the brain are called orexin neurons and it's quite interesting because these were found by two different groups of researchers at the same time. One group find them in mice and they called them orexin neurones because the mice were fat. So they assume that this was something involved in eating. However, the other group that found them, found them in dogs and the much more striking feature of these dogs was the dogs were bound along and then have a narcoleptic fit and just pass out and roll over and then suddenly just get back up as though nothing had happened and so they thought these were to do with sleep, and it turns out it’s both.
Chris - Where they Labradors, these dogs? Because in my experience Labradors eat just about anything until they pass out and then they sort of sleep it off and then come back to life and do the same again - rinse and repeat until they've gained about 30 stone.
Sam - I think they're doberman pinschers the dogs with narcolepsy. But yeah it's really amazing if you see a video of a narcoleptic dog because they will be in like the middle of a game of catch and then just fall over and sleep. So you think from your gut like glucose and insulin after a meal signal these and they make you feel sleepy.
Chris - And the purpose of doing that is you need to divert a lot of resources to processing that enormous male and then absorbing the calories and distributing it around the body I presume.
Sam - Yes so that's certainly one theory as to why it's evolved, so for example the snake increases its metabolic rate five fold after ingesting something like a piglet or something.
Chris - Big snake!
Sam - A python? Something like that or even or whatever it’s eaten, a mouse or whatever.
Chris - But the interesting thing about a snake is that that might dine once a month once every several months whereas we have to eat regularly. Is that just a reflection on the fact that a snake is cold blooded, has a lower metabolic rate and can literally sit there not burning off much energy so it doesn't need to eat. Whereas you and me are ferociously burning off calories so we need to replace them.
Sam - There's certainly an element of that but it is kind of interesting when you think how long humans can survive without eating because we can go many many days if not months without eating. So why we have evolved these patterns of eating more regularly versus other animals which do not eat very regularly - I mean there are mammals that don't eat for months at all like a bear when it hibernate doesn't eat. So why we have these specific patterns is quite an interesting question. I'm not really sure I have a good answer for it someone might.
17:42 - What is ozone?
What is ozone?
Chemist Pether Wothers takes a sniff at this question from listener, Garth.
Peter: Ozone is a form of oxygen. Now of course, we breathe in oxygen every day, all the time to stay alive. But the gas that we are breathing in is composed of two oxygen atoms united. So this is an oxygen molecule with the formula: 02.
Ozone is a different form of oxygen where actually three of these atoms of oxygen are united together. And this has completely different properties. This is poisonous and it's poisonous because it's too reactive for us.
Ozone can be used as a disinfectant, for instance. It is incredibly reactive, in the same way that bleach is very reactive; it can destroy tissue and so on. This is the sort of action that ozone will have on our bodies if we breathe this in or are exposed to it in high concentrations. But it can be useful. Of course everyone's heard about the ozone layer and that's a slightly different thing. This is actually partly used to protect our environment from ultraviolet light that would otherwise be hitting the earth. But ozone itself in low concentrations can be used. So, for instance I was walking into a toilet the other day and there was this very strange smell, and I thought, this must I must be ozone! I thought, am I going mad here or is this really ozone that I can smell?
Chris: Well, it was a toilet Peter.
Peter: (laughter) Well indeed! It was a toilet, yes but eventually I looked around and found at long last, this ozoniser that had been stuck on the wall. There are now companies that are making these things because it's actually a very easy form of disinfectant, because you can produce ozone in small concentrations, simply by passing an electrical discharge through oxygen -a spark
Chris: And what does that do to make the ozone, then?
Peter: The energy from the spark will rip apart O2 molecules and then you will, for a short period of time, get these incredibly reactive oxygen atoms. Now they don't want to stay like that, which is why we would of course, be normally breathing in O2 where two of them have bonded together, and maybe, if these two oxygen atoms find each other, they will reform an O2 molecule. But of course it's far more likely that one little oxygen atom will bump into another oxygen molecule rather than the other part that just fell apart. And so that would then form an O3 molecule. And so actually this is why anywhere that there’s a spark, regular sparks, you can sometimes smell this sort of slightly peculiar smell...
Chris: Like when you use power tools for example, a drill, or a hand blender, or hair dryer.
Peter: Or dodgem cars.
Chris: Dodgem cars! Yes, you get that very distinctive smell and that’s ozone is it?
Peter: It could be ozone, It could also be... so when you spark through air, of course air that we breathe in is not just O2 molecules, there’s a lot of nitrogen in there. The main gas is nitrogen, and so the other thing that you can easily form are oxides of nitrogen and those also have a rather peculiar smell. So sometimes, it’s not quite clear whether we are smelling the ozone or the nitrogen oxides.
Chris: and just returning to your former example: Did the ozoniser in the toilet help to neutralise nasty niffs or not?
Peter: I’m not sure whether it was for nasty niffs, or for any potential pathogens to some degree, if they are sort of just on the surfaces. But it certainly smelt better than usual!
20:53 - Why do stars group into galaxies?
Why do stars group into galaxies?
We received this question from Lloyd via the forum, Chris Smith put it to Astrophysicist Matt Bothwell...
Matt: That is a really big question: why does the universe look the way it does? It's also a really good question - Why do stars form these structures we call galaxies rather than just being a uniform sea of stars filling the universe? The very very short answer is because gravity made it that way. If we go back to the very very early universe, so before stars and before galaxies formed, the universe actually was very very uniform. But it wasn't completely uniform. There were little differences in the distribution of matter just because of random chance. So, this little bit of the universe over here might have a bit more matter than average and this part of the universe over there might have a bit less matter than average. And the action of gravity kind of magnifies or amplifies those differences. So the bit of the universe that has a bit more matter than average will have a bit of a stronger gravitational pull because of all of the matter and so it will kind of gobble up more matter than the less dense regions. And so there's a bit of a runaway positive feedback thing where the more dense regions grow and grow and grow and all the other regions get emptier and emptier and emptier. So eventually you fast forward and the universe ends up looking quite blobby, with these very very dense regions which eventually turn into galaxies separated by big empty spaces.
Chris: And that's where we are today.
Matt: Exactly yes. That's where we are today. So once stars start forming, these blobby regions eventually turn into galaxies which is why the universe looks the way it does.
Chris:Now that's a pretty basic question so let's ask you something a little bit harder then.
What's the ultimate fate of the universe then, because it is growing all the time isn't it?
It's getting bigger. As far as we know, the older it gets the faster it's growing as well. So what's the ultimate fate? Does it just get bigger and bigger and bigger ad infinitum.
Matt:That's a very good question that I don’t think we totally know the answer to. It all depends on what dark energy is doing and we don’t know very much about dark energy at all. It was only discovered in the late 1990s. We’ve known for about 100 years now that the universe is getting bigger and bigger and bigger - expanding after the Big Bang. But when astronomers in the late 90s went to measure the rate of this expansion, it actually turns out, against all expectations, that the expansion is getting faster and faster and faster - that there’s some mysterious stuff in the universe that seems to be pushing it apart at the seams. We’ve called this ‘Dark Energy’ that’s the name for the effect. We don’t really understand what it is. And so it could be that in the very far distant future, dark energy gets stronger and stronger and stronger and eventually just tears the universe apart at the seams. But like I said we've only known about this effect for about 20 years and I think we have a lot more to learn before we can say any real answer.
Chris: So if the universe is inflating in this way, does this mean then that given enough time, when you get your telescope out, it could just be a very boring thing that you see? Because everything could have got so far away and is moving apart from us so fast, that it's going faster than light can travel to us, so you just see black space?
Matt: That could be true. So there's this concept in cosmology called the cosmic horizon. So, very much like we have a horizon on Earth, it's part of the earth that we can’t see because the surface kind of curves away from us, there are regions of the universe that we completely cannot see because the light hasn't had time to reach us. So any light that needs more than the current age of the universe to reach us hasn’t had much chance to reach us, so we can't see it. And as the universe kind of accelerates and accelerates and dark energy gets stronger and stronger, the cosmic horizon is going to actually get closer and closer to us. More things are going to fall over the cosmic horizon. So as time goes by, we're actually going to be able to see less and less of the universe.
25:13 - Is listening to the radio whilst driving safe?
Is listening to the radio whilst driving safe?
Izzie Clarke from The Naked Scientists had this question for driving psychologist, Helen Keyes from Anglia Ruskin... Should we be telling all our listeners who are driving to turn us off?!
Helen: Fortunately not, we’re lucky. So there is one instance in which listening to the radio can be very dangerous for driving. Listening to speech is fine, in fact in some cases and in some ways, it can keep us awake and stimulate us so we can have preventative factors. But there is a caveat to that. We shouldn't listen to things that are heavily visual. So when we are listening, for example, to sports matches on the radio, this is a really bad idea. Simply because we're recruiting the same parts of our brain. So when you're using your visual imagination to visualise what the commentator is talking about it takes our visual attention directly from the road and we know that this is really hazardous.
Chris: So just when people fling their hands up and go “Yeah!”
Helen: It's not quite that dramatic! It’s just that any sort of visualisation task is a really bad idea when were driving. And the second part of that question was about how it compares to mobile phone use. Mobile phone use is quite interesting and we like to usually compare it to having a conversation with a passenger. So, mobile phone use is a lot more dangerous than having a conversation with a passenger and indeed, you're about four times more likely to be involved in a crash if you're on a mobile phone compared to speaking with a passenger. And we know that there's no difference to using a hands-free set, so I think that would surprise some people. It’s not necessarily about looking at your phone or using your phone, it's about the speech. Producing speech and listening to speech is quite complex. It seems easy to us because it's so effortless. That's merely because the brain devotes so many resources to speech perception. But actually, when we're talking on a mobile phone we know that there's a higher incidence of questions being asked and answered and there's a higher number of utterances per minute when on mobile versus talking to a passenger. So that makes it more dangerous - it takes up more of our resources. But secondly, it's really interesting: if you are speaking with a passenger in your car, they will moderate their conversation to the road environment. So if you're a driver and you're approaching a roundabout and your passenger is speaking with you, they will automatically stop speaking or they may even talk about the traffic: say, “Oh look here's a traffic jam”.
Chris: Or if they’re my wife, they flinch when they see something coming.
Helen: Flinching is very helpful!
Chris: It is, because it gets your attention, doesn't it? It makes you think “ooh” and then you realise you are getting a bit close to that.
Helen: It does, so obviously, if your wife is on the other end of the phone she may be just asking you a question and she wouldn't be moderating her conversational behaviour. So do not speak on a mobile phone, including hands-free. We are really trying to push to get hands- free to be made as illegal as using your phone in cars, because there's no difference there.
What's in tap water?
We received this question from Kit. Chris Smith put it to Chemist Peter Wothers to pour out an answer...
Peter - If it were a hundred percent H2O, my job would be a lot easier in many ways because when you're carrying out chemistry experiments you need to try and control all the variables, things that could change, and you don't know quite how they're changing. And one of the things of course is there anything that might be in your solvent, which could well be water. And we go to great lengths to try to make a pure water and this is incredibly difficult. So the purest sort of water that you can commonly come across would be distilled water and this is where you are heating it up and then turning it into steam and then condensing this. But what you're trying to remove here is what would be naturally occurring, certainly in any bottled mineral water that you buy, and also wouldn't really be removed unless there were extreme levels from any tap water and these would be certain dissolved ions such as sodium ions, potassium ions, magnesium, calcium...
Chris - Calcium, I know from where I live!
Peter - Exactly. So these are the things that wouldn't naturally be in water and they're not really worth removing from tap water. So they're definitely present there and it's very difficult to remove some of these things are not worth the effort generally. But of course some other things are added and perhaps one of those controversial things is fluoride ions. There's absolutely no doubt that this has helped to tackle tooth decay in this country because it protects the teeth makes, them much harder and more resistant to decay. So that is something that is deliberately added in very very small concentrations is highly monitored. But this can be very good for us. So it's definitely not pure 100 percent water.
Chris - Thank you very much Peter.
with Helen Keyes, Peter Wothers, Matt Bothwell and Sam Virtue
As always, Chris Smith had a quiz lined up for our brainy panel; astrophysicist Matt Bothwell, chemist Peter Wothers, psychologist Helen Keyes and physiologist Sam Virtue. Team One was Matt and Helen and Team Two was Peter and Sam.
[Transcript to follow]
36:42 - Can you cure yourself of diabetes?
Can you cure yourself of diabetes?
Listener Sam has this cure-ious question for physiologist, Sam Virtue.
Sam - Well the short answer is some people can and it's probably worth giving it a go. A lot of this research came from patients who were going to be undergoing bariatric surgery. And one of the things they aim to do before people have the surgery, because it’s quite hard to do surgery with lots and lots fat, is to try and get them to lose some weight. So they put them on very low calorie diets for several weeks ahead of the surgery. And they actually find these were pretty beneficial. Researchers led by a guy called Roy Taylor up in Newcastle have really been looking into this a lot and they, basically, put people on a diet which is about 600 calories, for eight weeks and we normally eat about 2000 calories, so that's a third of what we would normally eat. So this is pretty extreme. And when we looked at these subjects they lost about 14 kilos over the eight weeks and about 40 percent of them had recovered from having diabetes, and it wasn't just that they were more insulin sensitive. Their pancreas could make insulin again.
Chris - Should we point out that we're talking about type 2 diabetes, rather than type 1 diabetes where people are absolutely dependent on insulin to stay alive. Type 2 diabetes is the obesity associated diabetes that you would be working on.
Sam - Absolutely. And one of the things they found about the subjects who could basically reverse their diabetes is before they started the weight loss, these were the subjects who already had reasonable amounts of insulin. So if people had had diabetes for a long time, over 10 years, or they have very very low levels of insulin it was likely their pancreas was so badly damaged, just like a type 1 diabetic where the basal cells are destroyed by the immune system, that they couldn't recover. But subjects who had high blood glucose but high insulin, they just weren't making enough insulin for their body, they were the ones who were most likely to recover.
Chris - Do we know why, when a person does carry a bit too much weight, that the body's tissues essentially become deaf to their own insulin signals. So they can have paradoxically very high insulin levels but very high sugar levels. Do we understand that process?
Sam - That's exactly what I work on. There are several theories about it but the one we are interested in, is the idea that fat can accumulate in organs where it shouldn't. So fat can accumulate in liver, and the fat itself is what then poisons the cells and interferes with the signaling, essentially muffles the ability of the insulin to pass its signals down to do the things like say take up glucose.
Chris - And so when one loses weight to a profound degree you rob away some of that abnormally accumulated fat and therefore that muffled signal, the muffler is removed and now you can you can again see the insulin signal.
Sam - Indeed. And also fat can actually interfere with the production of insulin by the pancreas and one of the things they saw in the study, was in the subjects who particularly recovered well, they had much greater reductions in lipids within their pancreas. So yes that's very reasonable.
Why does acid burn?
Chris Smith put this burning to question from Dee to Chemist, Peter Wothers. Plus, we also heard from Jake on a similar theme, who says, "what naturally occurring substances also have the most extreme pHs?"...
Peter - So of course the burn that we're talking about here is actually just damage to the tissue. And that's the thing of course that our tissue can be relatively easily damaged. An easy way to do this is to pick up something hot, and that's going to damage that tissue there. But actually you can get burns from, of course, cold things and so we were talking earlier about liquid air being extremely cold. If you were to, certainly, tip your finger into liquid air and I do not recommend this for any period of time, you would destroy all the tissue there but a small splash on you may well cause a burn as well.
But of course, yes, you can indeed also get burnt by acid. Again this is just causing damage to the tissue. We normally have mechanisms to control very precisely the pH of the fluids in our tissue and so on, and adding concentrated acid is absolutely very far away from these normal conditions, which is why the damage is going to take place. But this is rather interesting, so tagging this on to the other question about the extremes of pH, actually it is possible to find incredibly acidic solutions in nature, and this is in certain mines notably ones that have pyrite. So this is iron sulfide, a form of iron sulfide, with the chemical formula FeS2, and this reacts with oxygen and water and can produce incredibly strong powerful solutions of sulfuric acid. And then to tie these two together actually there’s a beautiful story from the Middle Ages in various books on stones and so on. It's called the Fire Stone which probably, is actually because you can use it to start fires by smashing into a flint, but actually there are also descriptions if you squeezed this tight in your hand it will burn it.
Now of course maybe you are thinking that it's going to be burning in terms of because it's really hot and fiery, but actually it could burn your hands because the surface of this, again if there's moisture there and is reactive with the oxygen, could produce acid and so actually, you could get an acid burn from this mineral by holding it very tight. So actually these acids do occur in nature and they can be incredibly strong. In fact some of the record pHs are at minus 3. Now this sounds very odd but a strong sort of laboratory sulfuric acid. You'd get sort of one molar and this would have a pH of what is going to be zero is it? Yes it is, good, and so less dilute is actually 1, but so this is really concentrated when it starts go into negative and so really very strong solutions of sulfuric acid.
Chris - Matt?
Matt - Is there, like a theoretical endpoint for the pH scale, can you just keep on making stronger and stronger acid forever. Is just like a practical limit or is there a theoretical limit to how strong an acid can be?
Chris - That's because you were nasty to him about the universe, he’s getting his own back.
Peter - Although this quite a good question. So of course, I mean, the pH scale means the, it's the concentration of hydrogen ions per volume and so we are limited here, and so in the same way that actually there is a concentration of pure water. How much water can you fit in a certain volume, unless you start compressing it in a neutron star or something, there’s a limit to this. So pure concentrated sulfuric acid would be, sort of, a limit in some sense but then what really makes an acid, acid, is the water that's also present. So it's a little bit difficult. So absolutely, there is definitely a limit and you can’t put too many protons in a solution of water, and it’s the protons that are making this thing acidic.
What is a Nebula?
We received this question from listener, Francesca. Chris Smith put it to Astrophysicist Matt Bothwell...
Matt - So a nebula is just the name we give for a cloud of gas and dust in space. The name nebula comes from the Latin meaning clouds and there are all different kinds of nebula. And the reason they look so different is for the same reason that clouds on earth look different, just because there are different types and they form in different ways. There is a type called H2 region. So a H2 region is a star forming cloud in space to it's like a big cloud of molecular gas that is collapsing under gravity and turning into stars, and it gets illuminated by the light from the young stars and glows very nicely. So the Orion Nebula is a nice example of this. There are other nebulae called planetary nebula. These are actually a completely different formation mechanism, so planetary nebula are clouds of gas that are blown out by stars like towards the end of their life. The names are a bit of a misnomer. When early astronomers saw them, because they tend to be round, they thought they resembled planets. They called them planetary nebula but of course they’re dying stars. Galaxies as well, before we understood what galaxies actually were they were called Spiral Nebula. So about 100 years ago astronomers incorrectly thought that galaxies were, kind of, whirly clouds inside of our own Milky Way. But now we of course understand that they are you know much much further away than that.
44:46 - What's the most efficient machine?
What's the most efficient machine?
Steve sent this question in to our brainy panel. Chemist Peter Wothers, Astrophysicist Matt Bothwell and Human Physiologist Sam Virtue all had different thoughts on the matter...
Peter - What people were trying to do when they were trying to create perpetual motion machines would make something that would always be moving. And that is something that, of course, does happen in that, for instance, vibratrating bombs so a simple, going back to our oxygen molecule O2, this molecule is always vibrating so it is always moving. In fact, even if you cool this thing down, even to absolute zero, it is still going to moving which is quite remarkable.
Chris - Really. I thought absolute zero did stop. Is that true?
Peter - I think it has to be moving, yes.
Chris - Really. Is that the case. Wow! So nature has already invented a perpetual motion machine, is that what you’re saying?
Peter - But the problem is you can’t get it to do anything useful. So if that’s what you want out of your machine so this comes back to the efficiency thing, then there’s a problem.
Chris - Okay. So Peter has challenged Steve’s contention that there are no perpetual motion machines. What do you think Matt about the idea about efficiency? What does he actually mean by efficiency though Matt? What is that?
Matt - The efficiency of a machine is just the amount of useful work you can get out of the machine divided by how much energy you put in.
Chris - And so what sorts of levels of efficiency might we consider for various things around us in the world around us then?
Peter - The question actually is why is some of this energy lost, and so why can you not convert all of your energy into useful work? And then this comes down to the idea of disorder and entropy, that this is the key driving force and so everything is getting more and more disordered. Some of this energy, in a sense is actually creating a lot of disorder and this is what every machine has to do - you can’t convert all of your fire heat energy into lifting a weight, for instance, or something is always going to be lost.
Chris - Indeed, a coal fired power station is what, 50 percent efficient, isn’t it, between 30 and 50 percent? A car is about 30 percent efficient so, in other words, 70 percent of the fuel that you burn does not turn into movement of your car, which seems ridiculous, doesn’t it, when we put it those terms?
Peter - It sounds really ridiculous. I think some of the more efficient engines will then be working on fuel cells which is a very efficient way to get that energy out of - well the chemical energy there.
Chris - And this is where you’re exploiting the energy and bonds components, isn’t it, to actually make bonds in order to release some energy?
Peter- Yep. But even so, it is absolutely impossible to convert 100 percent of your energy into useful work energy. So you’re never going to get to 100 percent.
Chris - So it’s worth going to the gym because that’s kind of useful for where you come from, isn’t is Sam, with the obesity business? It’s a damn good job that the body isn’t 100 percent efficient because it would be a lot harder to get that weight off down the gym.
Sam - Also, biological systems are, essentially, machines as well, and they’re pretty good. I mean the efficiency of us, as humans, when we’re running will be over 30 percent and that’s fairly equivalent to some of the better motor cars, so yeah. And what humans really turn their energy into is heat, so that’s what we mostly lose it as. If we go to lift a weight or something down at the gym, maybe about 30 percent of the food we’d be consuming is going into lifting it and the rest is going into heat production.
Chris - It’s kind of good though because when you’re chilly and you shiver, you’re basically making your muscles do lots of pointless work and releasing lots of heat as a byproduct which you then shove back into your body to warm up on a cold day?
Sam - Yeah, absolutely. And actually there’s another type of organ we work on which is called brown adipose tissue, and this is an organ where it’s express purpose is not to store energy, but to convert energy into heat. So small organisms like mice, rats, and in fact infant humans have a lot of brown fat. We know know some adult humans have brown fat. And so I wonder if I could cheat and argue that this is a very very highly efficient organ because all it does is convert chemical energy into heat, and that’s it’s purpose. So, in a sense, it’s very inefficiency by the classical definition of have much work do you get out of it makes it incredibly efficient at doing it.
Chris - Because, as you say, kiddies have a lot more as a proportion than adults - we lose it as we get older, don’t we? Is that because children have a very big surface area to volume ratio so their rate of heat loss can be much higher, so they have a bigger challenge staying warm so they compensate by having this brown fat? Or is there some other reason why we lose it? Does it burn itself out as we get older?
Sam - No. It’s essentially what you’ve just suggested in the first point - it’s a device for making heat. Many adult humans, and a good proportion of them do have brown fat, but it’s certainly more prevalent and more active in infants. And so, being a bit of a geek, I have a three and a half year old and a one year old and I borrow the thermal camera from the lab and decided to try and photograph my son to see if his back lit up, which it did look quite convincing
Chris - It’s between the shoulder blades, isn’t it, you have a big patch of it?
Sam - Yes. And we have mainly in humans it’s found more actually in the neck, and there may be some between the shoulderblades as well in infant humans. But yeah, so it was probably not ethical.
Chris - So that’s your own inbuilt central heating system?
Sam - Into heat, yeah.
Chris - Matt?
Matt - I think my vote for a most efficient system, because I’m just piggybacking on what you said about biological systems, I think my vote for a most efficient system might be a person on a bike. You can transport 100 kilogrammes or more, hundreds and hundreds of miles on a relatively small input of energy.
Chris - So the wheel was an amazing thing?
Matt - It was, yeah.
Chris - I think it’s 5 thousand years old the wheel. So we probably made one of our most important invention in efficiency terms, you’re arguing, a long time ago.
Matt - Yeah, that’s right.
50:19 - Why do women live longer than men?
Why do women live longer than men?
Chris Smith put this question from Jim to physiologist, Sam Virtue. Plus, psychologist Helen Keyes is all too familiar with the risky business between genders.
Sam- Okay so that’s a good question and quite a big question because it’s not just men and women. It’s loads and loads of different animals throughout the animal kingdom, down to insects.
Chris - Where you see a sex bias? Where you will see a female bias?
Sam - Mostly it’s biased towards females living longer but there are some reversals and somewhere you don't have a bias. What it comes down to largely is that in many species, males and females have very different requirements in terms of how much effort they put into producing children essentially. In many species, males will mate and then disappear off whereas females will then have to produce the baby. For men, the optimum is to essentially mate with as many females as possible whereas for females you want to be picky about your mate because you invest a lot into that baby.
Chris - But if I could challenge that because that's all very well, you’re reproducing when you're young but we’re talking about people living a long time. Many many species don’t reproduce when they become old, including humans, so there must be something else which is driving the persistence of these older females in the population.
Sam - This seems to be quite a majorly human thing. That this sort of ageing aspect to it, in terms of the menopause in particular, being so far removed from when we die. A lot of species it will be a lot closer. Why that's occurred is a very good question and interestingly one of the hypotheses has actually been to do with the way human structures have built up. Favouring, bizarrely enough, the idea of men becoming more attractive and more suitable as mates as they age which has actually put a drive on male longevity.
Chris - Is that just wishful thinking?
Sam - It’s called the “Patriarchy Hypothesis” which then has dragged up the whole lifespan of both men and women. But then we have a bizarre question; why aren't the men longer lived than the women? And so then a flipside comes that males’ secondary sexual characteristics and tendencies towards violence and risk seeking behaviour, to try and compete for these mates, drive down their age. The two things combine.
Chris - If you look at conceptuses, the number of babies being conceived, there's a slight bias towards more male babies are conceived but then about the equivalent numbers of male and female babies are born. Then after that pretty much there’s an excess of females for ever.
Sam - If you say so, I’m not aware of that one.
Chris - It's an interesting figures that we see. It seems like there's this bias, initially in favour of males, in order perhaps to counteract the very thing you say, which is that males more risk prone. So who knows!? Helen, a lot of this must chime with your research on cars and driving and that kind of thing.
Helen - It does and I know from risk taking behaviour studies there is obviously a big difference between risk taking behaviour in young men and young women but this risk really decreases in older drivers as we get older. It can’t fully account for the difference in life expectancy between men and women. Although it does input into it. But as a psychologist, I think something really interesting to me is the protective factors of socialisation as we get older. Socialising with people protects you against all sorts of things, like Alzheimer's and dementias, but also of death itself. It adds years to your life. We know that that older women are more likely to have a greater social networking a richer social network than older males and I think this might feed into this longer life expectancy.
53:53 - Are some demographics better at driving?
Are some demographics better at driving?
Psychologist Helen Keyes from Anglia Ruskin drove home this question from Liz...
Helen - I always find this very funny. As a driving researcher, by a “better” driver we mean a safer driver and, unequivocally, women are far better drivers than males. Males account for 75% of road deaths but they’re responsible for upwards of 90% of fatal road accidents.
Chris - Sorry to interrupt but I just would like to clarify... If you stratify that by age, does that hold right the way across the age spectrum or is 90 percent of that people under 21?
Helen - It's a good question. It’s going to be different things feeding in here. At a younger age? Absolutely. We know that risk taking behavior is really prevalent among young male drivers compared to younger female drivers and differences do get less as we get older. But then some more differences start to kick in around ageing, which is something else I'm interested in. Older drivers are prone to errors when they're driving more than younger drivers. And gender differences hold for older people; older men are worse drivers than older women. But it does bring up an interesting question about how old is too old to drive.
There are things that are quite obvious to us. Older drivers, their vision is worse than younger drivers. As we get older we lose flexibility now lenses so our ability to focus on distances gets worse, our peripheral vision gets worse. But really importantly for night driving, the ability of our pupils to enlarge and take in light gets worse as we get older and it becomes quite fixed. Our night vision really suffers as we become old.
But interestingly as well we have a loss of white matter as we get old. And white matter is part of the brain where the nerve axons respond much quicker than in other parts of the brain and we have a lot of this activity happening in white matter when we are younger. So as we age we have a loss of white matter and these differences can't really be corrected for, these slower responses. We can’t correct for them just with glasses and hearing aids and better vision. Our brain actually responds more slowly as we get older.
Chris - Indeed the white matter is is the connections between different bits of the brain, isn't it? So if you lose those connections I suppose the bandwidth, the processing throughput rate, the brain can handle it is going to diminish a bit as we get older.
Helen - Absolutely right. We have myelin sheaths on these nerve axons, transmitting information that makes information going really fast. If we lose that it's really irreparable, we can't really compensate for that loss. There was a very interesting story in the news recently where police in three areas of the UK are going to start mandatory eyesight testing for every motorist that they stop. This is related to something called Cassie's law where an 87 year old male driver was pulled over, tested by police for his eyesight and he didn't pass that eyesight test but yet was allowed to continue driving.
We know that if we bring in these mandatory eyesight test for elderly people, it can have a real impact. We ask how old is too old to drive. At the moment, once you hit 70 in the UK, you have to renew your licence every three years. So we think that that might be a bit protective but really it's going to be on self report about whether your vision is still appropriate for driving.
Road safety researchers would like to propose maybe that once you hit 70, there are mandatory tests involved and not just eye tests. Like I talked about, this loss of white matter and in this slowing of responses, perhaps even mandatory driving tests every year or more frequently once hit 70 years of age.
Chris - You never know by the time US hit 70 years of age perhaps we won't be driving anyway. So this problem might sort of get solved by technology. We may be dumping ourselves off in our driverless car and it won't matter if we can even not see at all. We'll get where we need to go quite safely.
Helen - I hope so because I think driverless cars are absolutely the future. Although, that would do me out of a job! But I think there is something to balance here. When we say that as a demographic older drivers are more dangerous than younger drivers, we have to look at relative versus absolute risks. Relatively, older drivers are more error prone than younger drivers. But at an absolute level, they make far fewer journeys and when they do make journeys, they travel far fewer miles far less distance. On an absolute scale, really if we were to just target road safety, we'd probably still just be aiming at younger males... And getting them all off the road!