Why do women live for longer than men?

Why do women live longer than men? How do birds fly in a group? Why do loose stones hit my windshield? Why are some cremated ashes white and others grey? What's the point of a sneeze? Plus, engineering better batteries.

Eusebius - We've got a wonderful science story this morning. It seems like the chemists at the University of Glasgow have been up to some interesting stuff.

Chris - Yeah indeed. The world needs better batteries. And if you cast your mind back to the 1980s, anyone who saw a mobile phone from the 1980s would think you were from another planet. These things weren't called bricks for no reason. They were huge, and most of the size of the object was the battery compartment because we just weren't very good at packing huge amounts of energy into a small space. Luckily, things have got a lot better and modern day devices use lithium ion batteries which do have a much higher energy density and that means that we have been able to shrink our communications and other mobile devices down dramatically. But we're not there yet because many of the things we want to do, like have electric vehicles, which are much better the environment, they don't churn out lots of pollution. But also, at the moment, they don't go very far because we can't pack enough energy into the battery technology we have to make them have the range that we need, so people don't get whats called range anxiety. Scientists at Glasgow University, and this is Lee Cronyn and his team, have got a paper in the journal Nature Chemistry this week where they have come up with an entirely new concept. They have a battery where actually you pump the charge like a liquid in the same way as you would fill your car with petrol or diesel. You pump in a charged liquid. This is called a flow battery, and the way they do it is they have in the liquid which is just water, an oxide of tungsten, the same stuff that you have in the filament of old fashioned light bulbs. Now what's special about this is they've arranged the tungsten oxide into tiny cages called nanoclusters, and these cages can accommodate huge numbers of electrons. They can pack into each cluster 18 electrons, and this means that you can store a lot of charge, you can put the charge in very quickly so the battery doesn't overheat and get damaged which is the other constraint on modern batteries. But here's the amazing thing that Lee told me; at the moment if we're driving around in electric cars and you go into the petrol station, you fill your car up and it takes a few minutes and off you go. With an electric car you've got to find a charging point but it takes hours to charge the car up again. That's not practical. With their system, what you could do is drive your car into the garage, drain out the fluid which is in the battery, which is the now depleted fluid and just fill it up with charge fluid. It takes literally seconds and you've got a whole full tank of electricity and off you go again. And they reckon their present batteries that they're testing at the moment are about one and a half times better than the present generation of batteries we're putting it in cars. So actually already just the prototype is already about 50 percent better than what we already have, and they're looking at technology that's the next stage beyond this which is going to be many fold better. So a really dramatic story. Really impressive. Were actually getting there at last.

Eusebius - Stunning. Absolutely love it. [**] thanks so much for calling in. What question have you got for us?

[**] - Morning Eusebius. Morning Chris. I just want to find out why is it if I press twin hold the volume button on my decoder, if I press the volume button on the television, the one on the decoder stops working?

Chris - Ah. Well I don't know exactly how they're talking to each other, but I suspect it's with infrared. And the way these devices work is that there is an infrared emitter in the front of the remote control and it produces flashes of light at a certain frequency which the device can see. You can't see it because your eyes are not sensitive to infrared but the device is and it picks up, decodes that sequence of flashes, and it then knows what you want it to do and it may well be that either one of two things is happening. One is that the sequence of flashes that's the volume control for one device means something different to the other device. Or the two signals are interfering with each other because light has this feature called interference which is that light waves when they meet can actually add together and get brighter or dimmer according to whether they are travelling upwards or downwards at the same time or not. And so there are a number of things that could be happening. You could be changing the light signals that are reaching the device or you're sending in a signal that means something different because it's just the sequence of flashes that it's been programmed to interpret. So it may well be that it's been programmed to reprogram itself when you send the wrong signal. Either of those is a possibility.

Eusebius - Shane thank you so much for calling in. Hello Shane

Shane - Hello, how are you going. Love your program. All the way from Australia!

Eusebius - Oh that's wonderful to hear. Thanks so much. What question have you got for Chris?

Shane - God bless you guys. Listen, I do behavioural science and I work with certain developmental areas of technologies that are being exposed to Australians and there's great research now. Especially I'll refer to a Dr. Martin Paul from Washington State University and his studies have been extensive with electromagnetic frequency. And his findings have found that the voltage gated calcium channels in the cell's membrane is actually being disrupted by the frequency of the mobile phone. I'm just wondering. I didn't get the scientists name. What's his name?

Eusebius - Chris. What is your question for him Shane?

Shane - Hello. I'm just wondering is there any science to actually help counter that problem with the voltage gated calcium channels in regards to the mobile phone frequency disrupting cellular growth, especially with children being exposed, or do you think we need to regulate mobile phones better with children?

Eusebius - Okay. Chris, did you get that?

Chris - I did. And thank you for calling in all the way from Australia. How wonderful. You didn't say which bit of Australia you're from. Big country, wonderful country. One of my favorite countries, after South Africa, of course! But good to have you on the programme. Now the question here is the safety of mobile phones. And at the moment people are doing the world's biggest experiment that we've probably ever done because mobile devices outnumber people on the planet, and the number of people using them and notching up "talk-hours" and communicating hours is absolutely huge. And we've been doing this for a number of decades now. And so what people are looking for when they look for an association between something that could provoke something to happen and that thing happening is they look for what's called a "dose dependent relationship". So, in other words, we know what the dose is, we know how much people are being exposed to this sort of radiation. We know that from telephone records, so we know how many conversations people are having and for how long so we know what people's dose is. We also are making all kinds of health measurements and outcomes about people and so people are looking to see if there are changes in health outcomes which change in step with the thing that they're being exposed to. That's the dose dependent relationship because if something causes something to happen, if you increase the dose of something you should see more of those outcomes. People are looking really hard and they haven't found any strong correlations yet between mobile phone exposure and health outcomes - things like cancers or other changes. That's not to say there aren't some are going to happen because over a lifetime you're going to add up a bigger dose than in a short term. It may be we haven't looked for long enough. It may be that the variability in variation in people's exposure is too great to see a difference at the moment. But at the moment, based on tests in test tubes, tests in animals, and tests in humans there's no cause for concern but that doesn't mean we shouldnt stay vigilant and keep looking. And that's why research looking at possible influences of these sorts of radiations are important because we need to understand how they might be affecting us. Me personally, I think that if you just use a mobile phone a little bit you're probably not at great risk. I think the greater risk comes from changes to the way people think because these devices can lead to isolation, they can lead to social isolation, they can lead to fear of missing out. They can make people depressed because everyone is comparing themselves to everyone else all the time, and thinking everyone else is having a much better time than they are. So I think that the dangers go beyond just the electromagnetic risk, and I think that we are into a whole new era now with amazing availability of information but with that huge reward comes a cost And that's where we also need to not take our eye off the ball.

Eusebius - Thanks Shane. Thanks for calling in from Australia. John, thank you so much for holding on.

John - Hello.

Eusebius - Go ahead sir we could hear you. What is your question?

John - Are talking to me, to John?

Eusebius - Yes, I'm talking to you John.

John - The question why is it that women live longer than men....?

Eusebius - That line is not very clear but the essence of the question, Chris, ia and I'm not sure whether the operating assumption is true, you'll tell us. Why is it that women tend to live longer than men?

Chris -  Well the statistics we have on populations bears that out that women do, on average, live longer than men do. And there's a range of reasons why this might be true. One of them is that women are relatively protected against big killers of humans until the age of the menopause. In other words, when the oestrogen level is high, they have a lower risk of things like heart disease, high blood pressure, stroke and, as a result, since heart attacks account for about a third of all deaths or mortalities you're automatically straightaway reducing the risk of these things. Now we don't know exactly why oestrogen is so protective, but we know that it has effects on cholesterol levels, we know that it has effects on high blood pressure, and those things all have a risk bearing on your likelihood of developing heart disease and stroke. So that's one protective thing straight away. Then there are also other ways that women's physiology differs from men. So probably metabolism, oxidative stress, and so on, those things also have to have an effect. And we also think that perhaps we've selected over time for women outliving men because men are most useful when they're young. They can reproduce, they can contribute their DNA. But women, the grandmother theory says that women's contribution to family and upbringing doesn't just end when a woman ceases to be a mother herself, they also have a strong bearing when there's a grandmother in the family as well. And men are less useful when they get old and clapped out whereas women can have a strong nurturing effect and they can help to support families. And it might be that, historically, because of the way that family units and people have evolved and so on over thousands of years, it might be that that's why we've also selected for women to stick around a bit longer than men. But that's just more speculative than the hard science I've mentioned about oestrogen and the menopause and heart disease risk. 

Eusebius - Paul welcome to the show. What is your question?

Paul - Yeah. Hi Chris. Hi Eusebius. My question is this: when you take a pane of smoked glass, to toughen it it is put through a furnace. But prior to this process you need to if you need holes or notches made you need to do it before it's fired. Recently, I ordered a 8 millimetre piece of shower glass, just one panel, and I requested 8 millimitre holes in the panel to take a towel rail. I was told I can have 6 millimetre, or I can have 10 millimetre, but I can't have 8 millimetre because the diameter of the hole can't be the same size as the thickness of the glass as it tends to shatter in the furnace. They don't know why. I don't know why. And I wonder whether Chris knows why?

Eusebius - What a lovely question, Chris.

Chris - That's an amazing question. I'll tell you what I'm going to do, Paul, I'm going to take that to my materials science colleagues because that sounds like a wonderful conundrum that they would love to get their head around. And I don't want to give a hand wavy answer because there must be some really important reason for this. It might be a bit like the spaghetti question. Have you ever tried to break a bit of spaghetti? If you hold a bit of spaghetti, one end in each hand and you snap it so it would bend in the middle and break you say to people how many bits of spaghetti will I get? Well the answer is you will get more than three or at least three. It never breaks into two it breaks into at least three or more bits.

Eusebius - Is that so?

Chris - It is. You can try the experiment yourself and actually it took someone with a fast camera and a big mind to work out why. And the reason is that when you bend the spaghetti, as you're putting under tension and you then get a weak point which breaks the spaghetti, but because the spaghetti was under tension it then springs back in the opposite direction, bending the remaining bits back on themselves in the same way that you bent the first bit to break it. So then the next bit, because it's bending the wrong way too much, breaks itself; and that's why you get three or four bits of spaghetti showering off. Have a go everyone! Obviously not cooked spaghetti, it won't work with that! You've got to do with the hard stiff stuff but have a go and see if I'm right.

Eusebius - Okay Paul. I think that's one of the more interesting questions we've had in months. We'll replay Paul's call next week and then Chris can tell us what he found from his colleagues. Shall we do that Chris?

Chris - We'll do that. I'll get onto them this very morning straight after we finish the program. My friends at Material Science at the University of Cambridge and we'll see what they come up with. And just in case they're all on holiday because they do occasionally take a break, I'll warn you in advance that we've got the answer and we will definitely return to this because it's fascinating question.

Eusebius - Okay. Michael in Benoni, good morning to you.

Michael - Good morning Eusebius, and good morning Chris. I just wanted to how do birds that fly in a group keep their synchronised flight pattern logged even if one is distrubed or even [**] they're still on their syncronised flight pattern?

Eusebius - Okay. I've got deja vu. Has this question come up before, Chris?

Chris - This one hasn't. But we have talked about things with people sort of doing things in sync together before and this is another example of synchronization. If you think about armies marching, people walking hand in hand and talking, birds flying together, it is something that you see across the animal kingdom and timing is everything. We use timing in many aspects of our lives; when we're talking that's timing, when we're walking that's timing, and when we're walking up and down stairs that's timing. So there are circuits in our brains that enable us to do this. Birds have very good visual systems and they are also social animals that hang around in groups together. So they have evolved to use their sense of each other, their sense of space around themselves, and their visual system, and they integrate all this information and that's how they can maintain their position relative to the flock because at the end of the day if they get it wrong they're going to have a crash aren't they? Either against another bird or against a third object or they're going to plummet out of the sky. So they've evolved to do this is the simple get out of jail free answer to this. But the way they're doing is they have, these animals have very well developed bits of the brain that are concerned with movement and also integrating vision with movement. It's in their cerebellum: that's the part at the back of the brain, and they have evolved to do that because it makes such a difference to them being successful.

Eusebius - Let's take one from Twitter for a change. Elna [**] tweets the following, Chris. On the road sometimes loose stones are flung from a vehicle in front into your windscreen. A few times this has happened when the cars pass from the opposite side. Here's the question for Chris, Eusebius, can a stone be flung from the car like a bullet or is it flung up in the air and you happened to drive into it?

Chris - Yes. It's absolutely true that the car goes over a stone. The wheels are turning; usually what happens is the stone temporarily lodges in the tread of the tyre. So it's gripped by the tyre a bit and then as the tyre turns round, and the stone is now free of the road surface it's got enormous amount of momentum because it's been accelerated by the tyre going over it which means the tyre is flung upwards in the air because the tyre is turning. So the stone is lifted, but it's also possibly got some propulsion back in the opposite direction because the wheel was turning, so the stone has been accelerated in two directions. It's been accelerated in a circle but that means when you hit it it's basically travelling upwards but it's also got an element of movement back towards you. You are then driving into it so you've got some velocity towards it as well so actually the combined speed of impact can be even higher. The car on the opposite side of the road, usually it'll have lifted the stone up in the air and then you go smacking into it because relative to you it's coming towards you because you're driving towards it.

Eusebius - Tracy thank you so much for calling in today. What question have you got for us? Hello Tracy. Hi there.

Tracy - Hi. Hi Chris. I wonder if you can explain something to me. Could you explain the difference in colour between the post-cremated ashes of my two parents. My one parent died 15 years ago in one place. His ashes are white. My mother passed away five years ago in another city and her ashes are dark grey. Is this variation explicable or should I treat either one with suspicion? Thank you.

Chris - Hello. And a very interesting question. I've never been asked that. Athough one person did ask me a few years back they said could they turn cremated ashes into a pot plant because they wanted to make pots and then plant flowers in them, which I thought was an interesting idea. The answer is the way that you cremate people the techniques can vary, but you're using very high temperature which reduces the body to the just the bits that won't burn. And the composition of the body is mostly water so you get rid of all the water with the high temperature and then the tissue that's left is proteins and minerals, and so the ash that's left behind is the minerals that you basically can't burn off. Now it will vary a little bit between individuals because the composition and size of a person is going to be different so whats in their body is going to differ a bit between people. The temperature at which the furnace is operated is going to differ a bit between the individuals. And also the casket that they're in because some people have different coffins and some people have sort of cardboard coffins or wickerwork coffins some people have wooden coffins. Those will all make a difference because all that stuff ends up as part of the ash that you then scatter. So I strongly suspect that this is not some nefarious practice. It probably reflects the fact that you've got two different individuals of different sizes which were cremated maybe in different techniques, or at slightly different temperatures, in slightly different sort of dressings and caskets and all that kind of thing's going to make a difference to what you get back at the end of the day.

Eusebius - Okay. We can squeeze in a final question. You've been waiting very patiently Seth. Thank you so much for that. What question do you have for Chris?

Seth - Hi Chris. Hi Eusebius. I would like to find out what the purpose of a sneeze is? It seems to be fairly pleasurable before you sneeze, but once you've sneezes what happens to the body or is it a helpful thing to sneeze?

Chris - Hi Seth. You can look upon this two ways really because for the people that catch the bugs that you sneeze out it's not helpful. For the people that sneeze, it's very helpful. And the reason we sneeze: it's caused by irritation to your airways. Your airways are lined with very sensitive nerve cells and they can be stimulated either chemically so inflammation in your airways or damage to the airway linings because of chemicals, or because of damage from say a virus growing there, an inflammation, will trigger these nerves. Or if you stimulate the hairs that line, especially the outer part of your nose, they are also wired up to the nervous system and will make you want to sneeze. The purpose of a sneeze is to expel the cause of the irritant. And the body doesn't care what the irritant is whether it's a physical thing, a chemical thing, or a viralogical thing, it just wants it out. And by triggering the sneeze reflex, which is where enough stimulus of the nerve cells goes to a part of the brain called the brain stem. And those signals are added together, and when they reach a threshold it then triggers your reflex system, which is a sudden expulsion of air against initially you close off your vocal chords, you build very high pressure in your chest, and then you release it all at once either from your mouth or down your nose or both, and it hopefully expels whatever the obstruction is. And we've actually done experiments on the Naked Scientists; you can go to our website NakedScientist.com and have a look at this. We filmed a guy from the team sneezing. We made him sneeze by feeding him pepper. And we filmed the sneeze on a high high speed camera and we took 300 frames a second and filmed how fast the snot took to travel across a distance marker against a dark wall. And we took all the footage off the camera so we had all these images at 300 frames a second, so I joked and said that was 'sneeze frame photography.' And you can actually calculate it's about 100 kilometres to 160 kilometres an hour that the air rushes out at. And the other interesting thing is that one stimulus for sneezing that I didn't mention is bright light. Because there is another kind of sneezing called the photic sneeze reflex which is, if you look at bright light, about one person in five will find that very bright light that they're unaccustomed to, so sudden exposure to unaccustomed bright light, will trigger a sneezing fit and that's called the photic sneeze reflex. Scientists don't know exactly what happens but we do think it runs in families.

Eusebius - Have a beautiful weekend. Thank you Chris.

Chris - I'm looking forward to the weekend. See you soon!