The reason is that the venom snakes use is a protein. Proteins are made up of building blocks of what’s called amino acids. They’re the same stuff, effectively, as your Sunday roast: meat. That means that if you were to eat them – say I ate a snake and ate the poison sacks – if I just ate it and it went into my digestive system the acid and the enzymes in my stomach would just be able to break down the protein so it would fall apart and it would be harmless. It’s only actually toxic if it gets beyond the gut and it gets into the circulation of the body. That’s why one snake could, for instance, eat another snake, and it wouldn’t be poisoned by it. In the same way, a person who has diabetes and needs to inject the hormone insulin. Insulin is a protein and if you were to eat it by mouth the digestive tract would break it down. That’s why people have to inject insulin to make it work. So why don’t snakes poison themselves given they have the same toxin in their bodies. It’s exactly the same reason if for instance your pancreas makes a deadly cocktail of digestive juices which, if they got into your bloodstream, would kill you very rapidly. People who get a condition called acute pancreatitis do have a very high mortality rate. It does kill people because they literally eat themselves from the inside out. The reason that they don’t do that normally when you’re healthy is because the enzymes are made in cells in an inactive state. They’re exported from the cell into a duct which is lined with specially protecting cells that stop it going back in to the body’s own tissues and do any damage. The only place it can go is down the duct and then out into the digestive tract. If you put that into the context of the snake, it’s got a gland which knows how to make the proteins in the venom. They get exported into this duct which is a special holding bay, protected from the venom. It can’t go back the wrong way. When the snake bites you there are tiny muscle cells around those ducts and it squirts the venom down the fang (there’s a duct in there) and in to the holes that the teeth have made in you. That’s why the snake doesn’t die from its own venom because it keeps it in a specially adapted part of the body so it can’t get into the circulation. I did ask a snake venom researcher and he said you can also find snake venom antibodies in snakes to their own venom, to a certain extent. They kind of have their own antivenom built it. Possibly because they have exposed themselves at low level. I don’t know how protective that is so there’s two mechanisms there why a snake doesn’t poison itself.

I think this is about where the temperature has been taken from. Normally with your standard thermometer it is put either under the tongue or under the armpit. This is your peripheral temperature. Although these are reasonable estimates of what your core body temperature is it’s still an area of your body that’s exposed to outside temperatures so it’s going to be slightly cooler. A more accurate measurement would come from a rectal thermometer. Also, before you get carried away in the hospitals these days they use an infrared-sensitive thermometer that you may have seen, You put it into the ear and it beeps. It’ll take your temperature pretty much instantaneously. That’s just detecting infrared detected from the ear drum. It’s a dark cavernous place, it won’t be affected by any of the external infrared because obviously there are infrared rays bouncing about all around us. I don’t think she’s evolving back into a reptile.

It could be that you’re having a very hot bath and when you have a very hot bath your body temperature goes up very high. Normally you would regulate body temperature by sweating. When you sweat water moves onto the surface of your skin. That water evaporating then carries heat away from the body’s surface. That’s called latent heat of evaporation and when water evaporates in this way it carries away extra heat from you and cools you down. If you’re in a steamy bathroom it’s much harder for the water to evaporate and also if you’re submersed in the bath it’s impossible for the water to evaporate from that surface so your temperature goes up. This means you can actually end up feeling as though you’ve lost lots of water because you’re so warm and the body’s reflex is to encourage you to drink.

The reason why your phone interferes with your stereo is your stereo is actually a very inefficient radio. It’ll convert radio signals into sound signals. This used to happen when I was a kid. I lived right at the bottom of a hill of a really powerful medium wave transmitter. Because the signal was so powerful all sorts of things that wouldn’t act as radios will suddenly start behaving like ones. I could pick up Radio 5 on my computer and all sorts of things like that. So basically it’s picking up the mobile phone which is transmitting digital data which makes that horrible de-beep and chghghghgh type noises. You can also design the radio inside the phone so that it’s designed to ignore the wavelengths which it’s transmitting on. So anything about 2 or 3 GHz it will completely ignore them.

Anaerobic respiration is happening. This is so you get a different biochemical pathway that your body uses when there isn’t oxygen as an energy source available. You produce lots of lactate, lots of CO2 and there’s lots of hydrogen protons in the blood. That makes it acidic. Everybody has buffers in their blood to counteract the effects of this anaerobic respiration: buffers like bicarbonate which is alkaline so it means that you buffer the pH of your blood to keep it neutral.

So these are chemicals that soak up acid and essentially stop the acid being just acid. You can put them into your bloodstream and the blood won’t become acidic because the acid has bound onto something. That’s the buffer.

You can find in some people that can hold their breath for a particularly long period of time that they’ll excrete more of these buffers because they’ll be producing higher levels of them [lactates] in the blood. In people who can hold their breath for a very long period of time they’ll be very practised at it so they’ll be very relaxed. This is true if you’ve ever had a scuba diving lesson you might have found you were very nervous. So when you practise with these things, the same as scuba diving and holding your breath. You can slow down your respiration and relax a lot more so you can hold your breath for longer.

Chris: I was having this discussion when I was in Australia recently.  I was at dinner with a wonderful guy.  His name is Leslie Burnett and he’s actually president for the Australasian Society for Clinical Biochemists.  We were having this dinner and talking about this question and we were trying to work out the answer but because we’d drunk too much of another kind of water, the water of life, we kept getting the sums wrong on the back of the napkin.  He’s gone away and this has obviously peaked his curiosity because he’s written to me.  He says:

“Dear Chris, I hope you’ve now returned to Cambridge safely and haven’t got too much of an accent following your stay in Australia and New Zealand.  Regarding the dinner conversation we had about weight loss and drinking lots of water, I happened to go camping with a colleague of mine from Sydney University of Technology at the weekend.  We did the necessary calculations on thermal capacity.  If you recall, if most diets recommend you drink five to six glasses of tap water a day.  I think you lose a lot of weight just by the act of drinking cold water because you’re warming it up to body temperature and then passing it out as urine at 37 degrees.  Why bother with the diet of drinking cold water is all you need to do?”

He’s done the calculation and he says, “Right, ambient temperature of the water is 17 degrees centigrade.” That makes the calculation he uses in a minute, “and body temperature is 37 degrees Celsius.  If you take the glass of water to be 200ml (1/5 of a litre).  If you drink five of those a day that’s a litre of water in a day, let’s say.  It takes one calorie of energy to heat one ml of water by one degree Celsius.  In other words, heating the water from your ambient 17 degrees Celsius to body temperature, 37 degrees Celsius, is a 20-degree increase.  This will mean that you have to use 20 calories per ml of water, times a 1000.  That’s 20,000 calories to get the water up to body temperature.”

Here’s the problem.  The definition of a calorie that dietetics use (what you see on the back of a packet) isn’t a calorie.  It’s a kilocalorie, a thousand calories.  Although it gives you the impression it’s twenty thousand calories to heat the water up it’s actually 20 Calories.  As Leslie points out,

“Yes you will lose energy by drinking a litre of water and then passing it out as warm urine but the energy you use is only equivalent to eating a small apple.  Definitely less energy than you would gain by eating a block of chocolate or a packet of potato crisps.”

A packet of crisps, for example, contains about 200 calories so that’s about ten times the energy in the water.  You’d have to gulp down half of the Atlantic before you managed to burn off half of a chocolate bar.  There’s no easy answer, I’m afraid you have to go with the exercise and reduce our calories.  There’s no quick fix.

Chris: Yeah, this is really exciting.  I remember reading about this eight years ago when people began to discover this sort of thing.  There are some sea slugs which have evolved to eat algae (these are plant micro organisms) and these plants have chlorophyll in them because that’s how they capture the energy from the sun and turn it into chemical energy in the form of glucose.  These sea slugs have evolved to graze on the algae.  They have little outpouchings called diverticula in their gut.  They can put the chloroplasts which are the green bits in the algal cells that contain the chlorophyll into these little sacks.  They extend all the way to the surface of the slug’s skin.  So the chloroplast which can capture the sun’s energy like a miniature solar panel ends up under the skin of the slug.  The slug also has some genes in its body which it stole from the algae donkey’s years ago so it can keep these things alive.  They can persist in the body of the slug for up to four months.  So the slug can effectively photosynthesise.  It can capture energy from the sun and use it in its own body.

Dave: In a slightly less extreme way I think there are some forms of jellyfish which will keep whole algae inside them.  They swim up to the surface in the summer during the day and absorb lots of sun in the algae.  They eat the algae at night when they go down and hide away from all the predators.

Dave: It depends on your mirrors.  Normal mirrors which you use at home actually only reflect about 80% of the light so by the time it’s gone backwards and forwards a few times every time you’re going to lose 20% of what you’ve got left.  Light moves at about 300 million metres per second so it’s going to bounce backwards and forwards in your box very quickly.  Even the best possible mirrors we make will lose about 1% of light every time you do it.  So the answer is yes but in practicality, no.

Chris: What would you do with it if you could and how would you know it was in there? If you tried to detect it you’d soak it up and you can never do that, could you?

Dave: You could put some light in there and come back two months later and see if it’s still there but yeah, it’s not especially useful.

Not easily because (a) there are hundreds of different types of cold virus and (b) they’re continuously on the move.  They’re a moving target because they use a genetic form of information called RNA which makes mistakes when it copies itself and that means that they’re continuously changing their shape.  It’s like having a facelift at the level of a virus on a daily basis so you don’t recognise them from the perspective of your immune system very easily.  They can easily re-infect you and a really good example of this is norovirus which is causing diarrhoea and has had 3 million people locked to a loo seat for longer than they’d like in the UK this year.

Norovirus is an example of this.  It very quickly adapts and changes its appearance so, even though you’ve had it once, six months later you can catch it again because it looks entirely different by then.

They hide! The snails need to maintain moisture on their skin at all times so in the hot, dry weather they don’t want to be losing all that moisture.  Also, in the light of day they’re very exposed to predators.  They tend to hideaway.  If you lift up a few rocks or big plant pots in your garden you’ll probably find them there.

They’re definitely a lot more efficient than normal light bulbs.  They do take more energy to make than a normal lightbulb but the amount of energy they save in their lifetime is much more than the energy you lose in making them.

The reason for this is that the salt crystals (you can put sugar in it and do the same thing) act as what are called nucleation points.  They make it much more easy for bubbles of the vapour which is the boiling bit of water at the bottom of the pan to form.  It’s hard for a bubble to form in the first place because of the water crushing in on it because of the surface tension if you like.  Small bubbles are very hard to form and if you put crystals in then they disrupt the structure of the water, they make it much more energetically favourable for a bubble to pop into existence.  That’s why you get this intensification of the boiling point.