Kat -  Well, you’ll be asking the milkman what sort of blood group they have! No, this is all very simply explained. Blood group is determined by a set of genes. You get one gene each from your mum and one from your dad. Blood group’s determined by basically two different genes called A or B. You have certain versions of these and you can also get a version called O. These genes make proteins on the surface of your blood cells so if you have a gene that is A you make A proteins and they on the surface of your blood cells. If you have a gene for B that makes B proteins that go on the surface of your blood cells. If you have O then you don’t make any proteins. Going back to what I said about you having one gene from your mum, one from gene from your dad  - if you had one B gene and one O gene your blood group would be B because you’ve still got  a gene that’s making B proteins. Your blood cells are B. If you then were with someone else who had one B and one O and you had a baby with them your babies could either have BB genes, their blood group would definitely be B; they could be BO because they’ve one gene from you and maybe an O gene from mum or dad or they could have the two Os, in which case they would be blood group O. It’s perfectly possible to have two B parents having an O child from which you can actually infer both of you must be BO.

Chris -  That’s because group O is recessive.

Kat -  Exactly, group O is recessive because you have no proteins on the surface of your blood cells from this group. If you have even just one A or B gene that determines your blood type.

Helen -  I think you share a trait between about 40 and 60% of people who find yawns very catchable.  The answer is we don’t know.  We don’t really know why it is that yawns are so contagious.  I think we’re not even quite sure why we yawn anyway! There’s lots of ideas as to what that is.  We’re not alone in our catching of yawns.  Chimpanzees do it as well and it’s an unconscious process so we really don’t know what it is.  It could be early on in evolution we needed to communicate how sleepy we were because it was important for groups of people to go to sleep at the same time and wake up at the same time.  Things like that.  By yawning it created a synchronised behaviour and that sort of thing.  That could be a reason why.

People have actually looked at what’s going on inside our brains when we are catching yawns by putting people inside of magnetic resonance machines and looking at patterns of electricity inside your brain when you’re watching other people yawn.  It hasn’t really opened up much of an answer to what’s going on.  We get a lowering in activity of a particular part of the brain called the peri-amygdala region.  This is deactivated very strongly if you have a person who really wants to yawn.  The desire to yawn varies between different people.  We’re really left with a bit of a question mark on that one.

Although I did rather love some experiments I found a report of which is at a zoo - They wanted to see if this was cross-species so they went round with people looking at animals yawning to see if it made us yawn.  And seeing also if we could make animals yawn by yawning at them.  Unfortunately the answer is no.  Someone claimed they caught a yawn from a lion but I don’t know if that really counts!

Chris -  I feel a little bit like yawning with my pets. I have a pet dog and when that yawned I would feel the inclination.

Helen -  It’s possible.  It’s a very peculiar thing because it’s not about an open mouth.  If you cover up a yawn it’s still contagious.  It seems people are more self-aware and empathetic.  It’s something to do with imagining how that other person you’re looking at is feeling.  We begin yawning in the womb.  We don’t know enough about it and why it happens but it’s a very good question.  Keep working on it until we find out.

Chris -  There’s a researcher in New York called Gordon Gallup who did some work on yawns.  He showed students videos of people yawning and looked at who yawned in sympathy.  He then did two things.  He asked the students to breathe through their nose or to breathe with their mouth open or hold a cold compress on their forehead.  Both these strategies, when you hold a cold compress or breathe through the mouth you can effect yawning.  If you breathe through the mouth you yawn more; if you hold a cold compress on your head you yawn less.

His theory is that yawning cools the brain in some way.  It’s to do with alertness.  If you have an infectious yawning behaviour, if you have a group of people who are all sitting round a campfire at night and there’s a danger some predator might come along – if one person starts yawning it means one person’s getting a little on the tired side.  By cooling the brain and increasing alertness - when you have sleep deprivation brain temperature rises -  this means if everyone catches the yawn everyone is made more alert at once.  This keeps everyone looking for any danger.  This is his theory.

Chris -  Fire looks like a solid thing but it’s not. It’s actually just vapour. When you heat something up to a high temperature it shoves out chemicals which are volatile and flammable. They mix with oxygen which is coming from the air around them. They combust so they react with the oxygen and they burn releasing heat. They also produce some degradation products or burning products from combustion. When you make that it glows. It’s incandescent and it gives out light at different wavelengths and different chemicals make different coloured lights. That’s why flames have different colours. Sodium’s very common and that makes flames an orange colour. If you have incomplete combustion. If you have some sooty particles in the smoke or the vapour they’ll glow orange as well. This is why you then see this orange pattern.

Chris -  This is really clever but it goes back 100 years actually.  People discovered a paint in 1905 called zinc sulphide.  They found that when you shone light on this or something radioactive, radium, it could behave as what’s called a phosphor.  In chemicals like that, what happens with them is that when you put some energy in the form of light the light kicks some of the electrons up to higher energy levels than they would have normally.  Immediately you would expect them to fall back down again but they don’t.  In some cases these electrons stay at this slightly higher energy state for a variable amount of time and then they fall back to their normal energy level.  When they do so they give out the energy they soaked up.  They give it out in the visible spectrum and in most cases this is a sort of greeny colour.  Green is the colour the eye is most sensitive to in the dark.  That’s the colour combination most often used because you don’t have to have such a good effect for it to be visible.

It’s possible to make even better chemicals these days.  There’s one called strontium illuminate which is very, very good at soaking up lots of energy and then very slowly oozing it back out again.  I think it was Yamaha made a motorbike where the fairing had this around the outside edges so it would soak up light during the day and would have a sort of glow-in-the-dark motorbike at night.  The idea being that this would make it more visible.  You’re making a much bigger angle on someone’s eye when they’re looking at you in the dark so you’re much more likely to see the motorbike.

Kat -  That would look really spectacularly cool!

Helen -  I guess first you want to know what tannins are and why do plants have them.  It’s something called a secondary metabolite which basically means it’s something that plants make which isn’t absolutely essential for plant life.  It’s not part of growing or repairing itself or existing.  It’s something that’s going to add a little extra to the way they live their lives.  These are basically things that taste bad.  They interfere with things that try to eat plants.  They do things like they bind proteins that are eaten.  Once they get inside of the caterpillar or the cow or whatever it is eating the grass it stops it from being digested.  It puts off animals from wanting to eat different types of plants.

We (humans) eat tannins.  We actually quite like tannins in tea and wine.  Some animals quite like the taste of tannins and some adapt ways of being able to deal with them.  Essentially this is a kind of plant defence mechanism to try and stop them from being munched.  Some plants will produce tannins naturally anyway.  Once they’ve got themselves growing and they’re up doing quite well they’ll put tannins in parts of their leaves and stems just to generally keep herbivores away. 

Some plants actually do a rather clever thing which is because these are quite complex chemicals - they’re called polyphenols - they take a bit of energy to make so it might be better to only make them when you are being attacked by something.  There are mechanisms by which a mechanical effect, whether that’s actually something eating you or even just being damaged by wind, will actually trigger a pathway that synthesises tannins.  People have shown that even by just breaking off bits of leaf it triggers genes that code for an enzyme that’s part of a pathway that generally creates this tannin.  The really clever thing is, for which I really think plants are wonderful, if one plant over here is eaten by a caterpillar and it starts producing tannins it produces another substance (a type of pheromone, a volatile hormone) that tells other plants that tells other plants nearby to start producing tannins.  It’s plants communicating to each other and protecting themselves from creatures that are trying to eat them.

Chris -  This is all down to surface area.  If you chop up your swede into small chunks then it means there’s far more contact between the vegetable and the hot water.  If you have one very big swede you have a very big volume locked up inside your swede but not much surface area on the outside of the swede for the heat and the water to get into the vegetable matter.  If you chop it into small bits the surface area is now very high relative to the volume so it can get heat in much quicker.  The downside is that it can get cold much quicker once you put it on your plate.  Eat up quickly!

Kat -  There’s two reasons for this.  37 degrees is our internal core temperature and the temperature that’s on our skin is probably a bit lower.  I don’t know if this is specific to ladies but often your feet are a bit colder than the rest of your body and my boyfriend always whinges about it.  37 degrees is your core body temperature.  Temperatures that are lower than that will still feel hot to us on the outside.  The other reason is that it gets harder and harder to cool down your body the hotter it gets, the nearer it gets to 37 degrees.  Basically we’ve evolved systems in our bodies that kick in to cool us down before we get as hot as 37 degrees.  It’s really to protect us because once you start to approach a temperature of 37 degrees it does get very difficult to keep yourself cool.  Sweat doesn’t evaporate very easily, so you can’t cool yourself down.

Chris -  Some people say that the dinosaurs struggled with this because they had something called gigantothermy.  Going back to Les in Over’s swede once you have a very big body you don’t have a big surface area relative to the volume inside you and your metabolic rate is producing all of these chemical reactions that are very exothermic. They give out a lot of energy. Getting rid of that excess heat can be really quite tricky. Some of these dinosaurs struggled to keep themselves cool enough. Although they were effectively cold-blooded because they were reptiles they were effectively warm-blooded. Right in the core of the dinosaur they were so hot from not being able to get all their heat out that they were effectively as warm blooded as you and I.

Kat: Getting too hot is really very damaging for your body’s reactions once you get over a certain temperature you just can’t function properly.

Chris -  It is because lots of people say that snakes are in some way immune but the reason is the same reason that you don’t die from your own gastric stomach juices.  If they get in to the wrong part of your body they will kill you very effectively.  When people have pancreatitis which is where the pancreas which is connected to your gut and secretes all the enzymes that break down your lunch.  When that gets inflamed and the degrative juices get into your blood stream this can cause quite sever damage to your body and it can cause lung damage and other forms of inflammation.  That’s very bad.

The snake uses the same strategy that you do.  It makes the venom which is a kind of protein.  It’s a tiny protein which it can make lots of and it has it in a little sac which it stores up in its head.  It’s connected to the two fangs at the front which are hollow.  When the snake bites you this sac squirts a venom out, down the teeth and into your skin.  If you look at the venom gland it’s lined by very specialised cells that keep the venom there and not in the snake’s body.  There should be no access between the venom and the snake’s body.  When I spoke to someone who is a venom expert they said you can also detect antibody to their own venom in some snakes.  Just in case some spilled over I think they have this back-up plan which is they have some antivenom built in to mop it up and make sure it doesn’t go any further.

Helen -  I think my favourite thing for rumbling stomachs is the official word for it.

Chris-  Borborygmy.

Helen -  Borborygmy, that’s right!  Do you know where it comes from?  It’s one of those words where you think it must have some clever meaning but apparently the Greeks came up with it.  It’s just onomatopoeic.  It’s supposed sound like the sound of your stomach rumbling!

It’s all about your intestines being a bit of a long tube between your mouth and your bottom, if you like.  You have these waves of contraction that are trying to push food down.  It’s called peristalsis that pushes food through the system into your stomach, through your intestines.  It does this all the time and when it’s full of food there’s really no noise as it gets absorbed by the food.  When your stomach’s empty or there’s a gas bubble trying to make its way through the system it tends to resound a bit and make those kind of funny noises.  That’s basically what’s going on.  It’s happening all the time but usually you don’t hear it.

Kat -  This is a really interesting one because there’s anecdotal evidence that dogs can detect when someone’s going to have an epileptic fit.  There’s also a lot of evidence that actually they don’t.  In some cases where people are having seizures that aren’t genuine epilepsy but are brought on by psychological states, there’s some worry that dogs behaving in a certain way might actually cause them to have a seizure when they wouldn’t normally.

There are some dogs that are being trained to look after people with epilepsy once they’ve had a fit.  For example, by bringing them a blanket or getting help anmd making an alert.  If there is any truth in how dogs may detect fits before they happen maybe they’re picking up something in the changes in their owner’s behaviour.  There’s really very little really solid evidence about it.  It may be more the partnership.  If you have a dog for a long time they get to know what you’re like and what you do.

Helen -  That’s a very good question because I get bitten like anything when I go researching in the tropics.  It’s all about what it leaves behind inside you.  They actually pump saliva into you full of anti-coagulating compounds because they don’t want your blood to clot while they’re there trying to suck it up.  They pump you full of anti-coagulants and leeches do the same.  This is why you bleed a lot if you’ve had a leech bite.  Your body can have an auto-immune response to that which is why it can swell.  You can get used to it if you have a few over a few days.  Some people can get used to it like having shots against allergies.

Chris - The reason planes leave vapour trails is because they’re burning hydrocarbons, chains of carbon atoms linked together with hydrogen round it.  When this mixes with oxygen you make water and some carbon dioxide.  The vapour trail is the water and because the plane’s very high up in the air actually what you’re getting is ice.  Vapour trails are water vapour that often form ice crystals.  They leave those nice miniature clouds behind in the wake of the plane.

It is also possible to make much weaker vapour trails form without the plane's engines running.  As the plane flies, the wings create a vortex of lower air pressure.  This low pressure can lead to lower temperatures, where water vapour condenses forming vapour trails starting at the tips of the wings.