How can smoking marijuana affect your health?

How do we know the earth is round? Why do some people make noises during sex? Why do crabs move sideways? Why are some parts of the sea violent with lots of waves, whereas others aren't? How can smoking marijuana affect your health? How can some female bees reproduce without males? What causes motion sickness? And why do some females grow facial hair? Plus, scientists in Australia have uncovered evidence of the earliest animal. Eusebius McKaiser and Dr Chris Smith take on more of your questions on Talk Radio 702...

Eusebius - Good morning Chris!

Chris - Morning.

Eusebius - Interesting first story, we're going to be talking about fats. That is what many millions of years ago able to reveal some interesting things about some early known animal.

克里斯——是的,这个惊人的故事。th之一e big mysteries is how life on Earth got started and how we got here. Now we know life on Earth got started quick. So something like about four billion years ago the first lifeforms were already operating. But then things stayed pretty quiet for a long time until about six hundred million years ago and then suddenly we went from what was just microbes for billions of years to big stuff. And there are fossils from about five hundred seventy odd million years ago of these bizarre things that no one knows what they are. We just know there big fossils and they were alive. But no one can say, based on looking at them, were they animals or were they plants or were they just some bizarre evolutionary experiment? Now the way to nail this has been achieved by scientists in Australia this week and they've published the paper in the journal Science. Jochen Brocks and his colleagues obtained some fossils of a species called Dickinsonia. This looks a bit like, if you look at the pictures of Neil Armstrong's boot print on the Moon there's just a sort of blob with some trademarks, this fossil looks a bit like that. It's sort of bean shaped thing. In some cases they were a metre and a half across. They would have lived on the ocean floor, very flat, probably interacting or feeding on the microbial mat of material that was there, but that's all we know about them. We can't see a mouth, we can't see a bottom end, we can't see any other way that they would have moved around. so were they alive, were they an animal? What this group amazingly did with these fossils was to use a very aggressive chemical treatment to get out of this fossil, which is nearly 600 million years old, the fats and the cholesterol that would have been in the living tissue of that fossil when it was alive. And they've analysed the chemical fingerprint of that cholesterol and it is only found in living things like us. In other words animals. So what they have proved is that these things that were around, and very big at about five hundred and seventy million years ago, were the first big lifeforms on Earth. And so this really moves us forward a very long way because we now understand a lot more about the processes that would ultimately have given rise to us. These are our ancestors if you like, but it shows us that very quickly when it started to happen big life sprung up and was probably very peaceful life because it was there for millions of years and then it disappears. And I said to Jochen Brocks where did they all go? And he said well probably some new animals evolved that just ate these guys who had no way to defend themselves. So isn't history interesting and having a strange habit of repeating itself.

Eusebius - Absolutely fascinating. Paul good morning and welcome to the show. You had a question last week we didn't have time for. Put it to Chris right now.

Paul - Good morning everybody. My son is at university that he would be his degree. There's a lot of students that are now saying that the Earth is flat and they've got very good argument for it like, for example, the Earth spins and then if you're in the centre of the Earth like at the north or south pole you'd be fine, but if you moved close to he equator the Earth would throw you off. And they come will all these very good arguments. And my son says he's challenged me to prove to him undoubtedly that the Earth is round. He truely believes that the Earth is flat. There is physics and all that stuff and I'm not on that level. How can I prove to him that the Earth is round.

Eusebius - I want to add to that question if I may as well Chris. I've always wanted to know as well is the Earth actually around? What is its actual shape? We say the word round - those of you who are the scientist sometimes use the word spherical. What is the difference? What is the actual truth about its precise shape?

克里斯-好吧,首先,为了纠正任何of the notion the Earth is a sphere, okay. The Earth is not flat and I don't where these nutcases come from, and I'm sorry to use such dismissive language, but they're mad, okay. These people are mad. And hundreds of years ago they would be forgiven because they didn't have the education and access to the information we have today. These people are mad, the Earth is not flat, okay. If you look in space you can see evidence that things in space are not flat. The Moon is not flat. The earth is not flat. Mars is not flat. The Sun is not flat. They're all big round balls because of gravity. Gravity is a function of mass. Big things, lots of mass in one place creates gravity, therefore it pulls things towards itself and it pulls things through its center of mass which means things organise themselves in such a way to have the most efficient arrangement of the particles to give them as close a packing as they can achieve. And that means a sphere. So the Earth is a sphere. We know it's a sphere partly through observation. People have been into space and they've looked at the Earth from space. We know it's round. We've got satellites which are orbiting the Earth. They're going around in a big circle-ish so we know it's round. There's an International Space Station with people onboard it going round it at 400 kilometres above the Earth about, I dunno, 15 times a day. It's round. So that lays that one to rest. It's not perfectly round though Eusebius, you're quite right to raise this point. The earth has a bulge. Because the Earth is spinning north to south around its axis the equator feels, and I don't want to create arguments with physicists, but it feels a centrifugal force. We'll use that term loosely but basically because its spinning it creates a bulge around the equator. So its a bit fat around the middle like much of its human population and that means its not a perfect sphere but is good enough. So its a little bit bulgy around the middle but it is round. It's not flat.

Eusebius - Okay now this is the Naked Scientists. It's not talking sex but there's a scientific element to Mox's question that otherwise I would have described if it was with Dr Eve as an orgasmic question. Mox, what is your question? I'm sure Chris is very curious what I'm alluding to...

Mox - Yes please. Well good morning.

Eusebius - Good morning sir.

Mox - Yes, thanks. Dr. Naked right, I've been almost wondering about this concept of [**] animals. People and animals, human beings throughout the process whenever they're having therapy of sex at the time of screaming shouting. I don't know what causes that word? What happens in the body what tell us, what was happening in the mind of the person.

Eusebius - Lovely question!

Mox - Why does it comes with that?

Eusebius - So why do we scream when we have sex and is it unique to us?

克里斯-为什么有些人尖叫者?这不是唯一的to humans actually. Lots of animals do make noises but sometimes they make noises because it's not comfortable. And some animals like foxes, for example, to make sure that they actually have a successful coupling sometimes the male gets stuck inside the female for a period of time. And when they try to disentangle themselves actually it's terrifically painful for at least one of the two parties and that can cause yelping and shouting. But humans tend to do this not because they feel that they can't suppress it. Because if you ask people can you suppress these shouts and screams, in the same way that Venus Williams seems to make a lot of noise when she plays tennis and Serena as well, that there's no evidence that they couldn't not do that. But people do it because it gives them more encouragement. It gives them encouragement but it also gives their partner encouragement. So we think it's a sort of part of the bonding process and people do it because they're saying yes, I like that do it more and it's a very very encouraging way of saying do more of that I like it.

Eusebius - Teddy, good morning.

Teddy - Good morning. How are you Eusebius?

Eusebius - We're extremely well thank you Teddy. Speak up a little bit for me. What question have you got for us?

Teddy - Lkay. My question is not connected. I just wanted to know why do crabs walk sideways.

Eusebius - Why do crabs walk sideways Chris?

Chris - It is because of the function of their anatomy. Their legs are organized in such a way that the most efficient way for them to move without getting their legs all tangled up is to go sideways. And because if they were to walk forwards then the legs behind would crash into the legs in front of them and they'd have to evolve their anatomy in a different way and the way they move in a different way. So actually they have evolved to move sideways because that way they can move the fastest way they possibly can to get away from predators.

优西比乌- Anclumorlu。好morning to you.

Anclumorlu - Good morning. My question is about the Indian Ocean. We share the ocean with a couple of other countries, for instance in Devon and Cape Town the Indian Ocean is quite violent, its got a lot of waves. But as we go up north, like for instance in Zanzibar it's calm and quiet. It's actually you see this and I can swim a kilometre into the sea and there's nothing. But you can't do the same in [**] comes from?

Eusebius - Oh what a lovely question, yeah. Chris.

Chris - Yeah. Well the reason partly is because where you get down south you've obviously got an interface between not just the Indian Ocean but the Southern Ocean and around the corner is the Atlantic Ocean. So there's a meeting of many different bodies of water and lots of ocean currents. There's an upwelling of cold water coming from the Antarctic which comes up near Cape Town and along the southern coast of southern Africa, and all of these things are going to create local conditions. They're going to have different effects on wind. Wind is also going to have a very strong driving force as it comes across the open ocean. So there are all these different effects which affect how rough the sea is. Also the local geography and whether the sea has encountered a sort of a sudden abrupt change in depth which will cause waves to heap up, or whether the sea floor just slopes up gently so the sea just gently loses its energy against the sea floor as it comes in towards the land. So there's a whole range of different factors which are both physical and also geographical which affect how rough the sea is in a particular area. And I suspect that's the factors that are at play here.

Eusebius - I think we've got a question for you via our WhatsApp voice note number. Chris, let's have a listen to this one.

Bill - Hello Eusebius and Naked Science. My name is Bomanya I'm calling from [**]. Could the Naked Scientist help us and tell us what are the really true benefits of smoking marijuana? And what are the dangers? I'm worried in light of the judgment that was passed this week. Thank you.

Eusebius - You've probably caught wind of that judgment. It's been reported globally, Chris. At least the beginnings of decriminalization of the private cultivation and use of marijuana in small amounts is now something South Africans can do without falling foul of criminal law.

克里斯——是的。这是一个工厂,就像tobacco, if smoked can produce effects that some people like. Now there are pros and cons to this. The pros are the people who like doing that are doing something that they want to do and they're not doing it illegally. The downside is that actually there may well be considerable health consequences, especially if not done responsibly. The level of knowledge we have at the moment is that some of these marijuana plants, which have been bred for the drug industry, have very high levels of chemicals including one called THC tetrahydrocannabinol, which has very powerful profound psychoactive effects and has been linked to people experiencing psychosis; in other words schizophrenic type symptoms. And there is a link between people using marijuana and people developing some of these conditions. Although what we're not clear about at the moment is whether people use a lot of marijuana because they're developing one of these conditions and they use the marijuana to feel better, or whether the marijuana triggers the condition to happen in the first place. We're not entirely sure at the moment whether it's chicken or egg here. But we do know there is that strong association. There's also evidence that the use of marijuana does rewire your brain. It strongly affects the circuits in the brain that are concerned with reward and motivation and people who are users, long term chronic users of marijuana, do suffer from a lack of motivation and reward. The chemicals in marijuana also strongly stimulate the parts of the brain that are concerned with appetite and this is why people describe classically the marijuana munchies. People who use the drug say they then develop a serious hankering for high calorie food and they tend to binge. So it's also associated with weight gain. That's some of the sort of neurological effects.

Some of the other effects: you are smoking something if you smoke it. And if you smoke this stuff anything that smoke going into your lungs is going to have a very deleterious effect on your lungs. Theres a lot of tar in marijuana, its irritating to lung tissue and therefore may accelerate lung aging even beyond the effects of just the tobacco that you mix it with. So smoking is always bad. But marijuana may add an additive bad effect on your lung tissue and therefore you need to be aware of that if you use it.

Eusebius - Nigel, good morning to you. What's your question?

奈杰尔-嗨。我一个养蜂人的Western Cape bees - social honeybee. And the female worker bee cannot physically mate, but she can practice something called parthenogenesis, which means she can lay a fertilized egg. And I'm very curious as to know scientifically how that process actually works biologically within the bee? And then the second part of the question is what other animals, I believe ghekos and loads of different things can also potentially practice this? It's just something that I'm very curious and I'd just call this on the radio.

Eusebius - Okay.

Chris - Morning. Yeah. Wonderful question. Now the thing to consider here when you when you're talking about females and female reproduction there is this process you have referred to called parthenogenesis. Females can lay eggs, but if they haven't got anyone to mate with and they're going to lay an egg which is only got half the amount of genetic information in it. So what some species can do is to lay an egg which has got half the amount of genetic information, but then they can double up the genetic information that they do have so that they've got the right amount of genetic information in the egg and it can continue to develop. And now in a bee colony, the female is the one that's mating has the sperm, has the eggs, and can lay those eggs. And the queen bee will normally suppress any of the sister female bees reproductive processes with various pheromones and hormones. But sometimes as the queen ages - I believe it's when the queen ages - and her pheromones influence declines a bit then sometimes some of the other female workers can begin to become, or attempt to become reproductively active, but that's not the normal way. Normally the way this works is that the bees are foregoing their own reproduction in favour of supporting the queen because they're all genetically related and therefore by the Queen reproducing successfully that means that they're all indirectly keeping their genes in the population. Other animals do this too, and famously Komodo dragons have the ability to undergo parthenogenesis. And this was discovered and proven for the first time about ten years ago at a London zoo. What they showed is that Komodo dragons, if there's just a female, there's no male to mate with the female can produce offspring. The offspring though will default to male because in a Komodo dragon if you have, unlike a human where you have two X chromosomes making a female, if you have two of the same chromosomes the animal develops as a male. So if you have a female kept on her own she will produce, by parthanogenesis, a male offspring and then you've got a male and a female that could mate and have sex and produce offspring the more normal way. And so that's what we think has happened because if these animals were were washed away across the ocean onto a remote island or something, if a female on her own arrives there there's still the capacity to reproduce and start a new male and female, sexually reproducing breeding colony just from one female starter.

Eusebius - Okay. Thanks for your question. Much appreciated.

Eusebius - Lisa good morning. Yes I'd like to know about the motion sickness. I was once on a military ship a few years ago. I couldn't stand on my feet for the rest of the 24 hours. But earlier this year I was on a cruise ship and not had a single minute of that. What causes motion sickness?

Chris - Well to be honest we really don't know or don't understand this. I mean it seems totally illogical doesn't it that the chronic disturbance of what we call the vestibular apparatus. The vestibular system is inside your inner ear. It is a series of fluid filled canals which are organized in all three axis of movement, so side to side, front to back, and middle to you know each side. And those detect movement and they are used to match the movement of your eyes to the movement of your head so you can maintain constant balanced gaze. For some reason we don't understand, if you input lots of contrasting changing signals into that vestibular system by shaking around, moving around, rocking back and forwards, it really upsets the system. And your body decides that the reason that this is happening is because you must have been poisoned and therefore the most logical thing to do is to throw up. Now no-one knows why the body has reached this conclusion or how it got to do that, but that's what happens. Perhaps its something in our ancestry where these sorts of symptoms were caused by exposure to toxins and things in the environment and so it probably was a lifesaver to throw up. Perhaps that's where it came from. Its not also common to everybody. Some people get this worse than others. Also age is an effect. People tend to find that when they're young it's less profound and less pronounced and as they get older it's more of a problem for them. But also the type of vessel you're on, the amount of swell, how much things are changing, and whether or not you can actually maintain gaze on the horizon and see where you're going also makes a very big difference. So it's a very strong psychological thing with a neuroscience underpinning, and it's very unpleasant if you have it. But you can take antiemetics, anti-sickness drugs and they are quite effective. There are antihistamines, drugs like Cyclizine which can help you a bit. And there are some other other drugs, there's one called Metoclopramide which are quite good at suppressing these symptoms in some people.

Eusebius - Squeeze in a last question, Chris. We've got about a minute or two left. Molly, good morning to you. What is your question for Chris?

Molly - Morning. I'm female of 22 and I've just noticed that I'm growing a beard and no-one from my family seemingly has that. I'm worried it maybe something that I ate. Or is there a way to stop it? I'm afraid if I shave it will just grow more.

Eusebius - Molly started growing a beard in her 20s, Chris.

Chris - Yes, hello Molly. I'm sorry to hear about that. That can be quite distressing for you. The thing to bear in mind is that this does happen and usually facial hair grows for a number of reasons. In some people it just happens, in other people it can be under the influence of hormones. And usually facial hair is driven by the male hormone testosterone or related hormones called androgens. And if this is happening, and it suddenly started happening to you then something must have changed to make that happen. I would urge you to seek the advice of a doctor who may be able to do some hormone tests and see if you have certain conditions that can raise the level of male hormones in the bloodstream a little bit. Because women are very sensitive to these androgens and that may be the reason and it may be relatively easy to control. But don't panic because people think that if you trim beard or you trim facial hair it'll grow more. That isn't true. The hair is dead it doesn't know if it's being cut or not. So if you were to trim them for cosmetic reasons in the short term it's going to do any harm at all. I would urge you to go and see somebody who can assess you properly though and investigate and find out why this is suddenly started happening.

Eusebius - All the best to you, Molly. Thanks so much for that question. Chris thank you so much for sharing your knowledge with us. We'll do it again next week.

Chris - Thank you Eusebius. Bye bye.