Nature's Master Timekeepers - EWTS #012

Joe: Hello and welcome to this episode of Enough with the Science. I'm Joe.

Senan: And I'm Senan. What do we do here, Joe?

Joe: Well basically, for anybody joining us for the first time, which maybe you, listener; we talk about science topics and Senan has the mind of a scientist. A great scientist. He keeps it in a jar under his bed. And he explains; we choose a topic every week and he tries to explain it to my tiny mind. So, what's the topic this week, Senan?

Senan: Hold on now, I'll just shoehorn in that brain that I have in the jar before we start talking about it. So Joe, tell me; now I know the answer from you before I even ask this question is going to be no.

Joe: You should never ask a question unless you know the answer.

Senan: Do you ever experience that horrible feeling of being late for something?

Joe: No.

Senan: You don't. I know you are the most punctual person on the planet.

Joe: No, I just have no conscience.

Senan: I, on the other hand, am very intimately familiar with the concept of feeling abysmal because you've been late for something you shouldn't have been late for. Anyway, the subject of this week's programme is what the hell is wrong with my brain. No, the subject of this week's programme is how animals and plants keep track of time and how important it is.

Joe: We don't have enough time for that Senan. We don't have enough time.

Senan: This is before the rabbits in the fields ran around with watches on their bushy tails.

Joe: Or they used to listen to the bells peeling from the village church at 6:00 PM.

Senan: I have a vision of you getting out a sharp knife in the kitchen and trying to peel a bell; it must be damn hard.

Joe: I'm going to leave that in there. I shouldn't, but I'm going to leave that in there. So, on to today's topic.

Senan: Right. Okay. It's a fundamental feature of life on Earth. So many processes; it's critical. Not just for humans, for animals, for plants. There are so many things that have to happen on time or the world just comes to an end as far as that creature is concerned. Flowers need to flower at a certain time; animals need to spawn at a certain time; humans need to get up in the morning and go to work at a certain time.

Joe: People have to tune into this podcast at a certain time.

Senan: And even bacteria are known to have... no they don't. They can tune into this podcast whenever they want. Hopefully often as they want to.

Joe: Good. Well caught.

Joe: But I was just checking if you were listening to me; that was all I was doing there.

Senan: I don't listen most of the time so you're lucky I picked up that one.

Senan: Anyway, there are so many different mechanisms because it has evolved in different animals for different reasons. There's loads of different mechanisms for how animals keep track of time. But let's just talk about us; well mammals, but particularly us. Believe it or not, almost all of our cells have their own little clock. Built into the cell there's a couple of DNA proteins called Clock and BMAL1. Lovely names that.

Joe: Yeah, they weren't really adventurous with the names. "This is the clock, what does it do?" What do you think?

Senan: Well look, I suppose some of them just wanted to have practical names rather than flowery ones. Anyway, these two proteins are responsible for the production of certain chemicals that, for want of a better description, build up in a reservoir in your cell. For about 12 hours during the day, there's a little pipe that is producing these chemicals and it's building up and building up. Eventually, there's so much of the stuff has been produced after about 12 hours that the pipe gets blocked and no more new stuff is getting produced. Then it takes about another 12 hours for the stuff that's in the reservoir, the stuff that has been produced, to gradually degrade before the pipe is unblocked and it all starts all over again. So the total thing is a 24-hour cycle.

Joe: That's a solar day.

Senan: Yeah, I mean we've evolved on a planet where the day is 24 hours and our biology has synchronised itself to that.

Joe: So this was present in all single-celled organisms?

Senan: Well, the particular mechanism I'm describing here is kind of unique to mammals but most organisms down to the level of bacteria have something analogous to that; some way of tracking time on a regular schedule. And various; it's all chemistry driven. So certain things are supposed to happen when that reservoir is full, certain things are supposed to happen when that reservoir is empty; and some things even react to maybe when it's half full or whatever. So it's a chemical scheduler, or chemical clock that's happening. Of course, there's a problem with that.

Senan: If you've got millions of clocks, because we have millions of cells in our body, they're not all going to stay in synchronisation if they're left to their own devices. They'll all be dancing to their own tune; the clocks will gradually go out of synchronisation like any clock does. So there needs to be something to keep them all in sync and that's where we come to the suprachiasmatic nucleus.

Joe: Charismatic?

Senan: Chiasmatic. Anyway, so I'm just going to call it SCN from now on. Anyway, it's a tiny part of our brain. 20,000 neurons sounds like a lot; it's actually not because there's billions of neurons in our brain, so it's a tiny part of our brain. It also uses our friends Clock and BMAL1 to keep track of time in those 20,000 neurons. But there's a couple of tricks it has up its sleeve. First of all, those neurons in that SCN area are all tightly aligned with each other. So they are talking to each other and making sure that all their clocks are on the same time.

Joe: Okay, so you basically have a big bunch of cells that are all aligned.

Senan: Yeah. Unlike all the other cells in your body, each cell doesn't really care too much what the clock in the neighbouring cell is doing, whereas these boys do; they keep an eye on what the neighbouring cells are doing. That's the first thing. The second is they have a very important resynchronisation mechanism because look at in the modern world, for example, if you fly halfway around the world to Australia or somewhere. Suddenly the day is happening when night used to happen. And all the processes in your body are happening literally at the opposite part of the day where they should be happening.

Senan: The SCN is connected to the retina of your eye and it receives signals of when it's bright and when it's dark. And it's actually able to gradually over a period of days; that's why jet lag takes a few days to wear off; gradually over a period of days it's able to resynchronise the clocks in your body to match the new reality of your now in Australia.

Joe: So it takes a few days and then suddenly you're aligned with the day and night.

Senan: Yeah, and then when you come back again you're all messed up. The end of your holiday. So yeah, and even it also like obviously in winter our days are a lot shorter and summer they're a lot longer; at least they are in this part of the world. If you're near the equator it's different.

Joe: What do people who live in the equator do? That's exactly 12 hours. Are they slightly more aligned with their internal clocks?

Senan: Yeah, they don't have the same seasonal variations that we probably experience. I suppose when you think about it when we were hunter-gatherers living on the plains or whatever; the time of year when there was more sunlight, there was also more food to be found. Whereas in the winter when there was less sunlight, it was okay for us to be more sedentary. We didn't have to go out and be active finding food all the time because there wasn't that much to be found. So yeah, that whole resynchronisation mechanism had a good reason to evolve even before the age of jets.

Joe: It's not just there; like all of this is not just there to cure jet lag. That's not why it's there.

Senan: No, it's just convenient, we're piggybacking on it.

Joe: I wonder did they ever do an experiment where they just kept someone in jet lag for a long; like just fly them to Australia and they're jet lagged and they're just getting over the jet lag there; fly them straight back.

Senan: Long haul pilots and air stewards must experience that kind of thing. I wonder; because there's definitely health implications of it being regularly disrupted. They know from research done on shift workers who are working during the night that they are more prone to certain metabolic disorders. Because typically your body; the processes inside your body are kind of run by hormones to a large extent. So hormones have to be released; certain ones at certain times to synchronise with other things that are happening in your body. And a lot of that is being driven by your clock; the cellular clock.

Senan: So I mean if people's hormones have been released at the wrong time, it's going to mess up the metabolism in their body. And it's certainly; in relation to the way food is absorbed it's known that people on shift work are more likely to suffer from things like obesity or diabetes or high cholesterol. And there's even a link to cancer because cancer is essentially DNA mutations. Your cells have an inbuilt DNA repair mechanism that runs, or is supposed to run, on a schedule to look for and repair DNA faults. Typically cancer only occurs where that repair mechanism has failed to identify a faulty piece of DNA and has allowed it to replicate. But if that DNA repair schedule is not correctly adhered to, there's a greater chance that some of these faulty genes will get through and cause cancer.

Joe: Scheduled antivirus is not working and something sneaks through.

Senan: Yeah, well just to be complete nitpicky now, cancer of course is not a virus per se. But yeah, no I get the analogy. So yeah, so it's serious stuff; it's important that the clocks are running right.

Joe: So for a good life, the more closely we can align with the 12 hour...

Senan: Yeah. Yeah, so it seems.

Joe: That we are built to.

Senan: Yeah. Now we are kind of flexible creatures. You know, obviously people live in the north of Russia and north of Canada and north of Norway where it's dark like all winter and they manage to get by; although there is issues with depression and so on that they have to deal with more so there than they do here. But still, we are kind of flexible in that there's a broad range of environmental conditions that we can still survive in.

Senan: So that's all about the automatic stuff that's going on in our bodies that we don't have to think about. But then there's the whole other side of our conscious experience of time. You know, what I'm talking about is sometimes time seems to go very fast and sometimes it seems to go very slow.

Joe: And we let the listeners decide which way it's going today.

Senan: I'm sure it's going super fast because it goes fast when you're in what they call a flow state or when you're "in the zone". You're deeply engaged in some task that requires a lot of concentration; it's a task that you get good satisfaction out of, so you know you're happy to be doing it. And time seems to pass really fast. A typical example is computer gaming. People can do hours long sessions of computer gaming and not realise that much time has gone by at all.

Senan: There's a really silly complicated scientific name for it called transient hypofrontality. Transient just means it only happens for a short period of time. Hypo actually means low, although you might think it should be something hyper, which would be high; hypo is low. What it means is that the part of your brain that normally tracks; consciously tracks how much time is passing, so you can have a fair idea how much is five minutes and how much is 15 minutes and so on...

Joe: Jack Reacher. Jack Reacher has a spot on one of those. He can tell almost to the minute.

Senan: To the minute?

Joe: Well yeah pretty much. He wakes up, he goes "it's 7:15". He doesn't need to look at a watch.

Senan: Oh that's a bit like; what's his name that was in Groundhog Day? Remember his clock went off every morning at the same time?

Joe: Yeah, that's not the same thing.

Senan: Well look, it's related.

Joe: It's not really. He's got a clock that's going off at the same time. Of course he's going to know what time it is. No, this Jack Reacher has this bit that you're talking about in the brain that kind of calculates time.

Senan: The super charismatic nucleus? No, no, I know what it was called.

Joe: No, this last thing that when we're in a flow state and we're conscious. So if you're conscious of time; but he's obviously got a very effective one.

Senan: Yeah, he must have. He's got some use.

Joe: For a fictional character.

Senan: Quick dissect him and see what he's made of. Anyway, the prefrontal cortex is the part of your brain that kind of consciously tracks how much time is going by; five minutes, 10 minutes, whatever it is. When you're in the zone, when you're deeply engaged in some task like we've just described, that actually goes quiet. It stops recording five minutes, 10 minutes, 15 minutes. And as a result, consciously you literally don't feel time passing. And you know, after an hour you stand up and you look at the clock and you think something wrong with that clock; it's an hour fast. So yeah, that's when you're deeply engaged. The opposite of course is when you're bored and time seems to crawl.

Joe: That never happens to me.

Senan: You never get bored?

Joe: It never happened. I never get bored.

Senan: Usually when you and I are in conversation I can see your eyes glazing over.

Joe: But that's because I'm thinking of something else. I'm not bored.

Senan: That's actually one of the characteristics of being bored is your mind starts to wander.

Joe: Ah now hold on a minute. That's a bit of an easy cop out. So I'm thinking of something else; "Oh yeah you're obviously bored." But I'm not bored. I'm not; time isn't dragging. Maybe I just have an inability to be bored.

Senan: You don't have the boredom gene.

Joe: I don't have the boredom gene.

Senan: You know they should do an experiment just to verify that. They should put you in prison and solitary confinement and just see how you get on.

Joe: Yeah.

Senan: We'd all be much happier to find that out in about 10 years from now.

Joe: Yeah, absolutely. I'd give that a go.

Senan: Anyway, you kind of; your brain goes off wandering into lots of different topics and because your brain is not busy paying attention to say some task that has you deeply engaged, it has more time for thinking about time passing. So you're kind of focusing more on the fact that time is passing slowly. So it's funny, it's all around psychology but yet we have this real flexible sense of how fast time is passing depending on what's going on around us.

Joe: It's like in a waiting room and you can hear the tick of the clock.

Senan: Yeah.

Joe: And the tick doesn't seem to be going anywhere. Stuck in one position.

Senan: Yeah, you're there waiting for the tock. It's going to tock any minute now. It's going to tock. It's going to tock. No, it doesn't. Just stays with the tick.

Senan: And there is neurochemical, i.e. brain chemistry factors at play here as well. So dopamine is a well-known brain chemical that's involved in all kinds of stuff. It's essentially a messenger chemical. And part of its role is to help the different parts of your brain that are trying to keep time to stay in sync with each other; to communicate with each other in terms of what time it is and how much time has passed and so on. And people that have problems with the amount of dopamine also have problems with actually having a sense of how much time has passed. An extreme case is Parkinson's which of course is a disease that is characterised by a low level of dopamine. And those people have really difficult problems knowing what time of day it is if they don't have a watch or a clock.

Senan: To a lesser extent some, like ADHD is one of those brain conditions that there's a lot of different flavours of it, or there's a spectrum of it, but some people with ADHD have what's referred to as time blindness. Where they can't adequately forecast how long it's going to take to get something done or how soon they should start doing something that needs to be done by a certain time. So yeah, it's interesting how the chemistry of your brain is also playing into this sense of how time is passing.

Joe: So if you just took loads of dopamine, what would that do?

Senan: Well I think there's happiness elements of it as well.

Joe: Ah okay. No, I meant like would you be super conscious of time? Would you just be really, really able to just tell how long something was going to take?

Senan: So I mean one of the primary medicines for ADHD is a thing called Ritalin and I think one of the effects of that is to boost the levels of dopamine in your brain. So that's interesting yeah; if somebody who already had normal dopamine levels took a lot of that it would be interesting to see what would happen.

Joe: Another experiment for next week. Give me the Ritalin and solitary confinement; let's see what happens.

Senan: At the same time hopefully. So I guess that's enough about humans. Let's talk about some of the animals.

Joe: Yes.

Senan: So briefly, we'll just briefly touch on hibernation because that's a kind of a different clock. That's a kind of a clock that certain things should happen at certain times of the year instead of at certain times of the day. And for mammals that hibernate like bears and squirrels, it's a different part of the brain, the hypothalamus, that is kind of the conductor of the orchestra for all that hibernation activity. So it's keeping an eye on various cues like the days getting shorter, the days getting colder; so we're talking about the autumn here; and maybe the supply of food getting lower and so on. And all those cues are kind of triggering its annual clock.

Senan: It's a couple of stages actually involved in hibernation; it's really interesting. The animal needs loads of energy to survive through the winter when they're not actively foraging for food. They need to have energy stored if you like to keep them alive in that period. So a couple of weeks before they're due to go into hibernation, a hormone is released by the hypothalamus that actually gives them this incredible appetite. This unquenchable appetite.

Joe: The munchies.

Senan: Yeah, the munchies exactly. And they go and they try and find as much food and they eat absolutely everything they can find to build up some layers of fat which will supply them with energy while they're asleep in the winter. So a few weeks go by; you've now got a tubby bear waddling around the place, and a different hormone is released into the system that induces what's known as torpor. That just means that all of the body's processes start slowing down and slowing down; everything slows down and the amount of energy the body is using is slowing down. But the animal is also induced to become sleepy by this as well. And it eventually I guess causes the animal to consciously decide to dig a hole somewhere or seek somewhere to hide.

Joe: This torpor doesn't happen to humans when they get old does it?

Senan: I don't know if that's there or not. Maybe it is, I don't know.

Joe: I mean even I like sleeping more now than I did 20 years ago.

Senan: Yeah actually it's an interesting point when you're younger you tend to have more energy. So is there an element of that or is there just generally other processes in the body that make us want to conserve energy as we get older? I'm not sure; that's very interesting. We must research that one and do an episode on it.

Joe: Okay. Aging.

Senan: We'll have to do an aging episode yeah. Seeing as between the two of us we have more than a century.

Joe: You have more of that century than me.

Senan: Well you can have some of it back if you like. Anyway, so that's hibernation and also obviously the animal needs to wake up at the right time. The right time is usually spring when there's food around, but also maybe the right time could be when there's mating going to happen because if you wake up at a time when there aren't other members of your species around wanting to mate with you, well then you're not going to mate and produce babies are you? So yeah, the actual waking up clock is also controlled by the hypothalamus in those animals.

Senan: Let's go into the sea. David Attenborough was asked one time during an interview which did he think was the most amazing animal? And without any hesitation he said salmon.

Joe: Cause they're delicious.

Senan: Yeah there is that. There is that. He'd had enough of the beef; he was heading for the salmon. But yeah, what they do is pretty amazing. So they're born in a river and they stay in the river until they grow to a juvenile fish size. And then they head out into the ocean and they spend several years in the ocean and they can literally swim halfway around the planet during that time.

Joe: In a shoal?

Senan: Not necessarily. They might be in a shoal; they might be singular. I think what probably happens is they shoal up with one group for a while and then maybe they bump into some other group and they shoal off with them for a while. That's probably what happens. The point about this is right; all of the salmon of a particular kind decide to come back to the river they were born in to spawn within a two week window. They arrive back within a two week window. Because they all need to be in the same place at the same time to reproduce, to mate.

Joe: Well only two of them do.

Senan: Well true enough yeah, but if it's only two the chances of them finding each other is a bit tricky. But you know how do we know it's only two? Maybe salmon have very exotic sex lives, who knows.

Joe: Look, with the amount of information we have about salmon, I think we'd know that.

Senan: Anyway some groups of salmon is two years; some groups of salmon is three years; some groups of salmon is seven years. But the point is all of the members of one group that head out of a particular river will arrive back at that river within a two week window.

Joe: So it's the one group that spawned together, headed off, and they all come back.

Senan: No, they didn't spawn; they were born together.

Joe: They were born together.

Senan: In that one river. And there's multiple mechanisms involved. There's two aspects to this; obviously there's the timing part and then there's the navigation part. So we'll just talk about the timing first because the navigation is pretty awesome too.

Senan: There's a hormone in their thyroid gland that goes through annual cycles. So it's a bit like earlier on we were talking about that BMAL and Clock proteins that we have that go through daily cycles of rise to a certain level and then fall and then rise again at the same time the next day. Well these have a hormone in their thyroid which is doing the same thing on an annual basis. So it's hitting a certain level once a year and it's essentially what scientists call an oscillator which is just tick-tock, tick-tock.

Joe: Except once a year is just tick.

Senan: Yes. Yeah. The salmon tick. And there's something in their system is counting the ticks. So it knows how many years have gone by; that's the first thing. Then there's a thing called DNA methylation.

Joe: Of course there is.

Senan: Which is a kind of a counter of age. So gradually from the time the animal is born, as they get older, the amount of methylation of the DNA; which just means that methyl molecules are getting attached onto the DNA. The amount of it is building up gradually and when it hits a certain level it triggers a mechanism that knows the animal has reached a certain age. So those are the two primary things that tell the animal when it's time to start heading home. But you know, if you have a salmon that was born in a river in County Kerry in Ireland and he's now cruising around off the coast of Canada somewhere; how in God's name is he going to find that river in Ireland that he has to get back to? I mean there's no landmarks in the ocean, there's no signposts. How does he do that?

Senan: We believe, although it's a theory we haven't proved it, we believe that they're sensing the earth's magnetic field and they might even be able to see it in their vision because there are a kind of cell, cryptochromes they're called, in the eyes of salmon which engage in what's known as quantum entanglement. Now we're going fairly far down the rabbit hole at this point.

Joe: Way down the salmon hole.

Senan: So anyway, this is something that Einstein theorised about but didn't really believe might happen; we now know it does happen. Einstein wasn't talking about salmon by the way. But he called it "spooky action at a distance". And essentially subatomic particles, the building blocks of atoms, can have a property called spin. And it's possible to get two separate electrons for example with the same spin entangled. In other words, they're keeping their spin synchronised with each other even though they could be separated by light years. They could be millions of miles apart in space. If the spin of one changes, the spin of the other immediately changes to match. So essentially exceeding the speed of light. So that's why Einstein called it spooky action at a distance because it was the only known thing, or theorised thing, that might actually go faster than the speed of light. This somehow, these two particles were communicating with each other through some other mechanism that was able to exceed light speed.

Senan: Anyway, that was a bit of a digression. That's not really; the light speed part isn't really important for the salmon.

Joe: That's like four years of college digression.

Senan: Essentially these cells that are in, or chemicals that are in some of the cells of the salmon's eyes; when light hits them it causes two electrons in two separate molecules to become entangled. So these two electrons have the same spin. Normally these electrons would have a random decaying spin where it's changing all over the place and no stability in it. Because these two are now synchronised, these two electrons in two separate molecules are now synchronised, it's stable; it stays that way. And for reasons I don't personally understand, it allows those cells to detect the earth's magnetic field.

Joe: Okay. I just have one question.

Senan: Yeah.

Joe: How do they know this?

Senan: I don't know but they know that robins do it; that's the big question. They know for sure robins do it. How they know robins do it I don't know but I think they've discovered the same kinds of cells that the robins have in the eyes of the salmon.

Joe: I'd love to know how they figured it out for robins. But because these cells are in the salmon's eyes, that's why they think they might actually be able to see the earth's magnetic field.

Senan: I don't know if it's in their eyes or if it's somewhere else in their brain or whatever.

Joe: But the robins can detect it?

Senan: They can detect; yeah for navigation. Because a lot of people, certainly in this part of the world, you see robins in the winter and people assume that robins don't migrate to other countries but actually some of them do. Some of them do go off and navigate their way down to warmer climates in Africa or wherever from here in Ireland.

Joe: Okay so salmon are using the magnetic field of the earth to find their way back to home.

Senan: Yeah to; it's like finding your way back to the eye of a needle from the other end of the country you know. It's like incredible that they're able to do it. So that's salmon.

Senan: We'll briefly talk about a plant that does something not quite as amazing as salmon but still pretty amazing.

Joe: But I suppose the cycles; like our cycles are getting bigger and bigger. So like we have a daily cycle in our cells and then the salmon is now two, three or seven years; and the bears and squirrels were one year.

Senan: So now bamboo. Bamboo yeah, we're talking about anywhere between 65 and 120 years these guys have a clock that runs for. So we're talking about; say you've got two forests. All the bamboo of a particular species in Forest A will all flower at the same time. All the bamboo of the same species in Forest B will flower together but at a different time. So the first bunch in Forest A might go in January and the second lads might go in March or something like that, right. Except we're talking about years here, not months. So the bamboo plant flowers once and then it dies.

Senan: But these guys all together know like 65, 80, 90 years after they initially were burst out of their seeds and became new plants; they suddenly have somehow figured out it's time to flower. But the really weird part is; if I take a bunch of the bamboo from Forest A and I bring them to another country on the other side of the world, and maybe 30 years goes by until the clock has finally reached the time for them to flower. They will still flower at the same time as the ones in Forest A that they were with.

Joe: This is quantum entanglement! You take the bamboo, you go light years to a different planet; flowers at the same time.

Senan: You could be on to something there Joe. We could get a Nobel Prize out of this episode. You just never know. Hopefully some scientist who understands this stuff will actually follow it up and get a grant for the research.

Senan: So yeah, it's pretty cool what they can do.

Joe: It's just the clocks. I mean the fact that there is an internal mechanism that can keep track of solar years and days that is inbuilt in the DNA and goes on for 80 years or more.

Senan: Yeah. Yeah. It's phenomenal that it can trigger so accurately in separate plants in separate places. So we're nearly running out of time here but I'm just going to very briefly mention some other interesting animals.

Senan: Cicadas. You know those old movies where the scenes at nighttime in the jungle you'd hear in the background all these cricket-like noises? They're actually cicadas.

Joe: I'm sure that's how it's pronounced. Cicadas.

Senan: I have no idea. It could be kick-a-das. It's probably kick-a-das yeah. So periodical kick-a-das...

Joe: Kick-a-das.

Senan: Are a particular type of kick-a-da that you know like most insects they have a larva grub stage in the first part of their life and then later they change into a flying insect. The larva stage is lived underground by them. And some are on a 13-year cycle, some are on a 17-year cycle. But all the ones in one place together, after 13 or 17 years spent underground, will all at the same time emerge and become flying insects so they can all mate with each other. How do they keep track of that? Because underground they don't have any light to...

Joe: No watches? No TV?

Senan: No watches, no TV. They can't hear the peeling of the bells, one assumes. But somehow they're able to keep track. Now there's a theory that it might be due to the fluid coming out of tree roots. So these guys are living in the ground around tree roots and certain chemicals are exuded by tree roots into the soil. And the nature of those chemicals changes depending on the time of year. So the stuff produced by the trees in the winter is different from the stuff produced by the trees in the summer. They think that these bugs, these kick-a-das in the ground, might be able to sense those changes and count how many times; bit like the rings on a tree; count how many times the fluid has gone through a cycle of changes.

Joe: And 13 times or 17 times. It's really odd numbers though. You could understand if it was like; okay someone do four years and someone do eight years and do 12.

Senan: So those are both prime numbers. Those are both prime numbers and it might allow them to skip over other say predators that are on a schedule that is maybe not prime numbers. It might be, who knows. They just picked awkward numbers to be on their own.

Joe: Yeah.

Senan: So look, we could go on talking about the amazing antics of animals and their clocks for the rest of the day but I think probably we have now gotten our users out of the flow state and into...

Joe: Into the "what is this about" state.

Senan: Yeah. So we're definitely thoroughly and absolutely out of time here. So it's goodbye from me until the next time.

Joe: Good luck from me on Enough with the Science. Hope you can join us for the next episode. Take it easy.

Senan: Bye.