Latest / Daniel and Kelly’s Extraordinary Universe / Listener Questions #54

Transcript

Listener Questions #54 · Daniel and Kelly’s Extraordinary Universe

• 0:07
  Speaker 1: Renovations were meant to make the reflecting pool American flag blue.
• 0:12
  Speaker 1: So what caused the massive algal bloom with its stomach-churning hue?
• 0:17
  Speaker 2: Do you have to be aware to have a memory?
• 0:19
  Speaker 2: Or can you mindlessly recall things that are purely sensory?
• 0:24
  Speaker 1: I want to learn more about the charismatic banana slug.
• 0:27
  Speaker 1: And I'll throw Kelly a bone. She can give slug
• 0:30
  Speaker 1: parasites a plug.
• 0:32
  Speaker 2: Whatever questions are keeping you up at night. You know
• 0:35
  Speaker 2: that Daniel and Kelly's answers will make it all right.
• 0:38
  Speaker 1: Listener questions episode number 54.
• 0:41
  Speaker 3: 54.
• 0:41
  Speaker 1: Not a prime.
• 0:59
  Speaker 2: Hi, I'm Daniel. I'm a particle physicist. I love thinking
• 1:02
  Speaker 2: about aliens. And I was wrong again about the Nobel Prize.
• 1:07
  Speaker 1: Hello, I'm Kelly Wintersmith. I study parasites and space, and
• 1:10
  Speaker 1: I really don't have any predictions when Nobel Prize time
• 1:12
  Speaker 1: comes along. And usually I don't actually even pay attention
• 1:15
  Speaker 1: to the announcement. How were you wrong this year? Oh,
• 1:18
  Speaker 1: was this a project that you could have been involved in?
• 1:21
  Speaker 4: No.
• 1:22
  Speaker 2: Oh, yeah. That's right. My record is flawless.
• 1:27
  Speaker 1: Is that four projects you could have?
• 1:28
  Speaker 2: That is four now. Oh, no. So the Nobel Prize
• 1:31
  Speaker 2: was awarded this week to Francis Halzen, an awesome guy
• 1:34
  Speaker 2: who wrote a great textbook and the guy who conceived
• 1:37
  Speaker 2: of the amazing idea of using a cubic kilometer of
• 1:41
  Speaker 2: ice at the South Pole to see neutrinos. This is
• 1:45
  Speaker 2: the project where they drilled a kilometer down and dropped
• 1:48
  Speaker 2: cameras in there and then let it refreeze. Now they
• 1:50
  Speaker 2: have literally an ice cube to see neutrinos. And when
• 1:54
  Speaker 2: I was a grad student... In the 90s at Berkeley,
• 1:56
  Speaker 2: there were folks working on this very early on. And
• 1:59
  Speaker 2: I could have gone in on the ground floor of
• 2:02
  Speaker 2: this Nobel Prize winning experiment. But I thought, that's crazy.
• 2:06
  Speaker 2: They'll never get that to work. Which is what I
• 2:08
  Speaker 2: also said about many other experiments that went on to
• 2:11
  Speaker 2: win the Nobel Prize. So, you know, when Daniel thinks
• 2:14
  Speaker 2: your idea is impractical, you're destined for Nobel gold.
• 2:17
  Speaker 1: You are on the right track. Do not back down.
• 2:22
  Speaker 1: Double your efforts.
• 2:24
  Speaker 2: Daniel's won a Nobel Prize in some alternative universe, but
• 2:27
  Speaker 2: not this one.
• 2:28
  Speaker 1: Oh, man, maybe four or five alternative universes, but not
• 2:32
  Speaker 1: this one. But that's okay. You love what you do,
• 2:34
  Speaker 1: and you don't need a prize to feel good about it.
• 2:36
  Speaker 2: That's right. Yes, I didn't want the Nobel Prize anyway.
• 2:39
  Speaker 2: No sour grapes here. Absolutely not.
• 2:41
  Speaker 1: That's right. Well, that's good.
• 2:44
  Speaker 2: But we're not talking about Daniel's lack of curiosity in
• 2:47
  Speaker 2: Nobel Prize-winning experiments. We're talking about the listeners and the
• 2:50
  Speaker 2: questions they have about the nature of the universe. how
• 2:53
  Speaker 2: things work, why things work, and we're here to explain
• 2:56
  Speaker 2: all of it to you.
• 2:58
  Speaker 1: And first up today, we have a question from Discord,
• 3:01
  Speaker 1: and I am maintaining my tradition of not getting first
• 3:04
  Speaker 1: names ahead of time. So we have a question from
• 3:07
  Speaker 1: Dernal K from our Discord community.
• 3:10
  Speaker 4: Hi, Daniel and Kelly. This is David from Dallas via
• 3:13
  Speaker 4: New Zealand, Australia, and England. Yes, I've lived in lots
• 3:17
  Speaker 4: of places. On Discord, I'm Dernal K, which is Colonel
• 3:21
  Speaker 4: D switched up to be unique. My question might be
• 3:24
  Speaker 4: fun if it's not crossing our currently topical line is,
• 3:28
  Speaker 4: how do we get algal blooms in ponds and how
• 3:31
  Speaker 4: that impacts the aquatic ecosystems in waterways and ponds?
• 3:36
  Speaker 2: All right. This is a very topical question. Unusual for us, Kelly.
• 3:40
  Speaker 5: It is.
• 3:40
  Speaker 1: However, one, I... Let it sit on my list for
• 3:44
  Speaker 1: a while so it's not super topical anymore.
• 3:46
  Speaker 2: Trying to stay irrelevant.
• 3:47
  Speaker 4: Good.
• 3:48
  Speaker 1: That's how we roll. But also, after the 2012 renovations
• 3:53
  Speaker 1: of the reflecting pool, which were, you know, not during
• 3:56
  Speaker 1: a Trump presidency, there were also algal blooms in the
• 3:59
  Speaker 1: reflecting pool. So this is a recurring problem.
• 4:02
  Speaker 2: OK.
• 4:02
  Speaker 1: And so, you know, that's my attempt at being apolitical.
• 4:05
  Speaker 1: But let's let's jump into the the science here.
• 4:09
  Speaker 2: So what is an algal bloom, first of all? Is
• 4:11
  Speaker 2: it just a bunch of algae in a pool?
• 4:13
  Speaker 1: It's a bunch of algae or a bunch of cyanobacteria.
• 4:16
  Speaker 1: So these are both organisms that photosynthesize. They are in
• 4:21
  Speaker 1: very different places on the tree of life. And actually,
• 4:24
  Speaker 1: we think that algae and other plants got the ability
• 4:27
  Speaker 1: to photosynthesize because way deep in the past, one of
• 4:32
  Speaker 1: them managed to incorporate a cyanobacteria, which is a bacteria
• 4:37
  Speaker 1: that can do photosynthesis. And that ended up becoming the chloroplast.
• 4:40
  Speaker 2: Oh, this is like what we talked about recently on
• 4:42
  Speaker 2: the symbiosis episode.
• 4:44
  Speaker 1: Yeah, except you and I are like time travelers. Yes,
• 4:47
  Speaker 1: we've already recorded the symbiosis episode, but I don't think
• 4:50
  Speaker 1: it will have come out by the time this listener
• 4:52
  Speaker 1: question episode comes out. So stay tuned.
• 4:53
  Speaker 2: Preview of the symbiosis episode.
• 4:55
  Speaker 1: That's right. That's right. Time traveling extraordinaries.
• 4:58
  Speaker 2: Awesome.
• 4:59
  Speaker 1: Anyway, both algae and cyanobacteria use photosynthesis. And when you
• 5:03
  Speaker 1: say there's an algal bloom, even though cyanobacteria are not algae,
• 5:07
  Speaker 1: people will still... refer to an overgrowth of both cyanobacteria
• 5:11
  Speaker 1: and algae as algal blooms.
• 5:14
  Speaker 2: So you're saying common names are not super clear and
• 5:17
  Speaker 2: descriptive sometimes.
• 5:18
  Speaker 1: Which is why sometimes it's helpful to use scientific names. Yes,
• 5:21
  Speaker 1: that's right.
• 5:22
  Speaker 2: I saw a comic about that from Zach. I was
• 5:24
  Speaker 2: wondering if that's been part of the conversation over there.
• 5:28
  Speaker 1: No, but you know, Zach Wienersmith listens to DKEU, and
• 5:33
  Speaker 1: I've been listening to his podcast, Last Humans in the Loop.
• 5:35
  Speaker 2: It's good.
• 5:36
  Speaker 1: I've been enjoying it. I'm glad you're liking it, too.
• 5:38
  Speaker 2: Yeah, yeah.
• 5:39
  Speaker 1: OK, so back on track. When do you get massive
• 5:43
  Speaker 1: growths of these photosynthesizing organisms? And some of the things
• 5:48
  Speaker 1: that cause a lot of growth in these organisms are, one,
• 5:51
  Speaker 1: loading of phosphorus. So for a lot of algae in
• 5:56
  Speaker 1: freshwater systems, the thing that limits their growth is the
• 5:59
  Speaker 1: availability of phosphorus in the environment.
• 6:01
  Speaker 2: Phosphorus. Why phosphorus?
• 6:03
  Speaker 1: Phosphorus. Why phosphorus? So I should know that, but I
• 6:08
  Speaker 1: also am going to point out that that's clearly biochemistry.
• 6:11
  Speaker 1: So let's go ahead and throw to Katrina.
• 6:16
  Speaker 3: Well, phosphorus is important for life in general, but what's
• 6:20
  Speaker 3: really interesting about phosphorus is that it doesn't go into
• 6:23
  Speaker 3: the atmosphere. So a lot of the other resources like nitrogen, oxygen,
• 6:28
  Speaker 3: et cetera, have a gas phase in And so you
• 6:32
  Speaker 3: can just sip them out of the air. And microbes
• 6:34
  Speaker 3: are so creative that if you like try to grow
• 6:37
  Speaker 3: them in water that doesn't have any nitrogen, they're like,
• 6:39
  Speaker 3: no problem for me.
• 6:40
  Speaker 2: I'll just fix it out of the atmosphere.
• 6:43
  Speaker 3: However, for phosphorus, it's a little harder because it has
• 6:47
  Speaker 3: to come out of a solid form, like out of
• 6:49
  Speaker 3: the rocks. So as rain occurs and like the sediment
• 6:54
  Speaker 3: is coming out of the rocks and into the water sources,
• 6:57
  Speaker 3: the cyanobacteria can grab the phosphorus from there. What's really
• 7:02
  Speaker 3: cool about them.
• 7:03
  Speaker 2: Is that they can hold on to the phosphorus.
• 7:05
  Speaker 3: So if it rains in the spring, it doesn't matter
• 7:08
  Speaker 3: if it's like August, the cells hold on to the
• 7:11
  Speaker 3: phosphorus and it doesn't like run out right away. But
• 7:15
  Speaker 3: if they go long enough without any rain or like
• 7:17
  Speaker 3: perturbation from the solid sources nearby, they will totally run
• 7:21
  Speaker 3: out of their phosphorus. And that concludes my statement about
• 7:25
  Speaker 3: cyanobacteria and phosphorus. I wish I could tell you all
• 7:28
  Speaker 3: about phages and how you could use them to control
• 7:30
  Speaker 3: algal blooms. And I also wish I could tell you
• 7:33
  Speaker 3: about agriculture and how phosphorus is a really important resource
• 7:36
  Speaker 3: that can be limiting for agriculture.
• 7:40
  Speaker 1: But humans give algae a leg up because we have
• 7:43
  Speaker 1: phosphorus in our fertilizer because our plants also need phosphorus
• 7:47
  Speaker 1: to grow.
• 7:48
  Speaker 2: Mm-hmm.
• 7:49
  Speaker 1: And so we apply fertilizer to our yards. We apply
• 7:52
  Speaker 1: fertilizer with phosphorus to our agricultural crops.
• 7:55
  Speaker 2: Yeah.
• 7:56
  Speaker 1: Our animals, like our cows, defecate out piles with phosphorus
• 8:01
  Speaker 1: in it. And then when it rains, that phosphorus accumulates
• 8:05
  Speaker 1: in the rain and then ends up in our waterways.
• 8:08
  Speaker 4: Hmm.
• 8:09
  Speaker 1: And so this is what causes eutrophication which is essentially
• 8:12
  Speaker 1: just lots of nutrients in the water which allows the
• 8:16
  Speaker 1: algae to grow like crazy because it's no longer limited
• 8:18
  Speaker 1: by phosphorus anymore and so often you'll get an algal
• 8:21
  Speaker 1: bloom because there's been nutrient loading in that system.
• 8:24
  Speaker 2: So the way you described it suggests that like humans
• 8:27
  Speaker 2: and cows are putting more phosphorus into the system than
• 8:30
  Speaker 2: you find naturally, I guess. And that's because of like
• 8:34
  Speaker 2: human civilization or whatever.
• 8:36
  Speaker 1: Yeah.
• 8:37
  Speaker 2: But like these things are living near humans for a
• 8:40
  Speaker 2: long time. Why isn't there just always more phosphorus? Like
• 8:43
  Speaker 2: why aren't we always in algal bloom?
• 8:46
  Speaker 1: We are in algal blooms a lot more now than
• 8:48
  Speaker 1: we were before. And some areas like Lake Erie, the
• 8:52
  Speaker 1: lakes have gone what's called eutrophic, which is to say
• 8:55
  Speaker 1: they almost always have more algae than would be desirable
• 8:58
  Speaker 1: growing in them. And so this does happen a lot.
• 9:01
  Speaker 1: And algal blooms are happening more and more often. And
• 9:04
  Speaker 1: that's a combination of... More phosphorus runoff, but it's also
• 9:07
  Speaker 1: a combination of warming temperatures, which increase the water temperature,
• 9:11
  Speaker 1: which makes it easier for algae to grow. And I
• 9:13
  Speaker 1: should say that, you know, Lake Erie, there was a
• 9:14
  Speaker 1: period where we were doing a really good job of
• 9:16
  Speaker 1: keeping runoff with phosphorus and nitrogen because nitrogen is sometimes
• 9:21
  Speaker 1: also a limiting factor. And our fertilizers have that, too.
• 9:23
  Speaker 1: We were doing a good job of keeping that from
• 9:25
  Speaker 1: getting into the waterways. And Lake Erie was looking nicer.
• 9:28
  Speaker 1: And then we started doing more fertilizer. I think the
• 9:31
  Speaker 1: problem in this case was agricultural fertilizer. We started doing
• 9:34
  Speaker 1: more agricultural stuff. And now Lake Erie is starting to
• 9:36
  Speaker 1: have algal bloom problems again.
• 9:39
  Speaker 2: And why is it a problem? Like, is it just
• 9:41
  Speaker 2: it doesn't look as nice? This is like a human
• 9:43
  Speaker 2: aesthetic thing? Or is it like, you know, tip off
• 9:46
  Speaker 2: the balance of the ecosystem and everything collapses and pretty
• 9:49
  Speaker 2: soon it's just goo on the planet?
• 9:51
  Speaker 1: Oh, good question. OK, so the answer is multifactorial. So
• 9:55
  Speaker 1: one of the problems is that, okay, so algae produce
• 9:59
  Speaker 1: oxygen during the day through the process of photosynthesis, but
• 10:02
  Speaker 1: at night, they actually suck oxygen out of The environment
• 10:07
  Speaker 1: when they were doing respiration. So if you have massive
• 10:10
  Speaker 1: amounts of algae at night, they suck the oxygen out
• 10:15
  Speaker 1: of the water and a big algal mat on the
• 10:18
  Speaker 1: surface will block sunlight to the plants growing below. And
• 10:21
  Speaker 1: so now they're not producing oxygen. And at some point,
• 10:25
  Speaker 1: often these algal blooms die. end and the algae die
• 10:28
  Speaker 1: off in large numbers. And when they die off, they
• 10:31
  Speaker 1: get decomposed by bacteria and those bacteria create low oxygen environments.
• 10:36
  Speaker 1: And so one of the problems is these algal blooms
• 10:38
  Speaker 1: are associated with sucking the oxygen out of the water
• 10:41
  Speaker 1: and you often end up with massive fish kills afterwards.
• 10:44
  Speaker 2: Oh, yeah.
• 10:45
  Speaker 1: So really bad for the environment. But also, if the
• 10:48
  Speaker 1: quote unquote algal bloom is caused by cyanobacteria, cyanobacteria release toxins.
• 10:55
  Speaker 1: And these toxins can either be really bad for your liver.
• 10:58
  Speaker 1: Some of them are neurotoxins. There are lots of different
• 11:01
  Speaker 1: species of cyanobacteria. They produce different kinds of toxins.
• 11:04
  Speaker 2: Do the toxins turn you blue?
• 11:06
  Speaker 1: You know, that would be interesting.
• 11:09
  Speaker 2: I mean, we are on brand for cyanobacteria, right? They
• 11:12
  Speaker 2: should turn you cyan.
• 11:14
  Speaker 1: Well, they're also called blue-green algae sometimes, which is, you know,
• 11:17
  Speaker 1: not a good name. It's like a physicist named them
• 11:19
  Speaker 1: or something, you know. But, for example, I grew up
• 11:25
  Speaker 1: in Toledo, and my parents still live there, and Toledo
• 11:28
  Speaker 1: has their water from Lake Erie. And a couple years ago,
• 11:31
  Speaker 1: there was a do-not-drink-the-water warning because there was so much
• 11:35
  Speaker 1: cyanobacteria growing in Lake Erie, and that toxin... that they make,
• 11:39
  Speaker 1: microcystin in this case, was in the water and it
• 11:41
  Speaker 1: would have been like dangerous for your liver to drink
• 11:43
  Speaker 1: the water. And so a lot of money is spent
• 11:46
  Speaker 1: every year on filtering water in very particular ways to
• 11:49
  Speaker 1: remove cyanobacteria and toxins in areas where they're present. So
• 11:53
  Speaker 1: it's a ecological, financial, and human health problem.
• 11:57
  Speaker 2: So we're on one hand making it worse by putting
• 12:01
  Speaker 2: phosphorus everywhere. And on the other hand, struggling against it,
• 12:04
  Speaker 2: constantly trying to remove it. Exactly.
• 12:06
  Speaker 1: Yep. And and we're also making it worse by warming
• 12:10
  Speaker 1: our planets. And those warmer temperatures also result in more
• 12:13
  Speaker 1: algal growth. Other things that contribute to algal bloom are sunlight.
• 12:18
  Speaker 1: So you're more likely to get algal growth on a
• 12:20
  Speaker 1: sunny day than a cloudy day. And calm water tends
• 12:24
  Speaker 1: to be more conducive to the growth of like algal
• 12:27
  Speaker 1: mats and clumps of algae. And so let's go through
• 12:32
  Speaker 1: our list again. We've got phosphorus, warm water, sunlight, and
• 12:35
  Speaker 1: calm water. The reflecting pool in Washington, D.C. was the
• 12:40
  Speaker 1: perfect storm.
• 12:42
  Speaker 2: It's like what you would design if you wanted an
• 12:44
  Speaker 2: algal bloom.
• 12:45
  Speaker 1: Yes, that's right. If you wanted an algal bloom, these
• 12:47
  Speaker 1: are the conditions you would create.
• 12:49
  Speaker 2: Okay.
• 12:50
  Speaker 1: So first of all, it was painted so that it
• 12:52
  Speaker 1: would look American flag blue.
• 12:54
  Speaker 2: Right.
• 12:54
  Speaker 1: This was a darker shade than was previously covering the
• 12:58
  Speaker 1: bottom of the reflecting pool. And darker shades mean the
• 13:01
  Speaker 1: water was warming up more because that darker paint was,
• 13:05
  Speaker 1: what is it, absorbed? What is the physics answer for
• 13:07
  Speaker 1: why darker paint is bad, Daniel?
• 13:09
  Speaker 2: Right. Well, something is lighter because it's reflecting more of
• 13:13
  Speaker 2: the light. And it's darker. It's absorbing more of the light.
• 13:15
  Speaker 2: So it heats up.
• 13:16
  Speaker 1: There you go.
• 13:17
  Speaker 2: The way that, like, a black car will heat up
• 13:19
  Speaker 2: faster than a white car in the sun. Okay.
• 13:21
  Speaker 4: Yep.
• 13:21
  Speaker 1: And that water is meant to be still so that
• 13:23
  Speaker 1: you can see the reflection of the Lincoln Memorial and
• 13:27
  Speaker 1: the George Washington Monument. So that's calm water. And it's warm.
• 13:31
  Speaker 1: I think this was, what, June or July when this
• 13:33
  Speaker 1: was happening? Oh, it was meant for the July 4th celebration. So, yes,
• 13:36
  Speaker 1: this was happening in, like, June. So it was warming up.
• 13:39
  Speaker 1: And so what they think happens is that there was
• 13:41
  Speaker 1: algae that was still in the hoses, the lines that
• 13:46
  Speaker 1: feed the reflecting pool.
• 13:47
  Speaker 2: Okay.
• 13:48
  Speaker 1: And so while they were painting it, the algae was
• 13:50
  Speaker 1: growing in the lines. And then they turned the water on,
• 13:53
  Speaker 1: they filled it up, and they essentially injected the algae
• 13:57
  Speaker 1: into the reflecting pool.
• 13:58
  Speaker 2: Nice.
• 13:58
  Speaker 1: The water either comes from the tidal basin, which is
• 14:02
  Speaker 1: a man-made reservoir outside D.C. that has... Phosphorus from runoff
• 14:08
  Speaker 1: from the area, or sometimes they get it from the
• 14:11
  Speaker 1: city water supply. And if you get it from the
• 14:14
  Speaker 1: city water supply, there's still a chance that there will
• 14:16
  Speaker 1: be phosphorus in it because we use orthophosphates to line
• 14:21
  Speaker 1: the inside of metal pipes. So here's what you need
• 14:24
  Speaker 1: to know. They coat the metal pipes. They change the
• 14:27
  Speaker 1: pH right at the point where like the pipe and
• 14:29
  Speaker 1: the water meet. And that's important because if you have
• 14:32
  Speaker 1: lead pipes, you want to make sure that the water
• 14:35
  Speaker 1: is not causing the lead to leach out of the pipes.
• 14:38
  Speaker 1: And so putting orthophosphate in the water source means that
• 14:41
  Speaker 1: the pipes get a little bit coated. They're less likely
• 14:44
  Speaker 1: to leach out the lead. But now there's phosphorus in
• 14:47
  Speaker 1: the water, which promotes the growth of algae. So no
• 14:51
  Speaker 1: matter where the water came from when they refilled the
• 14:53
  Speaker 1: reflecting pool, there's a good chance that phosphorus was added
• 14:56
  Speaker 1: to the reflecting pool as well.
• 14:58
  Speaker 2: Even though this is orthophosphates, not just phosphates, are these
• 15:01
  Speaker 2: like that have had their teeth straightened or what's an orthophosphate?
• 15:05
  Speaker 2: I mean, the scientific name is perfectly clear, right? So
• 15:08
  Speaker 2: help us out here.
• 15:09
  Speaker 1: Oh, you're being not nice. So I looked at a
• 15:15
  Speaker 1: chemistry website to get the word orthophosphate. I'm so sorry.
• 15:19
  Speaker 1: You're right, you're right. And so it was chemical and
• 15:21
  Speaker 1: engineering news. And so I should have just said a
• 15:24
  Speaker 1: form of phosphate. I am retreating into my ignorance. But anyway.
• 15:30
  Speaker 2: Victory against chemistry.
• 15:32
  Speaker 1: That's right. That's right. Well, I feel like chemistry won
• 15:34
  Speaker 1: and I'm running away, but.
• 15:38
  Speaker 2: No, we have pushed back the chemistry. Go away, chemistry.
• 15:41
  Speaker 1: Go away, chemistry.
• 15:41
  Speaker 2: I'm running. So what could they have done to combat
• 15:44
  Speaker 2: the algal blooms in the reflecting pool, Kelly?
• 15:48
  Speaker 1: Yeah, what could they have done? So they could have,
• 15:51
  Speaker 1: I don't know, maybe put treatments in earlier to kill,
• 15:55
  Speaker 1: try to kill all of the algae. It looks like
• 15:57
  Speaker 1: after the algae grew, they tried to remove it using
• 16:00
  Speaker 1: like mechanical means, like vacuuming it out. And then I
• 16:03
  Speaker 1: think they dumped hydrogen peroxide in there, which I believe
• 16:07
  Speaker 1: is what messed up the lining at the bottom of
• 16:09
  Speaker 1: the reflecting pool because it was still in the process
• 16:11
  Speaker 1: of curing.
• 16:12
  Speaker 2: But I saw these pictures of them, like, emptying one-gallon
• 16:15
  Speaker 2: jugs of hydrogen peroxide, which I was like, I don't
• 16:18
  Speaker 2: know what that's really going to do anyway.
• 16:20
  Speaker 1: Well, and I think the algal blooms came back after that.
• 16:24
  Speaker 1: So some solutions that I've seen include keeping the water
• 16:28
  Speaker 1: more well aerated because more well aerated water supports bacteria
• 16:34
  Speaker 1: that compete with the algae. So you're less likely to
• 16:36
  Speaker 1: get an algal bloom.
• 16:37
  Speaker 2: I heard they were using these machines called nanobubblers, but
• 16:40
  Speaker 2: I never understood what they are and why the bubbles
• 16:43
  Speaker 2: are so nano.
• 16:44
  Speaker 1: Yeah, I think they dump in nanobubbles and there's something
• 16:49
  Speaker 1: about like the surface area of the bubble and the
• 16:51
  Speaker 1: bubble is impregnated with a certain kind of gas. I
• 16:53
  Speaker 1: didn't get into that science, but it was meant to
• 16:56
  Speaker 1: be a way to keep the oxygen supply in the
• 16:58
  Speaker 1: reflecting pool up for longer. And I think you can
• 17:01
  Speaker 1: put other things other than oxygen in there, like some
• 17:03
  Speaker 1: chemicals to try to kill the algae. But I'm not
• 17:05
  Speaker 1: an expert on that.
• 17:07
  Speaker 2: It's a shame that the scientific term nanobubbler isn't clear.
• 17:10
  Speaker 2: You know, it should just make sense on the surface,
• 17:12
  Speaker 2: you know, but it doesn't somehow.
• 17:14
  Speaker 1: Are you throwing shade on me? I can't tell anymore.
• 17:16
  Speaker 2: I can't tell anymore either.
• 17:19
  Speaker 4: Okay.
• 17:19
  Speaker 1: All right. So anyway, this is a long standing problem
• 17:22
  Speaker 1: because if you do have bubblers in there, then your
• 17:25
  Speaker 1: reflecting pool is not going to be perfectly still. And
• 17:27
  Speaker 1: that's kind of the whole point. And so, you know,
• 17:29
  Speaker 1: this thing I think was built in 1922. We've been
• 17:32
  Speaker 1: sort of set up for algal blooms ever since then.
• 17:35
  Speaker 1: And they have been a recurring problem. It's just difficult
• 17:38
  Speaker 1: to solve.
• 17:39
  Speaker 5: Okay.
• 17:40
  Speaker 4: Yeah.
• 17:40
  Speaker 2: Yeah.
• 17:41
  Speaker 1: Okay, so, Dirt LK. Does that answer your question? Let
• 17:46
  Speaker 1: me know.
• 17:46
  Speaker 6: Wow, thanks for the great discussion as always. So the
• 17:49
  Speaker 6: problem with the reflecting pool in Washington comes down to
• 17:52
  Speaker 6: bad chemistry. Hopefully there is a fix for that. This
• 17:55
  Speaker 6: reminded me of an organic chemistry lab where we had
• 17:58
  Speaker 6: to measure dissolved oxygen from different points around a pond
• 18:01
  Speaker 6: in the university park at Sydney University. Collecting samples in
• 18:06
  Speaker 6: bud flasks needed a very specific technique. No one needed
• 18:10
  Speaker 6: to titrate with the Wigler method. I've been a listener
• 18:14
  Speaker 6: since your episode with Ty and Daniel on The Expanse.
• 18:18
  Speaker 6: Thanks to the great podcast that keeps me entertained and
• 18:21
  Speaker 6: up to date on the latest science.
• 18:43
  Speaker 1: Next up, we have a question from Rosalyn about memory
• 18:46
  Speaker 1: and consciousness.
• 18:47
  Speaker 7: Hi, Danielle and Kelly. I have a question for you
• 18:50
  Speaker 7: about the relationship between memory and consciousness. From my understanding,
• 18:54
  Speaker 7: consciousness is a sense of oneself and working memories occur
• 19:00
  Speaker 7: in order for us to make sense of ourself in
• 19:02
  Speaker 7: the world around us, to help learn from past mistakes
• 19:07
  Speaker 7: and to aid in our survival in the future. So
• 19:10
  Speaker 7: my question is, Wouldn't the ability to create working memories
• 19:15
  Speaker 7: require on some level a sort of consciousness? Wouldn't something
• 19:20
  Speaker 7: need to know that it exists in that state and
• 19:25
  Speaker 7: that in order to continue to exist in that state,
• 19:28
  Speaker 7: it needs to retain a certain information about the world
• 19:32
  Speaker 7: and itself in relation to the world so that it
• 19:35
  Speaker 7: can continue to do so?
• 19:37
  Speaker 2: Am I like wildly off base here?
• 19:39
  Speaker 7: I just have a hard time understanding How one would
• 19:43
  Speaker 7: retain or how anything could retain a memory without having
• 19:47
  Speaker 7: a sense of self. that would necessitate why that particular
• 19:53
  Speaker 7: memory is important for the future thank you i appreciate you.
• 19:57
  Speaker 1: Guys daniel you love talking and thinking about consciousness.
• 20:03
  Speaker 2: You know, I'm a physicist, which means that I love
• 20:06
  Speaker 2: talking about stuff I have no training in and trying
• 20:09
  Speaker 2: to speak about it confidently. Wow.
• 20:13
  Speaker 1: Actually, one of many things I really appreciate you is
• 20:16
  Speaker 1: that you do rein that tendency in. I feel like
• 20:19
  Speaker 1: you are really– You're really good about being like, I'm
• 20:21
  Speaker 1: not a biologist. I don't know. Unlike Feynman, who's like,
• 20:24
  Speaker 1: I'm not a biologist. I don't know. But I'm going
• 20:26
  Speaker 1: to pretend I do.
• 20:27
  Speaker 3: Right.
• 20:27
  Speaker 2: And I'm smarter than the biologists.
• 20:28
  Speaker 1: That's right.
• 20:29
  Speaker 2: So, yeah, this is about memory and consciousness and also
• 20:32
  Speaker 2: like a sense of self. So there's a bunch of
• 20:34
  Speaker 2: topics in here. They're all getting sort of bundled together.
• 20:37
  Speaker 2: And Rosalind is asking, you know, which of these things
• 20:40
  Speaker 2: actually require the others? And I'm not a cognitive scientist,
• 20:44
  Speaker 2: nor a biologist, nor a philosopher, but I'm interested in
• 20:47
  Speaker 2: all of these things and like thinking about them. So
• 20:50
  Speaker 2: these are my thoughts, but, you know, that doesn't mean
• 20:52
  Speaker 2: that they are reasonable thoughts. I think this is what
• 20:56
  Speaker 2: Rosalyn wrote in here about, and she knows we're not experts.
• 20:59
  Speaker 2: So let's go.
• 21:01
  Speaker 1: That's right.
• 21:02
  Speaker 7: All right.
• 21:02
  Speaker 1: So I think first I'd like to try to, like,
• 21:04
  Speaker 1: untangle memory, consciousness, and sense of self. I feel like
• 21:08
  Speaker 1: those three terms feel like they could be interchangeable.
• 21:11
  Speaker 2: Yeah, but the question is basically how they differ and
• 21:14
  Speaker 2: whether one meets the other. So like, what is memory anyway?
• 21:17
  Speaker 2: There's lots of different kinds of memory, right? Like most broadly,
• 21:21
  Speaker 2: you could say memory is like a record of the past,
• 21:24
  Speaker 2: maybe something that affects how you act in the future. But,
• 21:28
  Speaker 2: you know, there's like working memory that holds information temporarily,
• 21:32
  Speaker 2: like a way you can remember what somebody said, like
• 21:35
  Speaker 2: digits of a phone number for a few seconds. You
• 21:37
  Speaker 2: have this like loop in your brain. There's like episodic memories,
• 21:41
  Speaker 2: remembering something that happened to you. There's just semantic memory,
• 21:45
  Speaker 2: like stored knowledge and facts, you know, like things you
• 21:48
  Speaker 2: know in your head. You know, the way Kelly has
• 21:50
  Speaker 2: like a huge pile of ridiculous scientific names, just like
• 21:53
  Speaker 2: filling up her noggin and preventing her from knowing other
• 21:56
  Speaker 2: useful stuff.
• 21:57
  Speaker 1: Oh my gosh, you are on a roll today. Look,
• 21:59
  Speaker 1: sometimes those Latin names have information in them that's helpful.
• 22:03
  Speaker 2: Yeah, sometimes, sometimes. And then there's like procedural memory, you know,
• 22:08
  Speaker 2: like how to ride a bicycle or even implicit memory,
• 22:11
  Speaker 2: things you don't explicitly remember but do change your behavior.
• 22:15
  Speaker 2: And so there's lots of different kinds of memory. And
• 22:18
  Speaker 2: not all of them seem to require you to be
• 22:20
  Speaker 2: like conscious or self-aware because, you know, like the memory
• 22:25
  Speaker 2: that you have doesn't always require you knowing like why
• 22:29
  Speaker 2: the information matters, right? Like, you know, evolution can design
• 22:34
  Speaker 2: a system that responds to history. In that sense, it
• 22:38
  Speaker 2: has a memory, but you might not be like consciously
• 22:42
  Speaker 2: aware of it. Like, for example, your immune system remembers
• 22:46
  Speaker 2: the bits and the pathogens that it's seen, right? It
• 22:49
  Speaker 2: has like some catalog inside of it. That is like
• 22:53
  Speaker 2: a memory. It says, oh, we've seen this. We know
• 22:54
  Speaker 2: how to respond to hear all the antibodies. But you
• 22:57
  Speaker 2: don't know that. You don't remember that. Like maybe you
• 23:00
  Speaker 2: remember being sick, but you don't remember the surface of
• 23:03
  Speaker 2: these things, right? And you're not aware of them. And
• 23:06
  Speaker 2: so information can be useful and it can be recorded
• 23:10
  Speaker 2: and it can affect the future without it being like
• 23:12
  Speaker 2: part of your conscious experience.
• 23:14
  Speaker 1: I'm going to regret saying this, but I've always thought
• 23:17
  Speaker 1: that immune system memory was a bad use of the
• 23:20
  Speaker 1: word memory, where we should have just come up with
• 23:22
  Speaker 1: a different word because that seems like something very different
• 23:26
  Speaker 1: than implicit memory or procedural memory, for example.
• 23:29
  Speaker 2: Well, I would say it's sort of more like semantic memory.
• 23:31
  Speaker 2: It's like stored knowledge and facts, you know, the way
• 23:34
  Speaker 2: like your computer has a memory, right? You put numbers
• 23:37
  Speaker 2: into the computer, they're still there. We call it memory
• 23:39
  Speaker 2: for a reason, right? It can recall it. you can
• 23:42
  Speaker 2: store it and recall it in that same way your
• 23:44
  Speaker 2: immune system has a memory of the pathogens it's seen,
• 23:48
  Speaker 2: even if you're not aware of them. I don't think
• 23:50
  Speaker 2: my computer is aware of the number 17 that I
• 23:52
  Speaker 2: put in this register over there. So yeah, that's an
• 23:55
  Speaker 2: example of like semantic memory that doesn't require you to
• 23:59
  Speaker 2: be aware. So we've been talking about awareness What do
• 24:03
  Speaker 2: we mean by that? Like, what is consciousness anyway? Man,
• 24:06
  Speaker 2: that's like, you know, not a subtopic. That's like such
• 24:10
  Speaker 2: a deep question that we can't answer today. It's even
• 24:12
  Speaker 2: harder to define what we mean than memory, which is
• 24:15
  Speaker 2: already tricky and slippery. You know, you could think of
• 24:18
  Speaker 2: it as like subjective experience. What is it like to
• 24:21
  Speaker 2: see something or to feel something or to hear something
• 24:24
  Speaker 2: or smell something? Philosophers use this word qualia. to describe
• 24:28
  Speaker 2: the experience of seeing red or eating chocolate or something.
• 24:33
  Speaker 2: And so that's like the basic concept of consciousness. But
• 24:38
  Speaker 2: then there's also this other side of it, which is
• 24:40
  Speaker 2: like a sense of self that Rosalind is talking about.
• 24:43
  Speaker 2: Sort of like a self-consciousness. So consciousness is like, I'm
• 24:48
  Speaker 2: feeling pain. Self-consciousness is like, I am a thing and
• 24:52
  Speaker 2: I am the thing experiencing the pain.
• 24:55
  Speaker 1: Okay.
• 24:55
  Speaker 2: You're like aware of the existence of yourself, not just
• 24:58
  Speaker 2: like raw, I'm feeling pain or I'm eating chocolate, but
• 25:01
  Speaker 2: like I'm a thing that is eating the chocolate. And
• 25:04
  Speaker 2: beyond that, I think Rosalind is referencing something deeper, which
• 25:08
  Speaker 2: is like an autobiographical identity. This feeling that like Daniel
• 25:12
  Speaker 2: is eating chocolate today is the same Daniel that went
• 25:15
  Speaker 2: for a jog yesterday to balance out that chocolate. You know, like,
• 25:19
  Speaker 2: I'm the same person who existed yesterday and tomorrow, and
• 25:23
  Speaker 2: my memories help define who I am, right? So, you know,
• 25:26
  Speaker 2: there's like actually experiencing things, that's consciousness. There's realizing that
• 25:31
  Speaker 2: you are a thing experiencing, so it's like turning that
• 25:33
  Speaker 2: consciousness inwards. And then there's the autobiographical self, which is
• 25:37
  Speaker 2: like telling a story about how you evolved through time.
• 25:41
  Speaker 2: So there's lots of different layers there of consciousness that
• 25:44
  Speaker 2: all have different relationships to the concept of memory.
• 25:47
  Speaker 5: Yeah.
• 25:48
  Speaker 1: So then is the question, which of those can exist
• 25:51
  Speaker 1: without the others?
• 25:52
  Speaker 2: Yeah, exactly. So like, can you be conscious without memory?
• 25:56
  Speaker 2: I think certainly you can, right? There are people, for example,
• 25:59
  Speaker 2: who can form long-term memories, right? But they're still here
• 26:03
  Speaker 2: in the world. They can eat chocolate. They can perceive.
• 26:05
  Speaker 2: They can have conversations. They can solve problems. They can
• 26:08
  Speaker 2: have emotions, right? They can appear conscious in the present
• 26:11
  Speaker 2: even if tomorrow or in five minutes they don't remember it, right?
• 26:15
  Speaker 2: So forming lasting memories doesn't appear necessary to be moment-to-moment conscious.
• 26:22
  Speaker 2: So you can have consciousness, you can have self-consciousness without
• 26:25
  Speaker 2: like even a sense of autobiographical identity or long-term memories.
• 26:29
  Speaker 1: Amazing, yeah.
• 26:30
  Speaker 2: Imagine, for example, like experiencing 10 seconds of the world
• 26:34
  Speaker 2: normally and then forgetting those 10 seconds. doesn't mean you
• 26:38
  Speaker 2: weren't aware. And maybe you were even aware of who
• 26:40
  Speaker 2: you were and your history. The fact that you don't
• 26:43
  Speaker 2: remember it later doesn't mean that the original experience was unconscious.
• 26:48
  Speaker 5: Yeah.
• 26:48
  Speaker 1: Okay.
• 26:49
  Speaker 2: And maybe you've had this experience where you're like driving somewhere,
• 26:52
  Speaker 2: but you're a little distracted. And then you get there
• 26:55
  Speaker 2: and you're like, I don't remember any of those red lights. Boy,
• 26:59
  Speaker 2: I hope I didn't like run over a bunch of
• 27:00
  Speaker 2: pedestrians without noticing.
• 27:02
  Speaker 1: I hate those moments.
• 27:03
  Speaker 2: Right? Aren't those terrifying?
• 27:05
  Speaker 1: How did I get here?
• 27:06
  Speaker 4: Yeah.
• 27:07
  Speaker 2: Probably your brain was doing it and you might have
• 27:10
  Speaker 2: even been aware of it in the moment, but you
• 27:12
  Speaker 2: weren't paying attention to it in a way that would
• 27:13
  Speaker 2: get recorded so that later you can retrieve it.
• 27:16
  Speaker 1: Please don't take away our licenses.
• 27:18
  Speaker 4: I know.
• 27:19
  Speaker 2: So probably in the moment if somebody said, hey, Kelly,
• 27:22
  Speaker 2: are you paying attention? You'd be like, yes, of course.
• 27:24
  Speaker 2: What are you talking about? And you probably did stop
• 27:26
  Speaker 2: for all those red lights.
• 27:27
  Speaker 4: Yeah.
• 27:27
  Speaker 2: But it wasn't interesting enough to be recalled. So you
• 27:31
  Speaker 2: were aware, you were conscious, you were self-conscious, but you
• 27:34
  Speaker 2: don't remember it.
• 27:35
  Speaker 1: Yes. Scary though that is.
• 27:37
  Speaker 2: Yeah. So let's flip it around. Can memory exist without consciousness? Right.
• 27:42
  Speaker 2: Like certainly you can learn stuff without consciously remembering every
• 27:47
  Speaker 2: time you learned it. Like I don't remember when I
• 27:49
  Speaker 2: learned arithmetic, but I can do it. Right. A lot
• 27:53
  Speaker 2: of implicit memory influences later choices, even if you don't
• 27:56
  Speaker 2: recall exactly why you've learned it.
• 27:59
  Speaker 1: But did you need to be conscious in the moment
• 28:02
  Speaker 1: to make that memory? Probably not. See, I feel like
• 28:07
  Speaker 1: I don't ever want to lead a discussion on consciousness
• 28:10
  Speaker 1: because every question is a, oh, Kelly needs 10 minutes
• 28:13
  Speaker 1: to think about this. Do I really know what these
• 28:17
  Speaker 1: terms mean? That's what I always go back to.
• 28:19
  Speaker 2: I would say that memory by itself is weak evidence
• 28:24
  Speaker 2: for consciousness. I don't know that you need to have
• 28:27
  Speaker 2: been conscious in order to remember something. You're not even
• 28:31
  Speaker 2: always aware of, you know, why you are doing something
• 28:35
  Speaker 2: or how something has influenced your behavior. And so it's
• 28:38
  Speaker 2: like somehow there in your memory, it's changed the way
• 28:42
  Speaker 2: you operate, but you don't remember learning it. And you
• 28:47
  Speaker 2: might not have even been paying attention to the facts
• 28:50
  Speaker 2: that have influenced you. But it does feel like our
• 28:53
  Speaker 2: sense of self, you know, being one person across time,
• 28:56
  Speaker 2: like Daniel said, is not the same person he was
• 28:59
  Speaker 2: a year ago. He knows more chemistry and biology now
• 29:02
  Speaker 2: than he did, but it's still the same person. You know,
• 29:05
  Speaker 2: I still feel like I am who I am. And
• 29:08
  Speaker 2: so memory sort of like stitches all those moments together
• 29:11
  Speaker 2: into this like biological narrative. And so this makes me
• 29:15
  Speaker 2: think of like Daniel Dennett's theory of consciousness. He wrote
• 29:18
  Speaker 2: this great book called Consciousness Explained.
• 29:21
  Speaker 1: What a Ballsy title.
• 29:22
  Speaker 2: Oh, wow. Yeah, I know. I loved it. And the
• 29:26
  Speaker 2: idea he attacks in that book is a sort of
• 29:29
  Speaker 2: intuitive notion of consciousness. I think a lot of people have,
• 29:32
  Speaker 2: which is that there's like a little dude inside your
• 29:35
  Speaker 2: brain watching the world like a movie theater. Right. He
• 29:38
  Speaker 2: calls this the Cartesian thing. like there's some little homunculus
• 29:42
  Speaker 2: in your brain and it's like you can't really experience
• 29:44
  Speaker 2: the world except it just gets the senses and it
• 29:47
  Speaker 2: sits there hearing and seeing and feeling but it's not
• 29:51
  Speaker 2: really an answer to the question of consciousness it just
• 29:53
  Speaker 2: sort of kicks it down the road Right. Because if
• 29:55
  Speaker 2: there's like a little person in your head watching a
• 29:57
  Speaker 2: movie about all of your senses, then like who's watching
• 30:01
  Speaker 2: the movie inside that little person's head.
• 30:04
  Speaker 5: Right.
• 30:04
  Speaker 3: Yeah.
• 30:04
  Speaker 1: Where did that do that come from?
• 30:06
  Speaker 2: Exactly. And so he's got this kind of bonkers theory
• 30:09
  Speaker 2: of consciousness. It's called the multiple drafts model. And it
• 30:13
  Speaker 2: says in the brain is constantly trying to make sense
• 30:15
  Speaker 2: of what happened and stitch it together into a story
• 30:18
  Speaker 2: about what has just happened to you. And so it's like,
• 30:22
  Speaker 2: it tries this, it tries that, it tries to weave
• 30:24
  Speaker 2: it all together into something that's simplified, that it can
• 30:28
  Speaker 2: tell as a story. But there's no actual moment of
• 30:31
  Speaker 2: consciousness in Dennett's theory. It is just a memory of
• 30:34
  Speaker 2: the story of what just happened. There is no like,
• 30:37
  Speaker 2: I am experiencing this now. It's just like, I'm recalling
• 30:41
  Speaker 2: what just happened like a bill a second ago. It's
• 30:45
  Speaker 2: this interesting theory because in his view, what we call
• 30:49
  Speaker 2: consciousness emerges from this like, distributed activity where you're like
• 30:53
  Speaker 2: processing this and processing that and then writing down your
• 30:57
  Speaker 2: like history. And there is no like, I am having
• 31:01
  Speaker 2: this experience now that's writing histories. You're like going back
• 31:03
  Speaker 2: and weaving it together. It's like a journalist telling a
• 31:07
  Speaker 2: story about what happened and forming a consensus among the journalists.
• 31:11
  Speaker 2: But there is no like, I'm feeling it right now.
• 31:15
  Speaker 2: And so in relation to Rosalind's question, It tells you
• 31:18
  Speaker 2: that consciousness itself is nothing but recalling the immediate past,
• 31:24
  Speaker 2: which is experiencing memory. And so I think Daniel Dennett,
• 31:28
  Speaker 2: may he rest in peace. would say that memory is
• 31:31
  Speaker 2: absolutely essential for consciousness because that's what consciousness is. It's
• 31:35
  Speaker 2: just the recollection of the immediate past. And like, there's
• 31:39
  Speaker 2: lots of criticisms of Dennett's idea, by far not like
• 31:42
  Speaker 2: a widely held view. My favorite criticism is that his
• 31:46
  Speaker 2: book should have been called Consciousness Explained Away instead of
• 31:49
  Speaker 2: Consciousness Explained. And so, you know, Rosalind, this is really hard.
• 31:56
  Speaker 2: Nobody knows the answer. These are just my unqualified thoughts.
• 32:00
  Speaker 2: You know, memory and consciousness are not the same thing.
• 32:02
  Speaker 2: Some kinds of memory you can have without consciousness or
• 32:06
  Speaker 2: a sense of self, right? It also seems like you
• 32:09
  Speaker 2: can be aware without remembering things. But it does seem
• 32:12
  Speaker 2: like memory is crucial to our experience of being a
• 32:16
  Speaker 2: continuous person, part of what defines who you are and
• 32:20
  Speaker 2: your identity. And so I think memory does help define
• 32:23
  Speaker 2: who we are and how that changes over time. And
• 32:26
  Speaker 2: so there's definitely a close relationship between these two concepts.
• 32:29
  Speaker 1: And I think it's important to mention, didn't Daniel Dennett
• 32:32
  Speaker 1: say something nice about, do aliens speak physics?
• 32:35
  Speaker 2: That's right. I wrote a whole chapter about whether we're
• 32:38
  Speaker 2: smart enough to understand what aliens... think and he's talked
• 32:41
  Speaker 2: about this like the limits of biological intelligence and i
• 32:45
  Speaker 2: sent him the book and i was like when you
• 32:47
  Speaker 2: take a look at this especially the parts where i
• 32:49
  Speaker 2: reference your work and let me know if i got
• 32:50
  Speaker 2: it right and he wrote me back just three words
• 32:52
  Speaker 2: he said this is good i'm so relieved you know
• 32:57
  Speaker 2: that thing where you step outside your field and you
• 32:59
  Speaker 2: write something and then you send it to experts and
• 33:00
  Speaker 2: you're like please tell me if i got this wrong
• 33:02
  Speaker 2: yep and you're terrified you're gonna get like 10 pages
• 33:05
  Speaker 2: of rant yep yep so The shorter the response, the better. Anyway,
• 33:10
  Speaker 2: that was a relief.
• 33:11
  Speaker 1: I once wrote a Nobel Prize winner to ask if
• 33:13
  Speaker 1: I could interview them about a topic. And they wrote
• 33:16
  Speaker 1: back and said, you didn't pick the most interesting thing
• 33:19
  Speaker 1: to talk about. And then didn't respond to my emails anymore.
• 33:22
  Speaker 2: Oh, no.
• 33:23
  Speaker 1: I was like, wow. I guess you have a lot
• 33:26
  Speaker 1: going on. All right. Anyway, so thank you to the
• 33:28
  Speaker 1: people who actually respond to emails.
• 33:30
  Speaker 2: That's right. Thank you.
• 33:51
  Speaker 1: All right, next up, we have a question from Paul
• 33:54
  Speaker 1: from New Hampshire, who's really into slugs.
• 33:57
  Speaker 5: Hey, Daniel and Kelly, since you often mention bananas, How
• 34:00
  Speaker 5: about an episode on banana slugs, plus slugs and snails
• 34:03
  Speaker 5: in general? Seems like a relevant topic given the UC
• 34:07
  Speaker 5: Santa Cruz connection. Though not a UC alumnus, I used
• 34:10
  Speaker 5: to live in Silicon Valley and would often hike in
• 34:13
  Speaker 5: the coastal forests, so I got to see banana slugs
• 34:15
  Speaker 5: in the wild. When I describe them, some people look
• 34:18
  Speaker 5: at me like I've been smoking banana peels, and I'm
• 34:21
  Speaker 5: sure Kelly can find some interesting slug parasites like rat lungworm.
• 34:25
  Speaker 2: I'm into slugs too. I'm banana slugs. Yeah. Go UC. Yeah.
• 34:29
  Speaker 1: Yeah.
• 34:30
  Speaker 2: Right.
• 34:30
  Speaker 1: So University of California, Santa Cruz, their mascot are the
• 34:34
  Speaker 1: banana slugs.
• 34:34
  Speaker 2: Awesome.
• 34:35
  Speaker 1: And I will note that I have been working on
• 34:37
  Speaker 1: answering Paul's very broad question from a number of different angles.
• 34:43
  Speaker 1: A while ago, we did an episode, and this was
• 34:45
  Speaker 1: partly in response to a question from Jane about slugs
• 34:48
  Speaker 1: and snails and whence shells came from and what the
• 34:53
  Speaker 1: purpose of the shells is and how the shells are made.
• 34:55
  Speaker 1: And so that was my beginning of the sluggy answers.
• 34:59
  Speaker 1: And then Paul also mentioned rat lungworm. We did a
• 35:02
  Speaker 1: whole episode on rat lungworm, which.
• 35:05
  Speaker 2: Terrifying episode.
• 35:06
  Speaker 1: I promise we will not talk about rat lungworm in
• 35:08
  Speaker 1: any detail again. I think the message that I am
• 35:12
  Speaker 1: getting is that was maybe the least enjoyed. Our guest
• 35:15
  Speaker 1: was amazing. It was very informative, but it made many
• 35:17
  Speaker 1: people squirm.
• 35:18
  Speaker 2: Yeah.
• 35:19
  Speaker 1: Which I totally get. And so now I am wrapping
• 35:21
  Speaker 1: up this question by talking about banana slugs. What do
• 35:25
  Speaker 1: you know about the banana slugs, Daniel?
• 35:28
  Speaker 2: They're big. They're yellow.
• 35:30
  Speaker 1: Sometimes yellow.
• 35:31
  Speaker 2: They're sometimes yellow. Okay. Can you lick them and get
• 35:34
  Speaker 2: some sort of interesting experience or is that something else?
• 35:39
  Speaker 1: No, I think no. Let's say no. So I believe
• 35:43
  Speaker 1: that there is a thing where sometimes people will go
• 35:47
  Speaker 1: ahead and smooch banana slugs and their lips tingle afterwards.
• 35:51
  Speaker 2: Oh, yeah, that's what it is.
• 35:52
  Speaker 1: Banana slugs will eat poison oak. They also eat mushrooms
• 35:57
  Speaker 1: that are very toxic to us. You should never pick
• 36:00
  Speaker 1: up a wild banana slug and stick it up to
• 36:03
  Speaker 1: your mouth because you don't know where that thing has been.
• 36:05
  Speaker 1: That's true. I don't know what's going on with the
• 36:09
  Speaker 1: tingliness there. But so, you know, maybe now's a good
• 36:12
  Speaker 1: time to talk about the like slime that they produce.
• 36:14
  Speaker 3: Yeah.
• 36:15
  Speaker 1: So the slime they produce has these amazing like granules
• 36:18
  Speaker 1: in them that suck up water. And this is part
• 36:21
  Speaker 1: of how banana slugs manage to stay moist is that
• 36:24
  Speaker 1: the slime is constantly like sucking up water. So it's
• 36:28
  Speaker 1: possible that when you put a banana slug on your lips, again,
• 36:31
  Speaker 1: do not do that. The tingling feeling you're feeling is
• 36:34
  Speaker 1: the moisture being sucked out of your lips, maybe. But
• 36:39
  Speaker 1: don't do that.
• 36:40
  Speaker 2: But that slime, they also— You're making it sound fun, though.
• 36:44
  Speaker 1: Well, that's not my fault. People make bad choices. I
• 36:49
  Speaker 1: am absolving myself of any responsibility.
• 36:52
  Speaker 2: Please sign this waiver before listening to this episode. That's right.
• 36:55
  Speaker 1: That's right. So this slime, like one, it helps them
• 36:58
  Speaker 1: move around their environment, like it lubricates the environment. It
• 37:00
  Speaker 1: helps them stay moist by sucking the moisture out of
• 37:03
  Speaker 1: the environment to try to keep them moist. But it
• 37:05
  Speaker 1: also is this great anti-predator technique. So when like a
• 37:09
  Speaker 1: salamander or a garter snake or a raccoon tries to
• 37:13
  Speaker 1: eat them, the slime like essentially starts multiplying as the
• 37:18
  Speaker 1: saliva inside the predator's mouth starts like getting sucked into
• 37:22
  Speaker 1: the slime to grow the size of the slime.
• 37:24
  Speaker 3: Wow.
• 37:25
  Speaker 1: And so there have been like videos of snakes that
• 37:27
  Speaker 1: are just their mouths are like full of slime and
• 37:30
  Speaker 1: like they're spitting the slugs out like, no, just forget it.
• 37:33
  Speaker 1: This was a mistake. I quit. I guess raccoons have
• 37:36
  Speaker 1: been observed to be very cleverly rolling the slug in
• 37:41
  Speaker 1: the dirt. And I think what it's doing is rolling
• 37:43
  Speaker 1: off the slime so that then it can eat it.
• 37:45
  Speaker 1: You know, I guess it could also just like. squeeze
• 37:48
  Speaker 1: it out like a paper towel or something. But anyway,
• 37:51
  Speaker 1: so this slime is kind of an amazing material that
• 37:55
  Speaker 1: helps them both stick to things and slide along their
• 37:58
  Speaker 1: environment and protects them from predators. Way to go, banana slugs.
• 38:03
  Speaker 7: Yeah.
• 38:03
  Speaker 1: But I think what these slugs are probably most well-known
• 38:06
  Speaker 1: for is their reproduction. And so if y'all have kids
• 38:11
  Speaker 1: around and you don't want them to hear about slug reproduction,
• 38:13
  Speaker 1: this is just a heads up that here it comes.
• 38:16
  Speaker 3: Uh.
• 38:17
  Speaker 1: So the slugs are hermaphrodites. They have really big wieners
• 38:22
  Speaker 1: in a lot of cases. And they have vaginas because
• 38:25
  Speaker 1: they're hermaphrodites. So they've got both sets of equipment. They
• 38:28
  Speaker 1: are able to self-fertilize. But what they usually do is
• 38:32
  Speaker 1: find a mate. When they find a mate, they begin
• 38:35
  Speaker 1: like fertilizing each other essentially at the same time. Although
• 38:38
  Speaker 1: sometimes you can observe slugs where just one of them
• 38:41
  Speaker 1: is using their penis and the other one is not.
• 38:44
  Speaker 2: All right, I got to ask, because you mentioned it
• 38:46
  Speaker 2: twice now. Yep. You say the slug has a really
• 38:48
  Speaker 2: big wiener. In relation to the slug, what does the
• 38:51
  Speaker 2: slug wiener look like? Like, give me a visual here.
• 38:55
  Speaker 1: Let's go to Google.
• 38:56
  Speaker 2: I'm glad this is not in my search history.
• 39:02
  Speaker 1: Oh my God, this is not the worst of... Okay,
• 39:05
  Speaker 1: so I would say it's about... Looking at the one
• 39:07
  Speaker 1: photo that I'm seeing right now, the wiener is about
• 39:10
  Speaker 1: the size of their head.
• 39:11
  Speaker 2: Okay, all right.
• 39:12
  Speaker 1: Yeah, I mean, that's pretty... Impressive.
• 39:17
  Speaker 2: Kelly is impressed.
• 39:18
  Speaker 1: Relative to the size of their body. Although these guys
• 39:20
  Speaker 1: can get really big. So like I was looking at
• 39:22
  Speaker 1: one of the measurements and like a big banana slug
• 39:26
  Speaker 1: can get from like my wrist to the crook of
• 39:28
  Speaker 1: my elbow. So like the length of my forearms. That's
• 39:30
  Speaker 1: a pretty big slug, right?
• 39:33
  Speaker 2: That's a huge slug.
• 39:34
  Speaker 1: Yeah, huge slug.
• 39:35
  Speaker 2: Okay.
• 39:35
  Speaker 1: But so what they're known for is they will go
• 39:37
  Speaker 1: ahead and have sex. And when sex is done, one
• 39:40
  Speaker 1: will go to pull their wiener out, but it seems
• 39:43
  Speaker 1: to get stuck. And so in these cases where it
• 39:46
  Speaker 1: seems to get stuck, it seems like for a while
• 39:48
  Speaker 1: they attempt to detach. But if detaching doesn't work, then
• 39:52
  Speaker 1: one of them will chew the wiener off.
• 39:55
  Speaker 2: Okay. We should have more warnings, Kelly. Why? I'm... Sorry?
• 40:02
  Speaker 2: All right, go ahead. What happens next?
• 40:04
  Speaker 1: That's called apophylation.
• 40:06
  Speaker 2: Uh-huh.
• 40:07
  Speaker 1: And so there's this big debate about why do they
• 40:12
  Speaker 1: do that? Is it like, for example, to make sure
• 40:15
  Speaker 1: that the mate who just lost the penis invests in
• 40:19
  Speaker 1: protecting the eggs that just got fertilized by the other individual?
• 40:23
  Speaker 1: I think at the end of the day, we don't
• 40:24
  Speaker 1: know why this happens. We all just know that it
• 40:26
  Speaker 1: kind of makes us uncomfortable to hear about, particularly the
• 40:29
  Speaker 1: male of the species.
• 40:31
  Speaker 2: I don't know how I feel about the theory that
• 40:33
  Speaker 2: it brings the family together. Oh, no, no, no.
• 40:35
  Speaker 1: That's not that's not at all what I'm saying. And so, OK,
• 40:38
  Speaker 1: so both individuals get their eggs fertilized in this interaction.
• 40:42
  Speaker 2: Yeah.
• 40:42
  Speaker 1: And so now they both have eggs that require a
• 40:45
  Speaker 1: little bit more like energy to finish like growing up
• 40:48
  Speaker 1: or whatever. If you don't have A penis. You can't
• 40:52
  Speaker 1: go find another partner and invest in it doesn't make
• 40:54
  Speaker 1: sense to invest in making more sperm because you don't
• 40:56
  Speaker 1: have a penis anymore. Yeah. And so you better invest
• 41:00
  Speaker 1: in making the set of eggs that you're growing like
• 41:02
  Speaker 1: really great.
• 41:03
  Speaker 2: Exactly.
• 41:04
  Speaker 5: Yeah.
• 41:04
  Speaker 2: No, that's what I understood completely. But it's like it
• 41:07
  Speaker 2: makes the parents invest in the kids. Right.
• 41:09
  Speaker 1: Oh, I thought you said invest in the family. And
• 41:11
  Speaker 1: I thought you were. I don't know. That's that was a.
• 41:14
  Speaker 1: More touchy-feely way of saying it than I– I don't
• 41:18
  Speaker 1: think anybody necessarily buys that. That's just a idea that's
• 41:21
  Speaker 1: floated out there. But I think at the end of
• 41:22
  Speaker 1: the day, we throw our hands up in the air
• 41:24
  Speaker 1: and we're like, why are you guys eating each other's wieners?
• 41:26
  Speaker 1: We don't know. That's a weird thing to do.
• 41:29
  Speaker 2: Glad we agree on that. All right.
• 41:32
  Speaker 1: Yeah, yeah, yeah. So there was this idea for a
• 41:34
  Speaker 1: long time that you'll go to some populations– And it
• 41:38
  Speaker 1: will be hard, if not impossible, to find a banana
• 41:41
  Speaker 1: slug with a wiener. And so the question was like, oh,
• 41:45
  Speaker 1: my gosh, did this population just like go to town
• 41:48
  Speaker 1: on the apophyllation situation? And it looks like actually in
• 41:52
  Speaker 1: some populations, the hermaphrodites are born without penises. And so
• 41:58
  Speaker 1: they can still fertilize themselves by like, you know, they've
• 42:01
  Speaker 1: got like an internal tube system where they can mix
• 42:03
  Speaker 1: the sperm and the eggs on their own. And they
• 42:06
  Speaker 1: can still accept sperm if they're able to find another
• 42:08
  Speaker 1: individual that has a penis. And in that way, they
• 42:11
  Speaker 1: can mate naturally. You know, with someone other than themselves.
• 42:14
  Speaker 1: But like why you see this diversity amongst populations in
• 42:19
  Speaker 1: some species of banana slugs where some of them have
• 42:21
  Speaker 1: penises and some of them don't. That's another open question.
• 42:24
  Speaker 1: And so there's lots of questions about the sex lives
• 42:27
  Speaker 1: of banana slugs that keep scientists.
• 42:29
  Speaker 4: Up at night.
• 42:30
  Speaker 2: Wow, that's a whole PhD topic right there.
• 42:32
  Speaker 1: That could be a couple PhD topics. There's some interesting
• 42:35
  Speaker 1: questions there about, like, sexual selection and... Anyway, that'll... Yeah.
• 42:39
  Speaker 1: We just need money, you know?
• 42:41
  Speaker 2: I hope some student doesn't bite off more than they
• 42:42
  Speaker 2: can chew, you know?
• 42:45
  Speaker 1: That was too much. Too much.
• 42:48
  Speaker 2: But.
• 42:49
  Speaker 1: Paul gave me an opening to talk about parasites. And
• 42:52
  Speaker 1: we're not going to talk about rat lungworm.
• 42:54
  Speaker 2: Yeah.
• 42:56
  Speaker 1: But we're going to talk real quick about biocontrol. So slugs,
• 43:01
  Speaker 1: if you are a gardener, slugs are like the bane
• 43:03
  Speaker 1: of your existence. So we bought six ducks to try
• 43:07
  Speaker 1: to control the slug population in Zach's garden. And it
• 43:10
  Speaker 1: turns out the ducks were more work than the slugs.
• 43:13
  Speaker 2: Yeah. Of course. And now you have ducks to take
• 43:15
  Speaker 2: care of.
• 43:16
  Speaker 1: Well, you know, they got taken care of by a predator, unfortunately.
• 43:20
  Speaker 1: But yeah, it was really sad. Betty White, her passing
• 43:24
  Speaker 1: was the hardest to deal with. But anyway, so OK,
• 43:27
  Speaker 1: so another option for getting rid of slugs in an
• 43:30
  Speaker 1: agricultural setting is. is to release nematodes, which are a
• 43:34
  Speaker 1: kind of like, you know, hard tube-ish shaped parasite. You
• 43:38
  Speaker 1: release these slug attacking nematodes into your garden. And when
• 43:42
  Speaker 1: a slug walks over them, the nematodes, which are parasites
• 43:45
  Speaker 1: in this case, are like, there's a host. And they
• 43:47
  Speaker 1: go ahead and they attack the slugs and they kill
• 43:49
  Speaker 1: the slugs. But the problem is these nematodes don't only
• 43:54
  Speaker 1: go after slugs that are bad for your garden. They
• 43:57
  Speaker 1: go after like whatever slug they find. And so on
• 44:01
  Speaker 1: three different continents, there is a product you can buy
• 44:04
  Speaker 1: called NEMA slug or NEMA slug 2.0. And these are
• 44:09
  Speaker 1: two different species of nematodes that can kill slugs. And
• 44:12
  Speaker 1: so there was a paper in BioRxiv in 2026 where
• 44:16
  Speaker 1: they wanted to know if we bring this into the
• 44:18
  Speaker 1: United States, because right now you're not allowed to use
• 44:20
  Speaker 1: it in the United States because we don't know what
• 44:22
  Speaker 1: it would do to like native slug populations. If we
• 44:25
  Speaker 1: brought it into the United States and started using it
• 44:27
  Speaker 1: in the Pacific Northwest where you find banana slugs, would
• 44:30
  Speaker 1: this kill banana slugs, too? And the answer does seem
• 44:33
  Speaker 1: to be yes. These nematodes will kill banana slugs. So
• 44:36
  Speaker 1: now the question is, will banana slugs, which tend to
• 44:39
  Speaker 1: live in like moist forest environments, which is to say
• 44:43
  Speaker 1: not really agricultural fields. Like, is there a risk of
• 44:47
  Speaker 1: these nematodes getting into those environments and killing the banana slugs?
• 44:51
  Speaker 1: That's something that we need to think about. But there
• 44:53
  Speaker 1: is some evidence that if we start using this agricultural
• 44:56
  Speaker 1: pest control method, there could be some implications for these
• 45:00
  Speaker 1: most charismatic of slugs.
• 45:04
  Speaker 2: All right. Thank you very much. Let's send that question
• 45:07
  Speaker 2: back to Paul and let him chew on it.
• 45:09
  Speaker 1: Or see if he wants to slug me after talking
• 45:11
  Speaker 1: about apophylations.
• 45:14
  Speaker 5: Hey, Kelly and Daniel. Thanks for answering my questions about
• 45:18
  Speaker 5: slugs and banana slugs in particular. I knew something of
• 45:21
  Speaker 5: the banana slug reproductive cycle, but not all the, uh, details.
• 45:26
  Speaker 5: I think they are a great example of creatures that
• 45:28
  Speaker 5: seem strange at first, but when you dig past appearances,
• 45:31
  Speaker 5: they're even more interesting than expected. We don't have banana
• 45:34
  Speaker 5: slugs here in New Hampshire, but at least I could
• 45:37
  Speaker 5: look at the banana slug plushie on my bookcase shelf.
• 45:40
  Speaker 2: Right next to my Cthulhu idol.
• 45:42
  Speaker 5: Thanks again.
• 45:43
  Speaker 2: All right. Thank you very much, everybody who's curious about
• 45:46
  Speaker 2: the universe and listens to the podcast. If you have
• 45:48
  Speaker 2: a question you'd like us to tackle, don't be shy.
• 45:50
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• 46:00
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• 46:02
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• 46:05
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• 46:07
  Speaker 1: Daniel and Kelly's Extraordinary Universe is edited by the amazing
• 46:11
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• 46:12
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• 46:22
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• 46:27
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• 46:32
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