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Science Of The Times EP2 - _Smart Male Fish Get All The Girls · Luke's English Podcast

• 0:07
  Speaker 1: Why?
• 0:07
  Speaker 2: I'm not mad like you.
• 0:12
  Speaker 1: Well, welcome back everyone.
• 0:13
  Speaker 3: It's the next episode of our podcast, The Science of
• 0:16
  Speaker 3: the Times.
• 0:17
  Speaker 1: How are you, Simon?
• 0:19
  Speaker 2: Yeah, feeling good. All ready for my trip to California.
• 0:23
  Speaker 1: Oh yeah, you're off to LA, isn't it?
• 0:25
  Speaker 2: Yeah, that's right, for the Biophysical Society annual meeting.
• 0:28
  Speaker 1: And is that something you go to every year?
• 0:31
  Speaker 2: Yeah, so it's going to be my 19th time. 19
• 0:34
  Speaker 2: years I've been going.
• 0:35
  Speaker 1: You're not that old.
• 0:36
  Speaker 2: I sadly am. We've already established the grey hair thing,
• 0:39
  Speaker 2: so yeah.
• 0:41
  Speaker 1: And so is it always in LA?
• 0:43
  Speaker 2: No, it alternates between, they do two years West Coast
• 0:46
  Speaker 2: and one year East Coast.
• 0:47
  Speaker 1: And you've been on the council there, is that right?
• 0:50
  Speaker 2: That's right, for three years. And so this year will
• 0:52
  Speaker 2: be my last one, my sort of council swan song. Oh, excellent.
• 0:55
  Speaker 1: Well done. And are you talking as well?
• 0:57
  Speaker 2: Yeah, giving a talk.
• 0:58
  Speaker 1: What are you talking about?
• 1:00
  Speaker 2: Well, bacterial cell envelopes. Come on, man.
• 1:06
  Speaker 1: How about you?
• 1:06
  Speaker 2: What have you been up to?
• 1:07
  Speaker 1: I've been teaching.
• 1:09
  Speaker 2: What?
• 1:10
  Speaker 1: Yeah, I have.
• 1:11
  Speaker 3: I've been teaching our third year biology undergraduates and we've
• 1:14
  Speaker 3: been doing advanced ecology and evolution. And one of the
• 1:18
  Speaker 3: lectures I gave them, I decided not to do PowerPoint
• 1:21
  Speaker 3: and I was just writing on the board.
• 1:23
  Speaker 2: Gosh, that's brave, but I think it works really well.
• 1:26
  Speaker 1: I really enjoyed it. It was good fun. I think
• 1:29
  Speaker 1: they did, but some of them are probably still asleep.
• 1:32
  Speaker 2: Well, I'm glad you rediscovered the art of teaching, Tim.
• 1:37
  Speaker 3: Well, and so what we're going to do, whilst you're
• 1:39
  Speaker 3: off swanning around the world to exotic locations, I'm going
• 1:42
  Speaker 3: to chat to a group of scientists, a couple of them,
• 1:45
  Speaker 3: who are based in Canberra, in Australian National University, and
• 1:50
  Speaker 3: they're fish experts.
• 1:51
  Speaker 1: Okay. And what they've been doing is they've been assessing
• 1:55
  Speaker 1: fish for their cognitive abilities.
• 1:57
  Speaker 2: Oh, okay.
• 1:59
  Speaker 1: Did you know fish varied in their cognitive abilities?
• 2:02
  Speaker 2: I'm afraid I didn't. I didn't know there were levels
• 2:04
  Speaker 2: of intellect amongst fish.
• 2:05
  Speaker 1: No, absolutely.
• 2:06
  Speaker 3: It turns out there are. And so they've got a paper,
• 2:08
  Speaker 3: a really exciting paper coming out. And contrary to what
• 2:11
  Speaker 3: we all think, that goldfish just forget everything after three seconds,
• 2:15
  Speaker 3: it turns out these fish do vary. And I wouldn't,
• 2:18
  Speaker 3: they're not solving ordinary differential equations or anything like that.
• 2:22
  Speaker 1: No, not yet.
• 2:24
  Speaker 3: But it turns out from the paper, by the sound
• 2:26
  Speaker 3: of it, that clever fish, clever males, get more matings
• 2:29
  Speaker 3: and more offspring.
• 2:30
  Speaker 1: So if that's heritable, we're going to end up with?
• 2:33
  Speaker 2: We're very, very clever fish, aren't we?
• 2:35
  Speaker 1: I know, I know. They get harder to catch, harder
• 2:37
  Speaker 1: to fry. Could be difficult. Anyway, these are little of Hish,
• 2:40
  Speaker 1: I think. But anyway, I'll find out more. It's fascinating.
• 2:43
  Speaker 1: And I'll report back.
• 2:44
  Speaker 2: I'll look forward to it.
• 2:45
  Speaker 1: Yeah, well, have a great trip.
• 2:46
  Speaker 2: Thank you, Tim. See you soon.
• 2:48
  Speaker 1: Okay.
• 2:49
  Speaker 3: Well, thank you very much for joining us, Ivan and Michael.
• 2:53
  Speaker 3: It's a real pleasure to have you here. And I
• 2:56
  Speaker 3: know it's a bit getting a bit late in Canberra,
• 2:59
  Speaker 3: where you're based at Australian National University. But Congratulations on
• 3:04
  Speaker 3: your paper, which is coming out in Nature, Ecology and Evolution,
• 3:08
  Speaker 3: or it's just out once we release this. And it's
• 3:11
  Speaker 3: entitled Paternity Analysis Reveals Sexual Selection on Cognitive Performance in
• 3:16
  Speaker 3: Mosquito Fish. And perhaps actually I'll let you introduce yourselves
• 3:19
  Speaker 3: one at a time and just say a little bit
• 3:21
  Speaker 3: about who you are and what you do. Do you
• 3:23
  Speaker 3: want to go first, Ivan? Because you're the first author
• 3:25
  Speaker 3: on this paper. You did all the hard work, clearly.
• 3:28
  Speaker 4: Sure. Thanks, Tim. I'm really happy to be here. Thanks
• 3:31
  Speaker 4: for inviting me. I'm really looking forward to chat about
• 3:34
  Speaker 4: it a bit. Yep, my name is Ivan, last name
• 3:37
  Speaker 4: Dino Gradov. I was originally born in Russia, in Moscow,
• 3:42
  Speaker 4: then studied a bit in the US, did my bachelor's
• 3:44
  Speaker 4: degree there, then moved to Australia to join Michael's lab
• 3:49
  Speaker 4: and work on behavioral ecology and cognitive project in his lab. Yeah,
• 3:55
  Speaker 4: so happy to be here.
• 3:57
  Speaker 5: And I'm Michael Jennings. I grew up in South Africa
• 4:02
  Speaker 5: and moved to Australia at the turn of the century
• 4:06
  Speaker 5: and have been here for the last 25 years or so.
• 4:09
  Speaker 5: And I'm the head of the lab in which Ivan
• 4:12
  Speaker 5: did his PhD and did this work that we're looking
• 4:15
  Speaker 5: forward to sharing with you.
• 4:17
  Speaker 1: No, well, fantastic.
• 4:18
  Speaker 3: Well, perhaps we can start a little bit if you
• 4:20
  Speaker 3: can tell us something about mosquito fish, because I'm not
• 4:23
  Speaker 3: sure all of our listeners will be familiar with them.
• 4:26
  Speaker 3: They're not the sorts of fish that end up on
• 4:28
  Speaker 3: our plates with a helping of chips. So tell us,
• 4:32
  Speaker 3: give us a little bit of background of mosquito fish.
• 4:34
  Speaker 3: How big are they? Where do they live? Where are
• 4:36
  Speaker 3: they found? And probably a little bit about their mating behavior, right?
• 4:41
  Speaker 3: Given the findings of your paper.
• 4:44
  Speaker 1: Sure.
• 4:45
  Speaker 4: So mosquito fish are fish endemic to South America, but
• 4:49
  Speaker 4: now they became a global pest. They are invasive in
• 4:53
  Speaker 4: most of the continents around the world. You can find
• 4:56
  Speaker 4: them in Australia as well in small ponds and rivers
• 4:58
  Speaker 4: around the country. They're freshwater fish. They're tiny. There's nothing
• 5:02
  Speaker 4: sort of too interesting about them at first glance. They're
• 5:06
  Speaker 4: just gray, but they do have a very interesting mating system,
• 5:10
  Speaker 4: which we take advantage of in our research. So the
• 5:13
  Speaker 4: males essentially try to mate as much as possible. They
• 5:17
  Speaker 4: always look for mating opportunities with females. They harass them
• 5:20
  Speaker 4: all the time. They try to to sneak up on
• 5:23
  Speaker 4: the females. And the interesting thing about the females is
• 5:27
  Speaker 4: they appear larger than the males, and they give birth
• 5:30
  Speaker 4: to live fish. So rather than laying eggs, they give
• 5:34
  Speaker 4: birth to live fish.
• 5:38
  Speaker 1: What else? Why are they called mosquito?
• 5:41
  Speaker 3: Sorry, Michael, go ahead.
• 5:43
  Speaker 4: No, no, no, you go, Tim.
• 5:46
  Speaker 5: The answer to your question I'm anticipating is why mosquito fish.
• 5:49
  Speaker 5: And this is because the reason that they are so
• 5:52
  Speaker 5: widespread in a pest across the world is that they
• 5:55
  Speaker 5: were introduced to control mosquitoes. And they are voracious eaters. Unfortunately,
• 6:00
  Speaker 5: they're also very aggressive and they attack native fish. So often, say,
• 6:05
  Speaker 5: for example, in Australia, when we find them in the streams,
• 6:08
  Speaker 5: they pretty much wiped out everything else due to their
• 6:11
  Speaker 5: aggressive nature, despite being the size of matchsticks.
• 6:15
  Speaker 1: And do they eat mosquito larvae, in fact?
• 6:20
  Speaker 5: Yeah, but I don't think the benefits were worth it.
• 6:27
  Speaker 3: The reason I ask is one of the fish that
• 6:30
  Speaker 3: I work on are these little things called guppies, and
• 6:32
  Speaker 3: a bit like mosquito fish, they've been introduced around the world.
• 6:35
  Speaker 3: They're probably not quite as destructive, and they were introduced
• 6:38
  Speaker 3: to eat mosquito larvae, but it turns out they don't
• 6:42
  Speaker 3: like them very much, so they weren't a very good
• 6:46
  Speaker 3: control agent.
• 6:47
  Speaker 1: But Okay.
• 6:49
  Speaker 3: So, so tell us a little bit about, um, you know, the,
• 6:53
  Speaker 3: the experiments that you did with these mosquito fish. So
• 6:56
  Speaker 3: it sounds like the males are swimming around looking for
• 6:58
  Speaker 3: females to mate with. They will mate at any opportunity.
• 7:01
  Speaker 3: Does the female have a lot of say in the, in,
• 7:03
  Speaker 3: in terms of who she mates with or.
• 7:06
  Speaker 4: Uh, that's an interesting question. Um, there are some studies
• 7:10
  Speaker 4: looking at the female preference of mosquito fish. Uh, but
• 7:13
  Speaker 4: it seems like that the reality is that it's the
• 7:16
  Speaker 4: males and male behavior that decides whether they will be
• 7:19
  Speaker 4: able to mate with a female or not. Females definitely
• 7:22
  Speaker 4: have some say in it. They can try to avoid
• 7:24
  Speaker 4: some males and they will be more inclined to approach others.
• 7:27
  Speaker 4: But I think the final decision is going to be
• 7:30
  Speaker 4: after the males.
• 7:31
  Speaker 3: And do different males have different mating strategies then? You know,
• 7:35
  Speaker 3: some of them sort of sneaking up and some of
• 7:37
  Speaker 3: them displaying. How does it work in the streams?
• 7:41
  Speaker 5: Yes.
• 7:41
  Speaker 4: So we generally distinguish two main mating strategy in these males. Firstly,
• 7:46
  Speaker 4: they can just try to harass the females and they
• 7:48
  Speaker 4: will not stop doing that until they get a mating opportunity.
• 7:51
  Speaker 4: But then the mating only takes a split of a second.
• 7:55
  Speaker 4: That's all it takes for them to fertilize a female.
• 7:59
  Speaker 4: But there's a different strategy. So those males that compete
• 8:01
  Speaker 4: with each other might get distracted. And in the meantime,
• 8:05
  Speaker 4: another male, who we call a sneaker male, might be
• 8:11
  Speaker 4: a bit stealthy and approach the female and mate with
• 8:14
  Speaker 4: her while the other males are not looking.
• 8:17
  Speaker 3: And then after they've mated, do the males hang around
• 8:19
  Speaker 3: to try and stop other males sneaking in? Do they
• 8:22
  Speaker 3: sort of guard their mate or not? Do they just
• 8:25
  Speaker 3: swim off looking for another female?
• 8:27
  Speaker 4: No, not really. So it's quite common in this fish
• 8:29
  Speaker 4: that a female can mate with several different males within
• 8:34
  Speaker 4: a small time interval.
• 8:37
  Speaker 3: And not wishing to rush to the punchline too quickly,
• 8:40
  Speaker 3: but essentially you found that cleverer fish, or those who
• 8:45
  Speaker 3: perform better on cognitive tasks, tended to get more paternity.
• 8:51
  Speaker 3: They tended to be the father of more offspring than those.
• 8:54
  Speaker 3: I mean, these are tiny little matchstick-sized fish, as you've
• 8:57
  Speaker 3: described them. What on earth made you think that that
• 9:00
  Speaker 3: might be intelligent?
• 9:03
  Speaker 4: Yes, so fish intelligence in general is quite underestimated. You
• 9:08
  Speaker 4: might have heard that there's a popular myth about three
• 9:11
  Speaker 4: second memory in goldfish and nothing can be further from
• 9:15
  Speaker 4: the truth. Fish are quite smart. They learn things, they
• 9:18
  Speaker 4: can store information for days and weeks as far as
• 9:22
  Speaker 4: we know for some fish. They can solve mazes, they
• 9:25
  Speaker 4: can solve pretty complex tasks. And coming back to your question, Sorry.
• 9:32
  Speaker 1: Yeah. No, it's all right. That's fine.
• 9:34
  Speaker 3: So why did you think they were a good study
• 9:36
  Speaker 3: system to look at intelligence rather than chimpanzees or, you know,
• 9:41
  Speaker 3: ravens or something?
• 9:43
  Speaker 4: So in addition, sorry, not only are they smart, but
• 9:47
  Speaker 4: they also happen to be a very convenient system for
• 9:49
  Speaker 4: us to study them. We can have hundreds of them
• 9:52
  Speaker 4: in the lab. They're quite easy to maintain, to take
• 9:54
  Speaker 4: care of. And they also have a pretty short generation time.
• 9:57
  Speaker 4: So um, within just a few months, we get a
• 10:00
  Speaker 4: new batch of, uh, fish coming in. So new generations.
• 10:04
  Speaker 4: So we can look at the long-term studies as well
• 10:08
  Speaker 4: and look at the effect of generations.
• 10:09
  Speaker 5: Yeah. A way to, a way to put it in perspective, uh,
• 10:12
  Speaker 5: for your listeners is I was at a talk the
• 10:15
  Speaker 5: other day by, um, a colleague who's worked on fairy
• 10:18
  Speaker 5: wrens in Australia for the last 30 years. This is
• 10:20
  Speaker 5: a very famous long-term study. And they have 10,000 individuals
• 10:25
  Speaker 5: that they've marked over these 30 years, which is phenomenal.
• 10:29
  Speaker 5: But to put it in perspective, in this study, we
• 10:33
  Speaker 5: determined the paternity of about 2,500 of individuals. And that
• 10:39
  Speaker 5: was in one study. It took a year or two,
• 10:42
  Speaker 5: of course, but... that's a sort of order of magnitude
• 10:45
  Speaker 5: more data than you could collect with working on a bird,
• 10:49
  Speaker 5: for example.
• 10:50
  Speaker 3: No, I mean, it's one of the reasons we work
• 10:53
  Speaker 3: on guppies as well. Exactly the same deal. They're a
• 10:56
  Speaker 3: good system in many ways to study things. Sorry, Ivan,
• 11:00
  Speaker 3: I think I interrupted you then.
• 11:01
  Speaker 1: You were going to say something.
• 11:02
  Speaker 4: No, that's all right. But you were right in saying
• 11:04
  Speaker 4: that our general conclusion was that smarter individuals do get
• 11:09
  Speaker 4: more offspring, so they have better paternity. So there is
• 11:12
  Speaker 4: something about intelligence that gives them an edge in either
• 11:16
  Speaker 4: securing mating opportunities, having more sex, producing more babies. We
• 11:20
  Speaker 4: couldn't quite pinpoint what exactly gives them an edge in
• 11:23
  Speaker 4: our study, but the main conclusion is it is the
• 11:26
  Speaker 4: fact that smarter individuals do get more babies at the end.
• 11:29
  Speaker 3: So how do you work out how smart a male
• 11:32
  Speaker 3: fish is? I mean, they're not doing their times tables
• 11:36
  Speaker 3: or anything like that, are they? I think you used
• 11:39
  Speaker 3: five different cognitive tests. Perhaps you can can go through them. So, yeah,
• 11:45
  Speaker 3: why don't you start going through them and telling us
• 11:48
  Speaker 3: what each one of those means. And they're called reversal, associative, spatial, impulsive,
• 11:54
  Speaker 3: and inhibitory. But I have to say, until I read
• 11:56
  Speaker 3: your paper, I didn't know what those mean, so I
• 11:57
  Speaker 3: suspect most of our listeners won't.
• 12:00
  Speaker 4: So I'll start by saying that it is notoriously tricky
• 12:03
  Speaker 4: to pinpoint intelligence of any animal, even a human. Even so,
• 12:08
  Speaker 4: a tiny little fish with a tiny brain But biologists
• 12:14
  Speaker 4: generally agree on the definition of cognitive abilities. It is
• 12:18
  Speaker 4: an ability to acquire information from the environment, its ability
• 12:22
  Speaker 4: to store it, to remember it, and ability to apply
• 12:26
  Speaker 4: it to the environment, to make conclusions about things that
• 12:30
  Speaker 4: you see around you. But it's also important to say
• 12:33
  Speaker 4: that it's not a single trait, right? It's not a
• 12:36
  Speaker 4: single skill. Different regions of our brain are likely responsible
• 12:40
  Speaker 4: for different cognitive abilities, what we call different cognitive domains.
• 12:45
  Speaker 4: So we decided to use not just one test, but
• 12:50
  Speaker 4: what's called a cognitive battery. So a battery of five
• 12:53
  Speaker 4: different tests. I'll briefly go through all of them. So
• 12:57
  Speaker 4: first test I can talk about is called inhibitory control,
• 13:01
  Speaker 4: or more commonly known as self-control. Essentially what we do
• 13:04
  Speaker 4: is we put a transparent wall in front of a fish,
• 13:08
  Speaker 4: And behind that wall, there is a reward. And the reward,
• 13:12
  Speaker 4: in our case, is usually just a group of other fish.
• 13:15
  Speaker 4: They're very social, so they really like to swim with
• 13:17
  Speaker 4: their group. So they want to go through the wall
• 13:20
  Speaker 4: and reach that reward. And obviously, they'll be bumping into
• 13:23
  Speaker 4: that wall. And we measure how long it takes them
• 13:26
  Speaker 4: to realize that there is a barrier in front of them.
• 13:28
  Speaker 4: And what they should do is to sort of say,
• 13:31
  Speaker 4: hold on a second, that's not getting anywhere. I should
• 13:35
  Speaker 4: find another way around it, right? So that's an ability
• 13:37
  Speaker 4: to control your impulse to just go forward and instead
• 13:41
  Speaker 4: take a second to think and move around the object.
• 13:46
  Speaker 4: And there's a second variation of this test, which we
• 13:49
  Speaker 4: call impulsiveness. So consider a scenario where the fish do
• 13:53
  Speaker 4: it for the first time. This is their naive response
• 13:56
  Speaker 4: to the barrier. They've never seen it before. But then
• 13:58
  Speaker 4: if you introduce them to that barrier again and again
• 14:01
  Speaker 4: and again, hopefully what they should realize, they should remember
• 14:04
  Speaker 4: that the barrier is there. So their time should improve
• 14:08
  Speaker 4: with consecutive trials. So in that case, a dumb fish
• 14:11
  Speaker 4: would sort of fall into the same trap again and
• 14:14
  Speaker 4: again and would go to that barrier and keep hitting
• 14:16
  Speaker 4: it every single time.
• 14:17
  Speaker 3: So there are some fish that basically just keep swimming
• 14:22
  Speaker 3: into a wall is essentially what you're saying.
• 14:24
  Speaker 4: Yes, we definitely saw that. A fish just hitting the
• 14:26
  Speaker 4: wall for five minutes straight, nothing really improving. Yeah, so
• 14:31
  Speaker 4: that's pretty clear evidence that something is not working there.
• 14:35
  Speaker 1: And then the other three?
• 14:37
  Speaker 4: Yeah. Now, the next test is called spatial learning. Essentially,
• 14:42
  Speaker 4: it's just a very simple maze. There's a couple of
• 14:44
  Speaker 4: dead ends, and there's one correct path to the reward.
• 14:47
  Speaker 4: So we just see how long it takes the fish
• 14:49
  Speaker 4: to go through the maze, and then we expose the
• 14:52
  Speaker 4: fish to the same maze again a few times to
• 14:55
  Speaker 4: see whether the fish remembers the layout. So that's pretty simple.
• 14:58
  Speaker 4: You might have seen something similar in those sort of
• 15:00
  Speaker 4: classic rat or mice studies where they sort of run
• 15:04
  Speaker 4: around the little maze. fish can do that as well.
• 15:06
  Speaker 4: And I think it's ecologically relevant as well because they
• 15:09
  Speaker 4: have to navigate in small ponds where there's a lot
• 15:12
  Speaker 4: of algae, a lot of debris. So we believe that's
• 15:15
  Speaker 4: a relevant skill for them.
• 15:16
  Speaker 3: And did you ever find any fish that couldn't get
• 15:19
  Speaker 3: through the maze? I mean, that never succeeded to get
• 15:21
  Speaker 3: through it or did most of them solve it in
• 15:23
  Speaker 3: the end?
• 15:25
  Speaker 4: We definitely have quite a lot of fish tested. So yes,
• 15:30
  Speaker 4: some of them weren't able to reach the end. An
• 15:33
  Speaker 4: interesting fact is that We're actually not sure what was
• 15:38
  Speaker 4: the reason why they weren't able to solve it because
• 15:40
  Speaker 4: I suspect that for some fish, it might not be cognition,
• 15:44
  Speaker 4: but it might be stress levels. So it's an important
• 15:49
  Speaker 4: part of these experiments that we keep exposing fish to
• 15:51
  Speaker 4: a very unfamiliar environment and they do experience stress. So
• 15:55
  Speaker 4: for some fish, it might be the case that they
• 15:57
  Speaker 4: are not willing to explore. They want to stay in
• 16:01
  Speaker 4: the beginning zone at the start because they're not interested
• 16:04
  Speaker 4: in going out there and exploring because it might be dangerous, right?
• 16:09
  Speaker 1: And then the last two, I think, are what? Reversal
• 16:11
  Speaker 1: and associative. Is that right? Yes, correct.
• 16:14
  Speaker 4: So associative test is very simple. Sorry, I'll do that again.
• 16:21
  Speaker 4: Associative learning test is quite simple. Essentially, we present a
• 16:24
  Speaker 4: fish with two different paths. One marked with, let's say,
• 16:28
  Speaker 4: red color, the other one with a green color. And
• 16:30
  Speaker 4: the green color always leads to a reward. The red
• 16:33
  Speaker 4: color leads to a dead end. Then we give the
• 16:36
  Speaker 4: fish a few trials to memorize that the green color
• 16:42
  Speaker 4: is always associated with the reward, even if we move
• 16:45
  Speaker 4: the location of the corridors around. So then we look
• 16:48
  Speaker 4: at how long does it take the fish to establish
• 16:51
  Speaker 4: that association, that green is good, red is bad, right?
• 16:55
  Speaker 4: Then the reversal test actually builds on top of that one.
• 16:59
  Speaker 4: Now that the fish has learned that green is good
• 17:02
  Speaker 4: and red is bad, we swap the meaning of the
• 17:06
  Speaker 4: colors on them immediately after they've learned it. So from
• 17:09
  Speaker 4: now on, the red color will be good. It will
• 17:12
  Speaker 4: lead to the reward and the green color would lead
• 17:15
  Speaker 4: to a dead end. So essentially what that skill tests
• 17:18
  Speaker 4: is their ability to sort of erase an old existing
• 17:21
  Speaker 4: association and create a new one in its place. And
• 17:25
  Speaker 4: it's believed to be a different skill set and people
• 17:28
  Speaker 4: tested in humans and other animals as well.
• 17:31
  Speaker 3: And what you found was that these things weren't particularly
• 17:35
  Speaker 3: well correlated. So a fish that was hopeless at getting
• 17:38
  Speaker 3: around the barrier kept on swimming into it and knocking
• 17:41
  Speaker 3: itself out. It might be, that didn't mean it wouldn't
• 17:45
  Speaker 3: be good at solving the maze or it wouldn't be
• 17:46
  Speaker 3: good at reversal.
• 17:47
  Speaker 1: Is that right?
• 17:49
  Speaker 4: Yes, that's correct. There is a term called general intelligence,
• 17:54
  Speaker 4: which was introduced in 1900s by Spearman. That was a
• 17:57
  Speaker 4: term to describe intelligence intelligence in humans. So, for example,
• 18:05
  Speaker 4: imagine that you were to test scores of high schoolers
• 18:09
  Speaker 4: in maths, English, history, physics, and so on. The general
• 18:14
  Speaker 4: intelligence hypothesis would tell us that if you have a
• 18:16
  Speaker 4: smart kid, they would score highly in every single test, right?
• 18:20
  Speaker 4: Because they are just overall smart. But an alternative scenario
• 18:25
  Speaker 4: is you might have someone who is really good at maths,
• 18:28
  Speaker 4: just because they have that sort of skill set, but
• 18:31
  Speaker 4: they'll have poor scores and everything else. And it's an
• 18:34
  Speaker 4: ongoing debate. We're not sure whether general intelligence exists in
• 18:37
  Speaker 4: animals or not. There is also sort of a secondary
• 18:40
  Speaker 4: goal of our study to test if something like that
• 18:42
  Speaker 4: exists in fish. And we didn't find any evidence for
• 18:46
  Speaker 4: general intelligence. In other words, these tests were not correlated.
• 18:50
  Speaker 4: So if someone has a good associative learning scores, it
• 18:53
  Speaker 4: does not mean that they will be good at solving
• 18:55
  Speaker 4: a maze or self-control.
• 18:58
  Speaker 1: And then you, so then you correlated these things.
• 19:01
  Speaker 3: You statistically examined how each of these measures of cognitive ability,
• 19:05
  Speaker 3: of intelligence, correlated with male reproductive success and the number
• 19:11
  Speaker 3: of offspring they produced. And Michael, what did you, you
• 19:15
  Speaker 3: found that the spatial measure of cognition was most strongly associated.
• 19:21
  Speaker 1: Is that right?
• 19:23
  Speaker 4: Yes.
• 19:23
  Speaker 5: So there were three that were associated. There was the
• 19:26
  Speaker 5: spatial ability, inhibitory control, the ability to show self-control, and
• 19:33
  Speaker 5: then impulsiveness. And impulsiveness was a little bit unexpected in
• 19:36
  Speaker 5: terms of the direction of the relationship. So for the spatial,
• 19:40
  Speaker 5: pretty straightforward. Fish that were good at solving the maze
• 19:44
  Speaker 5: gained more offspring. um inhibitory control same thing fish that
• 19:49
  Speaker 5: didn't swim into that barrier all the time and smack
• 19:51
  Speaker 5: their heads into a pointless wall did better but for
• 19:56
  Speaker 5: impulsiveness it turned out the ones that were persistent so
• 19:58
  Speaker 5: remember that was the first time they encountered the transparent
• 20:01
  Speaker 5: barrier the ones that refused to give up and swim
• 20:04
  Speaker 5: around actually had higher paternity So you can sort of
• 20:08
  Speaker 5: think of that as a measure of initial determination before
• 20:12
  Speaker 5: you've had the chance to repeatedly encounter something and learn
• 20:15
  Speaker 5: that maybe it's time to try a different approach. So
• 20:19
  Speaker 5: those three parameters were correlated, related to paternity, how many
• 20:25
  Speaker 5: offspring the fish got.
• 20:28
  Speaker 3: And so part of this, a little part of this
• 20:30
  Speaker 3: might be females somehow being able to assess intelligent males.
• 20:34
  Speaker 3: but a lot of it might be intelligent males being
• 20:37
  Speaker 3: able to outwit less intelligent males.
• 20:40
  Speaker 1: Is that right? I mean, what do you think is
• 20:41
  Speaker 1: going on?
• 20:42
  Speaker 3: How's all this actually corresponding to increased reproductive success in
• 20:48
  Speaker 3: the smarter males?
• 20:50
  Speaker 5: Why don't you have your view and I'll have mine, Ivan?
• 20:52
  Speaker 4: Okay, sure.
• 20:53
  Speaker 1: Excellent.
• 20:55
  Speaker 4: Yeah, there's definitely a couple of different things that could
• 20:57
  Speaker 4: be happening. I think the most likely one is that
• 21:02
  Speaker 4: males that are smarter... First of all, given that our
• 21:07
  Speaker 4: measures of cognition that correlate with paternity are inhibitory control
• 21:12
  Speaker 4: and spatial ability, spatial ability is the ability to solve
• 21:15
  Speaker 4: the maze, right? So the way we provided the mating
• 21:20
  Speaker 4: opportunity to these fish is we put them all in
• 21:23
  Speaker 4: a big pond. And there were some obstacles in there
• 21:25
  Speaker 4: as well, like rocks and some debris and so on.
• 21:28
  Speaker 4: So perhaps that ability to navigate effectively, to remember the
• 21:31
  Speaker 4: environment and quickly make the decision where to go, allowed
• 21:35
  Speaker 4: them to quickly find the female and therefore make more babies.
• 21:40
  Speaker 4: The other one was inhibitory control. So that's potentially ability
• 21:44
  Speaker 4: to control your own impulses. So maybe they knew that
• 21:47
  Speaker 4: they should give up when it was impossible to chase
• 21:49
  Speaker 4: the female down, or maybe they knew that they should
• 21:52
  Speaker 4: persist when there was an opportunity, give them an opportunity
• 21:56
  Speaker 4: to approach the females have more babies. So I think
• 21:59
  Speaker 4: it's all about males' behavior rather than females' choice in
• 22:03
  Speaker 4: that case.
• 22:04
  Speaker 3: But Michael, you're not entirely convinced by the sound of it.
• 22:06
  Speaker 3: You have a different interpretation, do you?
• 22:09
  Speaker 5: I think that's a perfectly reasonable interpretation. I tend to
• 22:11
  Speaker 5: be a cynic and to undermine my own findings. And
• 22:17
  Speaker 5: I think this is an important one to say. I
• 22:20
  Speaker 5: would point out that this is a correlation. I'm classically
• 22:24
  Speaker 5: trained to do experiments and manipulate variables. So with intelligence,
• 22:29
  Speaker 5: we're not really making smart and dumb fish. What we
• 22:32
  Speaker 5: just find is that the fish that we categorize as
• 22:35
  Speaker 5: smart had more babies. So you have to ask yourself
• 22:38
  Speaker 5: what else might differ between a smart and a dumb fish.
• 22:42
  Speaker 5: And one thing I can think of is that perhaps
• 22:45
  Speaker 5: smart fish are in good physical condition, their brains develop nicely,
• 22:49
  Speaker 5: as did the rest of their body. And it is
• 22:51
  Speaker 5: possible that that those other features are actually what's driving
• 22:55
  Speaker 5: their success. They may be just stronger swimmers. They may
• 22:59
  Speaker 5: turn faster. They may dart forward more rapidly. So that's
• 23:02
  Speaker 5: an unexciting result. But I mention it because, as you
• 23:06
  Speaker 5: will know too, many people do selection studies in the wild.
• 23:10
  Speaker 5: And they tend to forget that they haven't shown a
• 23:13
  Speaker 5: causal relationship. They've simply shown a correlation. And you call
• 23:17
  Speaker 5: it a selection gradient, and it sounds fancier than a correlation.
• 23:23
  Speaker 5: that's probably a bit of overly technical, but this applies,
• 23:26
  Speaker 5: you know, for all your listeners, it applies to all
• 23:28
  Speaker 5: these studies where, you know, you give people different, where
• 23:31
  Speaker 5: people are on different diets. You need to distinguish between
• 23:34
  Speaker 5: observational studies versus studies where people are experimentally assigned food
• 23:39
  Speaker 5: or drugs. You can know if it's causal.
• 23:43
  Speaker 3: No, very, very wise words indeed. But so why didn't
• 23:47
  Speaker 3: you measure things like condition or degree of asymmetry or,
• 23:53
  Speaker 3: weight or shininess on these fish?
• 23:55
  Speaker 1: Why did you just focus on the cognitive tests?
• 23:58
  Speaker 4: We did measure a couple of other things. First of all,
• 24:01
  Speaker 4: we just measured general body length of these fish and
• 24:05
  Speaker 4: we found no correlation. So in other words, bigger fish
• 24:08
  Speaker 4: did not have more babies. We also looked at some
• 24:15
  Speaker 4: other behaviors of fish. There's a behavior called boldness. It's
• 24:19
  Speaker 4: a personality trait. Essentially, what it measures is How willing
• 24:24
  Speaker 4: the fish is to enter a novel or unfamiliar environment?
• 24:28
  Speaker 4: How prone is it to danger, to exposing itself to
• 24:33
  Speaker 4: potential predators and so on? We also looked at fish heterozygotity. Essentially,
• 24:38
  Speaker 4: it's just.
• 24:40
  Speaker 1: That's a genetic measure, isn't it?
• 24:41
  Speaker 4: Yeah, genetic measure, exactly. So we didn't find any correlations
• 24:45
  Speaker 4: between these measures with paternity. That being said, it's still
• 24:51
  Speaker 4: a very limited subset of variables that you can assess.
• 24:55
  Speaker 4: And I expect if we were to continue looking, as
• 24:58
  Speaker 4: Michael said, I expect that it's very likely that the
• 25:05
  Speaker 4: general body conditions of this fish would allow them to
• 25:09
  Speaker 4: have better cognition and therefore also better fraternity.
• 25:14
  Speaker 3: So I guess a couple more questions to finish off.
• 25:17
  Speaker 3: Do we know, do you know whether any of these
• 25:20
  Speaker 3: cognitive tests that you've measured are heritable? So in other words,
• 25:25
  Speaker 3: do the sons of spatially well-performing males, are they good
• 25:32
  Speaker 3: at spatial performance as well?
• 25:34
  Speaker 1: I didn't say that very well, but you know what
• 25:36
  Speaker 1: I mean.
• 25:36
  Speaker 5: Yeah, it's an excellent question, Tim, because obviously if a
• 25:40
  Speaker 5: trait's going to evolve, it needs to be heritable. So
• 25:43
  Speaker 5: if you're going to explain the evolution of greater intelligence,
• 25:46
  Speaker 5: there must be genes for intelligence. At least in the past,
• 25:49
  Speaker 5: there must have been genetic variation. So the short answer
• 25:52
  Speaker 5: is we don't know for these mosquito fish. But people
• 25:55
  Speaker 5: have done studies in other animals showing heritability of the, well,
• 26:01
  Speaker 5: let's say heritability of performance at these kind of intelligence
• 26:05
  Speaker 5: tests that we've applied. And obviously, as you know, in humans,
• 26:08
  Speaker 5: there's a controversial but very large literature on the heritability
• 26:12
  Speaker 5: of intelligence and there does seem to be some evidence
• 26:16
  Speaker 5: for heritability of intelligence. That would be my assessment of
• 26:20
  Speaker 5: the literature, as much as sometimes it is controversial. And
• 26:24
  Speaker 5: there are, for example, I think in some birds, there
• 26:28
  Speaker 5: have been some recent studies reporting heritability of the ability
• 26:31
  Speaker 5: to perform the very kinds of assays, the tests that
• 26:35
  Speaker 5: we've conducted by a group in Western Australia.
• 26:39
  Speaker 3: So it's too early to say that we're going to
• 26:41
  Speaker 3: end up with Einstein mosquito fish solving equations in relativity.
• 26:47
  Speaker 5: That would be terrifying given their pest-like nature. They're bad
• 26:51
  Speaker 5: enough as it is.
• 26:53
  Speaker 1: And so what next?
• 26:55
  Speaker 3: This is a lovely piece of work, so congratulations once again.
• 27:00
  Speaker 3: It's obviously generated some other questions that you're interested in doing,
• 27:03
  Speaker 3: but what are your next... What are the next things
• 27:05
  Speaker 3: that you're interested, I guess, not just in mosquito fish,
• 27:08
  Speaker 3: but elsewhere in the lab? I mean, there are so
• 27:10
  Speaker 3: many exciting questions around behavioural ecology and cognition. So, yeah,
• 27:15
  Speaker 3: what next?
• 27:17
  Speaker 1: Sure.
• 27:17
  Speaker 4: Well, you're right that there's definitely a lot of interesting
• 27:20
  Speaker 4: ideas that could be stemming from this project. First of all,
• 27:24
  Speaker 4: I think it would be interesting indeed to look more
• 27:26
  Speaker 4: closely at what particular behaviours drive better reproduction and therefore
• 27:32
  Speaker 4: better paternity. So perhaps we could link cognition with a
• 27:35
  Speaker 4: more specific behavioral trait. In addition, we have a few
• 27:39
  Speaker 4: people in the lab right now investigating what are sort
• 27:42
  Speaker 4: of environmental or biological factors that could impact cognition. Because
• 27:47
  Speaker 4: if cognition is indeed a trait that's being selected, whether
• 27:50
  Speaker 4: by natural selection or sexual selection, it's important for survival
• 27:54
  Speaker 4: and reproduction of these animals. And therefore, it's also important
• 27:57
  Speaker 4: for conservation. One of the other studies, for example, that
• 28:01
  Speaker 4: I did, in the lab with some colleagues, was looking
• 28:04
  Speaker 4: at the effect of increased temperature on cognition. And we
• 28:08
  Speaker 4: also found some results that suggest that these fish that
• 28:14
  Speaker 4: develop in elevated temperature and higher temperature tend to have
• 28:17
  Speaker 4: worse cognitive abilities. And therefore, you can make a connection
• 28:22
  Speaker 4: that decreased cognitive abilities, impaired cognitive abilities, would therefore reduce
• 28:30
  Speaker 4: reproductive or surviving potential of these animals. Therefore, it might
• 28:33
  Speaker 4: be important for conservation purposes. Not for these particular fish
• 28:36
  Speaker 4: because they're invasive, but you could potentially generalize those findings.
• 28:40
  Speaker 4: If this exists even in these tiny fish with tiny brains,
• 28:43
  Speaker 4: if cognition is important for them, then chances are it's
• 28:47
  Speaker 4: important for many, many other animals and fish.
• 28:50
  Speaker 3: And do you agree with that, Michael, or is this
• 28:52
  Speaker 3: conservation hook just the thing that we all do these
• 28:56
  Speaker 3: days when we work on biology?
• 28:58
  Speaker 4: How dare you, Tim.
• 29:01
  Speaker 5: Well, I was going to make a joke and say
• 29:04
  Speaker 5: I'm not sure what we're doing next because we currently
• 29:06
  Speaker 5: have no funding. So if there's any benefactor out there
• 29:10
  Speaker 5: who likes the idea of supporting this work, feel free
• 29:13
  Speaker 5: to get in touch. But more seriously... I think what
• 29:18
  Speaker 5: I would like to do is try and actually manipulate intelligence,
• 29:21
  Speaker 5: which is along the lines of what Ivan suggested. If
• 29:23
  Speaker 5: we know that something such as temperature or the amount
• 29:29
  Speaker 5: of sleep the fish get, how long the day versus
• 29:32
  Speaker 5: night is, if we could manipulate that to create smarter
• 29:35
  Speaker 5: and dumber fish and then look at their reproductive success,
• 29:39
  Speaker 5: I think that would be getting us closer to knowing
• 29:41
  Speaker 5: whether it's causal or not. So that could be an
• 29:44
  Speaker 5: interesting future challenge.
• 29:45
  Speaker 1: No, well, good luck and good luck in securing some
• 29:48
  Speaker 1: more funding.
• 29:48
  Speaker 3: I think we all know how challenging it is to
• 29:51
  Speaker 3: write grants and raise funds and find philanthropists and what
• 29:54
  Speaker 3: have you, but good luck. So congratulations once again on
• 29:58
  Speaker 3: a really Fantastic paper. I really enjoyed reading it and
• 30:01
  Speaker 3: I'm sure it will be well cited and well picked up.
• 30:04
  Speaker 3: We'll put a link below to the paper so that
• 30:09
  Speaker 3: people can go and find it if they're interested. But
• 30:13
  Speaker 3: thanks for taking the time. I know it's getting a
• 30:15
  Speaker 3: bit late in Australia, so I really appreciate it. Thank you.
• 30:19
  Speaker 5: Thank you very much, Tim.
• 30:20
  Speaker 4: Thanks very much.