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How did the diversity of life come about · Luke's English Podcast

• 0:00
  Speaker 1: Well, Simon, this is exciting. We've got a new sponsor.
• 0:02
  Speaker 2: Yeah, absolutely.
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  Speaker 3: So we're being sponsored by Pingooey Bags International, who are
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  Speaker 3: based in Oxford's world famous covered market.
• 0:10
  Speaker 1: They also have a website, don't they, where you can
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  Speaker 1: buy things. But you've got one of their products in
• 0:14
  Speaker 1: front of you. What's that?
• 0:15
  Speaker 4: I do.
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  Speaker 3: It's absolutely beautiful, actually. It's a smaller bag. It's called
• 0:19
  Speaker 3: La Petite Creperie Mini Grace. And it's from their latest,
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  Speaker 3: their spring summer range. And it's a vegan leather limited
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  Speaker 2: And I have to say, it's Beautiful.
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  Speaker 3: So it actually literally looks like a little shop front
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  Speaker 3: and it's beautifully made.
• 0:33
  Speaker 2: So you have one too, Tim?
• 0:35
  Speaker 1: I do. So this is called the London 234 Crossbody
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  Speaker 1: Go Anywhere Bag. It's made from canvas by Troop London,
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  Speaker 1: a British company. It's made from eco-friendly materials and it's
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  Speaker 1: beautifully handcrafted. It's got lots of pockets and it really
• 0:53
  Speaker 1: is fantastic. So I'm certainly going to be using this today.
• 0:58
  Speaker 1: Come down to the podcast with all my bits and
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  Speaker 1: bobs in it.
• 1:00
  Speaker 2: It does suit you, actually.
• 1:02
  Speaker 1: No, it does.
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  Speaker 4: It's great.
• 1:03
  Speaker 3: And so Pinguy refreshed their range twice yearly. So if
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  Speaker 3: you want to know more, it's really best to head
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  Speaker 3: over to their website to have a look. And we'll
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  Speaker 3: provide a link at the bottom of this video.
• 1:14
  Speaker 1: And thank you very much, Pinguy, for sponsoring us. I
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  Speaker 1: hope we sold some bags for you.
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  Speaker 3: And while you're there taking a look at their website,
• 1:21
  Speaker 3: please also hit like and subscribe to Science of the Times.
• 1:37
  Speaker 2: Hi everyone, I'm Simon Callett.
• 1:40
  Speaker 1: And I'm Tim Colson, and welcome to another episode of
• 1:42
  Speaker 1: Science of the Times.
• 1:44
  Speaker 2: So, Tim, what have you been up to this week?
• 1:47
  Speaker 1: It's kind of been a fairly typical week. Yeah, I
• 1:54
  Speaker 1: don't really know, to be honest. I did some gardening
• 1:56
  Speaker 1: at the weekend. Oh, I was on, maybe that was
• 2:00
  Speaker 1: two weeks ago, I was on The Life Scientific. I
• 2:03
  Speaker 1: don't know if we talked about that, maybe not. Anyway,
• 2:05
  Speaker 1: if we didn't, another plug.
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  Speaker 3: Well, I listened to it and it was fantastic.
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  Speaker 2: Really, really cool. So well worth a listen, folks.
• 2:13
  Speaker 3: Listen to Jim Al-Khalili questioning Tim on Life Scientific.
• 2:18
  Speaker 1: Very fantastic. And actually, you have been up in Bradford.
• 2:20
  Speaker 1: You were doing a really big talk, weren't you, to
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  Speaker 1: the British?
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  Speaker 3: It was a Muslim institute inviting me to give the
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  Speaker 3: second Ibn-i-Sinna lecture. And it was, yeah, it was really nice.
• 2:34
  Speaker 3: It was in the City Hall in Bradford. hosted by
• 2:37
  Speaker 3: the Lord Mayor. So it took my parents over and
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  Speaker 3: they had a great time.
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  Speaker 2: So it was fun.
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  Speaker 1: And it went well, I assume.
• 2:44
  Speaker 2: I think so. Yeah, lots of questions.
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  Speaker 3: Lots of interesting questions about not just science and medicine,
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  Speaker 3: but AI actually. Sort of, you know, these topics that
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  Speaker 3: we've covered in the podcast and come up again and again.
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  Speaker 3: People sort of concerned, I think, about what the future
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  Speaker 3: has in store.
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  Speaker 2: When it comes to AI.
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  Speaker 1: No, well, congratulations on being asked to do that. That's
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  Speaker 1: a real honour. And I bet you were a bit nervous.
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  Speaker 1: I would have been.
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  Speaker 3: I was very nervous, especially when the mayor walked in in.
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  Speaker 2: All his gold.
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  Speaker 1: Oh, wow.
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  Speaker 2: You know, sat there thinking, oh, better do a good
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  Speaker 2: job here.
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  Speaker 1: He was all blinged up, was he?
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  Speaker 2: That's right.
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  Speaker 4: Cool.
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  Speaker 1: Well, today we've got a chap called Max Telford on.
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  Speaker 1: And so he's... He's a bit like me. He's a zoologist,
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  Speaker 1: but he's actually interested in the tree of life.
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  Speaker 4: Cool.
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  Speaker 3: And he's just written a book sort of going through
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  Speaker 3: the journey and trying to solve the big question. So
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  Speaker 3: where do we all come from and how are we
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  Speaker 3: all related?
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  Speaker 1: No, that's right. And he really focuses in particular on
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  Speaker 1: the animal tree of life. But he does go right
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  Speaker 1: the way back to life's beginning. So it's a good read. Well,
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  Speaker 1: should we get him on?
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  Speaker 2: Yeah, let's go for it.
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  Speaker 1: Fantastic. So Max has now joined us on the line. Max,
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  Speaker 1: would you like to introduce yourself and say a little
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  Speaker 1: bit about who you are and where you are?
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  Speaker 4: So I'm Max Telford. I'm a zoologist at University College London.
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  Speaker 4: I've been interested for 35 years, perhaps a little bit more,
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  Speaker 4: in the animal tree of life. So I'm a zoologist
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  Speaker 4: rather than just a general biologist. And I've been working
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  Speaker 4: on some of the thornier problems of how big animal
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  Speaker 4: groups fit together and how they're related to each other.
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  Speaker 1: And all the best people are zoologists. So congratulations on your, um,
• 4:38
  Speaker 1: new book that just came out last month. I really
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  Speaker 1: enjoyed reading it. Um, it's called, um, the tree of
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  Speaker 1: life solving sciences, greatest puzzle. Uh, and that's, um, that's
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  Speaker 1: published by John Murray. So, um, we'll put a link
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  Speaker 1: below for our, our readers, our listeners, so they can, um,
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  Speaker 1: they can go and read it. And I thoroughly recommend
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  Speaker 1: it's worth reading. I know you've had a look at
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  Speaker 1: it as well, haven't you?
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  Speaker 2: Yeah, absolutely. It was absolutely fascinating.
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  Speaker 3: And I think for me, not only did I find
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  Speaker 3: the book fascinating, but I was also found it fascinating,
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  Speaker 3: your fascination, you know, with the tree of life and
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  Speaker 3: trying to sort of get to the bottom of this, you.
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  Speaker 2: Know, billion year, you know, journey really.
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  Speaker 3: And sort of, I'm interested in what sort of, Before
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  Speaker 3: we get into the book and what it's about, what
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  Speaker 3: that motivation is and where it comes from.
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  Speaker 4: Yeah, it's funny. I've been thinking about this. I became
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  Speaker 4: a zoologist because I loved animals and I was interested
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  Speaker 4: in natural history as a teenager. I think the two
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  Speaker 4: big influences that got me going were, first, Jacques Cousteau.
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  Speaker 4: I really wanted to be a marine biologist. And aged 18,
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  Speaker 4: I went and trained to become a scuba diver and
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  Speaker 4: then realized I got incredibly seasick. So that was kind
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  Speaker 4: of ruled that one out. And the other big influence
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  Speaker 4: was David Attenborough's Life on Earth series, which both the series,
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  Speaker 4: which is obviously beautiful, beautifully made, you know, incredible natural
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  Speaker 4: history videos, but also the book, which I, you know,
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  Speaker 4: I read multiple times as a teenager. So I absolutely
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  Speaker 4: loved it. zoology. But I think the other thing about
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  Speaker 4: Life on Earth is that it's, in a sense, it's
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  Speaker 4: a phylogenetic book. It takes a trip up the tree
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  Speaker 4: of life, starting at the origin of life, four billion
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  Speaker 4: years ago, and moving up sort of gradually heading towards humans.
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  Speaker 4: And I sort of take, you know, rather cheekily, or
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  Speaker 4: perhaps obviously, take a similar path towards the end of
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  Speaker 4: my book, when I try and take a sort of
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  Speaker 4: broader view of what the tree of life actually looks like,
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  Speaker 4: but with a focus on ending up at humans.
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  Speaker 1: And so have you always enjoyed classifying things? Because as
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  Speaker 1: you talk about in the book, you know, there are
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  Speaker 1: various branches to the tree of life. So I imagine
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  Speaker 1: you as a kid, for example, with all of your
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  Speaker 1: books in like perfect alphabetical order or pots of fossils
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  Speaker 1: or something.
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  Speaker 4: I'm not like that. I wasn't like that as a teenager, actually.
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  Speaker 4: I was sort of more going and digging out things
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  Speaker 4: out of cattle troughs and raising up mosquito larvae and
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  Speaker 4: stick insects and things. So I wasn't one of these
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  Speaker 4: undergraduates who already knew, you know, every species of butterfly
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  Speaker 4: and et cetera. I remember there was one guy... when
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  Speaker 4: I was an undergraduate who discovered a new species of
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  Speaker 4: woodlouse in the college garden where his university college. I
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  Speaker 4: wasn't like that. But I guess I'm more interested in
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  Speaker 4: the big picture. I'm classifying. I've done some classifying. I've
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  Speaker 4: named a couple of branches of the tree of life.
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  Speaker 4: I guess my interest, I mean, I do have a
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  Speaker 4: slightly geeky interest in more knowing the shape of it
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  Speaker 4: and what that all means sort of gets tacked on later.
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  Speaker 4: So I think that's a slightly geeky bit to me,
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  Speaker 4: that I'm very interested in the mechanics of how we
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  Speaker 4: discover the truth, what the shape of the tree of
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  Speaker 4: life is. But really the point of the tree of
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  Speaker 4: life is not just to classify, it's to travel back
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  Speaker 4: in time and to know what happened in evolution.
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  Speaker 3: So, Max, if we just take a step back for
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  Speaker 3: those of our listeners who perhaps are a little bit
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  Speaker 3: unfamiliar with what the Tree of Life actually means, can
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  Speaker 3: you just explain what you mean when you say the
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  Speaker 3: Tree of Life and what it's trying, you know, what
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  Speaker 3: it does?
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  Speaker 4: Well, you could sort of think of it from the
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  Speaker 4: top down or from the bottom up. And from the
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  Speaker 4: top down, it's like looking at everything around us today.
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  Speaker 4: You can see the trees in my garden. It's London,
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  Speaker 4: so there's loads of wildlife. There's foxes, there's parakeets. So
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  Speaker 4: how all of those many different species of life, from
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  Speaker 4: humans to plants to bacteria to fungi, how they're all related.
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  Speaker 4: What's the family tree that unites all of those? Going
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  Speaker 4: back in time, where did they meet in the past?
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  Speaker 4: When did they have a common ancestor? But it might
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  Speaker 4: be easier to think of it from the bottom up.
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  Speaker 4: Think of the very first species of life on Earth.
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  Speaker 4: It's a species that certainly existed. We call it Luca,
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  Speaker 4: the last universal common ancestor. And you can think of
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  Speaker 4: that sprouting up like a tree. And at some point,
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  Speaker 4: that single species dividing into two, and that's going to
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  Speaker 4: form eventually two huge branches that still survive today. And
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  Speaker 4: those branches will go on to split and to split
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  Speaker 4: and to split to make more and more species. And
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  Speaker 4: as those species go up, they evolve, they change, they
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  Speaker 4: evolve new characters, they become plants or mammals or animals, mammals, whatever.
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  Speaker 4: And that is... It is that tree-like process of branching
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  Speaker 4: and moving through time and evolving and becoming different that
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  Speaker 4: has produced what we can see outside my window here,
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  Speaker 4: which is the huge diversity of life.
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  Speaker 1: That branching started a long time ago, right? Life is old.
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  Speaker 1: It's been around for a while.
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  Speaker 4: Life is, as far as we can tell, about 4
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  Speaker 4: billion years old. We've got fossils from about 3.5 billion
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  Speaker 4: years old. But rocks, 4 billion-year-old rocks are... very very
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  Speaker 4: rare if not you know non-existent so there are well
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  Speaker 4: sorry they are they do exist but they don't have
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  Speaker 4: fossils in them but there are signatures of life so
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  Speaker 4: molecules that is produced by life and not by geological
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  Speaker 4: processes that we can discover in rocks that are four
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  Speaker 4: billion years old which is basically as old as as
• 10:26
  Speaker 4: old as we're able to discover on on the planet.
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  Speaker 1: And the last universal common ancestor was a bit later
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  Speaker 1: than that is that right so life existed before Luca,
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  Speaker 1: but we don't know what that life looked like.
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  Speaker 4: So I think probably Luca existed about 4 billion years ago,
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  Speaker 4: but there was a period before Luca, which is effectively...
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  Speaker 4: So we can reconstruct what Luca looked like by following
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  Speaker 4: the tree down to that very, very earliest branching point.
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  Speaker 4: And if we look at those two branches coming out
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  Speaker 4: of Luca, there are the branch which is the bacteria,
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  Speaker 4: and there's another branch which is bacteria-like things called archaea,
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  Speaker 4: If we compare what their descendants, the things that are
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  Speaker 4: alive today, have in common, by logic, those things in
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  Speaker 4: common in those very ancient branches must have come from
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  Speaker 4: their common ancestor, which we can extrapolate back to. Essentially,
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  Speaker 4: we can go right back in time to Luca because
• 11:23
  Speaker 4: we can extrapolate back from their modern descendants. But before Luca,
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  Speaker 4: there's no other branches coming off it. There were other branches.
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  Speaker 4: There were presumably several species, many species, around at the
• 11:35
  Speaker 4: same time as Luca, but they've all gone extinct and
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  Speaker 4: Luca is the only one that's actually given rise to
• 11:39
  Speaker 4: anything that's still alive today.
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  Speaker 3: So when you mean they've gone extinct, we mean that
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  Speaker 3: nothing came forth from them afterwards, right? It was like
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  Speaker 3: the end of the line, is that right?
• 11:51
  Speaker 4: Well, they might as well have gone on, you know,
• 11:53
  Speaker 4: after the existence of Luca, but at some point they
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  Speaker 4: went extinct. So we've got no trace of them today
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  Speaker 4: and no way of tracing back down their branch today.
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  Speaker 4: to get to a place on the tree that is lower,
• 12:04
  Speaker 4: is further back in time than Luca.
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  Speaker 1: But your real interest is in animals, isn't it? And then,
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  Speaker 1: so the first animals... Genetics tells us, what, about 800
• 12:17
  Speaker 1: million years ago, the first fossils.
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  Speaker 4: There's a big argument about this.
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  Speaker 1: I know. So.
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  Speaker 4: Essentially, we can't find the first animal fossils. We're very
• 12:32
  Speaker 4: unlikely to find the very first one of a branch.
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  Speaker 4: We'll find them eventually. Fossils are quite rare, especially nearly
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  Speaker 4: a billion years old. But we can sort of estimate
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  Speaker 4: when they're likely to have existed by comparing how different
• 12:48
  Speaker 4: things are today and knowing how quickly differences build up
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  Speaker 4: in our genes. So if two things are 10% different
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  Speaker 4: and you know 1% things become different at 1% per
• 13:01
  Speaker 4: million years then 10% different means they're 10 million years separated.
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  Speaker 4: So we can sort of estimate when the first animals
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  Speaker 4: existed And this is where it gets tricky. And I'm
• 13:11
  Speaker 4: not a great expert on this. I'm basically a sceptic
• 13:14
  Speaker 4: about molecular clocks. OK.
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  Speaker 1: So the molecular clock is that 10% thing you were
• 13:19
  Speaker 1: just talking about?
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  Speaker 4: Exactly. So the molecular clock lets us use the difference,
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  Speaker 4: especially in the genes, between two existing creatures, two species,
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  Speaker 4: and to use that difference to estimate how distantly related
• 13:33
  Speaker 4: they are, effectively. And using the molecular clock, people come
• 13:37
  Speaker 4: up with estimates of the animals probably about 600 million
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  Speaker 4: years old. So that's for the bilaterians, actually. So that's
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  Speaker 4: a major group of animals. But the first fossils are 100,
• 13:49
  Speaker 4: 120 million years younger than that. So there's this huge
• 13:53
  Speaker 4: gap in the fossil record between where the molecular clocks
• 13:57
  Speaker 4: tell us that the animals first appeared and when we
• 14:00
  Speaker 4: actually first see the first one.
• 14:01
  Speaker 1: It's a big....
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  Speaker 4: Source of argument. There was a meeting in Canada last
• 14:06
  Speaker 4: week where everyone thought about it.
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  Speaker 2: And what makes you such a skeptic? Just because there
• 14:13
  Speaker 2: are no fossils?
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  Speaker 4: Because I have watched the gap between the molecular clock
• 14:24
  Speaker 4: estimates of when animals first appeared and the fossil estimates,
• 14:28
  Speaker 4: which haven't changed, get smaller and smaller and smaller and
• 14:32
  Speaker 4: smaller over the last 20 years. So the first molecular
• 14:36
  Speaker 4: clock estimates for the first appearance of animals was 1.2
• 14:40
  Speaker 4: billion years ago. And now it's about 600 million years. Essentially,
• 14:45
  Speaker 4: the clocks, as they get better, are converging on what
• 14:50
  Speaker 4: we can see in the fossil record, essentially.
• 14:52
  Speaker 1: But we also don't know what those first animals would
• 14:54
  Speaker 1: have looked like, do we? I mean, they're presumably very,
• 14:57
  Speaker 1: not much more than a sort of a mouth and
• 14:59
  Speaker 1: a gut, you know, surrounded by cells, presumably. But we
• 15:03
  Speaker 1: don't really know what they would have looked like. So
• 15:05
  Speaker 1: that must make, they're probably small. So that's going to
• 15:07
  Speaker 1: make it hard to find as well.
• 15:09
  Speaker 4: Well, we've got, so what I guess what, so just
• 15:12
  Speaker 4: like Luca, so there will be animals before the first
• 15:16
  Speaker 4: of the animals that gave rise to all the animals
• 15:19
  Speaker 4: alive today. So they were animal-like things and at some
• 15:22
  Speaker 4: point we've got what we call the crown group of
• 15:25
  Speaker 4: animals and so that is the last common ancestor of
• 15:29
  Speaker 4: all the most recent common ancestor of all the animals
• 15:33
  Speaker 4: that are alive today. So that's the ancestor of humans
• 15:36
  Speaker 4: and jellyfish and sponges. So a sponge is a very
• 15:40
  Speaker 4: very simple animal and so we can We can certainly
• 15:43
  Speaker 4: look at all the descendants of that very first animal.
• 15:47
  Speaker 4: We call it the ur-metazoan, the ur-animal. And we look
• 15:51
  Speaker 4: at the descendants and we can see what's in common
• 15:53
  Speaker 4: between them. And most obviously, they're all large. They've got
• 15:57
  Speaker 4: lots and lots of cells. And there are other large things.
• 16:01
  Speaker 4: Plants are large and fungi are large. But this is
• 16:04
  Speaker 4: something that lived in the bottom of the sea. If
• 16:07
  Speaker 4: we find something at 1,000 metres depth, it wasn't a
• 16:10
  Speaker 4: plant because there's no light there. So we do find
• 16:13
  Speaker 4: fossils about 570, 600 million years ago that are large,
• 16:20
  Speaker 4: obviously have lots of cells. And we know from the paleontology,
• 16:25
  Speaker 4: I'm not a paleontologist, so I'm guessing a little bit
• 16:29
  Speaker 4: or I'm exaggerating my knowledge a little bit. But we
• 16:32
  Speaker 4: know that they weren't plants because they were living in
• 16:35
  Speaker 4: deep water, etc., So we've got some things that clearly
• 16:39
  Speaker 4: were animals because of where they lived and how big
• 16:42
  Speaker 4: they are. And it's trying to fit those in with
• 16:47
  Speaker 4: the animals we know today and trying to see whether
• 16:49
  Speaker 4: they're similar or whether they're a unique group that's sort
• 16:52
  Speaker 4: of gone extinct and left nothing alive today.
• 16:57
  Speaker 3: And so when those fossils are analysed, is that a
• 17:02
  Speaker 3: genetic analysis.
• 17:03
  Speaker 2: Of the fossils?
• 17:05
  Speaker 4: No, there's no DNA. The oldest DNA is a couple
• 17:09
  Speaker 4: of million years old. And we're talking 600 million years old.
• 17:13
  Speaker 4: So there's no DNA at all. All you've got is
• 17:17
  Speaker 4: the impression of the animal's body or the species' body
• 17:23
  Speaker 4: left in the rock. So it's the shape. And sometimes
• 17:26
  Speaker 4: you can... I really shouldn't go too deeply into this.
• 17:28
  Speaker 4: I'm not a paleontologist. But sometimes... different structures, like your
• 17:34
  Speaker 4: nerve cord, or our nerve cord, a vertebrate's nerve cord,
• 17:39
  Speaker 4: a jellyfish doesn't have a nerve cord, but if you've
• 17:41
  Speaker 4: got a nerve cord, there's a lot of phosphorus in that,
• 17:45
  Speaker 4: for whatever reason, and that fossilises differently. So sometimes you
• 17:49
  Speaker 4: can see that this structure, this long, thin structure, was
• 17:54
  Speaker 4: probably a nerve cord rather than any other bit of
• 17:57
  Speaker 4: the body. I'm definitely, definitely straying off my expertise here.
• 18:03
  Speaker 4: Probably saying the wrong elements, et cetera, et cetera, but
• 18:05
  Speaker 4: the point is made.
• 18:07
  Speaker 1: Let's bring it back to something that you have spent
• 18:11
  Speaker 1: a lot of time studying. Bilaterians, it's a word you
• 18:16
  Speaker 1: met before, and it basically means that anything that's like
• 18:19
  Speaker 1: a tube-like animal with a mouth and a... Well, actually,
• 18:23
  Speaker 1: I think there's some bilaterians that only have one.
• 18:27
  Speaker 1: Entrance, but I tend to think of bilaterians as worm-like animals.
• 18:31
  Speaker 1: And I think worms are one of your, you know,
• 18:33
  Speaker 1: you write a lot about worms and bilaterians, but tell
• 18:36
  Speaker 1: us about when the bilaterians arose and what they are
• 18:38
  Speaker 1: and how we kind of, how they've become so incredibly common.
• 18:43
  Speaker 4: Yeah, so bilaterians, we can see that the bilaterian body
• 18:48
  Speaker 4: plan was very successful because nearly all animals are bilaterian.
• 18:52
  Speaker 4: So a bilaterian is simply something like me that's got
• 18:56
  Speaker 4: a A head at one end and a tail at
• 18:58
  Speaker 4: the other. A dorsal, like your back, which is different
• 19:03
  Speaker 4: from your belly.
• 19:03
  Speaker 1: I haven't got a tail.
• 19:06
  Speaker 4: You have. A front end and a back end. A
• 19:11
  Speaker 4: head end and a not head end. A back and
• 19:14
  Speaker 4: a belly, which are different from each other.
• 19:17
  Speaker 1: They're not symmetrical.
• 19:19
  Speaker 4: And that leaves you with the left and right, which
• 19:20
  Speaker 4: are mirror images of each other. So that's where the
• 19:22
  Speaker 4: name comes from. They're bilaterally symmetrical. They've essentially got a
• 19:25
  Speaker 4: left side which is a mirror image of their right side.
• 19:29
  Speaker 4: And this body planning is probably nothing to do with
• 19:31
  Speaker 4: the symmetry. It's probably to do with having a head
• 19:33
  Speaker 4: at one end, a gut with a mouth at one
• 19:36
  Speaker 4: end and an anus at the other, food going through
• 19:40
  Speaker 4: and various elaborations of that body, which is sort of
• 19:44
  Speaker 4: kind of more purposeful than a jellyfish. It's got a
• 19:47
  Speaker 4: direction of travel, which is forward and you end up
• 19:51
  Speaker 4: with a brain at one end and various sensory organs
• 19:56
  Speaker 4: at one end, your eyes and, you know, taste, etc.
• 20:01
  Speaker 4: And they're much more, you know, they've become very successful.
• 20:04
  Speaker 4: It was obviously a very good idea, a very good,
• 20:07
  Speaker 4: very successful body plan. So almost all animals are, almost
• 20:10
  Speaker 4: all major kinds of animals are bilaterians. And indeed, almost
• 20:14
  Speaker 4: all animals are bilaterians because most animals are insects.
• 20:18
  Speaker 1: And when did they arise, the bilaterians? They're, I think,
• 20:23
  Speaker 1: late Ediacaran, early Cambrian. But they were popular. They were
• 20:27
  Speaker 1: doing well by the early Cambrian, weren't they?
• 20:29
  Speaker 4: Well, so the Cambrianist, you know, the change between the
• 20:33
  Speaker 4: Ediacaran and the Cambrian... is defined by the first appearance
• 20:38
  Speaker 4: of bilaterian fossils. And actually, these fossils are not fossils
• 20:42
  Speaker 4: of bodies, but they're trace fossils, something called treptichnus. So
• 20:47
  Speaker 4: these are essentially a bilaterian animal scrabbling around on the bottom,
• 20:51
  Speaker 4: leaving a mark in the sediment. And that mark, essentially
• 20:55
  Speaker 4: that trackway, becoming fossilised.
• 20:57
  Speaker 1: And it looked like a worm, did it?
• 21:01
  Speaker 4: That... that looked like probably something like a priapolid or
• 21:05
  Speaker 4: a penis worm, which is something alive today. And so
• 21:08
  Speaker 4: essentially what it is is you've got this worm-like thing
• 21:11
  Speaker 4: and you can see from the marks that it's made
• 21:13
  Speaker 4: that it sort of had a head end that was
• 21:15
  Speaker 4: searching around looking for food. And that's kind of telling
• 21:18
  Speaker 4: us it's probably a little cleverer than a jellyfish, which
• 21:22
  Speaker 4: is sort of, you know, rather aimless, wandering around the sea,
• 21:26
  Speaker 4: you know, pulsing its umbrella. So this is something crawling
• 21:30
  Speaker 4: around looking for food. with a front end and a
• 21:32
  Speaker 4: back end, which are different from each other.
• 21:34
  Speaker 1: And if our listeners very carefully type penis worm into Google,
• 21:39
  Speaker 1: they will understand why it's been named along those lines.
• 21:43
  Speaker 4: Well, the scientific name is Priapulus, which was given to
• 21:47
  Speaker 4: it by Linnaeus. And yes, it has the same meaning.
• 21:52
  Speaker 1: It's appropriate. We should probably think about having a quick
• 21:57
  Speaker 1: break and going to our sponsors. So we'll be back
• 22:01
  Speaker 1: in a couple of minutes when we will continue and
• 22:05
  Speaker 1: we'll sort of move up towards the modern day, I suspect.
• 22:09
  Speaker 4: Hi, Tim.
• 22:10
  Speaker 3: You're looking particularly snazzy today.
• 22:12
  Speaker 2: What are you wearing?
• 22:13
  Speaker 1: I'm wearing a piece from a company called Grace and Garbo.
• 22:17
  Speaker 1: And actually, you know a little bit more about them
• 22:19
  Speaker 1: than I do, to be honest.
• 22:20
  Speaker 2: Yeah, you're right, I do.
• 22:21
  Speaker 1: You're the fashion queen.
• 22:24
  Speaker 2: I'm also wearing a piece from Grayson Garbo.
• 22:26
  Speaker 3: So this is a delightful knitwear outfit set.
• 22:30
  Speaker 2: Up in Birmingham.
• 22:31
  Speaker 3: What they do is they source knitwear, quality knitwear from
• 22:35
  Speaker 3: all around the world. It's vintage, one-off pieces, many of
• 22:39
  Speaker 3: which they then hand embellish, like the one you're wearing
• 22:42
  Speaker 3: today with its beautiful purple flowers. And so they're big
• 22:45
  Speaker 3: on sustainability and You know, nothing goes to waste. Everything
• 22:49
  Speaker 3: is sort of recycled and reused. And if you want
• 22:52
  Speaker 3: to know more about them, then have a look at
• 22:54
  Speaker 3: the link beneath this episode.
• 22:57
  Speaker 1: And thank you very much to them for supporting our podcast.
• 23:00
  Speaker 1: I hope their sales soar.
• 23:03
  Speaker 3: Thanks a lot, Grace and Garvo.
• 23:05
  Speaker 1: Well, welcome back and welcome again to our guest, Max Telford,
• 23:11
  Speaker 1: who's recently published The Tree of Life, Solving Science's Greatest Puzzle,
• 23:15
  Speaker 1: published by John Murray. And we're sort of we're in
• 23:18
  Speaker 1: the Cambrian and the Cambrian explosion is something that had
• 23:23
  Speaker 1: even been discovered when I was at school. But it
• 23:26
  Speaker 1: was an important time for animals, wasn't it, Max?
• 23:29
  Speaker 4: I think even Darwin knew about it. Darwin thought of
• 23:32
  Speaker 4: this as one of his abominable mysteries. He was a
• 23:34
  Speaker 4: few years ahead of me. So why this sudden appearance of...
• 23:42
  Speaker 4: So the conundrum is that out of nowhere, you don't
• 23:46
  Speaker 4: get just a bilaterian, an animal with a left and
• 23:50
  Speaker 4: a right. You get all sorts of different ones. So
• 23:52
  Speaker 4: you get arthropods and penis worms and primitive fish-like things
• 23:58
  Speaker 4: and primitive mollusk-like things. And I could probably go on
• 24:01
  Speaker 4: a few more. So these appear as if from nowhere,
• 24:05
  Speaker 4: but we know they're all related and we know that they...
• 24:09
  Speaker 4: must have had some time to become different from each other.
• 24:13
  Speaker 4: You can't become as different as an arthropod is from
• 24:17
  Speaker 4: an earthworm instantaneously. So some time must have passed before
• 24:24
  Speaker 4: their common ancestor existed, between the point at which their
• 24:29
  Speaker 4: common ancestor existed and at which they appear in the
• 24:33
  Speaker 4: fossil record. So I sort of hinted at this before,
• 24:37
  Speaker 4: that this.
• 24:39
  Speaker 4: Estimate of when they first appeared is older than their
• 24:42
  Speaker 4: first actual appearance in the fossil record. And so there's
• 24:45
  Speaker 4: this conundrum that people are still arguing about.
• 24:50
  Speaker 3: So Max, geographically, these appearances, are they all over the
• 24:54
  Speaker 3: world when they start appearing or are they sort of
• 24:57
  Speaker 3: discrete localisations?
• 24:58
  Speaker 4: They're all over the world, but I think that the thing,
• 25:02
  Speaker 4: and they're sort of spread out in time. So the
• 25:03
  Speaker 4: Cambrian lasts for tens of millions of years. And the
• 25:09
  Speaker 4: most famous ones actually are Middle Cambrian. So these are
• 25:12
  Speaker 4: the famous Burgess Shale fossils. So this isn't the first appearance.
• 25:16
  Speaker 4: But yeah, they're found all over the world. Well, not everywhere,
• 25:20
  Speaker 4: because rocks that old are rare. But where we find
• 25:24
  Speaker 4: rocks that old, we're finding evidence of bilaterian animals.
• 25:30
  Speaker 1: And that was back in the time of just all
• 25:32
  Speaker 1: the land. There was nothing living on the land.
• 25:35
  Speaker 4: Obviously, plants hadn't.
• 25:37
  Speaker 1: And was it just one big continent?
• 25:40
  Speaker 4: Yes, you've got me there, Tim. Don't worry. Certainly the
• 25:44
  Speaker 4: continents were moving around, and I think you're right that
• 25:47
  Speaker 4: Pangaea was around at the time of the Cambrian explosion.
• 25:50
  Speaker 1: So I think.
• 25:51
  Speaker 3: It's important for our listeners just to get an idea
• 25:54
  Speaker 3: of the scope of what we're talking about here, right?
• 25:56
  Speaker 3: So the time span is millions of years. The geography
• 26:00
  Speaker 3: is all over the world, which the Earth doesn't look
• 26:03
  Speaker 3: like it looks like now. And so to try and
• 26:06
  Speaker 3: put that into a sort of... not put it into
• 26:10
  Speaker 3: a modern context, but in the world we are in now,
• 26:12
  Speaker 3: and there's, I guess, a level of imagination also that
• 26:15
  Speaker 3: has to come into it when you're trying to piece
• 26:17
  Speaker 3: these things together and imagine the world. You don't have
• 26:20
  Speaker 3: photographs or anything like that of what it looked like then.
• 26:23
  Speaker 3: So there's, I guess, the layers of complexity.
• 26:26
  Speaker 2: Are enormous, right?
• 26:27
  Speaker 4: Yeah, and it's these millions and billions. It's hard to
• 26:33
  Speaker 4: picture these. And so I use, in the book, I
• 26:35
  Speaker 4: use this sort of... human timescale to try and get
• 26:40
  Speaker 4: some idea of how much time is passing. And what's extraordinary,
• 26:45
  Speaker 4: so my human timescale is the soles of its feet
• 26:49
  Speaker 4: are the beginning of the formation of the Earth, which
• 26:52
  Speaker 4: is about 4.5 billion years ago. And the very top
• 26:55
  Speaker 4: of the head is today. And so as we move
• 26:58
  Speaker 4: up that body, we can see things happening and sort
• 27:02
  Speaker 4: of get some grasp of when it happened in the
• 27:06
  Speaker 4: history of the Earth. And what's extraordinary is that on
• 27:09
  Speaker 4: that time scale, the animals appear at the bottom of
• 27:12
  Speaker 4: the chit. So really, really recent thing. And humans, you know,
• 27:17
  Speaker 4: it's the last cell on the top of your head.
• 27:20
  Speaker 4: So it's incredibly recent in the geological time scale.
• 27:26
  Speaker 1: So let's kind of think a little bit about the
• 27:29
  Speaker 1: process of how evolution works and how new characteristics are made.
• 27:36
  Speaker 1: You have a chapter on the insect wing, for example,
• 27:39
  Speaker 1: and where insect wings came from that I thought was
• 27:42
  Speaker 1: really fascinating. So perhaps explain, you know, where we think
• 27:47
  Speaker 1: insect wings come from and why we think that's the case,
• 27:51
  Speaker 1: because it really is, it goes all the way back
• 27:53
  Speaker 1: to one of the animals that was swimming around in
• 27:55
  Speaker 1: the Cambrian, one of the.
• 27:56
  Speaker 4: Predators, no less. Yeah, so there's been actually rumbling on
• 28:01
  Speaker 4: for probably 100 years about is an argument about how
• 28:06
  Speaker 4: insect wings first evolved. And there were really two ideas.
• 28:10
  Speaker 4: The first is that essentially we had a wingless insect
• 28:15
  Speaker 4: with a carapace, so the exoskeleton, the body effectively, which
• 28:21
  Speaker 4: had a slight flaring sticking out. And these flared bits
• 28:26
  Speaker 4: gave it some minor ability to glide. And this was
• 28:29
  Speaker 4: something that could be picked up on by evolution and exaggerated.
• 28:33
  Speaker 4: and the gliding would get better and better and better.
• 28:35
  Speaker 4: So theory number one, the wings are part of the dorsal,
• 28:42
  Speaker 4: the exoskeleton, the skeleton on the back of the animal.
• 28:45
  Speaker 4: And then the second idea is that we know that
• 28:49
  Speaker 4: insects are relatively closely related to crustaceans, and crustaceans at
• 28:53
  Speaker 4: the bottom of their legs have a sort of flappy
• 28:55
  Speaker 4: bit sticking out, which is a gill, because crustaceans live
• 28:59
  Speaker 4: in the water. And they have these feathery things sticking
• 29:02
  Speaker 4: out which absorb oxygen from the water and do various
• 29:06
  Speaker 4: other things. And so the other idea is that when insects,
• 29:10
  Speaker 4: which came from the crustaceans, when they emerged from the water,
• 29:14
  Speaker 4: they still had these gills and they essentially used that
• 29:18
  Speaker 4: flappy thing and used it in some way to help
• 29:23
  Speaker 4: them glide and then flap and then have powered flight,
• 29:26
  Speaker 4: et cetera, et cetera. And the way we've tried to
• 29:30
  Speaker 4: differentiate between these is by looking at gene expression. And
• 29:33
  Speaker 4: what we've actually found, what's been found recently, is that
• 29:36
  Speaker 4: if you look at the genes that are switched on
• 29:38
  Speaker 4: in the cells of a crust gill we find the
• 29:42
  Speaker 4: same genes switched on in the cells of an insect
• 29:45
  Speaker 4: wing so suggesting that that they're essentially the same structure
• 29:49
  Speaker 4: because they share these two structures which share a lot
• 29:52
  Speaker 4: in common they're special genes involved in building an insect
• 29:57
  Speaker 4: skill are the same genes that are involved in, sorry,
• 30:01
  Speaker 4: a crustacean's gill are the same genes involved in building
• 30:04
  Speaker 4: an insect's wing.
• 30:05
  Speaker 1: But it took a long time, right?
• 30:08
  Speaker 4: It would have been very slow and, you know, quite
• 30:12
  Speaker 4: possibly the gills, you know, many of the most primitive
• 30:15
  Speaker 4: insects still have spent a lot of their life in water,
• 30:19
  Speaker 4: things like mayflies and dragonflies, etc. And they have gills.
• 30:25
  Speaker 4: And the gills, they're at the end of the body
• 30:27
  Speaker 4: in mayflies and dragonflies, but they have those same genes
• 30:32
  Speaker 4: that are switched on in other crustacean gills and other
• 30:34
  Speaker 4: bits of the body and in insect wings.
• 30:37
  Speaker 1: So it's a bit of a story of evolution really
• 30:40
  Speaker 1: finding a way to co-opt genes that did one thing.
• 30:44
  Speaker 1: Evolution rarely sort of comes up with a whole new
• 30:47
  Speaker 1: characteristic like wings or like a large neocortex from scratch.
• 30:54
  Speaker 1: It often... it often kind of uses genes, it repurposes
• 30:58
  Speaker 1: genes for new purposes. That happens again and again, and
• 31:02
  Speaker 1: something that you kind of cover in the book a
• 31:03
  Speaker 1: little bit.
• 31:04
  Speaker 4: Yeah, absolutely. And I guess in this context, you'd think
• 31:08
  Speaker 4: of it on a slightly larger scale. You'd think of
• 31:10
  Speaker 4: it as repurposing a gill. And the gill is obviously
• 31:13
  Speaker 4: built by genes. But sometimes we think of genes being
• 31:16
  Speaker 4: repurposed because an enzyme that does one thing then gets
• 31:19
  Speaker 4: repurposed and does something similar but different. But in this case,
• 31:23
  Speaker 4: it's a whole structure being repurposed in very much the
• 31:27
  Speaker 4: same way that the front legs of a dinosaur have
• 31:31
  Speaker 4: become repurposed to become the wings of a bird. So
• 31:34
  Speaker 4: it's the same structure with the same bones built by
• 31:36
  Speaker 4: the same genes, but it's been changed gradually over time
• 31:41
  Speaker 4: in the same mysterious process. Something developed, a flying dinosaur
• 31:48
  Speaker 4: is fairly extraordinary.
• 31:50
  Speaker 1: And it's great that dinosaurs are still around in the
• 31:52
  Speaker 1: form of dinosaurs.
• 31:53
  Speaker 4: Yeah, yeah, yeah.
• 31:55
  Speaker 2: Men and dinosaurs, right?
• 31:56
  Speaker 3: It's a strange thing. Men are always fascinated by dinosaurs.
• 32:00
  Speaker 1: We had a pet emu a few years ago when
• 32:04
  Speaker 1: my father-in-law's farm, he rescued it, and that emu made
• 32:09
  Speaker 1: me realise that, yes, dinosaurs would have, A, been terrifying,
• 32:13
  Speaker 1: and this was like a dinosaur. It was an awful animal.
• 32:16
  Speaker 4: Yeah.
• 32:16
  Speaker 1: Yeah.
• 32:17
  Speaker 3: I think my favourite, obviously, you probably know what I'm
• 32:20
  Speaker 3: going to say, Tim, being essentially a bacteriologist, I think
• 32:24
  Speaker 3: my favourite really is the mitochondrion, right? Just that, you know,
• 32:30
  Speaker 3: essentially it was probably a bacterium.
• 32:33
  Speaker 4: Well, yeah, you're absolutely right. So I talked about, a
• 32:38
  Speaker 4: while ago, I talked about these two branches coming out
• 32:41
  Speaker 4: of leuka, one being the bacteria... The eubacterium, the proper bacteria,
• 32:46
  Speaker 4: and the other being the archaea, which used to be
• 32:48
  Speaker 4: called the archaebacteria. So these are very, very simple creatures, tiny,
• 32:53
  Speaker 4: tiny single-celled creatures. But at some point, one species of
• 32:58
  Speaker 4: eubacterium and one species of archaean have come together to
• 33:03
  Speaker 4: form a completely new cell, which is a much more
• 33:06
  Speaker 4: complex cell. And so the archaebacterium has... essentially turned into
• 33:12
  Speaker 4: the mitochondria in all eukaryotic cells. So our cells are,
• 33:17
  Speaker 4: all of our cells and all eukaryotic cells, so all
• 33:20
  Speaker 4: large-ish cells, complex cells, have this structure called a mitochondrion,
• 33:26
  Speaker 4: which is literally another creature living inside our cells. And
• 33:30
  Speaker 4: it's been there for billions of years, a couple of
• 33:32
  Speaker 4: billion years.
• 33:33
  Speaker 1: And the animals couldn't have happened unless... eukaryote cells evolved, right?
• 33:38
  Speaker 1: And that, you know, we are eukaryotes as are plants
• 33:41
  Speaker 1: and fungi and what have you.
• 33:43
  Speaker 4: Correct. But people always talk about the inevitability of things.
• 33:49
  Speaker 4: I think it wasn't very inevitable to get animals. It
• 33:51
  Speaker 4: took two billion years before anyone had the idea of
• 33:54
  Speaker 4: making an animal. So it wasn't an obvious thing to do.
• 33:59
  Speaker 1: No, that's fair enough. So how complete... is the animal
• 34:02
  Speaker 1: tree of life then? I mean, you know, is your
• 34:05
  Speaker 1: job done? You've written this book. Can I finally retire
• 34:11
  Speaker 1: as a zoologist?
• 34:12
  Speaker 4: I think, well, there's various ways in which it's not complete,
• 34:16
  Speaker 4: thank goodness, and my career continues. First of all, there's
• 34:20
  Speaker 4: bits we argue about. So some of it's easy. It's
• 34:23
  Speaker 4: very obvious that mammals all belong together and that birds
• 34:27
  Speaker 4: belong somewhere else. So there's big bits of the tree
• 34:30
  Speaker 4: which we can So, very confidently, we've solved this bit.
• 34:35
  Speaker 4: But the bits I work on are the tricky bits
• 34:38
  Speaker 4: where we've got weird organisms which have thrown away half
• 34:42
  Speaker 4: their genes or become very simple in other ways. There's
• 34:47
  Speaker 4: occasions on the tree where lots of species appeared all
• 34:50
  Speaker 4: at once. And so untangling their exact relationships is very,
• 34:54
  Speaker 4: very difficult. So these things called adaptive radiations, a good
• 34:58
  Speaker 4: example being the Darwin's finches or the fishes in the
• 35:03
  Speaker 4: African Great Lakes. So there's lots of bits of the
• 35:06
  Speaker 4: tree which I think are very important and need sorting
• 35:10
  Speaker 4: out and I argue with people over and have been
• 35:13
  Speaker 4: doing for the last 30 years. So there's plenty still
• 35:17
  Speaker 4: to solve and there's mistakes we've been made that need correcting, etc.
• 35:21
  Speaker 4: And the other way in which it's incomplete is all
• 35:24
  Speaker 4: the species, all the extinct ones that we're never going
• 35:28
  Speaker 4: to know because they haven't left fossils yet. Almost no
• 35:32
  Speaker 4: bacteria have left. There's probably literally trillions of bacterial species
• 35:37
  Speaker 4: that have gone extinct and we'll never know about. There's
• 35:40
  Speaker 4: lots of things alive today that we don't know yet.
• 35:46
  Speaker 4: There was a paper a couple of weeks ago where
• 35:49
  Speaker 4: somebody took one teaspoon of soil, sequenced it using the
• 35:53
  Speaker 4: very latest sequencing technology, and found a genome, so DNA,
• 36:00
  Speaker 4: from about 800 species of mostly bacteria, almost none of
• 36:05
  Speaker 4: which were known to science before. So that's one teaspoon
• 36:08
  Speaker 4: of soil from one place in the world. So there's millions,
• 36:12
  Speaker 4: and according to some people, a trillion species alive today
• 36:16
  Speaker 4: that we have no idea about yet. And then, of course,
• 36:20
  Speaker 4: there's the future, which we don't know what's going to happen.
• 36:22
  Speaker 4: And I'm not going to worry too much about that.
• 36:25
  Speaker 4: Not a lot I can do about that.
• 36:27
  Speaker 3: Well, what's the thing that I guess sort of what's
• 36:30
  Speaker 3: your next big thing, Max? What's the thing that you
• 36:32
  Speaker 3: feel most excited about now sort of moving on with
• 36:35
  Speaker 3: your work?
• 36:36
  Speaker 4: Well, a slightly quixotic quest, I suppose, which we went
• 36:43
  Speaker 4: a couple of years ago to Argentina in search of
• 36:46
  Speaker 4: a worm, which would be very interesting if it exists.
• 36:50
  Speaker 4: So this is a worm called Salinella. And it was
• 36:53
  Speaker 4: described in the late 19th century by a German called
• 36:58
  Speaker 4: Johannes Frenzel. And he was in Argentina. So he wrote
• 37:05
  Speaker 4: various papers about it. He described it as the simplest
• 37:08
  Speaker 4: animal that exists at all alive today. It's basically a tube.
• 37:14
  Speaker 1: He hasn't met my dog, Woofler. He's not a simple animal. Anyway,
• 37:19
  Speaker 1: I'm joking. He's obviously quite complex.
• 37:21
  Speaker 4: Even simpler than Woofler. Salinella, if Frenzel is to be believed,
• 37:28
  Speaker 4: is simply a tube of cells. So it's a gut
• 37:31
  Speaker 4: and nothing else. So a mouth at one end, anus
• 37:33
  Speaker 4: at the other, and nothing else to it at all.
• 37:35
  Speaker 4: And so it would be very exciting to go and
• 37:38
  Speaker 4: discover this, to study this simplest of all animals, if
• 37:43
  Speaker 4: it really is that simple. But nobody's seen it since
• 37:47
  Speaker 4: Frenzel described it in the late 19th century.
• 37:51
  Speaker 1: And is that because the habitat it lived in is gone,
• 37:55
  Speaker 1: do you think? I mean, you mention in the book
• 37:57
  Speaker 1: that it's probably, you know, the salt marshes, I think
• 38:01
  Speaker 1: it was, where he said he'd found it, don't really
• 38:03
  Speaker 1: exist there anymore.
• 38:04
  Speaker 4: Yes, so we went there and it's the Argentinian Pampas,
• 38:09
  Speaker 4: which is just a huge flat area to the east
• 38:13
  Speaker 4: of the Andes. And presumably, I don't know, I wasn't
• 38:17
  Speaker 4: there in the 19th century, but it was covered with
• 38:19
  Speaker 4: pampas grass and little else. And today, we went there
• 38:23
  Speaker 4: a couple of years ago, it's completely and utterly covered
• 38:26
  Speaker 4: with farms. So as you drive along, there's nothing there.
• 38:30
  Speaker 4: but soya and alfalfa and whatever else. And they're all
• 38:34
  Speaker 4: fenced off, so it's very difficult to go and look
• 38:38
  Speaker 4: for potential sources of this creature. But slightly worse than
• 38:44
  Speaker 4: that is the ambiguous papers that Frenzel wrote. So they
• 38:47
  Speaker 4: were sort of written quite professionally and published in good journals,
• 38:53
  Speaker 4: but the methods section leaves a lot to be desired,
• 38:57
  Speaker 4: shall we say. He describes how he got a soil sample,
• 39:03
  Speaker 4: salt and mud in it, from a friend of his,
• 39:07
  Speaker 4: from the region of Rio Cuarto, which is where we went,
• 39:10
  Speaker 4: but doesn't say where. So we don't even know if
• 39:14
  Speaker 4: the region of Rio Cuarto means within a mile of
• 39:16
  Speaker 4: the town or within 50 miles of the town. So,
• 39:20
  Speaker 4: you know, it's not easy to start with. And then
• 39:23
  Speaker 4: he puts this sample in some water and then he
• 39:27
  Speaker 4: leaves this on a windowsill for about three months and
• 39:31
  Speaker 4: he tops it up with tap water from time to
• 39:34
  Speaker 4: time and he puts in some pond weed. And at
• 39:38
  Speaker 4: one point he says he drops a bit of iodine in,
• 39:40
  Speaker 4: but it sounds like it was a mistake or an
• 39:42
  Speaker 4: accident and he doesn't tell us how much. And then
• 39:45
  Speaker 4: after three months he discovers in the bottom of this,
• 39:48
  Speaker 4: you know, this jar on his windowsill this magical and
• 39:53
  Speaker 4: potentially very, very exciting worm, our most distant animal relative,
• 39:58
  Speaker 4: if Frenzel is to be believed.
• 39:59
  Speaker 1: Still alive?
• 40:00
  Speaker 4: Still alive, yeah.
• 40:02
  Speaker 1: Sounds a bit dodgy, doesn't it, really?
• 40:05
  Speaker 4: Yes, I forgot to mention, at one point he says,
• 40:08
  Speaker 4: quite a lot of sand and flies blew into the
• 40:11
  Speaker 4: water through the window. So, honestly, we don't know where
• 40:15
  Speaker 4: the soil sample came from, we don't know where the
• 40:18
  Speaker 4: worms came from, and the whole thing is very mysterious
• 40:22
  Speaker 4: but anyway we got there having studied Google Maps and
• 40:27
  Speaker 4: looked for possible sources of salty sandy soil so we're
• 40:32
  Speaker 4: looking for bare patches with a white crust you can
• 40:35
  Speaker 4: zoom in on Google and a tiny number of them
• 40:39
  Speaker 4: were within sort of reach of a track or a
• 40:42
  Speaker 4: road we couldn't actually get to them because it was
• 40:44
  Speaker 4: all fenced off but my colleague Philip who I was
• 40:47
  Speaker 4: with had a a drone. So we went zooming in, looking,
• 40:52
  Speaker 4: looking down and then, you know, inevitably there was it
• 40:55
  Speaker 4: was just a muddy pool or something. So we, what
• 40:58
  Speaker 4: we've really discovered is how difficult it is going to
• 41:01
  Speaker 4: be to rediscover this work.
• 41:03
  Speaker 1: If it actually did exist.
• 41:05
  Speaker 4: If it, if it isn't a figment of Frenzel's imagination.
• 41:08
  Speaker 3: I think the reviewers of that paper need to have
• 41:10
  Speaker 3: a word of themselves.
• 41:13
  Speaker 1: No, I think that's right. Well, I mean, I think
• 41:16
  Speaker 1: we're kind of running out of time, so we better
• 41:18
  Speaker 1: draw this to a close. But I mean, good luck
• 41:21
  Speaker 1: with your continued research and finding that worm. And I mean,
• 41:26
  Speaker 1: we could talk and talk and talk, but your book
• 41:29
  Speaker 1: published by John Murray, The Tree of Life, Solving Science's
• 41:32
  Speaker 1: Greatest Puzzle, is well worth a read. And thank you
• 41:34
  Speaker 1: very much, Max, for coming on our podcast. And I
• 41:37
  Speaker 1: think we've both really enjoyed talking to you.
• 41:38
  Speaker 2: If you find the worm, please come back.
• 41:41
  Speaker 4: I will do, without a doubt.
• 41:43
  Speaker 1: Fantastic. Thank you. Well, I thought that was really interesting, Saima.
• 41:47
  Speaker 1: I mean, you know, I thought I did some slightly
• 41:50
  Speaker 1: kind of bonkers field work. But imagine going off to
• 41:53
  Speaker 1: Argentina to dig around for a worm that someone from
• 41:56
  Speaker 1: a couple of hundred years ago or, you know, 150
• 41:59
  Speaker 1: years ago claimed to have found.
• 42:03
  Speaker 3: Yes, it's quite funny. I was wondering, you know, the
• 42:06
  Speaker 3: person who wrote the paper, you know, was he totally sober?
• 42:09
  Speaker 2: Had he smoked something? Can we test that? But I mean, remarkable.
• 42:13
  Speaker 3: Commitment to, you know, to his field to go out
• 42:17
  Speaker 3: there and look for that.
• 42:18
  Speaker 2: And I sincerely hope he finds it.
• 42:20
  Speaker 1: I tell you one thing I really loved, you know,
• 42:23
  Speaker 1: trying to understand the how quite how long life has
• 42:26
  Speaker 1: been around. I hadn't heard his analogy until I read
• 42:30
  Speaker 1: his book about going up the height of the human
• 42:32
  Speaker 1: body and sort of how at what point different, you know,
• 42:37
  Speaker 1: different different animals and different life forms arose. Really fascinating.
• 42:42
  Speaker 2: We're here, right? Animals are at the chin level, is
• 42:45
  Speaker 2: that right?
• 42:46
  Speaker 1: That's right. And then humans are just like the very
• 42:49
  Speaker 1: top layer of skin. So we think we're so important,
• 42:53
  Speaker 1: we've been around for ages, but actually we're just less
• 42:57
  Speaker 1: than a blink of an eye of geological time. Absolutely.
• 43:00
  Speaker 3: I think at school I really struggled with the spatial
• 43:03
  Speaker 3: scales of biology, which of course you don't have in
• 43:06
  Speaker 3: the same way in chemistry. And then now, on top
• 43:09
  Speaker 3: of that, when you consider the temporal scales as well,
• 43:13
  Speaker 3: it becomes quite mind-boggling, I think.
• 43:15
  Speaker 1: No, it does. But I thought he did a great job.
• 43:17
  Speaker 1: And I have to say, I enjoyed talking to him,
• 43:18
  Speaker 1: but I did enjoy his book. So I'd encourage our
• 43:21
  Speaker 1: listeners to go and have a read.
• 43:23
  Speaker 2: Oh, sure. Absolutely.
• 43:25
  Speaker 1: Okay. What are we doing next week?
• 43:29
  Speaker 3: Next week?
• 43:30
  Speaker 2: Who do we... Ah, we have Ian next week, right?
• 43:32
  Speaker 1: Ian Golden. I think that's right. I think we're going
• 43:34
  Speaker 1: to be talking about migration and how important it's been
• 43:37
  Speaker 1: over human history.
• 43:38
  Speaker 3: That's right so it's specifically human migration um over again
• 43:43
  Speaker 3: a long long time span i actually heard ian give
• 43:46
  Speaker 3: a talk um at the woodstock book festival a science
• 43:49
  Speaker 3: festival a few weeks back and he did a great
• 43:52
  Speaker 3: job and uh yeah i was thrilled when he was
• 43:54
  Speaker 3: agreed to come on the podcast.
• 43:55
  Speaker 1: No no it's great it's fantastic well i look forward
• 43:58
  Speaker 1: to that but otherwise have.
• 43:59
  Speaker 2: A good week yep i'll see you around tim
• 44:01
  Speaker 1: Okay thanks a lot bye everyone