From the Cambrian Explosion to swimming pigs – Professor Brian Cox

October 23, 2014 • 4:10 am

by Matthew Cobb

My University of Manchester colleague Brian Cox has a new TV series out at the moment, called Human Universe, which looks at the big questions – why are we here, are we alone etc. Last Tuesday’s episode was about the possibility of alien life (high for microbes, reckons Brian, probably zero for a star-spanning civilisation that coincides with ours). It included one of the best clips I have seen in a long time. For reasons that remain obscure to the viewer, Brian explains the Cambrian Explosion in the presence of some swimming pigs the film crew found on the shore of a beautiful desert island (and that’s ‘desert’ as in an old-fashioned way of saying ‘deserted’ not as in ‘lots of sand and aridity’). Here’s a clip that someone with an interest in pigs has uploaded:

54 thoughts on “From the Cambrian Explosion to swimming pigs – Professor Brian Cox”

  2. Yes, there seems to be a lot of travel to distant locations for no particular reason in there! Mind you, if I was presenting the series then I’m sure I’d insist that it was absolutely essential for me to travel to easter island to do a short piece to camera about the environment.

    (Though of course recent work suggests that the easter island eco-catastrophe hypothesis isn’t as simple as the version he presented).

    1. Yeah, but they only send him abroad. Neil deGrasse-Tyson got to visit a black hole and to shrink to molecular level and explore a strand of DNA.

  5. They are very pretty, but pigs are BAD for island life – they wipe out ground nesting birds & damage native ecosystems… 🙁

    2. Not if they go swimming often enough…as the sharks would say…What’s on the menu tonight…pork.

  6. Matthew, Jerry: Is there any reason to suppose that alien life will have Earth-like nucleic acid based genetics? How much is biochemical evolution constrained by polymer chemistry, i.e., what are the biochemical limits for all possible evolved life-form types? Also, would tiny unicellular non-DNA creatures be called ‘microbes’? They wouldn’t (and won’t) if I know anything about taxonomists.

    1. I am not an expert, but this is definitely a reasonable starting point:

      https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

      My guess is there are a lot of opportunities for mechanisms of self-assembly which are energetically favorable that would cause planet -wide construction of things like solar panel crystals that simply grow, like ice, over the surface, but whose emergent properties could be considered life-like. Such might be the case of dwarf planets where the elemental composition is reasonable and the need for energy collection requires large spaces. I think Dyson proposed something like this.

    2. There was a programme about life’s origins on earth a few years ago that actually included a bit about looking for evidence of early or primitive life with a different make up to our universal common ancestor. Mainly to try and ascertain if it had arisen more than once on earth but become extinct or out competed by our UCA. Which in turn would increase the likelihood of something elsewhere. It was looking to see if life has to be the way it is.

      But I can’t for the life of me remember the details and haven’t a clue whether the research found anything at all.

      1. There’s quite a lot of that sort of thing. It’s popular “Discovery-fodder”. Not necessarily bad, but often poorly researched, repetitive and done very much to a budget.

      2. Since the LUCA was an DNA/protein cell, but our UCA lineage started out as an RNA/dipeptide cell or something similar (from ribosome studies), it is a given that a lot of lineages went extinct. With or without any parallel emergences of life.

        But I don’t think Darwin’s prediction was any worse under similar circumstances, that existing life uses new attempts at emergence as nutrients. It would be a very unlikely happenstance or productive life emergence process that resulted in separate lineages in the short time period that people predict it took. (On the order of 10 000 – 100 000 years.)

        Perhaps the initial mass extinction was a result of the impact tail, which happened up to the first evidences we have of continental crust. A similar mass extinction would have happened at the oxygenation of the atmosphere. Surviving organisms could evolve enzymes that shielded against NO damage (present in CO2 atmospheres from volcanism fro example) for use with OO – those proteins are rooted in NO shielding. But likely it killed off a lot of diversity in the process.

        Life is robust, no doubt.

    3. They’re big questions.
      It’s hard to come up with a mechanism for transmitting hereditary information that doesn’t depend on variations in repetition of a small number of basic units. Alan Cairns-Smith in the 1960s to recent has been proposing that patterns of crystal lattice fault in clay minerals could transmit information with some copying errors, and produced some geological evidence for it happening. That’s interesting, and potentially very interesting in respect of the question of biogenesis, since such minerals can have catalytic activity in biochemical reactions. However, it is hard to see how such systems could develop much further once hereditary systems developed which could take place in the liquid phase, rather than the solid phase.
      Outwith that (range of) mineralogical exceptions, I can’t think of linearly-structured crystals that could provide a data-storage-playback mechanism. So that leaves organic polymers as a hereditary material. However, whether it’s nucleic acids, or some other organic polymer … that’s a thornier question. Celluloses, for example, could use a variety of sugar molecules as an information store ; but would the etheric linkages in the chain be too stable for easy use? (OK, “polysaccarides”, not celluloses) Chitin is another natural polymeric compound that is widely distributed in nature (arthropods, molluscs … and somewhere else that slips my mind) which also seems to have hereditary potential, but again also has those troublesome etheric oxygen linkages. Maybe you really need to have the distinct “backbone plus links” that DNA/ RNA has.
      There has been quite a lot of work on whether or not life could work using RNA instead of DNA. It certainly has passed several decades of “sniff tests” (because people continue to work on it), More esoteric systems such as PNA (nucleic acids with a peptide backbone instead of a ribose-sugar-phosphate backbone) are under investigation.
      All of these ideas are under consideration because they seem to work to some degree in slightly alkaline water solution. If you know the chemistry of liquid methane, or liquid ammonia, then you’re a better chemist than I am, Gunga Din!

      Also, would tiny unicellular non-DNA creatures be called ‘microbes’? They wouldn’t (and won’t) if I know anything about taxonomists.

      In the late-1990s there was a flurry of interest in some weird organisms discovered in oil well samples from Australia which had a filamentous structure considerably narrower than any previously reported organism. Which raised all sorts of questions – how does the hereditary machinery of life fit in there? (reference Unwins, P. J. R., Webb, R. I., and Taylor, A. P. “Novel Nano-organisms from Australian Sandstones,” American Mineralogist, 83, 1541 (1999) ; Philippa Unwins did her PhD at Aberdeen when I was an undergraduate student, and was as memorable then as her PR photos still are). Philippa and team called their little oddity “nanobes” for “nanometre-scale microbes”. However the cite previous work from people working on kidney bacteria, who described their organisms as “nannobacteria” (I recognise Philippa in “We do not follow Folk’s convention of spelling” ; i.e. “WE get it right!”)
      So, you’ve got two hats in the spelling-bee ring already. Maybe more.
      I’ve not heard of follow-up work from Unwins et al ; I deduce that their further work revealed the nanobes to be a conventional filamentous bacterium or fungus, but of unusually fine structure. Quite how that works, I don’t know.
      I just did a bit more digging around, and the GSA have made available a DVD of a talk by Philippa, at http://www.qld.gsa.org.au/video.htm ; that’s the first new data I’ve seen for years. Unfortunately, finding new results gets absolutely buried in the swarms of SETI and more woo-ish repeats of the original, quite sober, work.

    4. How much is biochemical evolution constrained by polymer chemistry, i.e., what are the biochemical limits for all possible evolved life-form types?

      I would place a bet that on terrestrial planets in the radiative habitable zone (i.e. surface liquid water) RNA and something like DNA is inevitable.

      Those planets would start out with a CO2 atmosphere, so slightly acidic oceans with Fe dissolved as FeII. That is the ideal environment for making biomolecules, especially since Fe dissolution will give you alkaline crust zones as the alkaline concentrate.

      There are several pathways to production of carbon chains, but once you hit 3C you will get hexoses and so pentoses for free. A hot FeII ocean catalyses it, using the same pathway as we still do today and roughly at the same efficiency, just much slower. Granted, you need a membrane or some other product separation to swing the pathway from breaking down 6C to producing it instead. People assume membranes was present, inorganic from chemical gardens or organic from lipids or perhaps random peptides.

      From pentoses, still with FeII catalysis, the environment should be able to produce purine nucleotides in a similar way.

      As it happens RNA is a good catalyst in an FeII ocean, so you kick the door down on evolving RNA protocells. It also happens to be the case that RNA is the only identified polymer that straddles the thermodynamic requirement on replication in a cellular environment given by free energy requirements in its production. It is Goldilocks stable, not too stable to produce without proteins or replicate, but stable enough to survive between replication cycles.*

      As for DNA eventually evolving from an RNA/protein UCA, separating replication from protein synthesis is more robust under parasitism. And since we have double stranded RNA viruses, it arguably shows that parasitism evolved at the time.

      An interesting pathway to DNA has been suggested after discovering that some prokaryotes use it as a phosphate storage. They are making superfluous chromosome copies in phosphate rich environments, and down-regulate that when phosphate is scarce. Perhaps RNA cell lineages originally evolved the stabler DNA for that purpose, then co-opted it into the genetic machinery.

      *I think this is the main difficulty with suggested alternatives. They were promoted before the England paper on replication and its free energy bottleneck requirement.

  7. I’ll have to catch up with the series. I watched the first programme and found it pretty disappointing.The Guardian had a piece the day after entitled “Brian Cox’s Human Universe presents a fatally flawed view of evolution” which I though might be picked up and disected by one of the main contributors on WEIT.

      1. He was interviewed the other day (BBC radio 4 I think) and the interviewer started to go down that road. Prof Cox saw it coming and quickly and fairly emphatically nipped it in the bud.

    2. I, too, have only watched the first episode so far (others await on my hard drive) and I, too, was disappointed. It seemed to ramble quite a lot, and could easily have been condensed to half an hour. Little would have been lost, and it’s easier to follow the thread of an argument when it is presented at a normal talking pace. The long delays while we admire the pretty pictures just disrupt the flow of the explanation.

      I’m sure I read somewhere many years ago that it is a recognised fact that a lecture presented at a slow pace is much harder to follow than one presented as normal speech.

  8. The swimming pigs were definitely the highlight.

    *Spoiler alert*

    His argument at the end of the programme for why he thinks we are probably the only technologically advanced civilization in the galaxy (because we haven’t yet encountered a von Neumann machine)was bizarre. Not least because we are a technologically advanced civilization who are nowhere near to producing such machines. And also, I couldn’t quite gather what would motivate a civilization to populate the galaxy with such machines. So the answer as to why we don’t see them is that no one has bothered to make them.

    1. Curiosity has motivated us to send spacecraft to every planet in our solar system. Presumably it will someday motivate our descendants to send probes to nearby exoplanets. If you have the technological ability to create self-replicating machines, then sending probes to millions or billions of stars is not much more difficult than sending them to a handful of stars, so your return-on-investment in terms of knowledge gained goes up (literally) exponentially.

      Of course it takes millennia to collect such knowledge by this method, so you wouldn’t attempt this unless your civilization is stable over that sort of time scale. So maybe that explains why we don’t see them.

      1. Curiosity has motivated us to send spacecraft to every planet in our solar system.

        For some definitions of planet, such as the IAU’s.
        During the kerfuffle over Pluto, I did my own thinking about what constitutes a planet, and decided that I favoured the “self-gravitate into a spheroid” criterion, regardless of size or composition”. Essentially, by the time you get to that size, you’re going to be cooking out the volatiles, but also starting to attract in other material, which is going to start rapidly grow. I understand the IAU’s logic, but I don’t really accept it.
        This particular parrot has a lot of squawking still to do. When New Horizons approaches Pluto (sorry, “PLuto”), I’ll expect the “it weren’t like that in my yoof!” brigade to be gargling and getting ready for a big shouting match.
        Personally, I don’t see physics allowing humanity to explore the universe with anything smaller than “generation ships”, at least not in the short term (geologist’s short term : 100kyr.) But doing scouting (and preliminary preparation of the ground, such as mapping and identifying stocks of metals and volatiles) using von Neumann machines seems an obvious stage to work through.
        Of course, you’d have to learn how to look after a closed ecology first. We don’t seem to have understood that, as a species, yet.

        1. My attitude to von Neumann machines is that releasing them would be dangerously irresponsible and might earn a planetary death sentence if there’s a galactic police force out there. If competent to survive and reproduce, disperse, and deal with threats, they would not only count as a form of life but would certainly evolve by natural selection. Whatever the original builder-installed program, evolution would favour self-interested goals when they inevitably came into conflict with preexisting species and civilisations, including us (and the cops). Shoot on sight, I reckon.

          1. …but would certainly evolve by natural selection.

            Not at all. Accurate copying of digital data is a solved problem; with enough redundancy, the probability of an undetected mutation can be made arbitrarily small. Apple, for instance, is able to distribute billions of copies of iOS with essentially zero errors. (Any errors that do occur are detected, discarded, and retried.)

            Evolvability of von Neumann probes is a feature that would have to be deliberately designed in, by artificially limiting the copying fidelity and allowing errors to go through uncorrected.

          3. Berserker!
            Ummm, memory fade. Who was the coordinator of that SF universe? Fred Saberhagen.
            Whether you could programme the von Neumann machines to stay within range of some beacon from Earth, or from the advancing front of human civilisation … well, you’d want to get some benefit from them, even if it’s only sending back detailed reports and stockpiling metals, volatiles and a radio beacon.
            It’s not something that’s going to happen quickly. We do have time to work out the implications. Even if it’s as simple as “when you get to a new system, and can’t pick up the human-characteristic radio traffic, then perform a normal survey and stock-pile, then travel to the closest potential target system to the last station where you heard the humans.”

      1. Where are they?
        (And when the pantomime season starts again, “Behind YOU!”

    3. I find all attempts to answer Fermi’s Question bizarre.

      The reason is displayed prominent in the common name in use today: it isn’t certain to be a paradox. You have a lot of potential for false negatives (in fact I would argue like you they are natural).

      Without a proper constraint attempts to predict anything is premature. (No proper constraint on observations and theories both, SETI has barely begun to empty out the possible search space.)

  9. There is something endearing about pigs, despite the damage that they can do. They are intelligent, attractive, mostly friendly creatures that have only one drawback – at least from the pig’s point of view: they make the most magnificent bacon…

    1. I too love pigs. I haven’t eaten pig for a long, long time because I love them so much. I recently signed a petition to change how they are transported and treated because it is horribly cruel. There was a video showing hurt pigs being kicked and shocked into trucks for transport and they talked about how in the winter, the pigs are frozen onto the truck and many arrive dead. Really horrible industry!

      1. One of the best things that has happened in the UK, and to a lesser extent in the EU, is a huge betterment of animal welfare – and pigs in particular. A fair number of animals are now reared outside, with shelter provided by “pig arks” which are rather like small Nissan huts from WW2. They are allowed to display natural behaviour – rooting for example – and I just cannot believe that more humane treatment of the animals isn’t just for their benefit. I strongly feel that the end result actually tastes better.

  10. I’m sure this wasn’t the intent, but seeing pigs swim in the ocean made me think of the gradual evolutionary steps other mammals like whales might have taken over millions of years until they eventually left land for good.

    1. A quick google shows that these porkers live on an uninhabited island off the Bahamas. Two things have come to mind: firstly, swimming is not the most natural thing for a pig to do – or at least not as a matter of course.So this behaviour is a learnt one – especially where the piglets are concerned. People come to the island by boat and the pigs have learnt to swim out to them in the frequently fulfilled hope of food. Secondly, and rather sweetly, the pigs swim with their snouts in the air, rather like a miniature snorkel. Again, this behaviour is possibly a learnt one .

          1. Yes, and by “land” (how inexact!) I meant to exclude those adapted to a part aquatic life; to talk about those who might have to swim only occasionally, like cervids crossing a river, say…

    2. Not having played the series off the PVR, I don’t know exactly what Cox et al were going on about, but when I heard about swimming pigs, I thought “someone is making a point about the origin of whales”.

    1. I think he may have learned the hard way about contact with sharply pointed trotters on d*g-paddling pigs.

        1. Yes, I am careful when I meet pigs – at petting zoos and such. I like to touch their cute snouts and they can’t bite me easily when they are in their pens so it’s much safer that way.

          You just don’t know with strange pigs. 🙂

    1. Ugh! It said ‘animated music video’ in the title. I could detect nothing that could remotely be called ‘music’ in the ten seconds it took me to crank the volume to zero and locate the Delete button.

      🙁

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