Major Transitions in Evolution

The changes we’re starting to go through now are so big that we need to step back and take a very long view to get any sort of handle on them. I’m struggling to do this now. This book has been very helpful:

• Tim Lenton and Andrew Watson, Revolutions That Made the Earth, Oxford U. Press, Oxford, 2011.

There’s a lot in it, and I’d love to tell you about all of it… but for now, let me just list 8 major transitions life on Earth may have gone through:

1. Compartments. This transition takes us from self-replicating molecules to self-replicating molecules in ‘compartments’—membranes of some sort. A compartment separates ‘self’ from ‘other’, and it’s crucial to life as we know it. When did this transition happen? Certainly after 4.4 billion years ago, when the Earth first got a solid crust. Probably after 3.85 billion years ago, when the Late Heavy Bombardment ended. Certainly before 3.3 billion years ago, when the earliest well-established microfossils are found. Probably before 3.8 billion years ago, which is the age of the Isua greenstone belt—a formation that contains graphite specks with less carbon-13 than average, a hint of life.

2. Groups of genes. This transition takes us from independent self-replicating molecules to self-replicating molecules linked into long chains, probably RNA. When did this happen? I have no idea; I’m not sure anyone does. Probably sometime between 4.4 and 3.3 billion years ago!

3. Genetic code. This transition takes us from a world where RNA both stored information and catalyzed reactions to a world where DNA stores the information used to build for proteins, which catalyze reactions. When did this happen? Again, probably sometime between 4.4 and 3.3 billion years ago!

4. Eukaryotes. This transition takes us from prokaryotes to eukaryotes. Prokaryotes, like bacteria and archaea, have relatively simple cells, like this:

Eukaryotes—like animals, plants, fungi and protists—have cells with lots of internal parts called organelles. Here are some things you might see in a eukaryotic cell:

It’s now believed some organelles were originally independent prokaryotes that got swallowed up but survived as symbiotic partners: so-called endosymbionts. The evidence is especially good for mitochondria and chloroplasts, which have their own DNA. When did this transition occur? Some experts say around 1.85 billion years ago. Nick Butterfield has seen fossils of red algae dating back to 1.2 billion years ago, so eukaryotes were definitely around by then. The authors of this book date eukaryotes to “roughly 2 billion years ago, give or take 0.5 billion years.”

5. Sex. This transition takes us from populations of asexually reproducing clones to populations that reproduce sexually. When did this happen? Roughly around the time eukaryotes arose. The authors write:

We would like to know if the evolution of sex is really separate from the evolution of eukaryotes, or whether the two are so closely related that sex co-evolved with the eukaryotic cell. It would help if we knew precisely why organisms bother with sex, but we don’t.

6. Cell differentiation. This transition takes us from single-celled protists to multi-celled animals, plants and fungi where different cells specialize to play different roles. When did this happen? The oldest known animal fossils are some early sponges in the Trezona Formation in South Australia… they go back 665 million years. Plants may go back 1.2 billion years, and fungi perhaps around 1.4 billion years. Just for fun, here’s a typical plant cell:

but of course the point is that thanks to differentiation, different cells in the organism look different!

7. Social colonies. This transition takes us from solitary individuals to social organizations such as colonies of ants, bees and termites, or the somewhat different societies of birds and mammals. Sociality has arisen independently many times, but it’s hard to say when because it’s hard to find fossil evidence! In the early Triassic, about 250 million years ago, we find fossilized burrows containing up to twenty cynodonts of a type known as Trirachodon:

Cynodonts are classified as synapsids, a group of animals that includes mammals but also ‘proto-mammals’ like these. By the late Triassic, there’s also evidence for social behavior among termites. It would be funny if proto-mammals beat the insects to sociality. I bet the insects got there first: the fossil record is not always complete!

8. Language. This is the transition from societies without language (for example, earlier primates) to societies with (for example, us). When did this happen? Alas, it’s even harder to read off the beginning of language from the fossil record than the arrival of social behavior! I’ll just quote Wikipedia:

Some scholars assume the development of primitive language-like systems (proto-language) as early as Homo habilis, while others place the development of primitive symbolic communication only with Homo erectus (1.8 million years ago) or Homo heidelbergensis (0.6 million years ago) and the development of language proper with Homo sapiens sapiens less than 100,000 years ago.

So that’s a list of 8 ‘major transitions’! With each one we get a higher level of organization, while preserving the structures that came before. At least that’s true of the first 7: the last is a work in progress.

In fact, this list was first propounded here:

• Eörs Szathmáry and John Maynard Smith, The major evolutionary transitions, Nature 374 (1995), 227-232.

and these authors expanded on their ideas here:

• Eörs Szathmáry and John Maynard Smith, The Major Transitions in Evolution, Oxford U. Press, Oxford, 1995.

I haven’t read that book yet, alas. Lenton and Watson actually argue for a different, shorter list:

1. The origin of life, before 3.8 billion years ago.

2. The Great Oxidation, when photosynthesis put oxygen into the atmosphere between 3.4 and 2.5 billion years ago.

3. The rise of complex life (eukaryotes), roughly 2 billion years ago.

4. The rise of humanity, roughly 0 billion years ago.

They consider these to be the “truly difficult events that may have determined the pace of evolution”.

Of course the latest revolution, humanity, is not complete. There is no guarantee that it will have a happy ending. Lenton and Watson sketch several alternative futures:

1. Apocalypse.

2. Retreat.

3. Revolution.

I’ll say more about these later. This is what Azimuth is ultimately all about.

53 Responses to Major Transitions in Evolution

  1. Tim van Beek says:

    I’d like to learn more about the basics of evolution first – you have mentioned several books already here, are there some you would recommend to an interested physicist?

    8. Language.

    Humans or primates aren’t the only ones using language, or are they? What about whales and dolphins? Asked differently: What is the definition of language here?

    5. Sex.

    It would help if we knew precisely why organisms bother with sex, but we don’t.

    Of course the usual explanation is that a recombination of genes enhances mutation -> enhances evolution. This has always bothered me because I find it hard to believe that evolution is driven by random recombinations (and errors in this process) of genetic codes.

    This seems to be the motivation for some people to come up with alternatives like intelligent design. The one point where I agree with intelligent design is that the very mechanism of change from one generation to the next seems to be largely unkown – or rather the explanations that I know of are not satisfying.

    (BTW, John, I assume you figured out what this is all about in the meantime, compared to the state of the affair two years ago :-)

    • John Baez says:

      Tim wrote:

      I’d like to learn more about the basics of evolution first – you have mentioned several books already here, are there some you would recommend to an interested physicist?

      I don’t really know where you’re starting. I gradually acquired a crude working knowledge of evolution, molecular biology and paleontology over decades of random reading. Given this, I found the following book to be incredibly exciting:

      • Massimo Pigliucci and Gerd B. Müller, editors, Evolution – The Extended Synthesis, MIT Press, Cambridge, Massachusetts, 2010.

      However, the “extended synthesis” is meant to correct and extend a previous consensus, which is often called the modern synthesis. So if the tenets of the modern synthesis don’t seem familiar to you—look at the link and see!—maybe some more background reading would be good.

      Steven Jay Gould’s many books of essays are lots of fun to read, but he’s opinionated and some other experts think he’s wrong about some important things. I forget how clear he is about saying what’s the “conventional wisdom” and what are his own views. So, enjoy him, learn from him, but be careful.

      E. O. Wilson’s books are also fun to read. Dawkins’ books The Selfish Gene and The Extended Phenotype are a bit more technical, but very exciting. Lynn Marguiis has also written some very exciting books, such as Origins of Sex: Three Billion Years of Genetic Recombination and Symbiotic Planet: A New Look at Evolution.

      But what’s a good well-rounded introduction to evolutionary biology? Does anyone here know?

    • John Baez says:

      Tim wrote:

      Humans or primates aren’t the only ones using language, or are they? What about whales and dolphins? Asked differently: What is the definition of language here?

      I’ll look to see how these people (Lenton and Watson, Szathmáry and Maynard Smith) attempt to define ‘language’, but this is a hotly argued subject and I don’t think anyone’s definition will suffice to stop the arguments.

      Most scientists I’ve read don’t say that dolphins and whales have ‘language’, because nobody has been able to take their calls, analyze them, and find a discrete set of building blocks (roughly, ‘words’) that get combined in patterns following rules we can understand (roughly, ‘grammar’). Indeed, I get the impression that dolphin and whale calls are still largely mysterious, though people have been studying them for decades. Maybe our concept of ‘language’ is too limited, being based on one particular species.

      The title of this article is bit flaky, but the article itself sounds interesting:

      • Keith Cooper, Dolphin studies could reveal secrets of extraterrestrial intelligence, Astrobiology Magazine, 2 September 2011.

      Zipf’s law says that the frequency of appearance of a word is inversely proportional to its rank when you list words by frequency. For example, the 6th most common word will show up about 1/6 as often as the most common one. Why? It’s very controversial, but some argue that Zipf’s law arises from trying to maximize the rate of information transmission.

      Now scientists have done a similar analysis of dolphin whistles. It’s tricky, since we don’t know what a dolphin “word” is, or even if they have words! But based on some assumptions, the scientists get Zipf’s law.

      For squirrel monkeys, they instead get an exponent of -0.6. “You can combine the calls any way you want and you won’t get a -1 slope.” They believes this “suboptimal” power law reflects the animals’ limited social behavior.

      • Tim van Beek says:

        John wrote:

        Most scientists I’ve read don’t say that dolphins and whales have ‘language’, because nobody has been able to take their calls, analyze them, and find a discrete set of building blocks (roughly, ‘words’) that get combined in patterns following rules we can understand (roughly, ‘grammar’). Indeed, I get the impression that dolphin and whale calls are still largely mysterious, though people have been studying them for decades. Maybe our concept of ‘language’ is too limited, being based on one particular species.

        The use of “language” could be inferred from coordinated social behaviour that does not correspond to an instinct, as described here (Smithsonian’s National Zoological Park) with respect to dolphins and sharks:

        In the presence of a shark, dolphin anti-predator behavior varies with the circumstances. Some simply swim away from the shark, others ram or bite it, and yet others launch coordinated group attacks to drive the predators away.

        The ability to launch a coordinated group attack that is based on free decisions by each individual, rather than a collective instinct as it seems to be the case with ants etc., could be an indication of the ability to communicate on a verbal-like level.

        • John Baez says:

          Tim wrote:

          The use of “language” could be inferred from coordinated social behaviour that does not correspond to an instinct…

          I would say that’s evidence for “communication”, but most people interested in this subject say that “language” is more specialized than “communication”.

          For example, wolf packs are well-organized, and the wolves communicate by sounds and also perhaps facial and bodily expressions, but most people don’t say wolves have “language”.

          So what’s “language”? The Wikipedia article lists some characteristic features:

          • The arbitrariness of the linguistic sign, meaning that there is no predictable connection between a linguistic sign and its meaning;

          • The fact that linguistic structures are built by combining elements into larger structures that can be seen as layered, e.g. how sounds build words and words build phrases;

          • The way language is built from a finite set of clearly distinguishable building-blocks;

          • The productivity of the linguistic system, meaning that the finite number of linguistic elements can be combined into a theoretically infinite number of syntactically allowed combinations.

          One can imagine systems that have some but not all of these features. Then people could argue about whether they count as “language”. The first feature doesn’t seem all that important, for example: if people used a language where the names of things looked or sounded like the things themselves, I’d still call that “language”.

          Of course ultimately it’s less productive to argue about the definition of “language” than to understand and classify the communication schemes that different animals, plants, computers, etc. use.

        • John Baez says:

          Tim wrote:

          The ability to launch a coordinated group attack that is based on free decisions by each individual, rather than a collective instinct as it seems to be the case with ants etc., could be an indication of the ability to communicate on a verbal-like level.

          By complete coincidence, someone on Google+, I think Matt Austern, pointed me to this talk about a mathematical theory of wolf packs!

          • Cristina Muro, A robotic model describing the formation of wolf-pack hunting behavioural patterns, 4 March 2011.

          She says:

          The way in which wolf-packs hunt is often used as a proof that a social structure and a system of communication sustain the relation between pack members, and, still, that this social structure is based on hierarchical rules.

          But she discusses a new theory:

          The pursuit and the encircling behaviors are in fact EMERGENT BEHAVIORS
          which arise from the combination of two simple rules for the individual behavior of each wolf, without any coordination or
          centralized action, nor communication between individuals.

          The rules are:

          1. Move towards the prey until a critical distance is reached.

          2. When close enough to the prey, move away from other wolves.

          She and her coworkers then give a mathematical formulation of these rules, and study their consequences.

      • Matías says:

        This comment makes me remember S.J. Gould saying how dolphins are more sophisticated communicators than humans as they have managed to understand at least some human-made languages and humans still don’t understand any dolphin-made one. Of course it’s easy to come with many reasons why this argument is flawed (on the other hand, Gould didn’t really extend on this so it’d be some unjustice to the argument as it stated to attack it fiercely).

        What’s funny about it (at least for me) is that many of the arguments used by anthropologists and semiologists for backing the affirmation that it’s the humans who are more sophisticated are flawed alike but don’t result in such a fierce and automatic intent for rebuttal as the other one.

        • John Baez says:

          The remark you attribute to Gould is attributed to Sagan here. Maybe they both said it.

          As Carl Sagan once famously said, “It is of interest to note that while some dolphins are reported to have learned English – up to 50 words used in correct context – no human being has been reported to have learned dolphinese.”

          “Carl Sagan was right!” said Lori Marino, a biopsychologist from Emory University in Atlanta, Georgia. “We still don’t understand the natural language system of dolphins and whales. We know a little bit more now, and there have been investigators working on this for decades, but we haven’t really cracked the code.”

          In that case, how can we be sure they even have a language? Justin Gregg, a researcher at the Dolphin Communication Project in Connecticut, is skeptical. “Most scientists, especially cognitive scientists, don’t think that dolphins have what linguists would define as language,” he said. “They have referential signaling, which a lot of animals do – squirrels and chickens can actually do that, and monkeys – and they have names for each other. But you can’t then say they have a language because human words can do so much more.”

      • Cristi says:

        Hello,
        This is somehow tangential but, regarding language, the origin of consciousness may also be relevant in dating the development of language, since people must be aware of what they are communicating.

        So I would like to take advantage of the wide range of expertise people have around here to ask: has anybody read Jayne’s book “The Origin of Consciousness in the Breakdown of the Bicameral Mind” , and what do you think about it?
        (You can look here for an overview, or wiki )

        Jaynes argues that consciousness, as he defines it, is a learned ability and that it is as recent as 3000 years old. Of course, his theory is controversial, but the origin of consciousness may also be considered a “revolution”, although not as biological as the 8 you described.

        Also, since other comments provide relevant references, Robin Dunbar’s “Grooming, Gossip, and the Evolution of Language” discusses the 8th transition (towards language) (but it’s a little boring in some places).

    • Matías says:

      A good book for evolution is Mark Ridley’s Evolution, it’s an undergraduate level textbook, very readable and the most comprehensive I found ’till now.

      The only things it lacks is some exposition of epigenetics and horizontal transfer but I think that given they had so recent development it’s better to read about them in specific updated reviews (and also with some previous background on the general of evolution).

    • John Baez says:

      Lenton and Watson wrote:

      It would help if we knew precisely why organisms bother with sex, but we don’t.

      Tim wrote:

      Of course the usual explanation is that a recombination of genes enhances mutation -> enhances evolution.

      That may be a usual ‘pop’ explanation, but for many decades that explanation was unsatisfying to evolutionary biologists, for the following reason.

      There seems to be a huge immediate problem with evolving toward sexual reproduction. A gene is selected for when it increases the chance of their own replication. But a sexual organism passes on only half its genes, while an asexual one passes on all its genes. So, a gene that increases the chance of sexual reproduction would seem to lower its own chance of getting passed on!

      There must be some loophole in this argument, or some compensating advantage to sexual reproduction, and people have come up with many candidates. However, it’s hard to argue that sexual reproduction will be favored merely because in the long run it enhances evolution. Evolution is presumably not ‘goal-oriented’ or (in the usual jargon) ‘teleological’.

      In other words, the first organism to start having sex wouldn’t say “hey baby, come on and try it—this is gonna be good, it’ll help us evolve faster.”

      There are a lot of interesting new ideas on the ‘evolution of evolvability’. Many are explained here:

      • Massimo Pigliucci and Gerd B. Müller, editors, Evolution – The Extended Synthesis, MIT Press, Cambridge, Massachusetts, 2010.

      But currently the most popular hypothesis on how sex evolved in the first place—as opposed to why sexually reproductive organisms evolve faster after they exist!—seems to be the Red Queen Hypothesis.

      • Matías says:

        Very interesting! I have already saved the slide-show about wolf-packs in my “mathematical biology” folder. Also I’ve found the concept of consciousness as “a learned process based on metaphorical language” which “did not arise far back in human evolution” intriguing and worth of some deep thought (in the link of Julian Jaynes provided by Cristi).

        About the short term advantage of sex, of the two main theories one is the Red Queen one you name, and the other one is that it sex enhances the power of selection against deleterious (i.e.: negative, sometimes deadly) mutations. It’s sometimes called “mutational theory” and was supported by Maynard Smith.

        In the middle of a book about information theory a simple model can be found that unifies the two hypothesis. The book is written by David J. MacKay and can be downloaded for free as a whole or as separate chapters here (the chapter of the model is number 19 and called “why have sex”).

        Somewhat technical note: the model doesn’t bring too much light into why aren’t we all autogamous recombinant polyploids instead of sex addicts (and the same goes for both hypothesis). Maybe some of you who know about information theory can solve this problem or help drop some of the unrealistic assumptions of the model. Would like to know if you do so.

        (John, thanks for correcting my english)

    • Marco says:

      Regarding why organisms bother with sex, you could find interesting a chapter in a book already mentioned on this blog or in the forum:

      • Leo W. Buss, Life Cycle Evolution in The Evolution of Individuality, Princeton University Press, Princeton, 1988.

      “The association between sex and cellular differentiation is causal; sex was a necessary precondition for the evolution of cellular differentiation. The evolutionary significance of sexuality lies not only in its potential advantages to the individual and the population [*], but also in its impact upon selection at the level of the cell lineage. By allowing the individual to override the selective advantage of the cell lineage, sex allowed the evolution of a trait that is disadvantageous in the somatic environment” pp 128-129

      [*] As far I have understood, the author means gene recombination.

      The book addresses the problem of the missing mechanism of change. I am not a biologist, I don’t know the current state of art and I don’t know if this book is a “safe” reading. Anyway, I found several facts about ontogenesis and the (pre)history of evolutionary theory I didn’t know.

  2. partandwhole says:

    John, you would likely be interested in findings published in Science this summer, that describe experimental support for the Red Queen hypothesis of why sex persists evolutionarily. The abstract:

    Most organisms reproduce through outcrossing, even though it comes with substantial costs. The Red Queen hypothesis proposes that selection from coevolving pathogens facilitates the persistence of outcrossing despite these costs. We used experimental coevolution to test the Red Queen hypothesis and found that coevolution with a bacterial pathogen (Serratia marcescens) resulted in significantly more outcrossing in mixed mating experimental populations of the nematode Caenorhabditis elegans. Furthermore, we found that coevolution with the pathogen rapidly drove obligately selfing populations to extinction, whereas outcrossing populations persisted through reciprocal coevolution. Thus, consistent with the Red Queen hypothesis, coevolving pathogens can select for biparental sex.

    http://www.sciencemag.org/content/333/6039/166.summary

    http://www.sciencemag.org/content/333/6039/216.short

    • John Baez says:

      Cool! So C. elegans can reproduce in various ways? I think I can guess what ‘outcrossing’ is, but I don’t know what ‘selfing’ is. Some sort of parthenogenesis? Anyway, it’s great that people have shown pathogens can push these nematodes toward ‘biparental sex’.

  3. William Felder says:

    Prairie dogs have a pretty sophisticated system of warning calls:

    http://www.johnpratt.com/items/docs/lds/meridian/2005/prairie_dog.html

    In particular, they’re able to distinguish coyotes from domesticated dogs, and if I’m not mistaken, they were shown to develop new signal sounds (or words) for seemingly threatening objects (introduced by the researchers) which they had never seen.

    Also, “prokaryote/eukaryote” is not mono-phyletic, no? (Archaea is closer to us than to bacteria.) The model should reflect that which is modeled. :)

      • Matías says:

        Jajaja, I was going to ask you why you didn’t like the first link while it seemed so interesting in its detailed explanation of the communication system of this prairie dogs, but then I read it speedily and it started getting weirder until the conclusion came. I don’t want to spoil it so I won’t cite it, but I recommend if anyone has a spare minute to skim through the webpage and read the conclusion… Now I’m a little upset as my prejudices don’t let me take seriously any of the otherwise interesting data they show.

        It’s interesting the plausible selfish role in the prairie dogs calls (explained in the Wikipedia entry you cite), because if they alternate between informative calls and panic-inducing ones, you could study animal deception (ex: when prairie dogs “lie”, when they are surrounded by unrelated prairie dogs?, when they are too far from a shelter?, etc.) with game theory.

        By the way, monophyly is a characteristic of taxons (groupings), not classification schemes, so it’s not really correct to say that the “prokaryote/eukaryote” classification is monophyletic as, for this example, the prokaryotes domain is paraphyletic and the eukaryotes is monophyletic. (Hope this is of some use and not only pedantry from my part.)

      • John Baez says:

        Just so everyone can understand this “monophyletic” business:

        (Click to enlarge.)

        The yellow group is monophyletic because it includes everything above a certain node in the tree. The blue group is paraphyletic because it consists of a monophyletic group minus one or more monophyletic subgroups—in this case just one, the birds. Any group that’s not monophyletic or paraphyletic is called polyphyletic.

        (And in case you’re a mathematician, ‘group’ here means ‘set’.)

        I don’t think it’s so terrible to say that once there were only prokaryotes, and then along came eukaryotes, even if prokaryotes include both bacteria and archaea:

        And by the way, this tree is a bit misleading. The ‘tree of life’ isn’t really a tree when you go far down enough! For example, eukaryotes were really formed by symbiosis from a bunch of different prokaryotes!

        So, the whole monophyletic/paraphyletic/polyphyletic terminology breaks down when we go back this far in time… or at least it needs to be generalized. I don’t know what the experts do about that, these days.

        • Martin Buchert says:

          John,

          of course you’ve got the topology dead on re the “root” of the tree. Interestingly, endosymbiosis (for the non-biologists here, that’s the generally accepted theory accounting for independent genomes within the mitochondria of all eukaryotic cells and within the chloroplasts of plant cells) is only one manifestation of Horizontal Gene Transfer (HGT). Sensu latu, HGT is a phenomenon that complicates (and confounds) cladistics, particularly at the base of the terrestrial tree of life in somewhat the same way that quantum effects confound Newtonian mechanics at micro scales.

          I’m a little out of date on this topic, but you may be interested to read Woese 2000 “Interpreting the universal phylogenetic tree” and particularly the section “When is a tree not a tree?” from Woese 2004 A New Biology for a New Century.

    • John Baez says:

      I suspect Slobodchikoff’s work on the language of prairie dogs will remain controversial until it’s replicated (or not). As Matías noted, it’s hard to believe things like this:

      The prairie dogs have different words for attributes such as color, size, and speed of travel. There were different words for different kinds of dogs, for a man with a yellow coat, and even for a man with a yellow coat with a gun.

      There was a nice radio show on this, which you can listen to:

      • Jad Abumrad and Robert Krulwich, New language discovered: Prairiedogese, 20 January 2011.

      It includes a game where you can listen to prairie dogs ‘talk’ and try to tell the difference between the different things they say.

    • Toby Bartels says:

      Indeed, prokaryotes are paraphyletic, but that’s to be expected when discussing a revolution: it will produce a revolutionary clade (monophyletic group) that incorporates the change and leave behind a reactionary grade (paraphyletic group) that doesn’t. This is true at least for revolutions 4–8 (although 5–7 happened more than once, so grouping together every revolutionary would be polyphyletic).

  4. Marc Harper says:

    Within language itself there have been several “evolutionary” transitions. Before the advent of writing, the storage of ideas encoded in languages was only in the brains of those understanding the language, and so at great risk to loss from say a local environmental disaster.

    Libraries, books, and electronic storage all increased both the capacity of the storage of ideas as well as the longevity. The major recent influence of computers and telecommunications has been the spread of ideas, which was of course much slower and geographically limited previously, as well as the ability to actively process and spread ideas without a human “middleman”. In the suggestive jargon of memetics, these would both be major steps in memetic evolution. If the evolution of ideas comes to be seen as an extension of biological evolution, we may one day view writing and electronic language processing as major transitions in evolution.

    You might be interested in the following paper: “Human language as a culturally transmitted replicator”, http://www.nature.com/nrg/journal/v10/n6/abs/nrg2560.html

  5. Ian Carmichael says:

    Two general works that seemed impressive for me were Zimmer’s The Tangled Bank and Prothero’s Evolution: What the Fossils Say and Why it Matters. A third which is more of a developmental examination of the idea is Peter Bowler’s Evolution: the History of an Idea.

    • sgadgil says:

      My recommendation for a book on evolution:

      • Richard Dawkins, The Greatest Show on Earth.

      This is really a book on the evidence for evolution, but has plenty of fascinating science illuminating evolution and is aimed at a general audience.

    • John Baez says:

      Thanks! I’ll check these out too. Back home in California I have a big fat illustrated book about life on Earth, by Dawkins. I forget what it’s called. The American edition lacked the beautiful colored photos of the British edition, but luckily I picked up this book in England.

      • Noah Snyder says:

        I read this book recently, and it was nice but was mostly old hat to me. Most of the examples are things you already know if you’ve read lots of pop evolutionary biology books. However, the stuff about development in C. Elegans is amazing, and I didn’t know about it before. (They know the complete developmental pathway of every cell in the organism, so that you can name them by which founder cell and then which side of each split it was on (there are 6 options here because cells can divide along any of the 3 axes).)

  6. benny says:

    not really a book, but the talk origins website (just google talk origins) is amazing. tons of faqs, debates (presented fairly) between creationists and evolutionists with annotations and rebuttals, documented histories of certain species evolving (such as the whale). it’s truly amazing.

  7. John Baez says:

    Over on Google+, Ralf Muschall corrected me:

    Cynodonts were not reptiles – the current convention AFAIK is to use the name “reptiles” for the part of amniotes that remained after synapsids split off.

    So now I’ve fixed my blog article. Cynodonts like this sociable Trirachodon:

    were among the synapsids, a group of animals that includes mammals but also ‘proto-mammals’ like these. I wonder how mammal-like these guys were, way back in the early Triassic. That’s 250 million years ago, only shortly after the Permian-Triassic extinction, long before the extinction of the dinosaurs 65 million years ago! Indeed dinosaurs didn’t even exist yet!

  8. There’s earlier evidence for social behaviour among insects: sophisticated wasp-like nest-building behaviour that is supposed to originate with some triassic hymenoptera from around 220 million years ago. It’s still not as far back as the Cynodont fossils, and there are no insect fossils, only nest fossils, but it is suggestive.

    http://www.nature.nps.gov/geology/paleontology/pub/grd3_3/pefo1.htm

  9. I posted a link to this thread for my 3,650 Facebook “friends.” The case can be made that the Internet is a nascent nervous system for the ecosphere, and thus a 9th phase of Evolution.

  10. Got Revolutions a few days ago, a jewel of a book. Currently reading it zigzag (avoiding Daisyworld for later). Among many things the book is a very smart way to call for a revolution. I love their term “Gaia device” for appropriate revolutionary “technology”. (I’m actually proposing such a “machine” for some years, but not holding my breath for it to get implemented anytime soon.) But this is not much elaborated in the last chapter of the book, except for the canonical Gaia device, carbon negative agriculture.

    • John Baez says:

      Great, I’m glad you got the book! It’s not very helpful when it comes to detailed plans of the future, but it’s great for understanding the past, and surely this carries useful lessons for us now. I hope to discuss it more here.

  11. Here is where the lessons of previous ‘revolutions’ are especially useful. As I said last time, they list four [...]

  12. P.F. Henshaw says:

    John, What’s special about speciation is that it’s an additive process that proceeds by a “punctuation”. That implies that nature *somehow* combines a radical discontinuity and complete continuity. What I’ve been trying to help you understand for years is the methodology that turns that seeming contradiction into a highly productive new line of research, for a wonderful new range of questions (like the ones you keep asking but don’t seem to want help with).

    Start from the before/after images of G.tumida (1) and then the path by which the evolutionary speciation jump took place (2), and then start asking questions. If you have no questions about how the evident processes emerged from their own environment, absent a theory to drive them, you won’t find the new line of research that is productive for exploring them.

    (1) http://synapse9.com/issues/images/Gp&t.jpg
    (2) http://synapse9.com/issues/images/GT-Fig2006-3.jpg

  13. Giampiero Campa says:

    I think that in Lenton and Watson’s list, the last item should realy be the “rise of agriculture” instead of the “rise of humanity”.

    in his last book, Pandora’s Seed, Spencer Wells argues that the fact that we started to act on the environment set in motion several feedback effects that really changed our life, and ultimately the world, for good.

    I am almost done reading it, and i have to say that i agree with him. If we were still hunters gatherers we would be still very much humans (perhaps even more so) and still use language a lot, but we wouldn’t have altered our own environment and we wouldn’t be facing either Apocalypse, Retreat or Revolution. We would just be the better hunters on the planet.

    • Martin Buchert says:

      I’ve not read Wells’ book, but we have an increasingly clear understanding that Homo sapiens’ revolutionary potency as an environmental engineer predates the domestication of plant species by many tens of thousands of years. Probably our earliest manifestation as an ecological force at regional to continental scales was when we began to structure ecosystems to our benefit via intentionally kindled fire.

      Some key voices here are Bill Cronon (UW Madison) and Steve Pyne (ASU).

      • I’ve become sort of a fire theorist (incl. psychopathologist) out of despair with the Late Homo S Sapiens’ performance at the open fire place out in the wild. The symptoms go from virtual coprophagia (burning plastic while grilling würstel) to basic fire-fuel process illiteracy (sitting in smoke, yet prohibiting tobacco smoking). It’s not just the stupid, it’s the denial of investing intelligence and taste in the maintenance of fire: The consumer mindset combined with compulsive throwaway disorder (into the fire) often manifests itself paradigamtically at the camp fire, ending in smoking debris and a cold dark wannabe tepee. One amazing thing is the vicious circle of stupidity: Folks can’t do fire for they’ve never seen a real fire burn for they can’t maintain one and so don’t even notice when it works.

        Never ever has civilization been that dependent on fire – yet they have no idea of it.

        So, my theory is: The prime revolution of mankind was usage of fire.

        It’s this exosomatic source of energy that discerns us from other animals. Plus, methinks the basic place / thing / process where we devoloped much of our intelligence (social and technological) is the open fireplace.

        Alas some time during Bronze Age, with the invention of the hotplate, intelligence turned into madness…

        • Georgiaberry says:

          I very much enjoyed reading your comment regarding fire – I am reminded every year at this time how divorced we are as a culture from the actuality of fire. My family heats our home with wood, and in the fall and winter, keeping up the fire becomes very naturally a main focus of our day. I often run into conflict with others who just set a thermostat and don’t give their comfort another thought. No, I can’t go to an impromptu dinner and movie, someone has to get home and feed the fire. No, we can’t come for a weekend visit, someone has to be home to tend the fire. Our connection with our home is strong and the rhythm of our lives changes naturally with the seasons. I find it very rewarding.

  14. Giampiero Campa says:

    Of course one could also argue that the rise of agriculture “had to happen” sooner or later, given our very human nature and capabilities.

    I am not sure, indeed chances are (as he explains in the book) that if it wasn’t for the Younger Dryas, we would still likely be all hunter-gatherers.

  15. Roger Witte says:

    In favour of language amongst dolphins and whales we have observations:

    1) Two whales meet and exchange calls. Amongst the calls are quotations from the characteristic song of a third whale, known to both of the other two. This is evidence for ‘names’ and ‘gossip’ although not definitive

    2) Two pairs of juvenile male dolphins meet and have a fight. The next day the losing pair gather together four more juvenile males and beat up the pair who originally won. The next day the original winners turn up with about a dozen friends … This is evidence for language and war

    Unfortunately I don’t remember the original sources where I came across either of these observations :(

    • John Baez says:

      Neat! Does someone out there know more details? If not, I’ll have to ask a dolphin.

    • John Baez says:

      Some people claim to have made big progress in understanding delphinese:

      The discovery of dolphin language, Wake Up World, 28 November 2011.

      This is a fairly disreputable website, featuring articles on ‘ancient aliens’ and ‘esoteric knowledge’, among other things. But the article looks interesting enough that I’ll read it tomorrow when I’m more awake. (I’m about to collapse right now.)

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