The meeting is on Sunday evening at 7:00 pm at The Franklin House, 263 Queen St. in Sreetsville. This is a relatively new Café Scientifique so new people are more than welcome. The talk is very informal (no slides or powerpoint) and there will be lots of time for discussion and debate. I'm told that various "refreshments" will be available to help make the evening more enjoyable.
(from Evolution by Accident)
Stephen Jay Gould wrote a book about the role of chance in evolution. He called it "Wonderful Life." On the surface it's a book about the Burgess Shale and the Cambrian explosion but there's a powerful message as well. Gould is interested in why some species survive while others go extinct. Are the survivors better adapted than the losers of is it a matter of luck? We could answer this question if we could carry out an experiment.
I call this experiment "replaying life's tape." You press the rewind button and, making sure you thoroughly erase everything that actually happens, go back to any time and place in the past—say, to the seas of the Burgess Shale. Then let the tape run again and see if the repetition looks at all like the original. If each replay strongly resembles life's actual pathway, then we must conclude that what really happened pretty much had to occur. But suppose that the experimental versions all yield sensible results strikingly different from the actual history of life? What could we then say about the predictability of self-conscious intelligence? or of mammals? or of vertebrates? or of life on land? or simply of multicellular persistence for 600 million years?
Stephen Jay Gould (1989) pp. 48-50
It was a silly analogy then and it's a silly analogy now. Every time you replay a tape it does indeed come out the same as last time. That's how tapes work.
ReplyDelete"You press the rewind button and, making sure you thoroughly erase everything that actually happens, ..."
DeleteGreat. And if you replay that tape, there will be nothing on it.
DeletePresumably the tape is *recording* what happens each time around. But I admit the analogy is somewhat confused given that the real issue is going back in time and not the medium used to record events.
Deletesome useful background reading
ReplyDeletehttp://bioinfo.med.utoronto.ca/Evolution_by_Accident/Evolution_by_Accident.html
http://tinyurl.com/pgl3z56
HHMI has come up some interesting resources at the high school and university freshman level for addressing evolution
ReplyDeleteA popular suite of activities is The Making of the Fittest: Natural Selection and Adaptation
http://www.hhmi.org/biointeractive/making-fittest-natural-selection-and-adaptation
Here is an excerpt from the video:
[DR. NACHMAN:] These are two different black mice and they each evolved on different lava flows. And the lava flows are hundreds of miles apart but the changes, the genetic changes that made these mice black, were different in each case. And what's amazing to me is how similar the black mice are. We didn't know when we started this whether we would find that they were the same genes or different genes. And we were really surprised to find that they were completely different genes. And yet, if you look at the mice they look almost identical.
[NARRATOR:] Clearly, there are different genetic ways to make a mouse dark. But once the beneficial mutations appear, natural selection, the non-random part of evolution, can, under very similar conditions, favor very similar adaptations.
[DR. NACHMAN:] In effect, each of these lava flows is like rewinding the tape of life [sic] and allowing evolution to occur again and again. And in each case, we find the dark mice have evolved.
[NARRATOR:] The rock pocket mice show us that evolution can and does repeat itself...and why evolutionary change is never-ending. As environments transform, so must the species that inhabit them, adapting and re-adapting in the great and complex battle of life.
I always thought this version of events somewhat “Panglossian” overstating the importance of Natural Selection and Adaptation in the grander scheme of things. For example, when rewinding and replaying the tape, the more likely outcome is always extinction.
Meanwhile, camouflage need not be the only successful option during the replay.
Finally, fixation of favorable alleles or combinations thereof (especially in smaller populations) need not NECESSARILY invoke Natural Selection and Adaptation.
I hope I am getting this all right... corrections and comment greatly appreciated
The history of life up to this time is heavily dependent on the asteroid collision that wiped out the dinosaurs. Had that not occurred, the history of life would be very different and the chances that we would be here at this point in time discussing the issue are remote.
ReplyDeleteIt is fairly clear that there is a strong random element to evolution. It is fairly clear that if something would have gone differently hundreds of millions of years ago, mammals as we know them would not exist now. It is fairly clear that humans as this very specific species that we are now are an accident and not at all inevitable.
ReplyDeleteBut I think that a lot of people overplay their hand trying to make that point. Convergence is a thing that exists, and unused niches don't stay unused for long.
Take that paragraph by Gould. Multi-cellular life? Even cyanobacteria have made the first step towards that kind of specialisation! And why would all of it die out? Just doesn't seem remotely plausible. Life on land - was he kidding? A massive empty area, originally without any competition but with plenty of energy and minerals for the taking, that has historically been colonised by dozens of lineages independently, and he somehow thought it conceivable that it could have gone uncolonised? No way.
Vertebrates? Basically just the concept of having stabilising elements inside the body. Maybe if we rewound the tape, something would evolve with the backbone on the front side and with six legs, but why would we assume that no worm would ever evolve stabilising elements on the inside?
Mammals? Again, how much similarity do we need before we count it? There are myriads of live-birthing vertebrates and invertebrates, and the nourishment doesn't have to come from teats for it to fulfil one of the prerequisites that make long-term parental care possible.
Intelligence? This I guess is the big one because so far we only have one example. And it might indeed be exceedingly rare. But still we already have several lineages that independently evolved ever more sophisticated brains; some corvids are in many ways more intelligent than chimpanzees. What else will follow in the next 200 million years? It is at least not obviously silly to assume that sentient life will evolve again sooner or later.
So I look over this Gould quote and think that it only works for a definition of "mammal", "vertebrate", etc. so narrow that nobody on this planet except a tiny minority of confused theologians would doubt that he is right. But if we ask for "something ecologically and morphologically pretty equivalent to vertebrates" or "some form of highly intelligent animal", then a lot of biologists would surely say that that part of morpho-space will be found again sooner or later given hundreds of millions of years to explore.
Let's remember that it's mostly religious people who are in the "humans were inevitable" camp, and for clear religious reasons.
DeleteI highly doubt there will be many believers ready to switch from the point of view that humans were created because the deity had humans in mind to the view that the deity had "something vaguely intelligent" in mind.
As it is, it's already hard to find believers willing to fully embrace evolution. Most people who tell you they have reconciled the two do so because they don't understand evolution, their religion, or both (most often it's both).
Also, there is another rarely mentioned aspect of the question:
Intelligence require complex organisms, and complex organisms are big and bulky. Being big and bulky means low effective population size, which in turn means that the role of drift in evolution is most significant precisely in the lineages that could plausibly evolve intelligence. Now, there are certain features that probably arise reliably and repeatedly precisely because drift is a major factor in some lineages, but on the balance, that means that the evolution of intelligent life is the most unpredictable (from the point of view of macroscopic factors) in its details.
Which has certain theological implications but that's a long discussion on its own.
I know, but of course I don't care about theological implications. And if people reconcile evolution and religion by being totally ignorant of what their religion is supposed to be like, more power to them. In my home country there are a lot of people who consider themselves Christian but would be surprised to hear that that means they need to believe in a literal Adam and in Jesus being a divine being as opposed to just a really swell moral teacher. In Bolivia I have seen a lot of people who consider themselves Catholics but who sacrifice to the Earth mother goddess Pachamama and to Ekeko the god of luck. It is all made up anyway, so why not make up something different?
Delete(The problem is certainly that its holy book anchors a religion to nonsense that can pop up again a few generations after one has thought it overcome, but that's a different issue.)
But anyway, I am happy to leave the theology to the religious. What gets me is when somebody thinks the best hypothetical examples to illustrate the importance of contingency include something as utterly implausible as life on land not evolving. Somebody sitting on the fence on the inevitability / contingency issue may well look at such an argument and conclude that the contingency side has lost its marbles, and I couldn't blame them.
I am just pointing out that his discussion can not be extracted out of its theological context. It's a good topic for purely scientific speculation (I don't think we will ever resolve the question conclusively), but in the real world religion is a big reason why we're having this debate.
Delete"Mammals? Again, how much similarity do we need before we count it? There are myriads of live-birthing vertebrates and invertebrates, and the nourishment doesn't have to come from teats for it to fulfil one of the prerequisites that make long-term parental care possible."
DeleteYes, but as in existing examples of fishes giving live birth or birds giving good parental care, just having these traits doesn't make them mammals, so neither would they be in the alternate history. The point is that the lactating furry animals called mammals would be unlikely to evolve again.
The point is that I doubt that that is the point. If somebody insists that very specifically humans were inevitable, then maybe. But who except a few confused believers does that? The real question is whether nearly all planets with life will sooner or later have multicellularity, life on land, animals with an internal skeleton, animals with an external skeleton, and increasingly more sophisticated brains.
DeleteOr if there are going to be planets with walking trees and 200 m long worms that eat granite. But the thing is, both of those are clearly physically impossible. What evolution can do isn't only constrained by prior mutations, it is even more constrained by what environmental opportunities are available, not least because the former can be overcome by throwing 500 million years at the problem.
It took more than three billion years of evolution for complex land-dwelling animals to evolve. That's not the kind of event that looks inevitable to me. Maybe if you replayed the experiment they would arise after two billion years but it's also possible that they would not have evolved by 3.5 billion years.
DeleteIf there is intelligent life on other planets then I suspect that it will be very different from us in ways that we probably can't even imagine. I wonder if each of those different life forms has developed theories about the inevitability of their evolution?
Or maybe Gould is right and intelligent life is such an improbable lucky accident that we are alone in the universe? We don't have enough evidence to conclude that complex multicellular life is inevitable so we have to consider other possibilities. That's the point that Gould was making and that's why he titled his book after the 1940s movie.
If somebody insists that very specifically humans were inevitable, then maybe. But who except a few confused believers does that?
DeleteKenneth Miller & Francis Collins for starters
Here is Jerry Coyne's indignant outrage in response
http://tinyurl.com/nap5z94
As discussed elsewhere, (and at the risk of provoking ire from some corners - Gould cut through the Gordian Knot of what should be a non-debate by invoking Non-overlapping magisteria
https://en.wikipedia.org/wiki/Non-overlapping_magisteria
Hey - I am not saying Gould is necessarily correct, I am saying Larry brought up Gould in the first place
DeleteBut if we ask for "something ecologically and morphologically pretty equivalent to vertebrates" or "some form of highly intelligent animal", then a lot of biologists would surely say that that part of morpho-space will be found again sooner or later given hundreds of millions of years to explore.
Now we are getting to something interesting. Theoretical morphology as a basic question has this: What are the hypothetically possible organisms (i.e. what would a universal morphospace look like), what are the hypothetically viable organisms (i.e which parts of the morphospace could be filled) and then what are the actual patterns of morphosapce filling. These questions are pretty wide open. However I would argue that your proposition that we would expect ecological equivalents to vertebrates to arise again rests on some bad ideas attached to some niche concepts. I like Günthers definition which defines an ecological niche as the overlap between a species ecological potential, i.e. the resources it can use, and the environments ecological licences, i.e. the resources present. This definition means that there are no vacant niches, although there can be vacant licences. The idea of vacant niches leads people to think that there are rather specific "targets" for evolution. If you think of it in terms of licenses you don't get this idea. If there's a forest ecosystem in which small branches fall of the trees and nothing makes use of them, what scenarios are there? A stick is a resource that in present ecosystems is utilized in many different ways. There are birds that build nests from them. There are fungi that grow on them. There are wasps that lay their eggs in them. There are ants that construct anthills from them. There are chimps that use them to poke at anthills...
Let's look at a specific type of ecological interaction: Insect damage on fossil leaves (I did some work on that, so that explains why I pick this examples). Leaves are of course a resource in an ecosystem that contains dicots. And there are quite a few insects that make use of them. When we look at fossil ecosystems we employ a classification scheme that rests on interactions that can be distinguished from one another in the fossil record. So far more than 200 interactions have been identified and given an identifier (a number preceeded by DT for damage type. So DT12 is an incision on the leaf margin for instance). Some of the DTs have no known recent counterparts. DT203 is a weird type of surface feeding, found in Messel, Eckfeld and Enspel. We don't know what insects produced this damage and they seem to have gone the way of the dodo. We do not see any "ecological equivalents" today.
A view of ecology that suggests that there are specific "slots" for species to evolve into is most certainly wrong. We do not find the same types of ecological structures throughout lifes history, even its relatively recent history.
Tom,
DeleteScience is a way of knowing and its ultimate aim is to arrive at "truth" about the universe. So far it has proven to be remarkably successful. There are many truths that science has discovered and most of these are universally accepted. (There are always kooks who will reject even the most obvious truths but let's not quibble.)
According to NOMA, religion, properly defined, is entirely outside of the domain of science. There is no overlap. I agree with that. Science and religion conflict and whenever religion attacks science, it loses.
Religion belongs entirely in a mythical magisterium where truth can be discovered by non-scientific means. It's a very popular domain because it includes homeopaths, UFO abductees, astrologers, and climate change deniers. It also includes Satanists, sorcerers, and Roman Catholics.
Here's the problem. The kook magisterium actually exists but has it ever discovered any truth about the universe that science hasn't revealed? In other words, is it a valid way of knowing or is it just a place where we park all those people who reject the only way of knowing that has proven to be successful?
The easiest way to answer that question is to come up with a "truth" that the kook magisterium has discovered and describe the way of knowing that led to the discovery. Remember that it has to be a way of knowing that's not scientific. Do you have such an example?
How about the existence of alien spaceships? There are thousands of people who believe with all their hearts that they have been abducted by aliens. Does the kook magisterium say that personal belief is a valid way of knowing the difference between what's true and what's not?
What about astrology? There are millions of people in the kook magisterium who believe that the stars rule your destiny in spite of all the scientific evidence against it. How does the kook magisterium justify that belief and conclude that astrology is true?
You inhabit that other magisterium—the one claiming that there are other ways of knowing about truth. You are well-placed to answer the question and show us one of those truths.
Go for it.
Hi Larry
DeleteThe thrust of my (admittedly non-profound) argument is that there are philosophical standpoints other than your embrace reductionist materialism that are completely compatible with modern science and that in fact many scientists can and do subscribe to such alternate POVs despite your attempt to dismiss these with your Reductio ad absurdum
Again, I cite:
http://www.nap.edu/openbook.php?record_id=6024
Seminal quote:
"Scientists, like many others, are touched with awe at the order and complexity of nature. Indeed, many scientists are deeply religious. But science and religion occupy two separate realms of human experience.
Demanding that they be combined detracts from the glory of each."
In other words, Gould (for one) would deem your so-called distinction between "rationalism and superstition" as a false dichotomy! I understand you (& John) disagree and I respect your POV, just as I respect and tend to agree with Gould’s.
But, we are rehashing: http://tinyurl.com/p2oknhf
re:
Here's the problem. The kook magisterium actually exists but has it ever discovered any truth about the universe that science hasn't revealed? In other words, is it a valid way of knowing or is it just a place where we park all those people who reject the only way of knowing that has proven to be successful?
The easiest way to answer that question is to come up with a "truth" that the kook magisterium has discovered and describe the way of knowing that led to the discovery. Remember that it has to be a way of knowing that's not scientific. Do you have such an example?
Let’s ignore your simultaneous begging of the question & Reductio ad absurdum for the moment; you will remember that I cited on earlier occasions the great Buddha and his non-theistic “four noble truths” arrived at by introspection: that life brings suffering, that suffering is part of living, that suffering can be ended and that there is a path that leads to the end of suffering.
My favorite quote along those lines by John Milton is reminiscent of Buddha:
"The mind is its own place and in itself, can make a Heaven of Hell, a Hell of Heaven."
I still submit therein lies much of value worthy of consideration that have more to do with ethics than epistemology. I am certain that many of Buddha’s truths (introspective reappraisals of a “correct” attitude to life) can be confirmed after the fact in some empirical fashion along the lines of a utilitarian redefinition of ethics; but then that would only buttress my rebuttal.
Best regards
Simon, you wrote, "Leaves are of course a resource in an ecosystem that contains dicots." As a pedantic botanist with a specialization in grasses and grass-like plants, I feel compelled to point out that leaves are of course also a resource in an ecosystem that contains monocots. Or ferns or gymnosperms, for that matter. (I hope you can forgive me.) :-)
Delete@bwilson: I would note that my sentence is stating an implication, not an equivalence. There are dicots -> leaves are a resource. It does not state There are dicots <- leaves are a resource and therefore the statement is correct, no matter whether dicotless ecosystems also have leaves as resources.
Delete@Larry: the only way of knowing that has proven to be successful
But is it? I'm always astonished by people who make these kinds of claims, given that mathematics and science are completely different ways of knowing, which means that if you stand by this statement you do reject mathematics.
@ Simon
Deleteyou raise an interesting point: would the gedankenexperimenten of Galileo and Einstein be considered non-empirical according to Larry's definition
ITMT - you are evoking memories of previous posts detailing the pitfalls of positivism
@ barb
DeleteBarb - what is your take on this paper:
http://www.ncbi.nlm.nih.gov/pubmed/11807559
I have been fascinated at the ubiquity of C4 metabolism in both monocots and dicots and frankly have been most uncomfortable at the invocation of convergent evolution by way of explanation
Hibberd & Quick may offer a resolution to this dilemma by proffering a ready-made exaptation.
your thoughts?
@ Simon
DeleteThis particular thread seems to be rehashing much.
Begging your indulgence, I am highlighting one of your excellent previous posts
http://sandwalk.blogspot.ca/2015/05/the-courtiers-start-replying.html?showComment=1432556984130#c6569219120851205147
best regards
Simon Gunkel says,
DeleteI'm always astonished by people who make these kinds of claims, given that mathematics and science are completely different ways of knowing, which means that if you stand by this statement you do reject mathematics.
Science is a way of knowing where truth is discovered using evidence and rational thinking. It's the way of knowing used by all legitimate academic disciplines. That includes history, English, and mathematics.
Please let me know of any truths discovered by mathematics using a different way of knowing that doesn't require rational thinking and evidence that it is true.
@ Larry
DeleteWhen contemplating mathematics , philosophers employ the terms 'true’ and ‘false’ in very different senses than a scientist arriving at empirical i.e contingent propositions.
In a sense, the entire field of mathematics could be considered one grand tautology!
http://plato.stanford.edu/entries/wittgenstein-mathematics/
I am not certain that Simon would agree with my over-simplification.
DeleteI was merely attempting to open the door to a sober consideration of alternatives to strict adherence to some uncompromising version of "positivism" which Larry and John seem to advocate.
Tom Muller says,
DeleteThe thrust of my (admittedly non-profound) argument is that there are philosophical standpoints other than your embrace reductionist materialism that are completely compatible with modern science and that in fact many scientists can and do subscribe to such alternate POVs ...
The thrust of my argument, and Jerry Coyne's, is that we are not talking about philosophical standpoints and we are not talking about the jobs that scientist do. We are talking about ways of knowing whether something is true or not true.
I am not philosophically committed to reductionism or materialism. I'm just interested in knowing what's true and what's not true. Science as a way of knowing has been very successful in that quest and, so far, the available evidence indicates that there are no supernatural beings. That's equivalent to materialism but it's a conclusion, not an a priori assumption. It can change if new evidence becomes available.
People committed to the philosophical stance of materialism find themselves in the fortunate position of holding a position that's compatible with what science has discovered. People committed to other stances, such as belief in gods that intervene in the world, find themselves in the awkward position of holding a belief that is not compatible with the scientific way of knowing.
That's fine but it's not the point. The point is whether there is any way of knowing that leads to truths that may conflict with the scientific way of knowing or supplement it with additional truths.
Please give me an example of a "philosophical standpoint" that's not in conflict with the scientific way of knowing (i.e. compatible) AND reveals truths that science can't discover.
Your Buddhist rules of behavior don't count even though you refer to them as truths. Lot's of societies make up rules of behavior and they are all subject to the same criteria; namely, do they make sense, and do they work. Just because they work to produce stable societies doesn't make them examples of true knowledge.
Jerry has done an excellent job of explaining why science and religion are in conflict. You should read his book. When you discuss this issue with others, make sure you are using the same definitions that Jerry and I (and many other) use.
None of us are saying that religious people can't do good work in biology or geology or any of the other traditional science disciplines. The same is true of astrologers and homeopaths. This does not mean that religion, astrology, and homeopathy are compatible with the broad definition of science as a way of knowing.
Science is a way of knowing where truth is discovered using evidence and rational thinking. It's the way of knowing used by all legitimate academic disciplines. That includes history, English, and mathematics.
DeletePlease let me know of any truths discovered by mathematics using a different way of knowing that doesn't require rational thinking and evidence that it is true.
Now you are defining science in such a broad and general way, that it does include things like theology. Science is defined through the use of empirical data. In the simplest terms it works through the hypothetico-deductive method, where a hypothesis is erected, then data is collected which could potentially lead to the rejection of the hypothesis. If the hypothesis is not rejected, it is deemed empirically adequate until it is rejected by new data.
This unifies science. Now, other academic disciplines have somewhat different approaches. Cultural studies use the historical-critical method, where source texts are contextualized and an argument is presented on which sources approximate the truth. Mathematics uses rules of inference and a set of axioms to prove sentences that follow from the axioms given the RUIs. That's how a formal deductive discipline works. You skimp over these differences, but they are not trivial at all. Even at its most theoretical science bows to empirical data. No matter how elegant our models may be, they can be invalidated by observations. That does not hold in mathematics. Nothing we could observe could ever invalidate the proof that there are infinitely many primes or that the interior angles of a triangle in euclidean geometry sum to Pi.
would the gedankenexperimenten of Galileo and Einstein be considered non-empirical according to Larry's definition
It seems like Larry is taking the opposite route here and somehow the irrationality of 2^0.5 is a scientific question. But I think Einstein himself thought of the EPR Gedankenexperiment as non-scientific (and then of course Bell showed that it was in fact scientific). Gallileis thought experiment has to be clearly included in science, as it is mainly about showing that the existing hypothesis of Aristotele was inconsistent.
@Simon Gunkel
DeleteYes, I use the broad definition of science when I talk about these issues. If you want to understand my meaning then you have to (provisionally) accept my definition. I've explained it repeatedly over the past few decades.
You are free to use another definition of science but in that case you'll have to offer up another word to describe what I call "science."
Simon Gunkel,
DeleteAgain your argument seems to rest on an extremely narrow view of what you would accept as being a convergence. Yes, if the planet is covered in dead leaves and small twigs that nobody so far uses then I would totally expect something to evolve in short order to consume that uncontested resource, whether you call that a target, a niche or a license. And does it matter if somebody nibbles at the leaf from the sides or from the surface? Does it matter if an intelligent being is a human or six-legged and scaly?
As far as I can tell, we find the same types of ecological structures and the same types of body plans and organs over and over again. Totally different groups of animals have evolved bilateral symmetry, mouth and anus, a specialised front segment with brain and sensory organs, gonads at the back, heart, kidneys, etc. that I would totally expect that to pop up again if the tape were rewound or on other planets. Same for plants, herbivores, carnivores, detrivores, etc., even down to the same few hunting strategies popping up over and over again. The only stuff that doesn't seem to fall into the same slots every time is something as detailed as whether your herbivores have hooves or soft feet, for example.
The only counter-argument against this ubiquitous convergence is that it is all somehow contingent after all due to some very deep constraint in the genome of the ancestor, even if that ancestor was still a little piece of jelly without an after. There are words for that kind of stock answer; making your hypothesis untestable, moving the goal-posts, pseudo-science.
I agree with you about the use of empirical data defining science, by the way.
Larry Moran,
We will have to agree to disagree. It seems you mostly see evolution as a random walk that can go nearly wherever it wants but for some strange reason only goes into a few of those many possible directions on each run of the tape. (Why does it not go everywhere it can? Not enough space for that many organisms?) I, on the other hand, see evolution as a random walk that is, in the long run, more heavily constrained by what can even possibly work than by whether it will find the things that work.
For example, I would not expect intelligent life on other planets, if it exists, to be that weirdly different because we can indeed imagine a lot of extremely weird stuff - just pick up a bunch of SF novels. The problem is that much of what those authors come up with is either physically, ecologically or evolutionarily impossible. It is great fun, for example, to invent an alien species that considers lying a virtue, but I am reasonably sure something like that will never work in practice.
Now you are defining science in such a broad and general way, that it does include things like theology.
DeleteI don't disagree with that definition. If there were sufficiently good reasons to think that God exists, then theology would be a legitimate science. Today there aren't such reasons so it's no longer a legitimate field of study, but it wasn't always that way. Which leads me to:
Science is defined through the use of empirical data.
That's not really how it is. That is a modern development based on the empirical success of using empirical data to understand the world. But if you go back in history, what we call "science" today used to be called "natural philosophy" until quite recently, which in turn split from general philosophy in the late Middle Ages. And philosophy itself only split from theology in the western world in the scholastic period, after a lot of fighting. There was no separation between theology, philosophy and the rudiments of science, and nobody thought of those things as separate fields of inquiry. Modern science is a descendant of medieval theology as foreign as they are to each other today.
The modern attempts to erect walls between the disciplines become really quite artificial when one considers the history of intellectual thought. And they mask that historic continuity in ways that actually hurt those trying to defend science against religion -- the realization that it was scholasticists like Aquinas who let the genie out of the bottle with their emphasis on reason (even if they eventually always fell back on revelation when they saw a need for that and even if what they applied reason to was outright silly a lot of the time) and that's why we have scientific atheism today is very powerful and should not be kept hidden.
Yes, I use the broad definition of science when I talk about these issues. If you want to understand my meaning then you have to (provisionally) accept my definition. I've explained it repeatedly over the past few decades.
DeleteAs far as I'm aware your definition is rather peculiar. Now, my native german has the word Wissenschaft, which is a broad umbrella term for all academic disciplines and it literally means "knowledge making". Science in english usually is equavalent to Naturwissenschaften, i.e. the making of knowledge about nature. The main issue with your term is that it makes your central claim vacuous. All valid ways of knowing are Wissenschaften and thus if you use science as an umbrella term for all working ways of knowing, then of course all working ways of knowing are science in that sense. However defining science in this way does neither tell us how we are to obtain knowledge, nor what constitutes that knowledge and not even what that knowledge is about. It's also worth noting that your definition of science does not make it a way of knowing, but a collection of different ways of knowing.
You are free to use another definition of science but in that case you'll have to offer up another word to describe what I call "science."
As noted above, such a term is available to me in german, but I'm not sure whether there is an equivalent in english.
As far as I can tell, we find the same types of ecological structures and the same types of body plans and organs over and over again. Totally different groups of animals have evolved bilateral symmetry,
DeleteI count one lineage where that happened (Bilateria). There are several instances where bilateral symmetry got lost again, though.
mouth and anus
Probably once, maximally twice (either two body openings happened before the Protostomia-Deuterostomia split or independently in both groups).
a specialised front segment with brain and sensory organs
Bilateria again
gonads at the back, heart, kidneys, etc.
It's Bilateria again for gonads and kidneys. Hearts are absent in most animals, a closed circulatory system only evolved in chordates.
So you have listed only traits that are abundant in todays biota because they were present in the common ancestor of most animals. They did not arise convergently multiple times.
that I would totally expect that to pop up again if the tape were rewound or on other planets.
Let's rewind the tape 700Ma or so, when the MRCA of the bilateria lived. There was one single species that had bilaterial symmetry, a gut with two openings, an accumulation of nerve cells in the frontal segment, some sensory cells close to that, gonads and kidneys positioned in some segment further back. You point to that and say: "This one had to evolve"? That's not different at all from pointing at a modern butterfly species and saying "this particular pattern of colors on the wings just had to evolve". The only reason you entertain that thought for the Urbilaterian is that of course it gave rise to the majority of animals later on. But consider this: One meteorite at the wrong place and the Urbilaterian would have been gone. Life would not have been the same and a radially symmetric AlexSL might make the same argument about Cnidocytes.
Same for plants
Photosynthesis: Evolved once in the Cyanobacteria. Through endosymbiosis ended up in Archaeplatida. And when it evolved it wiped out most of the existing life, because Oxygen is rather happy to mess with any biochemical pathway you might have. Life was damned lucky not to get wiped out completely.
herbivores, carnivores, detrivores, etc.,
Didn't exist for the first well over 2 billion years of life.
The only counter-argument against this ubiquitous convergence is that it is all somehow contingent after all due to some very deep constraint in the genome of the ancestor
Nope. The counter-argument to these particular examples is that they are not in fact instances of convergence, but represent ancestral states that one particular species had at one time.
DeleteI don't disagree with that definition. If there were sufficiently good reasons to think that God exists, then theology would be a legitimate science. Today there aren't such reasons so it's no longer a legitimate field of study, but it wasn't always that way.
And we are back to what I said in the other thread. Existence is not an issue. We do not have any good reason to think that Hilbert-spaces exist. Or that a euclidean plane exists. How about the set of all non-Borell subsets of C^12? Does that make mathematics a non-legitimate field of study?
For that matter, does energy exist? There are pretty good reasons to think it doesn't (The Noether theorem tells us that for every diff. symmetry in a dynamical system there is a function from the state space to R that is constant in time. If physics is governed by laws that are constant in time, then this produces such a function and that is how we define energy. If you want to you can apply this to any dynamical system and if you are willing to put some work into finding out something utterly trivial, work out the energy in population genetics, where the state space is given by allele frequencies at n loci). So if energy doesn't exist, how does high-energy physics have any standing?
The modern attempts to erect walls between the disciplines become really quite artificial when one considers the history of intellectual thought.
Well, I think that a) noting that there are different ways of knowing and classifying them actually helps. That people have been ignorant about these boundaries in the past is no good reason to ignore them now, but I also think that b) it is of course useful to remember that people were not aware of these boundaries in past discourse.
we have scientific atheism today
But do we? Most of the atheism these days is so at odds with science it isn't even funny. Dan Dennett has philosophical convictions that are as much at odds with evolutionary biology as Ken Hams (and Ken Ham bloody fool he is at least notices that, Dennett instead wrote a horrible book called "I don't get the central ideas of Darwin" [title may only be approximate]). We have 18th century answers to 13th century theology and they are all wrong, because they fundamentally conflict 19th and 20th (and 21st) century science.
And as we discussed in the other thread, you are free to redefine god in any way you want, but that doesn't change the fact that this is not the god the vast majority of both people and theologians believe in.
DeleteWell, I think that a) noting that there are different ways of knowing and classifying them actually helps. That people have been ignorant about these boundaries in the past is no good reason to ignore them now, but I also think that b) it is of course useful to remember that people were not aware of these boundaries in past discourse.
DeleteThere is only one set of real ways of knowing - those that work. The rest are ways of not knowing. You can go back and forth on this endlessly, but the fact remains -- empirical success is the only way we have of validating our "ways of knowing". I don't see how that contradicts modern science in any way, whether it's derived from 18th century thought or not (I don't agree it is).
But do we?
So you argued with examples (let's ignore there validity for a moment) in favor of the nonexistence of something. Do I need to explain the problem with that given the kind of argumentation you have brought here?
Simon Gunkel says,
DeleteAs noted above, such a term is available to me in german, but I'm not sure whether there is an equivalent in english.
Exactly. That's why we're stuck with different meanings of the English word "science." That's not a problem as long as you realize that I'm talking about "scientia" or "Wissenschaft." See John Wilkins discusses the "Demarcation Problem".
I side with those philosophers who prefer a broad definition of science—the one that's more akin to "scientia" or the German word Wissenschaft. According to this view, science is a way of knowing based on evidence, rational thinking, and healthy skepticism. As long as you are employing this approach, you are engaging in a scientific way of knowing. This includes economists, physicians, and philosophers.
We've discussed the demarcation problem extensively on this blog and this is not the place to continue that discussion. What's clear is that the standard methods of obtaining knowledge by "Wissenschaft" rely on evidence and rational thinking. You may quibble about the exact methodology but it does not include accepting truth based on faith or personal revelation.
Thus, science conflicts with religion as a way of knowing. Furthermore, there's no evidence that religion, or anything else, has a successful way of knowing not covered by science (Wissenschaft). That includes mathematics.
Obviously you know more about animal evolution than me, but yes, I assumed that that stuff had evolved twice. As for the loss of bilateral symmetry, it has also been gained independently from radial symmetry. But that is not the point. What is relevant is that only certain morphologies and physiologies allow an organism to move into a given space or make use of a given resource, and that if that resource is available the first one to hit that morphology and/or physiology will find themselves in Schlaraffenland. Yes, imagine a meteorite wiping out the Urbilaterian. Does that suddenly make it Not A Good Idea to have an after?
DeleteI am not saying "this one had to evolve" - quite the opposite. I am saying that if that one had died, it would be ludicrous to expect that everything else would happily stay in the jellyfish and sponge morphospace. For starters, they would, if they evolved in that direction, not face face any competition from the Urbilaterian. Maybe a cnidarian would be making the same argument now if such a meteorite had happened - but it would not look like today's cnidarians because its ancestors would have had vastly more opportunities and thus diversified into many more different morphologies that were on our planet barred by the lineages that figured them out them first.
As for photosynthesis, that is not quite true. Using water as the electon donor evolved only once, but there are other lineages of bacteria that have independently evolved photosynthesis. I assume the hard part to figure out is not how to use the energy source but how not to poison yourself with the resulting oxygen.
Didn't exist for the first well over 2 billion years of life.
Great. Somebody living in 1200 CE could just as well argue that if somebody had killed Leif Ericsson in a tavern brawl no European would ever have discovered America. Oh wait...
Obviously life has to start simple and without carnivores. I am not even saying that there might not be planets out there where something like Eukaryotes hasn't come up even after three and a half billion years. I am just saying that given enough time life must converge on the same few solutions because they work, because only a minuscule part of morphospace doesn't have you expire the second you hatch or germinate.
There is only one set of real ways of knowing - those that work. The rest are ways of not knowing. You can go back and forth on this endlessly, but the fact remains -- empirical success is the only way we have of validating our "ways of knowing".
DeleteWell, in this case you do reject mathematics, which does not in any way rest on empirical success. If you want to reject anything that is not empirical, you reject most if not all academic research. In fact, you have a hard time even justifying science with such a view.
I don't see how that contradicts modern science in any way, whether it's derived from 18th century thought or not (I don't agree it is).
???
Do I need to explain the problem with that given the kind of argumentation you have brought here?
Yes, you do, because I don't think there is one.
Thus, science conflicts with religion as a way of knowing. Furthermore, there's no evidence that religion, or anything else, has a successful way of knowing not covered by science (Wissenschaft).
Given your broad definition, the following is true:
a) Science is not a way of knowing at all. It encompasses several different ways of knowing, including
b) Theology as the practice of inferring statements from dogmata.
I'm not sure what religion is, then, but theology has operated as a science in your sense for a pretty long time. The explicit goal of scholasticism was to put catholicism on a rational foundation.
What is relevant is that only certain morphologies and physiologies allow an organism to move into a given space or make use of a given resource, and that if that resource is available the first one to hit that morphology and/or physiology will find themselves in Schlaraffenland
DeleteBut, to reiterate my earlier point about Günthers niche concept: These morphologies are not unique. There are usually multiple ways to make use of any given resource. The mouthparts of insects that produce surface feeding on leaves differs from those of insects that produce hole feeding on the same. Same resource, different usage and different meorphology. We should also note that resources sometimes remain vacant for very long times. Both vascular plants and insects were around in the Silurian. The first traces of herbivory are known from the Carboniferous. That's a span of 100 million years.
I am just saying that given enough time life must converge on the same few solutions because they work, because only a minuscule part of morphospace doesn't have you expire the second you hatch or germinate.
And that's where your reasoning is flawed. The argument is about what percentage of viable morphologies have actually been realized. The percentage of morphologies that is viable doesn't enter there. Imagine me stating that I have hidden one of my nostril hairs somewhere on earth. Your argument boils down to "It's easy to find, because earth is small compared to the known universe". But it's not easy to find at all.
BTW, how many eyes do you think animals should generally have (that's always an interesting one)?
I don't really care how exactly the mouth parts are formed, just as the exact way the brain is wired to the eyes doesn't matter for the question whether intelligent life may evolve again.
DeleteSure about the Caboniferous? I am quite certain I read about feeding traces from much earlier. Also, how would the food chain have worked without any herbivory? Insects just eating each other in a perpetuum mobile style cycle?
No, a better analogy is that you have left one cubic metre of bundled 100 Euro notes somewhere in the open in Germany and still expect it to be there five years later.
Do you really think that eyes are a good example for contingency given the awesome degree of convergence between octopod and vertebrate eyes? Also, it doesn't really matter; what seems more impressive is how it seems extremely easy and useful it seems to be for animals to evolve the ability to see.
Sure about the Caboniferous? I am quite certain I read about feeding traces from much earlier.
DeleteIndeed, see link.
Re Simon Gunkel
DeleteActually, energy is a well understood concept in mathematics. In the application of the mathematical theory of groups in physics, an operator that represents energy generates static time translations. Thus the statement that energy is a conserved quantity is equivalent to the statement that the laws of physics are invariant under static time translations, meaning that they are invariant in time. Other conservation laws of physics also have mathematical concepts. For instance, conservation of angular momentum is equivalent to the statement that the laws of physics are invariant under static coordinate rotations.
Sure about the Caboniferous? I am quite certain I read about feeding traces from much earlier.
DeleteIt got rather late when I was writing that reply. I was aware of the Labandeira paper Piotr cited and what I wanted to get at was the lag between the first appearance of leaves and the first traces of leaf feeding (since my work was focused on leaves, that's the figure I had in mind). Fig. 1 shows a lag of 76Myr for the FAD of leaves and the first traces, terrestrial ancestors of modern insects go back a bit further, assuming the molecular dates of Misof et al 2014 are fine, giving the ~100Ma lag I was thinking about. Bad phrasing on my part, yes, feeding on sporangia and stems goes back quite a bit further.
Also, how would the food chain have worked without any herbivory?
There were sources apart from vascular plants that are thought to have played a greater role in early terrestrial arthropods, primarily lichen and algal mats on tidal flats, both of which provided biomass.
@colnago80. Yes, I'm aware of the equivalence of conservation laws with invariances under some coordinate transformations. This is what the Noether theorem states (which I did explicitly cite up there) and not at all at odds with my argument.
Do you really think that eyes are a good example for contingency given the awesome degree of convergence between octopod and vertebrate eyes? Also, it doesn't really matter; what seems more impressive is how it seems extremely easy and useful it seems to be for animals to evolve the ability to see.
DeleteI did ask a specific question, about the number of eyes you would expect to find.
What is relevant is that once again, some light sensitive nerve cells were probably present in the Eumetazoan ancestor, which even predates the Urbilaterian. Cnidarians have orthologs of all bilaterian opsins for instance. Again, it's ascribing convergence to a state shared through common ancestry. And yes, the eyes of vertebrates and cephalopods show convergence. But then again, there is a wide range of eye setup among metazoans. Finally, to repeat my question: How many eyes would you expect?
Well, in this case you do reject mathematics, which does not in any way rest on empirical success.
DeleteNot sure it would be quite as popular (taught to schoolchildren, for example) were it not the basis for knowledge that has provide empirically "successful."
One can look at logic or mathematics divorced from empirical reality (e.g., how many angels can dance on the head of a pin), but science utilizes both logic and mathematics together with empiricism. Certainly logic and mathematics help to suggest empirical experiments that may advance scientific knowledge, and they help verify the correctness (or not) of those suggestions.
"provide empirically" s/b "proved empirically"
DeleteNot sure it would be quite as popular (taught to schoolchildren, for example) were it not the basis for knowledge that has provide empirically "successful."
DeleteDoes this matter, though? The question is whether mathematics produces knowledge, not whether that knowledge is useful.
One can look at logic or mathematics divorced from empirical reality (e.g., how many angels can dance on the head of a pin)
I don't think that your example is a mathematical question at all. A mathematical question divorced from empirical reality looks like anything methematicians publish. For instance, given X_i are random variables, with lim (n->inf) sum (i,j=1..n) COV(X_i,X_j)inf) sum(i=1..n) (X_i)/n =lim(n->inf) E( sum(i=1..n) (X_i)/n )=1
That is a stronger claim than for instance
lim(n->inf) VAR(( sum(i=1..n) (X_i)/n)=0
Although in practical applications, nobody bothers with the difference between p-almost sure convergence and L2 convergence (there are other sums of RVs which use different conditions which do have L2 convergence, but no not converge p-almost surely).
The question of whether mathematics produces knowledge is completely independent from its usefulness in science. In the same way that the truth of a scientific theory is independent from it's usefulness in engineering. Does my work on Oligocene insect herbivory have some practical applications? Nope. But it does produce knowledge.
Just noting that the question of practical applications is not the same as the question of usefulness to science.
DeleteIf one doesn't use logic and mathematics to determine fertile research/experimentation directions, then what would one use?
Hi Larry
DeleteAt first you say:
The thrust of my argument, and Jerry Coyne's, is that we are not talking about philosophical standpoints and we are not talking about the jobs that scientist do.
Then later on you continue with:
Please give me an example of a "philosophical [sic] standpoint" that's not in conflict with the scientific way of knowing (i.e. compatible) AND reveals truths that science can't discover.
I can do little to improve on Simon’s Teutonic responses (German is also my first language). Let me just say it is possible that the whole is greater than the sum of its parts, perhaps emergent properties are operative which do not lend themselves to reductionist analysis.
You are evoking memories of undergrad courses an some great books I needed to study such as Copeland’s Neurophilosophy: Toward a Unified Science of the Mind/Brain
Your particular definition of the “scientific way” according to your later endorsement of “demarcation” would appear to be empirical positivism aka material reductionism. In other words, some (including Popper) would suggest you are begging the question.
That is why Popper came up with his version of falsifiability in contradiction to Positivist verificationsim ( you seem to be endorsing verificationism), a distinction very well understood by Gould leading directly to his NOMA
According to your strictures, subjective truth is ipso fact impossible. Yet any philosophy freshman conversant with Descartes’s Discourses would counter that maybe it is really not all that simple.
OK – you always complain when I wax eloquent and take too long leaving you with some “non-reply”.
I will counter that my sense of self (i.e. the first person singular) and my current state of consciousness is very “real”. Not only that, it is real in a manner that cannot be addressed empirically by “other minds” like yours for example. As a result of this conundrum, some philosophers have resorted to “dualism” while others have gone so far to state that consciousness is therefore not real and must therefore be an "illusion".
We already signed off on this – both those proposed solutions are incorrect.
But yet again (as also mentioned above) we are rehashing.
http://sandwalk.blogspot.ca/2014/09/the-logic-of-lawyers.html?showComment=1410962851387#c685137994803165467
Simon Gunkel,
DeleteThis logic is making the contingency hypothesis irrefutable; in the end, everything was already predetermined in the genome of the first cell on the planet, right?
I do not expect any number of eyes, although I would expect that bilaterians would have the same number on the left as on the right, as with most of their organs. Further that organisms that need depth perception need to evolve more than one eye. I would also say that the facets of complex eyes and individual camera eyes cannot be compared in numbers if the functionality of one camera eye can only be achieved by having hundreds of facets.
in the end, everything was already predetermined in the genome of the first cell on the planet, right?
DeleteNope. I'm not sure where you are getting that from, though. We do know that the common ancestor of eumetazoa had light sensitive cells however and that no entirely new opsins have evolved among animals afterwards.
As to eyes, let's say that we are not counting individual facets. How many? 7? 12? Opabinia from the Burgess, one of the stars in Wonderful life had 5. I have 2. What number would you expect to come up?
Tom writes:
Delete"I have been fascinated at the ubiquity of C4 metabolism in both monocots and dicots and frankly have been most uncomfortable at the invocation of convergent evolution by way of explanation"
What explanation are you comfortable with?
@ N. Manning
DeleteRe: the ubiquity of C4 metabolism and convergent evolution.
I refer you to Barb’s answer below summarizing and explaining what only at first glance appeared to be a markedly naive ‘adaptationist’ rendition of evolution.
http://tinyurl.com/njpct3f
Given the remarkably limited repertoire of genes in a vertebrate genome and commonalities of the "developmental-genetic toolkit" amoung all vertebrates as often cited by those who ballyhoo the evodevo narrative… perhaps the story of C4 evolution has a meta-lesson.
If we should not be surprised at the frequent occurrence of C4 metabolism in plants, then perhaps should not be too quick to dismiss the notion that rewinding the tape would as likely regenerate “self-conscious intelligence” if indeed Piotr & Alex are correct that such intelligence has a decidedly strong selective advantage.
Simon,
DeleteI am getting that from it being the fallback position of those who think everything is randomness and contingency, even in this discussion: "Look, there is so much convergence, doesn't that show that some things will pop up over and over again?" - "Ah, but they only do because they are contingent on the common ancestor." This is making the all is contingency position unfalsifiable until we find at least one other Earth-like planet with life (if ever).
I really do not understand why I should nominate a number of expected eyes; I don't expect anything as detailed as that. On a different planet, the dominant large-sized animal clade may well walk around on two legs and a tail transformed to serve as third leg, and have four eyes and a beak as standard mouth-parts. So what? The thing is only that I can hardly believe that there will be planets where "heterotrophic multicellular organisms with active movement" will not be hit upon given enough time, and once you have that starting point, you can expect the same solutions to work as they did in our case: camouflage, fleeing, congregating in herds or flocks for mutual protection, parasitism, getting cleverer at exploiting opportunities... What exactly they look like is irrelevant.
... Or maybe 5 eyes like modern grasshoppers?
DeleteI am a big fan of P Z Myers’ blog.
DeleteMyers first alerted me to the suggestion that no basal non-bilaterian animals (except for placozoans) currently exist.
http://scienceblogs.com/pharyngula/2006/05/08/hox-genesis/
Myers also directed my attention to the amazing fact that like molluscs and vertebrates, the box Jellyfish also possess true eyes, complete with retinas, corneas and lenses.
Box Jellyfish can pursue evasive prey by using their eyes. At a minimum, this behavior implies an arc-reflex predicated on a central nervous system.
Textbook definitions of nerve-nets are clearly specious. Box Jellyfish ganglia may not be clustered at an anterior end; but their neural organization clearly is “central” even while spatially dispersed.
Regarding the repeated “convergent” evolution of eyes; no surprises really given identical molecular toolkits were present in all lineages from a common ancestor that was bilateral, triploblastic and with both rhabdomeric & ciliary photoreceptors
http://scienceblogs.com/pharyngula/2011/10/26/how-many-genes-does-it-take-to/
http://scienceblogs.com/pharyngula/2011/03/15/brachiopods-another-piece-in-t/
There are lots of big complex brains that don't produce civilizations. It
ReplyDeleteseems our brains didn't produce civilizations until the right plants appeared.
Thje right plants (and animals) did not just "appear". Some people, several times independently, hit upon the discovery that some of the edible grains can be cultivated in a convenient place rather than collected in the wild (with unpredictable results). Also, that some game animals could be controlled and gradually domesticated -- something that happened to the ancestors of dogs a long time before the advent of agriculture. But of course in some areas far from the centres of the neolithic transformation (Australia, southern Africa, the Arctic) hunter-gatherer populations have continued the ancestral ("uncivilised") subsistent mode of our species.
Deletesubsistent --> subsistence
DeleteI would argue that the mutations enabling wheat and maize pretty much just happened.
DeleteFor the purpose of thinking about SETI, lots of things leading to technology are iffy.
DeleteAll this college freshman speculation is just fine, but the only data we have to go on are the single history of life we have, either how many times some event has happened or how long it took to happen. Not much.
DeleteGiven that crappy data, though, once you get H. sapiens, technological civilization seems inevitable in short order, i.e. an eye-blink in geological time.
And plenty of niches remain unfilled for very long periods. Niches aren't platonic ideals; they depend on the structure of the biota. Gould's point was that evolution is a twisty and contingent process. Sometimes you can't get there from here, and even if some character would be highly advantageous there may be no pathway to it. If the niche for our sort of being is inevitably filled, why did it take 4 billion years?
My own view is that while our niche (if it can be called that) isn't inevitable, but that a (slow) arms race towards more sophisticated brains is inevitable once you have animals; that animals are inevitable once you have multicellularity, enough autotrophs to feed on, and enough time to evolve; and so on backwards.
DeleteSo why have so few animals participated in this arms race? A very few groups of vertebrates and one bunch of cephalopods. In what way is that inevitable? The history of evolution of intelligence could as easily be explained by a random walk as by any long-term trend.
DeleteMaybe it is only me, but I find it implausible that a very specific, complex trait such as our brain would evolve entirely through a random walk, without any selection.
DeleteAnd why have so few plants evolved high salinity tolerance? Surely if this trait was an advantage and selected for, all lineages of plants should evolve towards salinity tolerance at the same time, even epiphytes in a tropical rainforest? No, wait...
@ Alex
DeleteWasn't Gould the first to consider higher brain functions of the human to be another "spandrel"; a fortuitous accident of heterochrony, specifically neoteny?
I do not see how the ability to appreciate Bach's polyphony represented any selective advantage for my ancestors.
Music is syntax without compositional semantics. The ability to appreciate music (almost ceratinly older than spoken language) is closely related to the ability to compute the phrasal structure of speech. I hope you can see the selective advantage of language and the things it enables -- social cooperation and cultural memory.
DeleteMusic? I can believe its appreciation is a spandrel, in particular of speech, as Piotr argued. This might be of interest, not least with relevance to the question whether we are oh so special.
DeleteBut what would our higher brain functions be spandrels of? Is it so hard to imagine that being intelligent is an advantage that can be selected for under the right circumstances?
@ Piotr & Alex
DeleteAgreed,
...meaning either I probably misunderstood Gould when he described brain allometry as a fortuitous accident of heterochrony and a mere by-product of natural selection
... that - or others present are themselves misreading Gould by extrapolating Gould's understanding of randomness and contingency into a contradiction of neo-Darwinism Gould himself never endorsed.
Barb's insights regarding the frequency of independent C4 evolution in plants makes we wonder out loud if the power of adaptation can too easily be underestimated ergo my citation of the HHMI study with pocket mice above
@Petrushka
DeleteI would argue that the mutations enabling wheat and maize pretty much just happened.
Not sure what you mean by mutations here.
The ancestor of wheat was a perennial grass and you would have never recognized the ancestor of corn had you walked right by it.
Both underwent major artificial selection.
Much the same can be said for most fruits and vegetables that are staples of the modern diet, a good example being the banana, touted by certain creationists as proof of a god.
Maybe it is only me, but I find it implausible that a very specific, complex trait such as our brain would evolve entirely through a random walk, without any selection.
DeleteAgreed. Of course there was lots of selection. I merely point out that over the long term the evolution of intelligence appears little different from a random walk. This is because the environment, including the current characteristics of the species, presents opportunities for selection at fairly random times. There is no stately progression toward us, just a twisty path going nowhere in particular, or if you prefer, all manner of different directions depending on local conditions.
And plenty of niches remain unfilled for very long periods. Niches aren't platonic ideals...
ReplyDeleteExactly Jerry Coyne's rebuttal in the link cited above.
Ergo Gould's NOMA
Not sure what NOMA has to do with this, unless you're telling theists to go away and stop trying to make pronouncements about biology.
DeleteI trmber two references on this.
ReplyDeleteA simpson episode where Homer touching the slightest thing THEN changes the results in the future. Then Darwins talk on this.
Darwin stressed how fantastic the cause and effect was in creating biology results and so it could only be that rewinding/erased would lead to totally different results. he stressed this.
I'm creationist but would point out physics impact on biology lowers options.
A leg can only be formed certain way)s) to hold up a heavy creature and let it run.
It hints at how unlikely it was that fish evolved into creatures that investigate how they evolved. Then how rewinding it would effect things.
Hmmm. Something fishy about tyhis eh!
Tom, since the conversation you posted this on: "Barb - what is your take on this paper: http://www.ncbi.nlm.nih.gov/pubmed/11807559" has moved on, I'll reply here.
ReplyDeleteCool! Nice to see this. And not entirely surprising. If I remember correctly from biochemistry (too long ago), the compounds and bits of the chemical pathways used in C4 photosynthesis exist in all plants, but aren't used the same way. C4 photosynthesis is a rearrangement of C3 and related biochemical pathways.
C4 plants vary a lot in details of the chemistry and anatomy involved -- which bundle sheath cells are get big, etc., and some do C4 without the usual Kranz anatomy! This is pretty good evidence that C4 didn't evolve just once.
This finding of C4 within tissues of Nicotiana, usually considered a C3 plant, helps understanding how C4 can evolve over and over again.
I tried playing my tape if life backwards but it just kept telling me that Paul is dead.
ReplyDeleteLOL
Deletere
I tried playing my tape if life backwards but it just kept telling me that Paul is dead.
I would have thought you had to be 60 or over to get that joke!
Modern science is a descendant of medieval theology as foreign as they are to each other today.
ReplyDeleteI'd argue with that a bit and say the roots of modern science came from lots of different places, with medieval theology being only one (the importance of which can be debated). But mostly I wanted to say there's a good book I'm reading by Steven Weinberg on the history of science entitled "To Explain the World," which might be of interest to you and others in this thread.
Speaking of good books, "Wonderful Life" is one of my all time favorites. While this thread has gotten off on a very general tack, many of Gould's questions were more specific. How inevitable was it that, for example, radial symmetry, which was relatively prevalent among the Burgess Shale fauna, would now be so much less common than bilateral symmetry?
@ Alex
ReplyDeleteI think it fair to say that that some triploblastic urbilateran with eyes was the common ancestor to the Deuterostomes, Locotrophozoans and Ecdysozoans; and by regulatory gene “atavisms” would also be the ancestor of all modern Porifera, Cnidarians, Acoelomates and Pseudocoelomates...
... meaning no basal non-bilaterian animals (except for placozoans) have survived to today.
ITMT Martindale’s lab has effectively buried the specious textbook distinctions between protostomy and deuterostomy.
http://www.ib.usp.br/zoologia/evolution/papers/Martindale_01.pdf
I reckon the only distinction between the so-called protostomes and deuterostomes still remains French zoologist Geoffroy Saint-Hilaire’s (a colleague of Lamarck) original observation that all animals have identical body plans but there are only two ways to possess a central nervous system: cephalization with a ventral nerve cord and cephalization with a dorsal nerve cord. My Holy Grail is trying to figure out which came first.
...of course by "all animals" I meant to say "all eumetazoans" although I am becoming increasing unsure exactly what that term is supposed to mean anymore.
DeleteI wonder out loud... is cephalization derived or are so-called "nerve nets" derived?
Delete