Convergent evolution


(Scott koshland) #1

I am just catching up to Simon Conway Morris’s view of convergent evolution. I know that there are many post about this subject but would like to understand how people view this as a driving consideration in evolutionary development.


(Stephen Matheson) #2

I can’t tell what you’re asking, but maybe you want to discuss how convergence fits into evolutionary thought.

Convergence can be apparently random or more interestingly it can be strong evidence of an “attractor” in the landscape of form and function. (That phrase itself is very Conway Morris-esque.) My view is that convergence in organism form is an expected outcome of adaptation (fish and cetaceans both being torpedo-shaped, etc.), and I think that’s the view of everyone else. Adaptation to very similar environments drives evolution toward whatever solutions are available, and if there’s really only one good solution, then convergence is the predictable result.

Whenever we see convergence, at any level (there are some interesting examples of molecular convergence), we should look for some underlying principle (a design principle or a structural/functional constraint) that can explain it. There isn’t always such a principle, since convergence can in principle be random.

Maybe that wasn’t very helpful, since Conway Morris makes all of those points too.


(Scott koshland) #3

Thank you Stephen this is helpful. I am just trying to get an understanding of evolutionary convergence. Simon Conway Morris and his views seems quite interesting. Would it be correct to say that Conway Morris is saying that evolution tends to favor functional adaptations over random chance selection? Are his views on convergent evolution pretty well accepted? How do you take his point that nothing new has really been developed but just re-invented by a convergent evolution process? Would it be fair to contrast this with Stephen Jay Gould’s view that seems to say evolution is a more random walk and chance plays a more important role to determine form?


(Stephen Matheson) #4

No. He doesn’t present those as opposing ideas, because they aren’t. Also, “random chance selection” is gibberish. Selection is not random, and no one on any side of the convergence/contingency debate has ever said that.

Yes. The only debate is about what it means, on a meta-kinda-philosophical scale.

I hope he didn’t say that. That’s ridiculous.

Well, sort of. Gould championed contingency as opposed to convergence and predictability, but he wasn’t claiming that evolution is fully random. He was making a claim about the big transitions and events in natural history. So it’s important to not suggest that this is a debate about guidance vs. chance or something like that. But yes, Conway Morris and Gould are making very different claims about major evolutionary events.


(Scott koshland) #5

I think you know where I am going with this. I am coming from an information perspective. Conway Morris is a brilliant eloquent and articulate speaker especially for a Brit. I don’t want to try to misrepresent what Conway Morris has said. I think that perhaps some of Conway Morris comments were off the cuff and I really want to try to understand what the current thought is among the scientific community. I can understand that not one size fits all and that circumstances are important in directing the adaptations and evolution of species. As has been astutely said Marsupials didn’t develop ape like adaptations so not all niche get filled even though the potential was there.

When you say adaptations are solutions to fit an environment what is a solution? Is a solution knowledge?

Do Birds know how to fly?


(Matthew Pevarnik) #6

What exactly do you mean here? I’m not following what you’re trying to say.

Really the main requirement is staying alive to reproduce. Its not necessarily that there is a solution ever in mind beforehand, but certain solutions tend to work better than other due to physical constraints (streamlined body shape or surface area to volume concerns like with manatees).

What exactly do you mean here as well? I’m not following what you’re trying to say.


(Stephen Matheson) #7

‘Solution’ is a common non-technical term, a slight anthropomorphism (better understood as a metaphor, IMO) used by many biologists when describing and discussing adaptation. Here’s an example, and a nice piece written by a great scientist. So, in this context, a streamlined body in an aquatic animal is an adaptation which is a “solution” to the “problem” of water resistance.

Those strike me as semantic questions that are unlikely to lead to interesting conversation.


(Scott koshland) #8

Haha I think knowledge and it’s application is everything. It’s such a problem for scientist to understand. Knowledge. What is it? Again I don’t want to put words in Conway Morris mouth but I have seen him talk about these convergent adaptations incorporating similar knowledge (solutions :slightly_smiling_face:)which he briefly mentions Descartes view of knowledge. I think therefore I am. I suspect that Conway Morris didn’t want to go to far down this path as it may border on a more metaphysical question for him but I haven’t read his books.

So then I ask you does a bird or any other life form incorporate and apply knowledge in its design? (I am not going down an ID road here)


(Matthew Pevarnik) #9

What don’t scientists understand now? One thing that perhaps I could see is how say scientists can help us understand that we are warming our planet at an alarming rate but don’t necessarily provide all the solutions to that problem that requires a worldwide effort across many other disciplines. Is that kind of what you are thinking?

In a similar vein, the theory of evolution wonderfully describes how we got here, but does not really address questions of what then should we do or how should we live for the most part.

Birds try to stay alive, eat, sleep and have babies. Those babies are slightly different from their parents. Their babies do the same thing - traits that help the first part tend to be ‘naturally selected for.’ Certain combinations can arise idependently of one another because the same laws of physics apply to all organisms (minimizing the drag force is usually a good idea when predators are present). Generally speaking no organism is ‘adapting’ to their environment and then passing on their choices because any changes tend to be made in non-reproductive cells.


(Scott koshland) #10

Pevaquark.

I think you are mostly correct about adaptation but are you familiar with Conway Morris’s theory related to convergent evolution?

The question I ask is what is knowledge? How do you define knowledge? I saw some physicist struggling while discussing this.

I am asking if the design of a bird contains and applies knowledge of flight?


(Stephen Matheson) #11

It will always be a struggle to bring broad, vague, folk concepts like ‘knowledge’ into a scientific conversation, so that might explain the physicist’s difficulty. The only hope of having a coherent conversation on a topic like this is to begin with something like, “Now, in the current context, what I mean by ‘knowledge’ is…”

I think you could easily adopt definitions of the key words in that sentence such that the answer would be anywhere along the scale from yes to no.

But let me take a stab at one way to ask the question. Let’s assume that there is something called ‘knowledge’ that is heritable. My choice of ‘heritable’ is to capture the concept of ‘contains’ and ‘the design of’, and heritable things are genomes, biologically speaking. Organisms of all types (birds, beavers, trees, slime molds, bacteria) engage in elaborate species-specific behaviors (flying, nest building, dam building, light seeking, crawling, conjugating) that are either known to be or are reasonably assumed to be heritable. But we don’t usually know how the information is encoded or transmitted. Specifically: is there a set of genes that encodes a set of proteins that assembles a neural circuit that “contains” the “knowledge” of how to fly? Or is there a more complex interplay between protein expression and the environment, including the behaviors of parents/siblings/conspecifics?

Maybe that’s what you mean by your question, and if so, it’s an interesting and legitimate and current research question: the inheritance and genetic architecture of behavior. Personally, I like the “extended phenotype” view, popularized/outlined by Richard Dawkins in the book of the same name. Once you see the phenotype as something that needn’t reside within the body carrying the genotype, you notice that some of the questions (especially about behavior) become a little less mysterious.

Notice, though, that pondering this question, and seeking answers in biology, requires no semantic wordplay. Whether we’re talking about ‘knowledge’ is not helpful or interesting, at least not in my opinion.


#12

I think part of the problem is akin to asking how water molecules in a puddle ‘know’ how to fill a depression in the ground…


#13

O Magnum Mysterium…


(Scott koshland) #14

Argon.
Well I was just talking to my cellphone today and it talked back to me ! It knows me?!

Panpsychism No. But hold that thought. Does knowledge require consciousness or sentience? What is knowing? What is the relation between information -knowledge -consciousness?

I am going more down a bytes and information path for this.

I am sure you are aware of this discussion in physics and other sciences but please stroll through this discussion about information to maybe see my perspective.


(Scott koshland) #15

Stephen. Thanks. This is helpful.
Could you consider this in terms of the extended phenotype that becomes what I would call an integrated system to achieve flight? I would like to consider this is in more informational terms. The reason that I am using the word knowledge for lack of better word is to integrate this into an information theory format. I am looking at this from an information theory standpoint applying the concept of the information pyramid. The information pyramid is information organizing into knowledge that can be applied or utilized. I suppose that knowledge in the case of a bird could be essentially something like an aerodynamic equation which application is implicit in the structural design and the innate flight behavior of the bird. I think that knowledge may be considered information processing to gain a predictable result or solution. This law of aerodynamics is invariable and all the adaptations must incorporate this “knowledge” into their design. So though the bird doesn’t consciously know the aerodynamic equations it’s design is applying “knowledge” of this just as an engineer designing a plane would. This is essentially what you were describing as the streamlined body shapes in fish to reduce drag which would be complying to some “knowledge”of fluid dynamics or whatever. This is why I am interested in Conway Morris views on convergent evolution as the knowledge in the form of the laws are not variable but the applied actual design and form can vary still accomplishing the same result.

I am considering evolution in terms of an information learning system that follows the scientific process of hypothesis- test- theory. The adaptation is like a hypothesis that is tested and selected if positive then proving the hypothesis becoming a theory or if negative disproving the hypothesis. The hypothesis contains knowledge (or a solution) that is tested in an applied form and when selected is proven as a “theory” would and survives.


(Stephen Matheson) #16

My experience with “information theory” as used in discussions of evolution is that it is too vague to provide anything useful. I don’t want to discourage exploration of ideas about design space (my preferred term) or information/knowledge as a platform to think about how biological design gets actualized. But I can’t see anything specific or useful in what you have written so far. Maybe it’s just that I’m interested in different things, or maybe it’s just too hard to communicate (to me) what it is you are exploring.

With that said, I don’t think the extended phenotype is much of an “informational” thing. It is just the important acknowledgement that the influence of genes can and does extend well outside the body. That’s not really about “information,” at least not as far as I can tell.

As a metaphor, I think that works a bit. It’s probably too narrow and simplistic to go very far. Just my opinion.


(Scott koshland) #17

Thank you Stephen. Appreciate your thoughts.

You might enjoy having a look at this Conway Morris video on evolution. He is referring to the inevitability of evolution convergence and references that there must be an underlying principle to this. He is quite an amazing character

Well I think that you have to look at biology in terms of information theory because that is where physics is going and well life is ultimately complying with the laws of physics. It just that as we all know life is more complicated than just physics! As an aside What do you think of quantum biology? The concepts of quantum physics underlies all matter and must be at play in biology. There is an overall progression in life when considered in terms of evolution that eventually can lead into higher forms of conscious life. To get to consciousness it must be considered in terms of information and information processing. Physical structural adaptations alone do not seem to be the underlying driver of evolutionary developments.

I am trying to understand what is knowledge in the information pyramid? I am playing with the concept that knowledge is an information processing system that predicts determines creates and directs outcomes. So you can consider some equation such as F=MA as an information processor that amounts to knowledge. Have a look at this picture and then have a thought of all the information that is in the picture and what that represents in terms of information and knowledge.


(Stephen Matheson) #18

This is probably a lecture version of his book Life’s Solution. I know the book, and his work since, quite well. It’s pretty good stuff.

I wish you well. Your comments are still too vague for me to get much out of. I think you are doing a little too much with the meaning of words, and maybe not enough with ideas that can provide explanation or illumination. Defining, or redefining, words like ‘knowledge’… that just doesn’t seem very interesting to me. But you will always find me game for conversation about design, convergence, evolutionary “random walks,” and other topics that seem to me to be somewhat related to your ideas.


(Scott koshland) #19

Hi Stephen

Thanks I appreciate your comments and encouragement. The more that I listen to Conway Morris the more that I think that I am looking at this in the same perspective as what he is saying. He is really amazing with an incredible breadth of knowledge ( sorry there’s that word whatever it means?) and some incredible quotes.

I know many people at Biologos follow his work, he would be a great invite to speak at the Biologos Conference!


(system) #20

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