Dawkins was merely saying that in this huge multidimensional space, most points represent nonviable creatures (e.g. height of 5000 meters and mass of 0.1 gram). In a random leap from a point representing a viable creature to any other point, probabilistically that destination represents something that cannot live.
That said, I found Vladimyr's comments about viability to be very interesting and of course far more detailed and concrete than Dawkins' probabilistic metaphor. Bruce On Thu, May 12, 2011 at 9:33 PM, Nicholas Thompson <[email protected]> wrote: > Bruce, > > Suddenly can't think what the evidence would be for "most mutations are > lethal." Given the tremendous capacity of the developmental system to > absorb variation and produce a common result, how would we know. The best > we could know is that most visible mutations are lethal. > > This is a brain fart, isn't it. Oh Dear. > > Nick > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Bruce Sherwood > Sent: Thursday, May 12, 2011 8:44 PM > To: [email protected] > Subject: [FRIAM] What evolves? > > I'll take a stab at Russ's question, "What's the analogous force (or other > explanation) for void filling in evolution?" > > Dawkins presents what seemed to me a helpful way of seeing why mutations are > usually lethal. He invents a multidimensional space in which a point > represents a possible living creature, whose attributes are coordinates on > each of the very large number of axes (e.g. length, mass, number of legs, > etc.) He points out that this space is enormously empty, as most points > represent creatures that are not viable. Moreover, any mutation that > represents a big jump in this multidimensional space takes you to a point in > that space representing a nonviable creature. > > Viable creatures are represented by clouds of neighboring points, surrounded > by vast empty spaces. New species (to the extent that "species" is a > meaningful term) to be viable will be near these clouds. If a cloud is > densely occupied, a new species will most likely be found just outside the > cloud, exploiting an until-now "void" but with only small changes from the > attributes of existing creatures in this grouping. > > In this metaphor it seems to me that void-filling is "driven" > essentially "entropically" -- to exploit a larger space. The analogy would > be a gas confined in a small portion of a large empty box. > Remove the barriers, and it looks to the observer as though the gas is > "driven" to fill the void. But at a micro level all you see is molecules > running around randomly, sometimes colliding with other molecules or the > walls. According to mechanical laws, the gas could continue to occupy a > small portion of the otherwise empty box, or return to such a configuration > after making excursions. But there are so many more ways of arranging the > molecules to exploit the entire space of the box that there is a crushingly > large probability any time you look in the future of finding the box > completely filled. In the process of this filling, it "looks" to the > observer as though the gas is "driven" by some "force" to occupy the large > space. But that's an illusion. Or you can I suppose define an equivalent > "entropic force" > doing the driving. > > Incidentally, when I only recently read The Origin of Species I was struck > by how much ecology there is in the book. At one point Darwin specifically > says that one of the largest influences driving the evolution of species is > the other species in the environment. And the last few pages are a > wonderfully lyrical paean to an ecological view of interacting organisms > (his English river bank). > > Bruce Sherwood > > Russ Abbott russ.abbott at gmail.com > Thu May 12 00:13:53 EDT 2011 > Previous message: [FRIAM] What evolves? > Next message: [FRIAM] What evolves? > Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Lots to > respond to. First of all, Nick, why do you say I am discarding the > distinction between living and non-living. I don't recall saying that. > > To Dave's point: > > By "fitness" I mean nothing more than 'void filling' ... There is no > "process" anymore than there is a "process" when water in a flooding river > 'fills voids' on the other side of the levee. > > > That still leaves open the question of the scientific explanation for how > voids are filled. Is there a physical force that produces that result? In > the case of water going downhill, the force is gravity. What's the analogous > force (or other explanation) for void filling in evolution? > What's the scientific explanation for how it happens? > > *-- Russ Abbott* > *_____________________________________________* > *** Professor, Computer Science* > * California State University, Los Angeles* > > * Google voice: 747-*999-5105 > * blog: *http://russabbott.blogspot.com/ > vita: http://sites.google.com/site/russabbott/ > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, > unsubscribe, maps at http://www.friam.org > > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > lectures, archives, unsubscribe, maps at http://www.friam.org > ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
