Russ,
That's a good example about the difference between breeding for the best bird vs. the best bird environment, but they don't immediately seem to address whether variation is developmental or random. It's tricky to find the hard evidence, but I don't know of anyone saying they could show statistically that random variation would be constructive either. My hint is that the organizational processes we can observe the workings of generally do exhibit developmental variation, like we use in any programming or other design process. Once you think of the first part in the design, the process that seems to work better for people is adding a second related part, *if the first seemed to work*, and that way extending variations from prior variations experimentally, rather than randomly. It takes some effort to imagine how genetic variation could be 'tree like' instead of helter skelter. but there a number of ways. What you need is for competitive advantage to multiply related variations. In any case individual organism growth and development is clearly a branching process, and speciation seems to clearly be an extension of a prior branching process. Maybe speciation occurs by a branching process too. In speciation the form of the organism appears to extend its developmental trees as whole, all at once, something that a tree like variation process could do and a random variation process very likely not. So that's what I think would be sensible to look for. Besides, tree-like development could do one thing that random variation can't, produce developmental step changes that begin and end. That's what is apparently displayed by my little plankton. I'd really love to have the $'s to do a photo animation of how the smooth to then bulgy shapes on it's shell changed through the dips and turns of it's dramatic changes in size from one to another stable form. Phil From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Russ Abbott Sent: Monday, October 13, 2008 5:15 PM To: [EMAIL PROTECTED]; The Friday Morning Applied Complexity Coffee Group Subject: Re: [FRIAM] Selection, Reproductive rate, and Karrying Kapacity. One of my favorite books of the year is David Sloan Wilson's Evolution for Everyone. Wilson has been arguing for multi-level selection for quite a while -- and as far as I'm concerned he makes very good points. The fundamental insight is that everything is both a group and an individual. And hence virtually anything can evolve at the individual level -- even if it's a group. Wilson likes talking about religions (or religious groups united by religious practices) as an example of a group that competes evolutionarily. He argues that religious that promote hard work, support of fellow members of one's religious community, etc. tend to succeed. He also tells the story of the experient in which groups of hens were allowed to evolve. It was done in two ways. 1. Start with (say) a dozen cages, each with a certain number of hens. At the end of a given time, the best egg-layer in each cage were bred to create a second generaation of cages. Continue for a certain number of generations. 2. Start the same way, but after each generation, breed the best cage, regardless of how its individual members performed. Continue for a certain number of generations. The result: breeding cages was much more successful than breeding individuals. In this case it turns out that breeding individuals produced macho hens who pecked each other to death. Breeding cages produced cooperative hens who lived happily with each other and produced lots of eggs. The larger lesson is that groups often embody structures that support the group's success. To enable those structures the group needs members who play various roles. Simply selecting the most productive members of a group and rewarding them breaks down the group structure. -- Russ On Mon, Oct 13, 2008 at 11:18 AM, Nicholas Thompson <[EMAIL PROTECTED]> wrote: All, Here are some comments on various comments. I succumb, reluctantly, to the community norm about caps. [grumble, grumble] Glen Said ====> The idea of expansion and contraction is interesting: rapid expansion of populations (when selection is relaxed) vs. rapid contraction of populations (when selection is intensified). The human population went indeed through a phase of rapid expansion in the last decades while natural selection was released through cultural and technological progress. Seed Magazine has an article about human evolution and relaxed selection, too http://www.seedmagazine.com/news/2008/10/how_we_evolve_1.php <=== Nick Replies ===> I think this is a confusion between carrying capacity and selection. When, for some reason, carrying capacity is increased, the whole population can expand, but this does not stop selection. It may change the nature of selection from tracking how well individuals can make use of limited resources to how fast they can reproduce when times are flush, but there is no reason to think that raising the carrying capacity should "relax" selection. Russell Wrote ===> Any extinction event is a collapse of the food web. And selection only proceeds by means of extinction. So I'm not really quite sure what you're trying to nuance here. Nick Replies ===> OK. Here is where we disagree, I think. Let's worry this a bit, before we talk about anything else, because it seems absolutely central: When talking about selection, at what level of organization are we speaking? Gene, individual, small group, "deme", species, ecosystem? etc. I grew up under the influence of George Williams who argued that no entity above the individual could serve as a level of selection and of Richard Dawkins, who argued that no entity above the level of the gene could serve as a level of selection. So, in my world, species level selection is not a powerful cause of evolution. Indeed, on some definitions, species, by definition, cannot compete. Now, in the last decade, I have thrown off Williams' shackles and started to talk about selection at the level of the small group. And, indeed, I do know that some others have started talking about species-level selection. But species level selection has not become the received view, has it???? If not, the statement above must be EXTREMELY [whoops, _extremely_] controversial. Let's pause here and see what others say. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University ([EMAIL PROTECTED]) ============================================================ 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
