Global Brain consists of 21 chapters total, so I'm creating 7 seperate threads breaking the book into 3 chapter segments. Hopefully this format will keep the discussion somewhat organized and on track. You do not need to keep your discussions within these 7 threads.

Edited by: Chris OConnor  at: 10/30/05 4:32 pm

There are many forms of diversity generators. One is a physical type, a gamma or UV ray that strikes a cell, changing the DNA and causing a random mutation. The intermingling of DNA in sex is another.

Fighting, or "creative bickering" as Bloom calls it, also generates diversity by causing nearly identical organisms to separate from each other and head into different environments, which in turn select against the organisms in dissimilar ways. Much of this "creative bickering" happens between organisms that are most closely related genetically. This goes against one of the main tenets of the "selfish gene" theory, that the closer we are genetically, the more we will work together as a team to pass on our lineage. Infighting breaks up this tendency and fosters diversity by separating similar organisms into competing groups. (pgs. 93 - 94 in hardback)

As I recall we debated this on the human scale during The Lucifer Principle. Some said there is insufficient diversity between different groups or races of humans to contribute significantly to evolution. Bloom makes a succinct case that the variety of human groups are diversity generators at the end of chapter 10 (pgs. 98 - 99). Various cultures have differing standards of beauty and aggression which are rewarded or repressed in contradictory ways, affecting the gene pool in each group.

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Anthropologists have noted how a splinter culture's choice of sexual fixations makes some groups tall, some short, and even alters breast and penis shape. What's more, I've sketched in an earlier episode how every culture wires infant and toddler brains in slightly differents ways. As groups paraded their uniqueness with distinct dialects, methods, and beliefs, they were likely to have manufactured youngsters who saw the world from starkly different points of view.

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Edited by: LanDroid at: 2/13/03 7:42:34 pm

The Conformity Police and The Diversity Generators are in conflict, but also reinforce each other. As humans began to congregate in cities, conformist pressures increased.

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Despite its evocation of lust, strife, torment, and the wild, religion was used to synchronize the emotions and the symbol set of those who lived within the city's walls. This fervid enticement to cohesion and to the discipline of ritual geared the members of a town to think and work in harmony. (p. 104)

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But cities also promoted diversity - not everyone had to be a generalist, to provide for his or her own food. They could try new and creative lines of work. Towns developed unique technologies and styles, then traded with other cities that excelled in what they lacked.

But then on another level, within each town creative bickering separated members of a culture into rival subgroups vying for dominance, to determine what was rewarded or punished. "The more subcultures, the greater the playbook of vying strategies, and the sharper a community's combinatorial craftiness."

P.S. This sentence is rather delicious. Whew!
"They shrieked the slashing pain of sexual denial while roaring with an appetite for sexual savagery." (p. 104)

Edited by: LanDroid at: 2/13/03 8:45:42 pm

The Baldwin Effect
Bloom describes this in chapter 12, "once an advantageous behavior has been embraced by a population, it will gradually reshape the genetic string of the species which has adopted it, resulting in biological rewiring." He describes how spiny lobsters learned to migrate in a single line to avoid dangerous Winter conditions, then this behavior was hardened into the genome. "Generation after generation, the killing cold chiseled recalcitrant genes away until finally what began as innovation became instinct." (p. 111)

That's all well and good, but not being a student of biology I looked into it further and the first thing I ran across was this.

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According to H. F. Osborn, one of the three authors of 'Baldwin effect', adaptive evolution may not require neither natural selection nor the inheritance of acquired characteristics. An adaptive evolutionary change in population without natural selection means that an identical adaptive change in genetically different organisms of a population can take place without a systematic difference in the reproductive value between them, and these changes can also become irreversible on the level of genome without the difference in the reproductive value involved. The mechanisms which allow this are known and sketched in this paper. Their description requires an approach on the level of whole genome and a look to the organism as a self-organising and communicating system. Consequently, it is possible to have a theory of adaptive evolution, for which the evolution with natural selection is a special case.

www.zbi.ee/~kalevi/chkfin.htm

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Whoa, this may be off topic (not to mention over my head), but is this really describing changes to the genome without selection or inheritance???

Bloom describes the universal principle of reciprocity "you scratch my back & I'll scratch yours" and wonders if the Baldwin Effect made economic trade a human instinct. For 10,000 years, those "who had mastered the art of network maintenance and enrichment" such as "politicos, bureaucrats, warrior-generals, celebrities, aristocrats, businessmen, and priests" were amply rewarded and protected from scourges. "Homo isolatus will be replaced by homo commercialis."

In one particularly interesting section, he bolsters this argument with examples of how human evolution could take place much quicker than our narrow time perspective can perceive. "The gene for adult milkshake tolerance did not appear until well after the walls of Jericho were erected and Bos taurus was taught to toe the line." Immunity against malaria, measles, and smallpox probably happened in a similar time frame. Measles in particular is thought to have developed only since the domestication of cattle. Consider that "Native Americans", separated from other groups for 11,000 years lacked much of this immunity. (p. 114)

LanDroid

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This goes against one of the main tenets of the "selfish gene" theory, that the closer we are genetically, the more we will work together as a team to pass on our lineage.

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What you have taken issue with is kin selection, which operates at an entirely different scale from the (inevitable) action of selfish genes. In fact, the case presented speaks in favor of selfish genes as having broader explanatory power than kin selection alone. We may be selected for cooperation with our kin; when it happens, it happens because of the mathematics of shared genes. But if circumstances are such that genes "for" a different behaviour (different than getting along with kin) are preferentially propagated more than the kin selection genes, then of course they will come to predominate.

Edited by: Jeremy1952 at: 2/14/03 5:36:41 pm

Kalevi Kull Organisms can be proud to have been their own designers (by way of LanDroid)

I am pasting the core of Kull's analysis for discussion. It strikes me as interesting, but rather than showing evolution by natural selection as a special case of evolution, Kull has found a mechanism for a special case of natural selection.

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The mechanism to which I would like to draw attention, can be briefly described as consisting of the following statements. Most of these steps are quite trivial, however, the consequences from the whole set will not be so trivial.

(1) We need to notice that an organism can choose, which parts of its genome to use. Accordingly, the genome includes a functional and non-functional part. In most eukaryots, only a minor part of the genome is in use. The unused part consists (a) from non-coding DNA, which, still, may include some pseudogenes, and (b) from coding DNA, which is not currently used, but can be used in some other circumstances (e.g., in other cells of the organism, other period of ontogenesis, or other environmental conditions).

(2) An organism is able to change the used (functional) part of the genome during its lifetime, as dependent, for instance, on the conditions in which it lives.

(3) This change can be adaptive (due to self-organising nature of the organism) even if the conditions are new, that means if the particular combination of environmental factors has never been experienced before by this organism during its phylogeny. This derives from the nature of cell, as the cell is an adaptive system that changes its state continuously according to the communicative activity of its functional cycles.

(4) An organism as a self-organising system is able (due to its mobility and an ability temporarily not to move; and also, due to its ability to distinguish between different environmental situations) to choose the environment for living.

(5) If a population of similar organisms will meet new environmental conditions (when moving to a new place, or when the conditions change by themselves, or when the change in conditions results from the organisms local activity), then an adaptive change in the usage of genome may take place almost simultaneously for most of the specimens of the population.

(6) If the population keeps living in the new conditions (either due to the organismal preference for it, or due to the constancy of the new conditions), then the change in the usage of genome can be kept (repeated) over a number of generations.

(7) In the case of biparentally reproducing organisms, the organisms of a population keep to be similar. This is because if the genomes of the mates are not similar enough (i.e., recognisable or complementary), they cannot reproduce. Thus, the mortality due to the occasional big genetic changes is not specific to a genotype, but depends on the difference from the population mean.

(8) Due to the great similarity of individual genomes in a population, the simultaneous adaptive change in the usage of genome (in gene expression) may concern the same or similar areas of the genome in most of the organisms of the population.

(9) Some stochastic mutations, which appear in the area of the genome which is used (expressed) in the current conditions, lead to inviability of a part of the offspring. This appears with a probability which is proportional to the used part of the genome. Considering that the size of the expressed part of the genome does not differ significantly between the individuals of the population, it means that also the probability for such mutations cannot differ significantly between the individuals. I.e., the corresponding offspring mortality is not specific to a particular parental genotype.

(10) The mutations which appear in that currently unused fraction of the genome which has been in use in the previous environment, make the return to the previous functioning of the genome impossible. There is a great number of such mutations which may lead to this irreversibility. Since they appear in non-functional part of the genome, they do not influence the viability of organisms in the current conditions specifically.

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Kull asserts that organisms can deliberately use a different part of their genome. This seems plausible so long as the "part" is being expressed. Let's say most of us have the ability to digest a certain food that is not currently part of our diet, and we can almost all digest another food, which is a staple. Now suppose circumstances change, and food "a" becomes readily available, tastes good, and food "b" becomes scarce. We choose, individually, to eat food "a" instead of food "b". "Ability to digest" implies genetic expression; an enzyme, perhaps. The details don't matter, only that digesting foods a and b are both external representations of genetic activity.

Kull's argument, as I understand it, is that "food b eating" is no longer essential to survival, and therefore there is no longer selection pressure to keep "food b" enzymes functioning. A mutation that renders food b enzyme non-functional will not kill the individual, because she isn't eating food b anyway. Thus, over time, you end up with a population which can only eat food "a", even though the original change was volitional.

I think Kull is overlooking an important aspect, and underplaying another. As "b" becomes less important than "a", a becomes subject to selection pressure. Individuals with defective "a digesting enzyme genes" are selected out. On the other hand, "b digesting enzyme genes" have been accumulating defects, such that the later generations can't ever go back to "b" eating. But what is the physical mechanism of "can't go back?" An individual who tries to survive on "b" will now starve.

So, on both ends, the new gene and the old, it is friendly old natural selection doing the work. The only thing different is the correlation between them, and the manner by which the trend started.

LanDroid

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"The gene for adult milkshake tolerance did not appear until well after the walls of Jericho were erected. . ."

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I had to look it up; "milkshake" really is in the published version, so it is Bloom's editor, not Lan, who gets credit for this humorous anachronism.