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Real Thread on Evolution: Gould v Dawkins

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9/18/2011 5:37:48 PM
Posted: 5 years ago
I thought that, for a change of pace, we can have a thread that talks about the ACTUAL controversies within evolutionary theory as opposed to the pathetic challenges to universal common descent and such which we continually find ourselves in.

One of the age-old rivalries in biology was between Richard Dawkins gene-centric, non-punctuated, adaptionism and Gould's support for multiple levels of selection with major influence on gene-specific selection.

These are not incompatible. Instead, they are on different extremes of a spectrum within Evolutionary Theory. Here is a good summary of the contrast:

In Dawkins' argument, selection acts on lineages of replicators, which are mostly but not exclusively genes. Ideas and skills are the replicators in animals capable of social learning, and "the earliest replicators were certainly not genes". (p. 167) Genetic competition occurs through vehicle-building alliances, with selection dependent on repeatable influences on those vehicles. Other genetic replication strategies include Outlaws, the prospects of which are enhanced at the expense of vehicle adaptiveness. And extended phenotype genes advantageously enhance their environment. The vehicles of Dawkins replicators need not be individuals, but can also be groups, although animal cooperation is not sufficient to claim group selection. Evolution's central explanatory imperative is the existence of complex adaptation, which can only be explained by natural selection. This complex adaptation evolves gradually, with occasional replication errors resulting in large but survivable phenotypic change. Humans are unusual species in that they are vehicles for memes as well as genes, although humans are not exempt from evolutionary biological explanations. Extrapolationism is a sound working theory, with most evolutionary patterns the result of microevolutionary change over vast geological time. Major animal lineages are the result of ordinary speciation processes, although possibility-expanding changes may result in some form of lineage-level selection.

In contrast, Gould sees selection as usually acting on organisms in a local population, although in theory and practice, it can occur at many levels, with change at one level often affecting future options at other levels. Selection can occur at the group level, with some species lineages having characteristics which make extinction less likely, or speciation more likely. And while rare, selection can occur on genes within an organism. While selection is important, and requires understanding, it is just one of many factors explaining microevolutionary events and macroevolutionary patterns. Further, complex adaptations are but one phenomenon explanations in evolutionary biology. Extrapolationism is not a good theory, with large-scale patterns in the history of life not explainable by extrapolating from measurable events in local populations. Evolutionary biology needs a theory of variation, explaining the effect of variation supply on change potentiality. While humans are evolved animals, attempts to explain human behaviour using techniques from evolutionary biology have largely failed, "vitiated by one-sided understanding of evolutionary biology. They have often been biologically naive." (p. 170)

Obviously, both are right to some extent. Topic: whose conception of evolutionary theory more closely matches the empirical reality of common descent.

People who wish to challenge common descent in general, please make your own thread or go to an existing one. This thread is for those interested in ACTUAL scientific issues and controversies.
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9/19/2011 11:25:04 PM
Posted: 5 years ago
i don't understand how group selection could occur actually. the concept seems fundamentally confused. take organism x, say it has all these genes for pro social behavior. you could say that x evolved this way because it was beneficial to the group as a whole to have them... and then you have to explain how selection could act on a group. or you can simply say that part of organism x's environment is a bunch of other x's, and so being able to benefit from them is to its advantage. i *guess* you could call that group selection, but that makes it sound like its fundamentally different than selection based on individual genes, and thats disingenuous. its like trying to make a distinction between micro and macro evolution... its pointless and vacuous.

whole organism selection is in a similar boat... you can reduce it to a bunch of genes interacting with one another, having *other* genes as crucial bits of their environment, and nothing is lost... so why do we need to invent another level of selection in order to explain anything? of course we often *talk* about selection acting on individuals, but thats just a convenient shorthand... kind of like saying that atoms "want" to have full electron shells... its a way of referring to a complicated idea without having to take the time and effort to unpack it.

punctuated equilibrium i know least about, but on its face it seems both right and wrong- right in that the fossil record seems to show evolution proceeding in fits and starts, and wrong in that it implies the existence of some flaw in existing evolutionary theory. intuitively, it seems to make sense that changing environmental conditions would lead to changes in many genes at once, and that changes in one or two genes could be considered changes in environment, leading to further
genetic changes within the same organism, etc.

in case you can't tell, i tend to favor reductionist interpretations whenever possible. gould brought up some good points, but seemed too quick to dismiss the possibility that seeming anomalies could be explained by existing frameworks. that said, while i've read several of dawkins books on biology (the selfish gene and the ancestors tale) i have yet to develop the motivation to read goulds gigantic the structure of evolutionary theory. at 1464 pages it intimidates me :P . so i might be unfairly biased.
evidently i only come to ddo to avoid doing homework...
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9/22/2011 4:53:35 PM
Posted: 5 years ago

To begin, I am by no way any expert on this topic nor am I thoroughly familiar with either Hawkins or Gould, which certain makes my opinion less valid. But this is a fascinating topic, thus I will opine my thoughts…

I disagree with Hawkins that "ideas and skills" are replicators in any organism let alone social animals. Ideas and skills stem from intrinsic brain functions that rely on electrical and chemical interactions that have developed prior to any stimulus from natural selection. Moreover, multiple ideas and skill sets can be successful within a given environment. Further, the brains of social animals are very plastic, which enables us to adapt as circumstances dictate; but these are not germline changes and thus would not be able to be passed on to future generation. We can personally adapt to an environmental change, but that doesn't imply that we are making changes on the molecular level.

Also, I am not really sure what Hawkins is suggesting by "genetic competition". From where I sit, it would seem to mean that genes are competing with one another. I completely disagree with this idea. If anything the traits are competing, and even this is a stretch. Several different traits can be successful within a given niche. Moreover, a given trait can be generated by different genetic mechanisms---a perfect example of this is long-term potentiation.

Having said all that, I do agree with Hawkins's idea of gradual evolutionary changes over time as opposed to Gould's "punctuated equilibrium". But in general I am more inclined to agree with Gould's view of evolutionary biology. It would seem more likely that the unit of selection is the phenotype and not the gene—acting on populations, not individuals. Natural selection promotes successful traits by placing selective pressure on a given phenotype, which implies that the output of the genetic information (i.e., how the information is used) is being selected for not necessarily the gene. So, natural selection may select for new ways in which a gene's product—the protein--is being used within the context of its complex interactions with other proteins.