Number: 241 (Read 0 times) Date: 21 Feb 94 19:07:04 To: All Subject: Test for evolution ::

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Number: 241 (Read 0 times) Date: 21 Feb 94 19:07:04 From: Wayne Throop To: All Subject: Test for evolution From: (Wayne Throop) Organization: Alcatel Network Systems (Raleigh, NC) ::: Can "altruistic" traits be passed onto progeny ? There's the ::: Wynne-Edwards observation where in highly populated flocking birds, ::: some birds forego their reproductive capacity and only a few birds ::: reproduce. How do the net.evolutionist explain this? :: Of course. See, for example, "The Evolution of Cooperation" by Robert :: Axelrod. Dawkins talks about such things too. : From: (Ranjan S Muttiah) : Could you say a word or two about what they have to say ? How do they : distinguish this condition from the more familiar evolutionary : examples ? Sounds like they are deviating quite a bit from : Neo-Darwinism. Axelrod studied populations where the "payoff" of progeny was defined by the "Prisoner's Dilemma" payoff matrix. That is, it is always to immediate advantage to "defect", but when everyone follows that strategy, the payoff isn't optimal. In particular, by adding some specific more-real-world-like properties to the game, but retaining the payoff matrix that "encourages" non-cooperation, Axelrod showed how small initial populations of cooperators could arise, and eventually penetrate and overcome an existing population of non-cooperators. This forms the basis for how mutually altruistic behaviors could arise by evolutionary processes in the usual way: that is, altruistic strategies outperform non-altruistic strategies, when a population interacts with itself. Dawkins, in _The_Selfish_Gene_ (and quite apropos to the title) shows how behavior that is altruistic on the level of the organism is, nevertheless, selfish when considered from the viewpoint of the gene. In such cases, the altruism is performed towards organisms which are "known" to contain copies of the altruistic organisms's genes. Parents caring for their children is a simple case of this, as is bees caring for the queen, naked mole rats caring for the reproducing female, and so on. Let's take an interesting example of this that is right in front of everyone's noses, and yet very often overlooked. Look at things from the viewpoints of cells. The vast majority of cells in your body are "altruistic", in that they service the needs of other cells and the community at large, while only the gametes actually get to reproduce. However did multicellular organisms ever evolve then, if Ranjan's objection is valid? The answer is simple. If a given single cell line doesn't reproduce, yet provides resources to "sibling" cells that *do* reproduce, copies of that cell's genes are propogated. In general, the altruistic behaviors of cells make people think that evolution "act"s to the advantage of species, and the altruistic behaviors of parent, bees, NMRs and so on make people th ink that evolution "acts" to the advantage of groups or species. Dawkins' thesis is that this is exactly backwards, and that *all* such behaviors are *selfish* (or self-beneficial, and not altruistic) when viewed from the standpoint of genes, instead of higher-level entities. There is no special deviation at all from Darwinism, neo or otherwise, in either of these two models (mutualism or gene-selfishness). Yet both result in altruistic behaviors, and in fact the mathematical model of eusociality was used to *predict* the existance of the NMR. All perfectly Darwinian. How all this might be relevant to the bird behavior that Ranjan used to bring up the subject is obscure, since no specific behavior was advanced as an example. In fact, "only a few birds reproduce" and the rest "forego t heir reproductive capacity" may be simple selection. That is, all have some *chance* to reproduce (unlike bees, where workers have zero chance to reproduce. But even then, there's nothing odd from an evolutionary perspective there. -- Wayne Throop ---


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