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Thank you very much for letting me know about "Irreducible complexity". I'll investigate the argument. My objections to evolutions do not fall into such a rea

• avar 16y ago
  1) That's not correct. natural selection doesn't have a narrow/expand bias one way or the other. Lineages simply survive if they manage to produce offspring. Sometimes that's because they evolved some novel new thing (like birds learning to fly). Sometimes it's because they didn't do that, e.g. in the Cretaceous–Tertiary extinction event the boring mammals that were small and had a tendency to burrow to escape trouble survived. A variation that happens through a mutation doesn't need to be present in both breeding partners for it to survive. This is obvious if you look at common dominant[1] and non-dominant genes, like the tendency towards a certain haircolor. That trait might be passed on to the offspring, and would permeate if it was advantageous enough. A lot of variation also doesn't happen through mutation at all, but simply selection within a species. E.g. this happened to humanity [3] relatively recently. We lost a lot of biodiversity within Homo Sapiens simply because a lot of us died out. Most of the biomass on this planet never "expanded" in any significant sense. Multicellular life is still relatively rare, most of the biomass on earth is bacteria. 2) The notion that each species has an ecological niche is false. We live on a large planet, so there's a big opportunity for species that "do the same thing" (to simplify). Of course that's only true up to a point, consider the example of the Eastern Gray Squirrel displacing the Red Squirrel in the UK. 3) There's a lot of things that species could do but aren't doing. Not because that thing would be a "bad idea" as such, but simply because it hasn't evolved yet. E.g. insects could probably take up a lot more space than they do now if they grew larger, but that would require evolving a whole new breathing apparatus. Maybe monkeys would be better suited to trees if they had four hands, but two is all they (and the whole vertebrate line) had to work with. 4) I don't get this. Why do you think species should be much more inter-breed-able. They are to an extent, but once speciation occurs they aren't anymore. 1. http://en.wikipedia.org/wiki/Dominance_(genetics) http://en.wikipedia.org/wiki/Dominance_(genetics) 2. http://en.wikipedia.org/wiki/Eastern_Gray_Squirrel#Displacement_of_red_squirrels http://en.wikipedia.org/wiki/Eastern_Gray_Squirrel#Displacem... 3. http://en.wikipedia.org/wiki/Mitochondrial_Eve http://en.wikipedia.org/wiki/Mitochondrial_Eve
  • lelele 16y ago
    Thank you very much for your detailed explanation. I'll read the links you've provided, and more on the subject. > A variation that happens through a mutation doesn't need to be present in both breeding partners for it to survive. Indeed I didn't think about dominant genes... Thanks for pointing that out. However, I was more along a way of thinking which seems to have been disproved recently, as Wikipedia suggests: "Until recently, there has a been a dearth of hard evidence that supports this form of speciation, _with a general feeling that interbreeding would soon eliminate any genetic differences that might appear._ [example follows]" [1] 1. http://en.wikipedia.org/wiki/Speciation http://en.wikipedia.org/wiki/Speciation > 2) The notion that each species has an ecological niche is false. Exactly. I wonder why we have missing links among species. That is: why we don't have more half-bird-half-reptile around? They should have got along quite well with each other. IMO, if evolution were to bring speciation, I would have expected more of "a mess" of species around us. > 3) There's a lot of things that species could do but aren't doing. I was arguing that since - AFAIK - scientists think that life originated in water, why would animal lose the ability to get oxygen from water? Thas looks like losing an evolutionary advantage to me, and out of line with my understanding of evolution, which is deemed to be gradual: it would have had more sense becoming able to breath air while still being able to breath water. Were are species able to do both (the missing links)? Thank you very much again for having spent your time in making me more knowdlegeable.
• lotharbot 16y ago
  > ""natural selection" - as I understand it - narrows down variations, it does not expand them." The simple answer is that natural selection often reduces variability, but that does not mean it will reduce a species all the way to a single variation. Sometimes natural selection actually increases variability by favoring outliers (specialists) over the average (generalists). Consider a population with two food sources that require slightly different characteristics to access, for example, food sources at different water depths. They'll be most easily accessed by creatures whose neutral buoyancy puts them at that depth of water. Natural selection may favor individuals who are most able to generalize (that is, those who float right in between) or those who are most specialized (those who float right at the level of one food source or the other), depending on various details of the system. If you have the relevant mathematical background, you may want to look up some of the recent models of "adaptive speciation" (Ulf Dieckmann and Michael Doebeli have done some great work in this area; their book [0] has some great examples.) [0] http://books.google.com/books?id=Z-gCf7TD9-MC&lpg=PP1&ots=6XAgn7RZPJ&dq=adaptive%20speciation&pg=PP1#v=onepage&q&f=false http://books.google.com/books?id=Z-gCf7TD9-MC&lpg=PP1&#3...