From: David Rudiak <drudiak.nul> Date: Fri, 8 Oct 2010 10:43:39 -0700 (PDT) Archived: Sat, 09 Oct 2010 07:59:45 -0400 Subject: Re: Shostak's Search Shift? >From: J. Maynard Gelinas <j.maynard.gelinas.nul> >To: post.nul >Date: Thu, 7 Oct 2010 18:38:57 -0400 >Subject: Re: Shostak's Search Shift? >This post is a combined response to David Rudiak, Stanton >Friedman, and Jerome Clarke. My apologies for not responding >sooner as I've been ill. I'm responding in this manner simply to >cut back on redundant replies to the List. I'd like to thank >each of them for taking the time to respond, even if each >staunchly disagree with my position. And I also recognize that >as a newcomer here, I'm challenging several. very well known and >highly respected researchers of this topic. This is not meant to >be personally disrespectful. >To start with, David Rudiak responded to my argument against >evolutionarily common bilateral bipedalism. Here is the salient >portion of David's reply >>From: David Rudiak <drudiak.nul> >>To: post.nul >>Date: Mon, 4 Oct 2010 10:23:23 -0700 (PDT) >>Subject: Re: Shostak's Search Shift? >>This point keeps coming up, that there are supposedly strong >>scientific arguments that (biological) space aliens would not be >>humanoid but some other unimaginable form. These arguments are >>neither strong, informed, nor particularly scientific, at best >>highly speculative, and also at odds with what we observe >>evolution creating here on planet Earth, where natural selection >>forces in particular environmental niches produce many examples >>of convergent evolution of form. Or as the jingle goes, form >>follows function. >Hi David, thank you for your reply. Of course, I'm not a professional >Evolutionary Biologist, so please understand if I make an error. >However, I think your argument rests on a shaky foundation. Allow me >to repeat your point in my own words, so we both know our various >assertions are understood by the other. My interpretation is that you >are arguing that because some morphological forms show repetition >across varying Earth environments, that such might be the case across >extraterrestrial planetary environments. For example, mammals Europe >and North America might have a marsupial homologue in Australia. >Here's a web site that discusses common evolutionary traits between >mammals and marsupials: >http://www.nwcreation.net/marsupials.html >So, on the one hand you're correct. Certainly, across two >isolated habitats similar morphology to fill in similar >ecological niches evolved. However, I think there's a flaw in >your argument. First, you ignore just how close mammals and >marsupials are to one another on the evolutionary tree compared >to - say - long since extinct organisms from the Pre-Cambrian >and Cambrian era. I wasn't comparing mammals and marsupials, which are indeed very closely related, though even here there are interesting examples of convergent evolution of form, such as the Australian lion and big mammalian cats. Instead I made some comparisons across some widely disparate species in evolutionary history with some similar morphology, e.g. flying insects and birds or ichthyosaurs (reptiles) which evolved 150 million years before and looked almost identical to modern porpoises (mammals). In addition to many common morphological structures, both evolved from land animals and gave birth to live young, yet again far removed from one another in the evolutionary tree. The point is again, with similar ecological niches, form follows function. There are a limited number of optimal solutions for survival in particular ecological niches. Another example, predators often have forward-looking eyes (with good binocular vision) while prey have their eyes off to the side to give them a much wider field of view to look for predators. >This is a critical point, as many organisms >from that period do not follow bilateral forms. Most organisms >from that period are long since extinct. Actually very little is known about pre-Cambrian life forms since they were soft-bodied and didn't leave much fossil evidence behind. But I think you miss the big picture with your argument. There aren't a lot of geometrical symmetries to work with: radial, spherical, and bilateral (or no symmetry, such as sponges). All existed pre-Cambrian just as they do post- Cambrian. But ONLY bilateral symmetry results in streamlining and rapidly moving life forms. Bilateral symmetry is also more energy efficient for motion. Speed and energy efficiency both have highly significant survival value, which is why they were selected for. (Streamlining and energy efficiency is also why nearly all our craft, from canoes to submarines and jet airplanes are bilaterally symmetric--it is an optimal solution.) Those are the primary reasons why all higher and more complex life forms are bilateral symmetric, and it isn't going to matter which star system they evolve in. Bilateral symmetry is going to be king because of basic physics that is the same everywhere. Bilateral symmetry also leads to the development of a head end, nervous systems, and concentration of key sensory systems in the head end. All surviving spherical and radially symmetric life forms are rather inert or sluggish and none have complex nervous or sensory systems. They've had just as much time to evolve something interesting as the bilaterally symmetric forms, but obviously these symmetry forms are evolutionary dead ends in terms of complexity. So don't expect an alien star fish to step out of a space ship and shake "hands" with you. >The question then >becomes, did they go extinct by chance, selecting one set of >branches on the tree of life for Earth's current set of >organisms, or did they go extinct because such forms are >unsuitable across most environments? They didn't go extinct. They are still with us. They just didn't go anywhere exciting or complex. Bilateral symmetry is inherently superior. >We won't know the answer to >that question until we've surveyed life and its progenitors >across several exoplanets. Nope, isn't going to matter. >But right now I'd bet that most >professional evolutionary biologists would argue that former and >not the latter. That is was random chance that led to the >prevalence of bilateralism here on Earth. Nope. Again bilaterally symmetry inevitably leads to faster, more efficient, and more complex life forms. Radial and spherical symmetry does not. Chance has nothing to do with it. Doesn't matter where you are. >So, my counterargument to you is that while homologous form >across isolated ecological niches may be prevalent on Earth, >such as mammalian and marsupial forms, that is only because they >were so close on the evolutionary tree to begin with. Thus, >extrapolating similarities between mammals and marsupials in >order to argue for similarities between evolved organisms on >Earth to other unknown exoplanets may not be a valid argument. Sorry, but I never argued similarities between mammals and marsupials, so I don't understand why you keep saying that is the foundation of my arguments. I was arguing more general principles, such as the superiority of bilateral symmetry, or why major sensory systems like vision and hearing will necessarily concentrate near the head end. All of these have highly significant survival value. There was also the important restriction of dealing with technological beings capable of building space ships. So they better have something like big brains with good vision and appendages for fine manipulation, which also implies a certain minimal size and something like an internal skeleton for continued growth to that size. They also must necessarily be mostly land animals, unless you can figure out how to build fires and smelt metals underwater. So don't expect to shake hands with alien porpoises or octopi either, although alien amphibians might be a possibility. All such arguments apply to animals that would evolve in the natural world. If we were dealing with cybernetic beings instead that evolve outside of natural selection, then morphological forms could be wildly different. David Rudiak Listen to 'Strange Days... Indeed' - The PodCast At: http://www.virtuallystrange.net/ufo/sdi/program/ These contents above are copyright of the author and UFO UpDates - Toronto. They may not be reproduced without the express permission of both parties and are intended for educational use only.
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