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Thread: Evolution

  1. #1 Evolution 
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    so about the theory about evolution ,
    it is states that humans and chimps-mice came from the same ancestors
    and there is a DNA evidence , our DNA sequence and base sequence are 95% alike with chimps and 85% alike with mice!
    but this does not prove that humans have diverged from chimps or mice, why not chimps or mice have diverged from humans?? it could be a possibility right?? i don't get it, does anyone does?


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  3. #2  
    Forum Cosmic Wizard SkinWalker's Avatar
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    You got it all wrong. No one is saying we diverged from either chimps or mice.


    What is evident, however, is that chimps, mice and humans all share a common ancestor. That last common ancestor for humans and chimps is probably at about 6-8 million years ago (Ma). For humans and mice, its much further back, probably 50-70 Ma.

    The chimp-human LCA probably looks very different either a chimp or a human, but shares many morphological similarities with both.


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    but i saw some pictures in the net showing how the human is diverged from a chimp?
    and what are the common ancestors???
    ufff this is confusing!!
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    I'm not allowed to post copyrighted material here but you can go to youtube and type in "why are there still chimpanzees?"..one of the first videos you'll see will say RDF TV- Why are there still Chimpanzees?...click and watch. It will explain the human-chimp connection cursorily.

    We are distantly related to mice because they are mammals but they show up in the fossil record as early as 75 million years ago while our ancestors (the Homo lineage), came about perhaps 2-3 million years ago. Rodents are so much older and have had time to diversify so much that we are relatively far removed from them genetically as compared to say lemurs or howler monkeys. All of these creatures arose from rodent-like creatures, then shrew-like creatures and then there was further diversification leading to gorillas, chimps and us.
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    how did they find out this order??? why not humans then chimp??
    wait i will watch the video...
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    Quote Originally Posted by fatooma
    how did they find out this order??? .
    From a careful, detailed study of the fossil record, from comparative anatomy, and more recently from comparison of genomes.
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    Quote Originally Posted by fatooma
    how did they find out this order??? why not humans then chimp??
    wait i will watch the video...
    The order is quite obvious due to the information the fossil record provides. Fossils that are more morphologically similar to our own are likely ancestors. Little or no DNA will be preserved for genetic comparison due to decay over time. But we don't require it. Humans are the only mammals to walk upright continuously which means that a bipedal mammalian fossil (such as Lucy) which shares a similar overall skeletal structure and skull with us (especially important is the placement of the foramen magnum, which is much lower in the Homo lineage) is more than likely a closely related ancestor. Chimps have their own ancestry separate from us..our histories don't converge until 7 million years ago when we shared a common ancestor.
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    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Quote Originally Posted by fatooma
    how did they find out this order??? why not humans then chimp??
    wait i will watch the video...
    Both chimps and humans came after the chimp/human ancestor.
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  10. #9 Re: Evolution 
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    Quote Originally Posted by fatooma
    so about the theory about evolution ,
    it is states that humans and chimps-mice came from the same ancestors
    and there is a DNA evidence , our DNA sequence and base sequence are 95% alike with chimps and 85% alike with mice!
    As SkinWalker indicated, you have this wrong.

    Only portions of human DNA sequences are very similar to chimps and mice. In particular the gene portion, which is about 3% of human DNA sequences, and then only the gene sequences not contained in the Y chromosomes are about 90-95% similar to Chimpanzee gene sequences (when genes with no homologues are included) and about 90-98% similar to mice. The Y chromosome gene portion is less than 50% similar and the balance of human DNA sequence is not very similar to either chimps or mice.

    The DNA evidence for the relationships is weak though. Much of it is based on similarites of specific sequences of the genes that are common. Based on sequence divergence primarily in the non critical regions of the derived proteins, and assuming that more similar sequences imply a later common ancestor, one can construct a model of ancestral relationships. Keep in mind that this mathematical model is based on inference. When this model of systematics is put into practice the results are not as nearly clean as one might hope. Depending on the genes used in the model, one gets very different results indicating that the model assumptions are likely too simplistic.

    Humans and chimps are thought to be descended from a common ancestor due to similarities in appearance, structure and organ configuration. It is an inference based on pattern matching. The fossil record provides important clues about these similarities and how the similarities seem to converge as one goes back in time.

    but this does not prove that humans have diverged from chimps or mice, why not chimps or mice have diverged from humans?? it could be a possibility right?? i don't get it, does anyone does?
    If we presume that all mammals share a common ancestor as the theory does, then it is unlikely that the relationships are some other way though because the fossil record indicates a pattern of similarity that is far more consistent with the current model than a model based on a different relationship.
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    I really don't know how you see the DNA evidence as being weak. I find it completely compelling to the point of being beyond irrefutable.

    Initial sequence of the chimpanzee genome and comparison with the human genome
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    Quote Originally Posted by Zwirko
    I really don't know how you see the DNA evidence as being weak. I find it completely compelling to the point of being beyond irrefutable.

    Initial sequence of the chimpanzee genome and comparison with the human genome
    Perhaps you and I are looking at this differently. Let me try this:

    Weak in the sense that cataloging the differences between two genomes is possible for all organisms and one will get a mathematical construct of how one could begin with a common hypothetical genome and morph it into the two. The fact that you can build this model does not tell us that the hypothetical alterations proposed by the model is correct. It does not tell us that alterations actually occurred. So I don't see how this is irrefutable except that it is irrefutable that the mathematical model provides a mechanism to do exactly what the model designers set out to do.

    Since this same thing can be done for any two organisms, I don't see what is demonstrates and what alternatives it eliminates.

    What am I missing?
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  13. #12  
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    Quote Originally Posted by fatooma
    but i saw some pictures in the net showing how the human is diverged from a chimp?
    and what are the common ancestors???
    ufff this is confusing!!
    archeologist just haven't found the common ancestor for human and chimps or we have found it we just don't realize that it is the common ancestor.
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    Quote Originally Posted by Topalk
    Quote Originally Posted by fatooma
    but i saw some pictures in the net showing how the human is diverged from a chimp?
    and what are the common ancestors???
    ufff this is confusing!!
    archeologist just haven't found the common ancestor for human and chimps or we have found it we just don't realize that it is the common ancestor.
    That would be because archaeologists study past human societies.

    Though it is true that paleontologists have not found a good candidate for the last common ancestor to humans and chimps. Common ancestors are taxa from which both can be traced thus humans have a younger common ancestor with chimps then with new world monkeys which have a younger common ancestor with us then with say, rabbits.
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    Quote Originally Posted by cypress
    Weak in the sense that cataloging the differences between two genomes is possible for all organisms and one will get a mathematical construct of how one could begin with a common hypothetical genome and morph it into the two. The fact that you can build this model does not tell us that the hypothetical alterations proposed by the model is correct. It does not tell us that alterations actually occurred. So I don't see how this is irrefutable except that it is irrefutable that the mathematical model provides a mechanism to do exactly what the model designers set out to do.
    The mechanisms of evolution are not provided by the mathematics of genetic relationship or similarity.

    No mathematical "model" of an evolutionary tree provides mechanism, or proposes alterations. Nor are they designed to.

    The various genetic trees provide constraints, descriptions of the world that any proposed mechanism or history or theory must fit.
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  16. #15  
    Forum Cosmic Wizard SkinWalker's Avatar
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    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by Topalk
    Quote Originally Posted by fatooma
    but i saw some pictures in the net showing how the human is diverged from a chimp?
    and what are the common ancestors???
    ufff this is confusing!!
    archeologist just haven't found the common ancestor for human and chimps or we have found it we just don't realize that it is the common ancestor.
    That would be because archaeologists study past human societies.
    Actually, some of the world's most renowned archaeologists are looking for just this Last Common Ancestor: Tim White, Louise Leakey, and others come to mind. Though I would say that the line between paleoanthropologist (archaeologist) and paleontologist blurs somewhere in this search, that there are many who specialize in hominid archaeology is without question.
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  17. #16  
    Time Lord Paleoichneum's Avatar
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    Quote Originally Posted by SkinWalker
    Quote Originally Posted by Paleoichneum
    Quote Originally Posted by Topalk
    Quote Originally Posted by fatooma
    but i saw some pictures in the net showing how the human is diverged from a chimp?
    and what are the common ancestors???
    ufff this is confusing!!
    archeologist just haven't found the common ancestor for human and chimps or we have found it we just don't realize that it is the common ancestor.
    That would be because archaeologists study past human societies.
    Actually, some of the world's most renowned archaeologists are looking for just this Last Common Ancestor: Tim White, Louise Leakey, and others come to mind. Though I would say that the line between paleoanthropologist (archaeologist) and paleontologist blurs somewhere in this search, that there are many who specialize in hominid archaeology is without question.
    Lol, Ok I admit it was a bit of a hasty generalization. Working at an Eocene public fossil dig site one of the most common questions I get is if I am an archaeologist, so my post was a bit of a knee-jerk reaction. (or they want the raptors and rexs, lol)
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  18. #17  
    Forum Cosmic Wizard SkinWalker's Avatar
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    LOL... one of the most common responses I get when I say I'm an archaeologist is "oh,you dig up dinosaurs!"
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