"This is no more a proof of common ancestry than it is of common design. One does not look at the various cars on the market today and postulate that they share a common ancestor. One concludes, rather, that they have a common creator. There are many components and designs that are shared in common with various vehicles, and other parts that are unique to each type. If one wants precedence for what a similar genetic makeup means, one should look at what humans have created - it demonstrates a common designer, not a common ancestor. "
uhhh, sorry to say, but your example is a good one to SUPPORT the argument for a common ancestory to the automobile, not against it. common parts to each suggests a common ancestry, different parts suggests adaptation to different selective pressures (fuel economy, speed requirements, off road capability, etc.) These selective pressures have acted on a common auto "ancestor" to produce variablity and speciation within the automobile, thus the various types, colors, and styles we see today. A single designer theory would postulate that that designer would have had to replicate his design thousands of times and in thousands of different ways in response to FUTURE selective pressures the designer could know nothing about. hmmm. which sounds more plausible?
"And how, exactly, would one falsify the claim that all living things share a common ancestor? Normally falsifiability requires a repeatable, empirical experiment. Repeatable being beneficial, but not necessary - if the experiment is unrepeatable then it is far less demonstrated as a theory. What experiment do you recommend for falsifying common ancestry?"
er, again, experiments attempting to falsify common ancestry happen every time we sequence a genome. The moment we sequence a genome and find it to be completely unique; that would falsify common ancestry quite nicely.
as a final point, scientific theories are not ever meant to be absolutes (unlike religious theories); they merely attempt to explain observed phonomenon in the most efficacious way possible. the utility of a theory is simply if it works to explain most observable phenomenon relative to its scope. As new phenomenon are observed, new tools come to bear, new understandings gained, theories become "dropped" as newer theories fit observed data better. Science is NOT a religion, simply a way to look at the world to get the most out of it at the current moment in time, nothing more.
" The evolutionary trees constructed from gene sequence mirror those constructed by observing phenotypes."
actually, that often is not the case; there has been a huge argument brewing for at least a decade between morphologists (those who categorize based on phenotypic similarities) and genetecists (those that categorize on genotypic similarities).
there are many cases where the degree of genotype similarity does not coincide with phenotype similarities. Current cladistics (animal classification theory) is still sticking mostly with the phenotype model, primarily because it is extant and efficacious, but the geneticists are producing new models that predict and explain speciation and groupings in similarly usefull ways.
in the future, i expect students will have to be taught both classification methods, as they both have their uses, and often don't agree on classification.
cheers
perhaps THAT point was missed (thanks for the history lesson, BTW), but the posters point was about energy consumption of bipedal vs. qudrapedal locomotion, of which Leaky's experiment was not a good test of this. Great examples of experiments looking at energy efficiencies of various modes of locomotion can be found by doing searches on the research done on Kangaroo locomotion.
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"This is no more a proof of common ancestry than it is of common design. One does not look at the various cars on the market today and postulate that they share a common ancestor. One concludes, rather, that they have a common creator. There are many components and designs that are shared in common with various vehicles, and other parts that are unique to each type. If one wants precedence for what a similar genetic makeup means, one should look at what humans have created - it demonstrates a common designer, not a common ancestor. " uhhh, sorry to say, but your example is a good one to SUPPORT the argument for a common ancestory to the automobile, not against it. common parts to each suggests a common ancestry, different parts suggests adaptation to different selective pressures (fuel economy, speed requirements, off road capability, etc.) These selective pressures have acted on a common auto "ancestor" to produce variablity and speciation within the automobile, thus the various types, colors, and styles we see today. A single designer theory would postulate that that designer would have had to replicate his design thousands of times and in thousands of different ways in response to FUTURE selective pressures the designer could know nothing about. hmmm. which sounds more plausible? "And how, exactly, would one falsify the claim that all living things share a common ancestor? Normally falsifiability requires a repeatable, empirical experiment. Repeatable being beneficial, but not necessary - if the experiment is unrepeatable then it is far less demonstrated as a theory. What experiment do you recommend for falsifying common ancestry?" er, again, experiments attempting to falsify common ancestry happen every time we sequence a genome. The moment we sequence a genome and find it to be completely unique; that would falsify common ancestry quite nicely. as a final point, scientific theories are not ever meant to be absolutes (unlike religious theories); they merely attempt to explain observed phonomenon in the most efficacious way possible. the utility of a theory is simply if it works to explain most observable phenomenon relative to its scope. As new phenomenon are observed, new tools come to bear, new understandings gained, theories become "dropped" as newer theories fit observed data better. Science is NOT a religion, simply a way to look at the world to get the most out of it at the current moment in time, nothing more.
" The evolutionary trees constructed from gene sequence mirror those constructed by observing phenotypes." actually, that often is not the case; there has been a huge argument brewing for at least a decade between morphologists (those who categorize based on phenotypic similarities) and genetecists (those that categorize on genotypic similarities). there are many cases where the degree of genotype similarity does not coincide with phenotype similarities. Current cladistics (animal classification theory) is still sticking mostly with the phenotype model, primarily because it is extant and efficacious, but the geneticists are producing new models that predict and explain speciation and groupings in similarly usefull ways. in the future, i expect students will have to be taught both classification methods, as they both have their uses, and often don't agree on classification. cheers
perhaps THAT point was missed (thanks for the history lesson, BTW), but the posters point was about energy consumption of bipedal vs. qudrapedal locomotion, of which Leaky's experiment was not a good test of this. Great examples of experiments looking at energy efficiencies of various modes of locomotion can be found by doing searches on the research done on Kangaroo locomotion.