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Re: [evol-psych] Origin of bipedalism seems most closely tied to environmental changes

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  • Ronald C. Blue
    In the hot savanna a need to use the brain as a cooling tower increased. By standing up the angle of sun light changes so that one is cooler. The increase
    Message 1 of 8 , Apr 30, 2002
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      In the hot savanna a need to use the brain as a cooling tower increased. By
      standing up the angle of sun light changes so that one is cooler. The
      increase blood flow to the brain to expel heat allowed for a rapid increase
      in brain size which was useful tools and communication.

      Ron Blue
    • Leif Edward Ottesen Kennair
      Yes, this is the physiological-evolution/ adaptation is OK form of dualism Gould favours... which I suppose is the reason why giraffs also have large brains,
      Message 2 of 8 , May 1 2:27 AM
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        Yes, this is the physiological-evolution/ adaptation is OK form of dualism Gould favours... which I suppose is the reason why giraffs also have large brains, and that elephants adopt the same position and angle...

        The mere idea that chunks of cortex evolved i order to cool the blood is, apart from being oh so Aristotlian, quite an interesting just-so story-examplar.

        Cheers,

        Leif Edward

        ----- Original Message -----
        From: "Ronald C. Blue" <rblue@...>
        To: "Ian Pitchford" <ian.pitchford@...>; <evolutionary-psychology@yahoogroups.com>
        Cc: <a-lynn@...>
        Sent: Tuesday, April 30, 2002 10:10 PM
        Subject: Re: [evol-psych] Origin of bipedalism seems most closely tied to environmental changes


        > In the hot savanna a need to use the brain as a cooling tower increased. By
        > standing up the angle of sun light changes so that one is cooler. The
        > increase blood flow to the brain to expel heat allowed for a rapid increase
        > in brain size which was useful tools and communication.
        >
        > Ron Blue
        >
      • Steve Corsini
        Leif Edward Ottesen Kennair wrote The mere idea that chunks of cortex evolved in order to cool the blood is ... an example of the
        Message 3 of 8 , May 1 8:39 AM
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          Leif Edward Ottesen Kennair <leiedoke@...> wrote
           
          "The mere idea that chunks of cortex evolved in order to cool the blood is"...
           
          an example of the widespread misunderstanding of the whole process of evolution - the big cortex didn't evolve in order to do anything.  Individuals were born with bigger cortexes because of an inherent genetic disposition for big cortexes.
           
          The individuals with these bigger cortexes appear to have had some sort of advantage which enabled them to pass this disposition to the next generation.  The question is what sort of advantage would they have from having bigger cortexes which on the face of it would place them at a disadvantage because they require more energy to function - there are a whole range of perceivable benefits that we can see from having a bigger brain - seeing better, hearing better, dissipating heat, neural redundancy, better memory and problem solving, better skills at deception.....the list is just-so endless  
           
          The suggestion that the big brain is a heat disipating radiator is a reasonable explanation (see Fialkowski 1986 Current Anthropology 27:288-290, 1987 CA 28:540-543.) The whole suite of human heat adaptation; naked skin, sweating etc would have opened up a relatively vacant evolutionary niche - that of the midday hunter - if you visit the African savana today you would notice that most animals are inactive during the heat of the day - most hunting is done at dawn and dusk.  Few other animals can run marathon distances. 
           
          The fact that humans have great memories, social skills and vision are a consequence of bigger brains not the reason for having them.
           
          Steve Corsini, Consultant Archaeologist,
          Pickering Brook, Western Australia
        • Leif Edward Ottesen Kennair
          ... consequence of bigger brains not the reason for having them. The just-so story of no-function or physiological function is still just a just-so story.
          Message 4 of 8 , May 2 12:56 AM
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            Steve Corsini wrote:

            >The fact that humans have great memories, social skills and vision are a
            consequence of bigger brains not the reason for having them.

            The just-so story of no-function or physiological function is still just a
            just-so story. Establishing narrative validity does not make it more than a
            just-so story, or else the aquatic-ape theory (and this is neither for or
            against that theory) would be made true due to the pro-and-narrative-valid
            evidence gathered.

            Is there any analogy or homology?

            Do we have any examples of neuronal growth without neuronal function?

            Why were not the non neuronally functional neurons pruned/ atrophied?

            How do the cortex of the great apes fit into this?

            My conclusion is that this is an attempt at getting out of accepting
            psychological adaptation. Which is a form of dualism.

            The next step is usually to claim that this is not an adaptation, but rather
            an exaptation - and that therefore there is no way of predicting what arose.
            Thus Darwin and his theory may not be used to investigate psychology. And
            psychology is not inherently a biological or genetic study. Etc. Etc.

            I believe we have 3D vision to prevent us from jumping toward "small" trees,
            that really are distant trees. Colour vision to investigate ripeness of fruit.
            And thereafter I find it reasonable that we have other adaptations to solve
            other problems. Lashleys principle is not good enough anymore - if it were
            still an acceptable approach then I would not be as sure as I am that we have
            most of our cortex due to it being a lucky cooling contraption.

            Cheers,

            Leif Edward
          • Leif Edward Ottesen Kennair
            Correction, I meant: Lashleys principle is not good enough anymore - if it were still an acceptable approach then I would not be as sure as I am that we DO NOT
            Message 5 of 8 , May 2 2:04 AM
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              Correction, I meant:

              Lashleys principle is not good enough anymore - if it were still an acceptable
              approach then I would not be as sure as I am that we DO NOT have most of our
              cortex due to it being a lucky cooling contraption.
            • Herbert Gintis
              ... This sounds implausible to me. First, there is a clear tendency for primates to develop large brains even before the emergence of humans. Second, there
              Message 6 of 8 , May 2 5:32 AM
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                At 11:39 PM 5/1/2002 +0800, Steve Corsini wrote:
                The suggestion that the big brain is a heat disipating radiator is a reasonable explanation (see Fialkowski 1986 Current Anthropology 27:288-290, 1987 CA 28:540-543.) The whole suite of human heat adaptation; naked skin, sweating etc would have opened up a relatively vacant evolutionary niche - that of the midday hunter - if you visit the African savana today you would notice that most animals are inactive during the heat of the day - most hunting is done at dawn and dusk.  Few other animals can run marathon distances.
                 
                The fact that humans have great memories, social skills and vision are a consequence of bigger brains not the reason for having them.
                         This sounds implausible to me. First, there is a clear tendency for primates to develop large brains even before the emergence of humans. Second, there were correlated physiological changes having nothing to do with head dissipation, such as the physiological changes required for complex vocalizations, and the development of the nerves to the face. Finally, heat dissipater could not plausibly have accidentally involved the capacity for rapid and accurate information processing and computation. If anything, head dissipation would be a byproduct of brain development.

                Best,


                Herbert Gintis                                                       
                Professor of Economics, University of Massachusetts                       
                External Faculty, Santa Fe Institute, Santa Fe, NM
                15 Forbes Avenue, Northampton, MA 01060 413-586-7756
                Recent papers are posted on my web site.
                Get Game Theory Evolving (Princeton, 2000) at Amazon.com.
              • C. David Kreger
                Too bad Wheeler s analyses have been shown to be meaningless as a driving force, as they require the adaptation for the advantage to be incurred. If someone
                Message 7 of 8 , May 2 6:53 AM
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                  Too bad Wheeler's analyses have been shown to be meaningless as a
                  driving force, as they require the adaptation for the advantage to be
                  incurred. If someone wants to make the claim that our larger brains are
                  a consequence of needing to dissipate heat from a highly active brain,
                  well, that's a perfectly reasonable hypothesis I suppose, and testable
                  to a degree, since we have brains that are not very dense, and more and
                  longer connections between neurons, that communicate with electric
                  potentials that produce heat. However, claiming we evolved bigger
                  brains for the purpose of cooling our brain in the hot "midday" sun as
                  a result of becoming bipedal in order to exploit that extra time for
                  food exploitation, isn't a just-so story, its pretty dumb.

                  I wonder if Wheeler even still pushes his argument anyway, as he hasn't
                  published anything defending it in years. Of course, the evidence of
                  bipedalism seems to get older with every single find, which kind of
                  makes the whole idea passe anyways doesn't it....

                  CDK

                  --- Steve Corsini <sjcarc@...> wrote:
                  > Leif Edward Ottesen Kennair <leiedoke@...> wrote
                  >
                  > "The mere idea that chunks of cortex evolved in order to cool the
                  > blood is"...
                  >
                  > an example of the widespread misunderstanding of the whole process of
                  > evolution - the big cortex didn't evolve in order to do anything.
                  > Individuals were born with bigger cortexes because of an inherent
                  > genetic disposition for big cortexes.
                  >
                  > The individuals with these bigger cortexes appear to have had some
                  > sort of advantage which enabled them to pass this disposition to the
                  > next generation. The question is what sort of advantage would they
                  > have from having bigger cortexes which on the face of it would place
                  > them at a disadvantage because they require more energy to function -
                  > there are a whole range of perceivable benefits that we can see from
                  > having a bigger brain - seeing better, hearing better, dissipating
                  > heat, neural redundancy, better memory and problem solving, better
                  > skills at deception.....the list is just-so endless
                  >
                  > The suggestion that the big brain is a heat disipating radiator is a
                  > reasonable explanation (see Fialkowski 1986 Current Anthropology
                  > 27:288-290, 1987 CA 28:540-543.) The whole suite of human heat
                  > adaptation; naked skin, sweating etc would have opened up a
                  > relatively vacant evolutionary niche - that of the midday hunter - if
                  > you visit the African savana today you would notice that most animals
                  > are inactive during the heat of the day - most hunting is done at
                  > dawn and dusk. Few other animals can run marathon distances.
                  >
                  > The fact that humans have great memories, social skills and vision
                  > are a consequence of bigger brains not the reason for having them.
                  >
                  > Steve Corsini, Consultant Archaeologist,
                  > Pickering Brook, Western Australia
                  >


                  =====
                  C. David Kreger dkreger@...
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                • Ronald C. Blue
                  http://biology.uindy.edu/Biol504/HUMANSTRATEGY/19brainsize.htm Redundancy. Multiplication of neurons and circuits may have provided a greater margin of failure
                  Message 8 of 8 , May 2 9:49 AM
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                    http://biology.uindy.edu/Biol504/HUMANSTRATEGY/19brainsize.htm

                    Redundancy. Multiplication of neurons and circuits may have provided a
                    greater margin of failure under the stress of overheating in the African
                    savanna (Fialkowski 1986, 1988; Glassman 1987). This surplus of brain tissue
                    could later have been redesigned for additional functions resulting in an
                    increase in intellectual capacity as well as brain size.

                    The Radiator Hypothesis. Falk (1990) observes that hominid skulls and
                    circulatory systems have a pattern of venous drainage that could contribute
                    to cooling the brain. Since the brain is extremely sensitive to elevation in
                    temperature, she proposes that thermal control was a limiting factor. Brain
                    expansion quickly followed the solution to cooling it.


                    Falk, D. 1990-91. Brain evolution in Homo: the "radiator" theory (target
                    article). Behavioral and Brain Sciences 13: 333-344. Evolution of a venous
                    "radiator" for cooling the cortex: "Prime releaser" of brain evolution in
                    Homo (response to open peer commentary), 368-381. Author's response to
                    Continuing Commentary on Brain evolution in Homo: The "radiator" theory.
                    More on the radiator, 14: 529-530.
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