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Re: Aquatic Ape Hypothesis, potential fossil evidence,Oreopithecus/Ardipithecus link

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  • dons3148
    ... Marc - As said, salt is present in sweat as sweat is derived blood plasma, all the body is doing is conserving that salt by having the glands reabsorb
    Message 1 of 20 , Oct 1, 2010
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      --- In AAT@yahoogroups.com, Marc Verhaegen <m_verhaegen@...> wrote:
      >
      >
      > >>>>>> Sweat also exudes salts.  The human form could
      > >>>>>> never have evolved unless our ancestors lived
      > >>>>>> under conditions where those salts were being
      > >>>>>> automatically replaced.
      >
      > >>>>> Oh, bloody hell. That's a damn good argument for a
      > >>>>> sea-version. The tears argument from AAH also adds
      > >>>>> heavily to a salt water notion. It
      > >>>>> makes a Mediterrenean region interesting with reference
      > >>>>> to Oreopithecus, but other than that I'm left confused.
      >
      > >>>> Afr.apes also have body eccrine sweat glands (although less
      > >>>> than humans?), and gorillas are said to shed emotional tears.
      > >>>> This suggests a salt- or brackish waterside phase prior to
      > >>>> the LCA of chimps, humans & gorillas, ie, probably before the
      > >>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
      > >>>> lasting to the MSC or even later. This
      > >>>> early waterside phase was apparently different from the
      > >>>> coastal dispersal of Homo during the Pleistocene.
      >
      > >>> The human body does not sweat to lose 'salt', as the
      > >>> body will normally reabsorb most of the 'salt' from
      > >>> the sweat solution back into the sweat duct as we
      > >>> sweat.
      >
      > >> Eccrine glands secrete salt, but this is (largely) reabsorbed
      > >> in the ductus (double work for a zero result).
      >
      > > To do otherwise, would be to waste 'salt', Marc.
      >
      > If the eccrine glands hadn't secreted salt, the ducti didn't
      > have to reabsorb it.
      >



      Marc - As said, 'salt' is present in sweat as sweat is
      derived blood plasma, all the body is doing is conserving
      that 'salt' by having the glands reabsorb it as we sweat.




      > > 'Salt' is essential for the maintenance of human life.
      >
      > No problem at the coast, to the contrary.
      >


      The 'salt' balance within our bodies is essential
      for maintenance of life. (saltwater is too salty
      to drink, attempting to do so would result in
      dehydration)




      > > One reason 'salt' is present in sweat is that sweat
      > > is derived from blood, specifically blood plasma.
      >
      > It's present in sweat because we have abundant sweat
      > glands over our bodies.
      >



      Sweat is 90% water, body fluid is blood, blood plasma
      is 90% water, sweat is derived from blood plasma.

      [QUOTE]
      The clear secretion produced by merocrine glands is
      termed sweat, or sensible perspiration. Sweat is mostly
      water, but it does contain some electrolytes, since it
      is derived from blood plasma, although less concentrated.
      It therefore contains mainly sodium chloride, but also
      other small molecules in the blood. The presence of
      sodium chloride gives sweat a salty taste.




      > >> This suggests
      > >> a salt or brackish water phase followed by a
      > >> freshwater phase.
      >
      > > Unlikely, Marc...
      > > As the highest concentration of merocrine sweat glands
      > > in humans are in the palms of the hands and the soles
      > > of the feet, a pattern that would be expected in an
      > > animal who's ancestors once spent time in the trees
      > > climbing.
      >
      > Possible, but we differ from most primates in having these
      > glands all over our bodies: why?
      >


      Warm blooded mammals sweat, sweat or pant (primates
      and horses also have sweaty "armpits").

      Humans differ from other primates in having a larger
      number of sweat glands, a relatively hairless body
      and their reliance on sweating to thermoregulate
      their body temp.

      [QUOTE]
      Sweat glands, or sudoriferous glands, are exocrine
      glands found under the skin in all mammal species
      which are used for body temperature regulation
      (thermoregulation). In humans, apocrine and merocrine
      sweat glands form the primary method of cooling. Many
      other mammals, such as cats, dogs and pigs, rely on
      panting or other means as a primary source of
      cooling, but still have sweat glands which aid
      in thermoregulation. Sweat also serves to increase
      friction on the palms of hands or the pads of paws.
      [Wikipedia]




      > > Evidence of how our kidneys evolved would be a better
      > > indicator as to how our ancestors adapted to living
      > > and foraging on the shore.
      >
      > Than it's clear: human newborns have renculised kidneys
      >(typical of marine mammals), which afterwards grow into
      > more suid-like kidneys.
      >


      An ancestral adaptation of the human kidneys, as a
      result of ingesting large quantise of sea-foods on
      the shore?




      > > (as it is our kidneys
      > > that deal with excess 'salt' not our sweat glands).
      > > Sweat in mammals probably originally evolved to keep
      > > the skin from drying.
      >
      > Then why don't most mammals have eccrine skin glands.
      >


      Most mammals subsequently evolved hair, or fur
      to protect the skin.

      Merocrine or eccrine skin sweat glands are more
      common in primates.





      > > In humans, sweating is
      > > primarily a means of thermoregulation.
      >
      > >> The dispersal of Homo to different continents occurred along
      > >> the coasts = salt. Pachyostosis (erectus) also is seen in
      > >> saltwater habitats, but afterwards we re-evolved thinner
      > >> bones again (still slightly heavier than equally large
      > >> nonhuman terrestrials). --marc
      >
      > > Would think chimpanzee and gorilla have heavier/denser
      > > bones than Modern humans.
      >
      > No, it's He>>Hn>>Hs>apiths>others
      > (apiths marginally more, Hs a little bit more, Hn
      > considerably more, He very
      > much). --marc



      He was heavier built than chimpanzee today?
      (had heavier bones, more muscle mass)


      -- Bill






      > >>> (an adult has approx.3 million merocrine/
      > >>> eccrine sweat glands, to help in regulating
      > >>> body temp.)
      > >>> "Sweat glands produce sweat through a well understood
      > >>> process of secretion and reabsorption of sodium chloride
      > >>> salt. Secretion entails the movement of salt and water
      > >>> from sweat gland cells and into the sweat duct.
      > >>> Reabsorption occurs in the duct with the movement
      > >>> of salt from the sweat back into sweat duct cells.
      > >>> What remains is sweat, a salt solution with a
      > >>> relatively finely tuned concentration of sodium
      > >>> and chloride." [Wikipedia] -- Bill
      > >>
      > >>>>> I would still
      > >>>>> hold that we do not appear to be a fully-aquatic primate in any
      > >>>>> scenario. We can't traverse oceans, at most we can swim from island to
      > >>>>> island.
      > >>>>
      > >>>> The features of Homo (pachyostosis, external nose etc.) suggest a
      > >>>> semi-aquatic past, nobody ever suggested a fully "aquatic ape".
      > >>>>
      > >>>>> Either way, this IS a bit funky:
      > >>>>> http://www.youtube.com/watch?v=vF4PN8-2YSk&feature=related
      > >>>>
      > >>>> :-) Thanks, Engelbrecht.
      > >>>>
      > >>>>>>> And yes, it's a reversed perspective on the current
      > >>>>>>> orthodoxy, but again, no one is suggesting an aquatic ape
      > >>>>>>> with a biological niche akin to whales, a 'sea-ape' or
      > >>>>>>> something.
      > >>>>
      > >>>>>> Oh yes, they are. Listen to David Attenborough.
      > >>>>>> Or read your own words.  How else do you explain
      > >>>>>> naked skin and bipedalism?
      > >>>>
      > >>>>> Naked skin would be an aquatic adaptation in both aquatic or semi-
      > >>>>> aquatic variants.
      > >>>>
      > >>>> In semi-aquatics only in tropical medium-sized mammals (eg, babirusa).
      > >>>> Furlessness, however, is also seen in a few tropical terrestrial mammals.
      > >>>>
      > >>>>> Bipedalism would be a aquatic or semi-aquatic
      > >>>>> adaptation when compared to aquatic birds (penguins), but only when
      > >>>>> considering a similar division in birds and apes of fore and rear
      > >>>>> limbs into diverse functions, leading to bipedalism with a vertical
      > >>>>> spine during an aquatic adaptation.
      > >>>>
      > >>>>>> IF humans could live on
      > >>>>>> shellfish, after the manner of the ancestors
      > >>>>>> supposed by AAT theorists, then there would still
      > >>>>>> be plenty of such populations.
      > >>>>
      > >>>> In fact, "shellfish is best able to meet the adult requirement for these
      > >>>> brain selective minerals": I, Fe, Cu, Zn & Se (S.Cunnane "Survival of the
      > >>>> fattest") + of course, DHA.
      > >>>>
      > >>>>>>  But such food is
      > >>>>>> never more than a fraction of human diet, and
      > >>>>>> certainly never enough to establish a niche, or
      > >>>>>> justify enormous changes in morphology and
      > >>>>>> behaviour.
      > >>>>
      > >>>> Refs for this blabla?
      > >>>>
      > >>>>> Yes, the issue of diet. I remember studies of Lucy's teeth:
      > >>>>> http://www.physorg.com/news175415022.html
      > >>>>
      > >>>> Lucy is a hominid, a fossil relative of ours & Afr.apes, but not our
      > >>>> ancestor. A.afarensis had large airsacs (Dikika), curved phalanges
      > >>>> (below-branch), rel.short legs, no ext.nose, no large brain, it was
      > >>>> apparently an orthograde aquarboreal ape, living in swamp forests, feeding
      > >>>> on floating vegetation (incl.papyrus?), hard-shelled foods (cf resemblances
      > >>>> to sea otter dentition, A.Walker). Enamel microwear (glossy polishing)
      > >>>> suggests wet plant foods.
      > >>>>
      > >>>>> But it appears inconclusive, they couldn't quite figure out what she
      > >>>>> ate. Her thicker enamel would indicate one thing, but microscopic tear
      > >>>>> marks indicates something else. Best estiment was that she was largely
      > >>>>> a herbivore. (Have there been similar studies of the teeth of Ardi and
      > >>>>> Oreo?)
      > >>>>> As I understand it, they detected that elephants had an aquatic past
      > >>>>> from studying the teeth of its ancestor Moeritherium, and indeed
      > >>>>> looking at tear marks to deduce that it ate water plants. I have only
      > >>>>> found references to this study, so I don't know the details and if a
      > >>>>> comparative analysis with Lucy is possible.
      > >>>>> http://news.nationalgeographic.com/news/2008/04/080414-elephant-evolution.
      > >>>>> ht
      > >>>>> ml
      > >>>>> One notion could be that our modern disposition towards eating cereals
      > >>>>> (wheat, rice, etc.) might be a clue to Lucy's diet. Or is there some
      > >>>>> form of water plant (sea weed, etc.) that fit the profile of Lucy's
      > >>>>> teeth?
      > >>>>
      > >>>> Google papyrus boisei van der merwe.
      > >>>> A.boisei evolved from Lucy-like creatures. --marc
      >
    • Marc Verhaegen
      ... Bob, as generally know, sweat excreted by the gland before the reabsorption in the ductus is a lot more concentrated than blood plasma. ... No marine
      Message 2 of 20 , Oct 1, 2010
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        >>>>>>>> Sweat also exudes salts.  The human form could
        >>>>>>>> never have evolved unless our ancestors lived
        >>>>>>>> under conditions where those salts were being
        >>>>>>>> automatically replaced.

        >>>>>>> Oh, bloody hell. That's a damn good argument for a
        >>>>>>> sea-version. The tears argument from AAH also adds
        >>>>>>> heavily to a salt water notion. It
        >>>>>>> makes a Mediterrenean region interesting with reference
        >>>>>>> to Oreopithecus, but other than that I'm left confused.

        >>>>>> Afr.apes also have body eccrine sweat glands (although less
        >>>>>> than humans?), and gorillas are said to shed emotional tears.
        >>>>>> This suggests a salt- or brackish waterside phase prior to
        >>>>>> the LCA of chimps, humans & gorillas, ie, probably before the
        >>>>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
        >>>>>> lasting to the MSC or even later. This
        >>>>>> early waterside phase was apparently different from the
        >>>>>> coastal dispersal of Homo during the Pleistocene.

        >>>>> The human body does not sweat to lose 'salt', as the
        >>>>> body will normally reabsorb most of the 'salt' from
        >>>>> the sweat solution back into the sweat duct as we
        >>>>> sweat.

        >>>> Eccrine glands secrete salt, but this is (largely) reabsorbed
        >>>> in the ductus (double work for a zero result).

        >>> To do otherwise, would be to waste 'salt', Marc.

        >> If the eccrine glands hadn't secreted salt, the ducti didn't
        >> have to reabsorb it.

        > Marc - As said, 'salt' is present in sweat as sweat is
        > derived blood plasma, all the body is doing is conserving
        > that 'salt' by having the glands reabsorb it as we sweat.

        Bob, as generally know, sweat excreted by the gland before the reabsorption
        in the ductus is a lot more concentrated than blood plasma.

        >>> 'Salt' is essential for the maintenance of human life.

        >> No problem at the coast, to the contrary.

        > The 'salt' balance within our bodies is essential
        > for maintenance of life. (saltwater is too salty
        > to drink, attempting to do so would result in
        > dehydration)

        No marine mammal drinks sea water. They ingest more than enough salt with
        their diet.

        >>> One reason 'salt' is present in sweat is that sweat
        >>> is derived from blood, specifically blood plasma.

        >> It's present in sweat because we have abundant sweat
        >> glands over our bodies.

        > Sweat is 90% water, body fluid is blood, blood plasma
        > is 90% water, sweat is derived from blood plasma.
        > "The clear secretion produced by merocrine glands is
        > termed sweat, or sensible perspiration. Sweat is mostly
        > water, but it does contain some electrolytes, since it
        > is derived from blood plasma, although less concentrated.
        > It therefore contains mainly sodium chloride, but also
        > other small molecules in the blood. The presence of
        > sodium chloride gives sweat a salty taste."

        Bob, as said, the gland secrete is hypertonic, but the duct reabsorps
        sodium.

        >>>> This suggests
        >>>> a salt or brackish water phase followed by a
        >>>> freshwater phase.

        >>> Unlikely, Marc...
        >>> As the highest concentration of merocrine sweat glands
        >>> in humans are in the palms of the hands and the soles
        >>> of the feet, a pattern that would be expected in an
        >>> animal who's ancestors once spent time in the trees
        >>> climbing.

        >> Possible, but we differ from most primates in having these
        >> glands all over our bodies: why?

        > Warm blooded mammals sweat, sweat or pant (primates
        > and horses also have sweaty "armpits").
        > Humans differ from other primates in having a larger
        > number of sweat glands,

        So far ok.
        Why?

        > a relatively hairless body and their reliance on sweating
        > to thermoregulate their body temp.

        Now used in cooling, but not evolved for cooling, of course: otherwise all
        mammals had used it.

        > "Sweat glands, or sudoriferous glands, are exocrine
        > glands found under the skin in all mammal species
        > which are used for body temperature regulation
        > (thermoregulation). In humans, apocrine and merocrine
        > sweat glands form the primary method of cooling. Many
        > other mammals, such as cats, dogs and pigs, rely on
        > panting or other means as a primary source of
        > cooling, but still have sweat glands which aid
        > in thermoregulation. Sweat also serves to increase
        > friction on the palms of hands or the pads of paws."

        Yes, that leaves the question: why did we, as opposed to most other mammals,
        evolve body eccrines?

        >>> Evidence of how our kidneys evolved would be a better
        >>> indicator as to how our ancestors adapted to living
        >>> and foraging on the shore.

        >> Than it's clear: human newborns have renculised kidneys
        >> (typical of marine mammals), which afterwards grow into
        >> more suid-like kidneys.

        > An ancestral adaptation of the human kidneys, as a
        > result of ingesting large quantise of sea-foods on
        > the shore?

        No doubt IMO.

        >>> (as it is our kidneys
        >>> that deal with excess 'salt' not our sweat glands).
        >>> Sweat in mammals probably originally evolved to keep
        >>> the skin from drying.

        >> Then why don't most mammals have eccrine skin glands?

        > Most mammals subsequently evolved hair, or fur
        > to protect the skin.

        Most furred mammals don't have eccrine skin glands.
        Horses & camels (furred) sweat thermoactively.

        > Merocrine or eccrine skin sweat glands are more
        > common in primates.

        Hominids (HPG) have eccrine glands over the whole body, monkeys &
        prosimians, like carnivores, rodents etc., don't.

        >>> In humans, sweating is
        >>> primarily a means of thermoregulation.

        >>>> The dispersal of Homo to different continents occurred along
        >>>> the coasts = salt. Pachyostosis (erectus) also is seen in
        >>>> saltwater habitats, but afterwards we re-evolved thinner
        >>>> bones again (still slightly heavier than equally large
        >>>> nonhuman terrestrials). --marc

        >>> Would think chimpanzee and gorilla have heavier/denser
        >>> bones than Modern humans.

        >> No, it's He>>Hn>>Hs>apiths>others
        >> (apiths marginally more, Hs a little bit more, Hn
        >> considerably more, He very
        >> much). --marc

        > He was heavier built than chimpanzee today?
        > (had heavier bones,

        At least twice as heavy.

        > more muscle mass) -- Bill

        No: chimps are several times stronger than humans.

        Bones that are very heavy are also more brittle.

        --marc
      • dons3148
        ... Sweat is less concentrated than blood plasma, Marc. (An salt water is a lot more concentrated than blood plasma) [QUOTE] The clear secretion produced by
        Message 3 of 20 , Oct 2, 2010
        • 0 Attachment
          --- In AAT@yahoogroups.com, Marc Verhaegen <m_verhaegen@...> wrote:
          >
          >
          > >>>>>>>> Sweat also exudes salts.  The human form could
          > >>>>>>>> never have evolved unless our ancestors lived
          > >>>>>>>> under conditions where those salts were being
          > >>>>>>>> automatically replaced.
          >
          > >>>>>>> Oh, bloody hell. That's a damn good argument for a
          > >>>>>>> sea-version. The tears argument from AAH also adds
          > >>>>>>> heavily to a salt water notion. It
          > >>>>>>> makes a Mediterrenean region interesting with reference
          > >>>>>>> to Oreopithecus, but other than that I'm left confused.
          >
          > >>>>>> Afr.apes also have body eccrine sweat glands (although less
          > >>>>>> than humans?), and gorillas are said to shed emotional tears.
          > >>>>>> This suggests a salt- or brackish waterside phase prior to
          > >>>>>> the LCA of chimps, humans & gorillas, ie, probably before the
          > >>>>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
          > >>>>>> lasting to the MSC or even later. This
          > >>>>>> early waterside phase was apparently different from the
          > >>>>>> coastal dispersal of Homo during the Pleistocene.
          >
          > >>>>> The human body does not sweat to lose 'salt', as the
          > >>>>> body will normally reabsorb most of the 'salt' from
          > >>>>> the sweat solution back into the sweat duct as we
          > >>>>> sweat.
          >
          > >>>> Eccrine glands secrete salt, but this is (largely) reabsorbed
          > >>>> in the ductus (double work for a zero result).
          >
          > >>> To do otherwise, would be to waste 'salt', Marc.
          >
          > >> If the eccrine glands hadn't secreted salt, the ducti didn't
          > >> have to reabsorb it.
          >
          > > Marc - As said, 'salt' is present in sweat as sweat is
          > > derived blood plasma, all the body is doing is conserving
          > > that 'salt' by having the glands reabsorb it as we sweat.
          >





          > Bob, as generally know, sweat excreted by the gland before
          > the reabsorption in the ductus is a lot more concentrated
          > than blood plasma.
          >


          Sweat is less concentrated than blood plasma, Marc.
          (An salt water is a lot more concentrated than
          blood plasma)

          [QUOTE]
          The clear secretion produced by merocrine glands is termed
          sweat, or sensible perspiration. Sweat is mostly water, but
          it does contain some electrolytes, since it is derived from
          blood plasma, although less concentrated. It therefore
          contains mainly sodium chloride, but also other small
          molecules in the blood. The presence of sodium chloride
          gives sweat a salty taste.





          > >>> 'Salt' is essential for the maintenance of human life.
          >
          > >> No problem at the coast, to the contrary.
          >
          > > The 'salt' balance within our bodies is essential
          > > for maintenance of life. (saltwater is too salty
          > > to drink, attempting to do so would result in
          > > dehydration)
          >
          > No marine mammal drinks sea water. They ingest more than
          > enough salt with their diet.
          >
          > >>> One reason 'salt' is present in sweat is that sweat
          > >>> is derived from blood, specifically blood plasma.
          >
          > >> It's present in sweat because we have abundant sweat
          > >> glands over our bodies.
          >
          > > Sweat is 90% water, body fluid is blood, blood plasma
          > > is 90% water, sweat is derived from blood plasma.
          > > "The clear secretion produced by merocrine glands is
          > > termed sweat, or sensible perspiration. Sweat is mostly
          > > water, but it does contain some electrolytes, since it
          > > is derived from blood plasma, although less concentrated.
          > > It therefore contains mainly sodium chloride, but also
          > > other small molecules in the blood. The presence of
          > > sodium chloride gives sweat a salty taste."
          >
          > Bob, as said, the gland secrete is hypertonic, but the
          > duct reabsorps sodium.
          >



          Sodium an other content the body wants to conserve, it is
          the 90% + water content of sensible sweat that is used to
          lose body heat. (sweat is also said to contain a small
          amount of urea)




          > >>>> This suggests
          > >>>> a salt or brackish water phase followed by a
          > >>>> freshwater phase.
          >
          > >>> Unlikely, Marc...
          > >>> As the highest concentration of merocrine sweat glands
          > >>> in humans are in the palms of the hands and the soles
          > >>> of the feet, a pattern that would be expected in an
          > >>> animal who's ancestors once spent time in the trees
          > >>> climbing.
          >
          > >> Possible, but we differ from most primates in having these
          > >> glands all over our bodies: why?
          >
          > > Warm blooded mammals sweat, sweat or pant (primates
          > > and horses also have sweaty "armpits").
          > > Humans differ from other primates in having a larger
          > > number of sweat glands,
          >
          > So far ok.
          > Why?
          >


          To produce sensible perspiration, the type of sweat
          used to lose body heat,.

          In the other primates a lower number of sweat glands
          is probably sufficient for insensible sweating and for
          the higher concentration of sweat glands in friction
          surfaces like the palm of the hand and sole of the
          foot (for a better grip while climbing - humans have
          some 500 sweat glands per square cm in the palm
          of the hand)




          > > a relatively hairless body and their reliance on sweating
          > > to thermoregulate their body temp.
          >
          > Now used in cooling, but not evolved for cooling, of course:
          > otherwise all mammals had used it.
          >
          > > "Sweat glands, or sudoriferous glands, are exocrine
          > > glands found under the skin in all mammal species
          > > which are used for body temperature regulation
          > > (thermoregulation). In humans, apocrine and merocrine
          > > sweat glands form the primary method of cooling. Many
          > > other mammals, such as cats, dogs and pigs, rely on
          > > panting or other means as a primary source of
          > > cooling, but still have sweat glands which aid
          > > in thermoregulation. Sweat also serves to increase
          > > friction on the palms of hands or the pads of paws."
          >
          > Yes, that leaves the question: why did we, as opposed to
          > most other mammals, evolve body eccrines?
          >



          To lose body heat, humans differ from most mammals in
          having a relatively large brain in a medium sized
          primate body.




          > >>> Evidence of how our kidneys evolved would be a better
          > >>> indicator as to how our ancestors adapted to living
          > >>> and foraging on the shore.
          >
          > >> Than it's clear: human newborns have renculised kidneys
          > >> (typical of marine mammals), which afterwards grow into
          > >> more suid-like kidneys.
          >
          > > An ancestral adaptation of the human kidneys, as a
          > > result of ingesting large quantise of sea-foods on
          > > the shore?
          >
          > No doubt IMO.
          >
          > >>> (as it is our kidneys
          > >>> that deal with excess 'salt' not our sweat glands).
          > >>> Sweat in mammals probably originally evolved to keep
          > >>> the skin from drying.
          >
          > >> Then why don't most mammals have eccrine skin glands?
          >
          > > Most mammals subsequently evolved hair, or fur
          > > to protect the skin.
          >
          > Most furred mammals don't have eccrine skin glands.
          > Horses & camels (furred) sweat thermoactively.
          >



          Horses sweat, sweat profusely, furred/hairy species like
          dogs pant to lose heat, dogs also have eccrine glands in
          their paws.

          Incidentally horse sweat (an zebra) has an additional
          an unusual ingredient called latherin that acts to
          wet the horses hair when the horse sweats.

          See:
          http://eprints.gla.ac.uk/6387/





          > > Merocrine or eccrine skin sweat glands are more
          > > common in primates.
          >
          > Hominids (HPG) have eccrine glands over the whole body, monkeys &
          > prosimians, like carnivores, rodents etc., don't.
          >
          > >>> In humans, sweating is
          > >>> primarily a means of thermoregulation.
          >
          > >>>> The dispersal of Homo to different continents occurred along
          > >>>> the coasts = salt. Pachyostosis (erectus) also is seen in
          > >>>> saltwater habitats, but afterwards we re-evolved thinner
          > >>>> bones again (still slightly heavier than equally large
          > >>>> nonhuman terrestrials). --marc
          >
          > >>> Would think chimpanzee and gorilla have heavier/denser
          > >>> bones than Modern humans.
          >
          > >> No, it's He>>Hn>>Hs>apiths>others
          > >> (apiths marginally more, Hs a little bit more, Hn
          > >> considerably more, He very
          > >> much). --marc
          >
          > > He was heavier built than chimpanzee today?
          > > (had heavier bones,
          >
          > At least twice as heavy.
          >
          > > more muscle mass) -- Bill
          >
          > No: chimps are several times stronger than humans.
          >
          > Bones that are very heavy are also more brittle.
          >
          > --marc
          >



          He was twice as heavy as chimpanzee today?

          Some now claim that He was much smaller in terms
          of stature than has been generally accepted.

          (163 cm instead of 185 cm in the case of the
          Nariakotome Boy)


          -- Bill
        • Marc Verhaegen
          ... Again: - the gland itself produces a hypertonic solution, - the glandular duct reabsorbs sodium. ... Again: - terrestrial & freshwater mammals try to
          Message 4 of 20 , Oct 2, 2010
          • 0 Attachment
            >>>>>>>>>> Sweat also exudes salts.  The human form could
            >>>>>>>>>> never have evolved unless our ancestors lived
            >>>>>>>>>> under conditions where those salts were being
            >>>>>>>>>> automatically replaced.

            >>>>>>>>> Oh, bloody hell. That's a damn good argument for a
            >>>>>>>>> sea-version. The tears argument from AAH also adds
            >>>>>>>>> heavily to a salt water notion. It
            >>>>>>>>> makes a Mediterrenean region interesting with reference
            >>>>>>>>> to Oreopithecus, but other than that I'm left confused.

            >>>>>>>> Afr.apes also have body eccrine sweat glands (although less
            >>>>>>>> than humans?), and gorillas are said to shed emotional tears.
            >>>>>>>> This suggests a salt- or brackish waterside phase prior to
            >>>>>>>> the LCA of chimps, humans & gorillas, ie, probably before the
            >>>>>>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
            >>>>>>>> lasting to the MSC or even later. This
            >>>>>>>> early waterside phase was apparently different from the
            >>>>>>>> coastal dispersal of Homo during the Pleistocene.

            >>>>>>> The human body does not sweat to lose 'salt', as the
            >>>>>>> body will normally reabsorb most of the 'salt' from
            >>>>>>> the sweat solution back into the sweat duct as we
            >>>>>>> sweat.

            >>>>>> Eccrine glands secrete salt, but this is (largely) reabsorbed
            >>>>>> in the ductus (double work for a zero result).

            >>>>> To do otherwise, would be to waste 'salt', Marc.

            >>>> If the eccrine glands hadn't secreted salt, the ducti didn't
            >>>> have to reabsorb it.

            >>> Marc - As said, 'salt' is present in sweat as sweat is
            >>> derived blood plasma, all the body is doing is conserving
            >>> that 'salt' by having the glands reabsorb it as we sweat.

            >> Bob, as generally know, sweat excreted by the gland before
            >> the reabsorption in the ductus is a lot more concentrated
            >> than blood plasma.

            > Sweat is less concentrated than blood plasma, Marc.
            > (An salt water is a lot more concentrated than
            > blood plasma)

            Again:
            - the gland itself produces a hypertonic solution,
            - the glandular duct reabsorbs sodium.



            >>>>> 'Salt' is essential for the maintenance of human life.

            >>>> No problem at the coast, to the contrary.

            >>> The 'salt' balance within our bodies is essential
            >>> for maintenance of life. (saltwater is too salty
            >>> to drink, attempting to do so would result in
            >>> dehydration)

            >> No marine mammal drinks sea water.
            >> They ingest more than enough salt with their diet.



            >>>>> One reason 'salt' is present in sweat is that sweat
            >>>>> is derived from blood, specifically blood plasma.

            >>>> It's present in sweat because we have abundant sweat
            >>>> glands over our bodies.

            >>> Sweat is 90% water, body fluid is blood, blood plasma
            >>> is 90% water, sweat is derived from blood plasma.
            >>> "The clear secretion produced by merocrine glands is
            >>> termed sweat, or sensible perspiration. Sweat is mostly
            >>> water, but it does contain some electrolytes, since it
            >>> is derived from blood plasma, although less concentrated.
            >>> It therefore contains mainly sodium chloride, but also
            >>> other small molecules in the blood. The presence of
            >>> sodium chloride gives sweat a salty taste."

            >> Bob, as said, the gland secrete is hypertonic, but the
            >> duct reabsorbs sodium.

            > Sodium an other content the body wants to conserve, it is
            > the 90% + water content of sensible sweat that is used to
            > lose body heat. (sweat is also said to contain a small
            > amount of urea)

            Again:
            - terrestrial & freshwater mammals try to conserve sodium,
            - marine mammals try to get rid of sodium.

            >>>>>> This suggests
            >>>>>> a salt or brackish water phase followed by a
            >>>>>> freshwater phase.

            >>>>> Unlikely, Marc...
            >>>>> As the highest concentration of merocrine sweat glands
            >>>>> in humans are in the palms of the hands and the soles
            >>>>> of the feet, a pattern that would be expected in an
            >>>>> animal who's ancestors once spent time in the trees
            >>>>> climbing.

            >>>> Possible, but we differ from most primates in having these
            >>>> glands all over our bodies: why?

            >>> Warm blooded mammals sweat, sweat or pant (primates
            >>> and horses also have sweaty "armpits").
            >>> Humans differ from other primates in having a larger
            >>> number of sweat glands,

            >> So far ok.
            >> Why?

            > To produce sensible perspiration, the type of sweat
            > used to lose body heat.

            No: monkeys nor savanna mammals need body eccrines for thermoregulation.

            Humans have a rather inefficient & even dangerous (overheating, salt & water
            depletion...) method of cooling.

            > In the other primates a lower number of sweat glands
            > is probably sufficient for insensible sweating and for
            > the higher concentration of sweat glands in friction
            > surfaces like the palm of the hand and sole of the
            > foot (for a better grip while climbing - humans have
            > some 500 sweat glands per square cm in the palm
            > of the hand).

            This is not about solar & palmar eccrines (which are present in Primates,
            Rodentia, Carnivora & Pinnipedia & others AFAIK), but about body eccrines,
            which among primates are only seen in humans, chimps & gorillas (but I don't
            know about orangs).

            >>> a relatively hairless body and their reliance on sweating
            >>> to thermoregulate their body temp.

            >> Now used in cooling, but not evolved for cooling, of course:
            >> otherwise all mammals had used it.

            >>> "Sweat glands, or sudoriferous glands, are exocrine
            >>> glands found under the skin in all mammal species
            >>> which are used for body temperature regulation
            >>> (thermoregulation). In humans, apocrine and merocrine
            >>> sweat glands form the primary method of cooling. Many
            >>> other mammals, such as cats, dogs and pigs, rely on
            >>> panting or other means as a primary source of
            >>> cooling, but still have sweat glands which aid
            >>> in thermoregulation. Sweat also serves to increase
            >>> friction on the palms of hands or the pads of paws."

            >> Yes, that leaves the question: why did we, as opposed to
            >> most other mammals, evolve body eccrines?

            > To lose body heat, humans differ from most mammals in
            > having a relatively large brain in a medium sized
            > primate body.

            The usual just-so thinking of savanna believers: there's no evidence for
            this "explanation".
            Much more efficient protections against overheating of body & brain are, eg,
            - the development of a fur,
            - allowing the body Tp to rise during the evening & lower during the
            mornings, as in all savanna mammals (eg, oryxes can tolerate a Tp of 45°C),
            - loss of SC fat, etc.

            We use our sweat glands for thermoregulation because we had them (for salt
            excretion), just like sealions on land: they sweat abundantly thermoactively
            through their apo- & eccrine glands on their flippers when overheated on
            land.

            >>>>> Evidence of how our kidneys evolved would be a better
            >>>>> indicator as to how our ancestors adapted to living
            >>>>> and foraging on the shore.

            >>>> Than it's clear: human newborns have renculised kidneys
            >>>> (typical of marine mammals), which afterwards grow into
            >>>> more suid-like kidneys.

            >>> An ancestral adaptation of the human kidneys, as a
            >>> result of ingesting large quantise of sea-foods on
            >>> the shore?

            >> No doubt IMO.

            >>>>> (as it is our kidneys
            >>>>> that deal with excess 'salt' not our sweat glands).
            >>>>> Sweat in mammals probably originally evolved to keep
            >>>>> the skin from drying.

            >>>> Then why don't most mammals have eccrine skin glands?

            >>> Most mammals subsequently evolved hair, or fur
            >>> to protect the skin.

            >> Most furred mammals don't have eccrine skin glands.
            >> Horses & camels (furred) sweat thermoactively.

            > Horses sweat, sweat profusely, furred/hairy species like
            > dogs pant to lose heat, dogs also have eccrine glands in
            > their paws.
            > Incidentally horse sweat (an zebra) has an additional
            > an unusual ingredient called latherin that acts to
            > wet the horses hair when the horse sweats.
            > http://eprints.gla.ac.uk/6387/

            Thanks for the link, but the point is that horses sweat & have furs: the
            connection between thermoactive sweating & naked skin is not clear (although
            furseals sweat thermoactively through their naked flippers).

            >>> Merocrine or eccrine skin sweat glands are more
            >>> common in primates.

            >> Hominids (HPG) have eccrine glands over the whole body, monkeys &
            >> prosimians, like carnivores, rodents etc., don't.

            >>>>> In humans, sweating is
            >>>>> primarily a means of thermoregulation.

            >>>>>> The dispersal of Homo to different continents occurred along
            >>>>>> the coasts = salt. Pachyostosis (erectus) also is seen in
            >>>>>> saltwater habitats, but afterwards we re-evolved thinner
            >>>>>> bones again (still slightly heavier than equally large
            >>>>>> nonhuman terrestrials). --marc

            >>>>> Would think chimpanzee and gorilla have heavier/denser
            >>>>> bones than Modern humans.

            >>>> No, it's He>>Hn>>Hs>apiths>others
            >>>> (apiths marginally more, Hs a little bit more, Hn
            >>>> considerably more, He very much). --marc

            >>> He was heavier built than chimpanzee today?
            >>> (had heavier bones,

            >> At least twice as heavy.

            The skeleton I meant.

            >>> more muscle mass) -- Bill

            >> No: chimps are several times stronger than humans.
            >> Bones that are very heavy are also more brittle.

            > He was twice as heavy as chimpanzee today?

            He's bones were. Very dense bones as in seacows are not stronger, but more
            brittle (calcium/collagen ratio?). H.erectus was very slow on land: heavy
            skeleton & possibly thick SC fat.

            > Some now claim that He was much smaller in terms
            > of stature than has been generally accepted.
            > (163 cm instead of 185 cm in the case of the
            > Nariokotome Boy) -- Bill

            We've discussed this many times here. WT-15k had remarkably low vertebrae
            (only 2/3 of ours - why?) + more dorsally projecting processus spinosi (ours
            are mid-thoracally more caudally oriented, I guess for stabilisation in
            upright walking), and also otherwise he was different from us postcranially,
            eg, flaring ilia + longer & more horizontal femoral necks (presumably for
            femoral ad+adduction, ie, not for running: for swimming?). WT-15k died in a
            swamp amid reeds, shells, fish & hippo footprints. His (moderate:
            freshwater?) pachyostosis suggests he dived regularly for sessile foods. I
            don't think it's wise trying to extrapolate WT-15k's "length" from that of
            standing Hs adolescents (eg, rel.long legs, but also a remarkably low torso,
            which was possibly not habitually vertical: for wading &/of diving?).
            (Note WT-15 might have been +-different from Mojokerto or so, eg, inland vs
            coastal?)

            --marc
          • dons3148
            ... Marc - I think you may mean a hypotonic solution a solution weaker than blood plasma, not hypertonic solution. [QUOTE] Hypertonic solution: A Hypertonic
            Message 5 of 20 , Oct 2, 2010
            • 0 Attachment
              --- In AAT@yahoogroups.com, Marc Verhaegen <m_verhaegen@...> wrote:
              >
              >
              > >>>>>>>>>> Sweat also exudes salts.  The human form could
              > >>>>>>>>>> never have evolved unless our ancestors lived
              > >>>>>>>>>> under conditions where those salts were being
              > >>>>>>>>>> automatically replaced.
              >
              > >>>>>>>>> Oh, bloody hell. That's a damn good argument for a
              > >>>>>>>>> sea-version. The tears argument from AAH also adds
              > >>>>>>>>> heavily to a salt water notion. It
              > >>>>>>>>> makes a Mediterrenean region interesting with reference
              > >>>>>>>>> to Oreopithecus, but other than that I'm left confused.
              >
              > >>>>>>>> Afr.apes also have body eccrine sweat glands (although less
              > >>>>>>>> than humans?), and gorillas are said to shed emotional tears.
              > >>>>>>>> This suggests a salt- or brackish waterside phase prior to
              > >>>>>>>> the LCA of chimps, humans & gorillas, ie, probably before the
              > >>>>>>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
              > >>>>>>>> lasting to the MSC or even later. This
              > >>>>>>>> early waterside phase was apparently different from the
              > >>>>>>>> coastal dispersal of Homo during the Pleistocene.
              >
              > >>>>>>> The human body does not sweat to lose 'salt', as the
              > >>>>>>> body will normally reabsorb most of the 'salt' from
              > >>>>>>> the sweat solution back into the sweat duct as we
              > >>>>>>> sweat.
              >
              > >>>>>> Eccrine glands secrete salt, but this is (largely) reabsorbed
              > >>>>>> in the ductus (double work for a zero result).
              >
              > >>>>> To do otherwise, would be to waste 'salt', Marc.
              >
              > >>>> If the eccrine glands hadn't secreted salt, the ducti didn't
              > >>>> have to reabsorb it.
              >
              > >>> Marc - As said, 'salt' is present in sweat as sweat is
              > >>> derived blood plasma, all the body is doing is conserving
              > >>> that 'salt' by having the glands reabsorb it as we sweat.
              >
              > >> Bob, as generally know, sweat excreted by the gland before
              > >> the reabsorption in the ductus is a lot more concentrated
              > >> than blood plasma.
              >




              > > Sweat is less concentrated than blood plasma, Marc.
              > > (An salt water is a lot more concentrated than
              > > blood plasma)
              >
              > Again:
              > - the gland itself produces a hypertonic solution,
              > - the glandular duct reabsorbs sodium.
              >



              Marc - I think you may mean a hypotonic solution a
              solution weaker than blood plasma, not hypertonic
              solution.



              [QUOTE]
              Hypertonic solution:
              A Hypertonic solution contains a higher concentration
              of electrolytes than that found in body cells. If such
              a solution is allowed to enter the blood stream, the
              osmotic pressure difference between the blood and the
              cells will cause water to flow out of the cells, which
              will then shrink. This may cause serious harm, or
              even be fatal.

              _______________________________





              >
              > >>>>> 'Salt' is essential for the maintenance of human life.
              >
              > >>>> No problem at the coast, to the contrary.
              >
              > >>> The 'salt' balance within our bodies is essential
              > >>> for maintenance of life. (saltwater is too salty
              > >>> to drink, attempting to do so would result in
              > >>> dehydration)
              >
              > >> No marine mammal drinks sea water.
              > >> They ingest more than enough salt with their diet.
              >
              >
              >
              > >>>>> One reason 'salt' is present in sweat is that sweat
              > >>>>> is derived from blood, specifically blood plasma.
              >
              > >>>> It's present in sweat because we have abundant sweat
              > >>>> glands over our bodies.
              >
              > >>> Sweat is 90% water, body fluid is blood, blood plasma
              > >>> is 90% water, sweat is derived from blood plasma.
              > >>> "The clear secretion produced by merocrine glands is
              > >>> termed sweat, or sensible perspiration. Sweat is mostly
              > >>> water, but it does contain some electrolytes, since it
              > >>> is derived from blood plasma, although less concentrated.
              > >>> It therefore contains mainly sodium chloride, but also
              > >>> other small molecules in the blood. The presence of
              > >>> sodium chloride gives sweat a salty taste."
              >
              > >> Bob, as said, the gland secrete is hypertonic, but the
              > >> duct reabsorbs sodium.
              >
              > > Sodium an other content the body wants to conserve, it is
              > > the 90% + water content of sensible sweat that is used to
              > > lose body heat. (sweat is also said to contain a small
              > > amount of urea)
              >
              > Again:
              > - terrestrial & freshwater mammals try to conserve sodium,
              > - marine mammals try to get rid of sodium.
              >



              We have kidneys, it is a function of the kidneys
              to get rid of excess sodium.

              It would probably take you days to secrete the 'salt'
              through the skin that can be lost spending a few
              seconds urinating.

              The 'salt' content of sweat is next to nothing, sweat
              is more than 90% water





              > >>>>>> This suggests
              > >>>>>> a salt or brackish water phase followed by a
              > >>>>>> freshwater phase.
              >
              > >>>>> Unlikely, Marc...
              > >>>>> As the highest concentration of merocrine sweat glands
              > >>>>> in humans are in the palms of the hands and the soles
              > >>>>> of the feet, a pattern that would be expected in an
              > >>>>> animal who's ancestors once spent time in the trees
              > >>>>> climbing.
              >
              > >>>> Possible, but we differ from most primates in having these
              > >>>> glands all over our bodies: why?
              >
              > >>> Warm blooded mammals sweat, sweat or pant (primates
              > >>> and horses also have sweaty "armpits").
              > >>> Humans differ from other primates in having a larger
              > >>> number of sweat glands,
              >
              > >> So far ok.
              > >> Why?
              >
              > > To produce sensible perspiration, the type of sweat
              > > used to lose body heat.
              >
              > No: monkeys nor savanna mammals need body eccrines for
              > thermoregulation.
              >



              It was a reference to why humans sweat, not
              other primates.




              > Humans have a rather inefficient & even dangerous (overheating,
              > salt & water depletion...) method of cooling.
              >



              Yes, as sweat is derived from blood plasma excessive
              sensible sweating can cause problems.





              > > In the other primates a lower number of sweat glands
              > > is probably sufficient for insensible sweating and for
              > > the higher concentration of sweat glands in friction
              > > surfaces like the palm of the hand and sole of the
              > > foot (for a better grip while climbing - humans have
              > > some 500 sweat glands per square cm in the palm
              > > of the hand).
              >
              > This is not about solar & palmar eccrines (which are present
              > in Primates, Rodentia, Carnivora & Pinnipedia & others AFAIK),
              > but about body eccrines, which among primates are only seen
              > in humans, chimps & gorillas (but I don't
              > know about orangs).
              >



              Exact same eccrine sweat glands, but a different function.
              There is a much higher concentration of the sweat glands
              in the palms of the hands and the soles of the feet.





              > >>> a relatively hairless body and their reliance on sweating
              > >>> to thermoregulate their body temp.
              >
              > >> Now used in cooling, but not evolved for cooling, of course:
              > >> otherwise all mammals had used it.
              >
              > >>> "Sweat glands, or sudoriferous glands, are exocrine
              > >>> glands found under the skin in all mammal species
              > >>> which are used for body temperature regulation
              > >>> (thermoregulation). In humans, apocrine and merocrine
              > >>> sweat glands form the primary method of cooling. Many
              > >>> other mammals, such as cats, dogs and pigs, rely on
              > >>> panting or other means as a primary source of
              > >>> cooling, but still have sweat glands which aid
              > >>> in thermoregulation. Sweat also serves to increase
              > >>> friction on the palms of hands or the pads of paws."
              >
              > >> Yes, that leaves the question: why did we, as opposed to
              > >> most other mammals, evolve body eccrines?
              >
              > > To lose body heat, humans differ from most mammals in
              > > having a relatively large brain in a medium sized
              > > primate body.
              >
              > The usual just-so thinking of savanna believers: there's no
              > evidence for this "explanation".



              Humans have simply adapted to use sweat, to cool
              their relatively hairless skin.




              > Much more efficient protections against overheating of body
              > & brain are, eg,
              > - the development of a fur,
              > - allowing the body Tp to rise during the evening & lower during the
              > mornings, as in all savanna mammals (eg, oryxes can tolerate a Tp of 45°C),
              > - loss of SC fat, etc.
              >



              The human brain is heat sensitive anything above 40/42.C
              can be fatal, humans do not have the tiny brain of oryxes.

              Cooling our relatively hairless skin with sweat is
              fast and efficient, in most circumstances.




              > We use our sweat glands for thermoregulation because we had them (for salt
              > excretion), just like sealions on land: they sweat abundantly thermoactively
              > through their apo- & eccrine glands on their flippers when overheated on
              > land.
              >



              Our sweat glands are an inefficient way of secreting
              'salt' from the body (sweat is more than 90% water
              with next to no 'salt' content) our kidneys do a
              far better job.




              > >>>>> Evidence of how our kidneys evolved would be a better
              > >>>>> indicator as to how our ancestors adapted to living
              > >>>>> and foraging on the shore.
              >
              > >>>> Than it's clear: human newborns have renculised kidneys
              > >>>> (typical of marine mammals), which afterwards grow into
              > >>>> more suid-like kidneys.
              >
              > >>> An ancestral adaptation of the human kidneys, as a
              > >>> result of ingesting large quantise of sea-foods on
              > >>> the shore?
              >
              > >> No doubt IMO.
              >
              > >>>>> (as it is our kidneys
              > >>>>> that deal with excess 'salt' not our sweat glands).
              > >>>>> Sweat in mammals probably originally evolved to keep
              > >>>>> the skin from drying.
              >
              > >>>> Then why don't most mammals have eccrine skin glands?
              >
              > >>> Most mammals subsequently evolved hair, or fur
              > >>> to protect the skin.
              >
              > >> Most furred mammals don't have eccrine skin glands.
              > >> Horses & camels (furred) sweat thermoactively.
              >
              > > Horses sweat, sweat profusely, furred/hairy species like
              > > dogs pant to lose heat, dogs also have eccrine glands in
              > > their paws.
              > > Incidentally horse sweat (an zebra) has an additional
              > > an unusual ingredient called latherin that acts to
              > > wet the horses hair when the horse sweats.
              > > http://eprints.gla.ac.uk/6387/
              >
              > Thanks for the link, but the point is that horses sweat
              > & have furs: the connection between thermoactive sweating
              > & naked skin is not clear (although furseals sweat
              > thermoactively through their naked flippers).
              >



              Humans have a relatively hairless skin, a bare almost
              hairless skin makes sweating a pretty effective means
              of cooling our body.





              > >>> Merocrine or eccrine skin sweat glands are more
              > >>> common in primates.
              >
              > >> Hominids (HPG) have eccrine glands over the whole body, monkeys &
              > >> prosimians, like carnivores, rodents etc., don't.
              >
              > >>>>> In humans, sweating is
              > >>>>> primarily a means of thermoregulation.
              >
              > >>>>>> The dispersal of Homo to different continents occurred along
              > >>>>>> the coasts = salt. Pachyostosis (erectus) also is seen in
              > >>>>>> saltwater habitats, but afterwards we re-evolved thinner
              > >>>>>> bones again (still slightly heavier than equally large
              > >>>>>> nonhuman terrestrials). --marc
              >
              > >>>>> Would think chimpanzee and gorilla have heavier/denser
              > >>>>> bones than Modern humans.
              >
              > >>>> No, it's He>>Hn>>Hs>apiths>others
              > >>>> (apiths marginally more, Hs a little bit more, Hn
              > >>>> considerably more, He very much). --marc
              >
              > >>> He was heavier built than chimpanzee today?
              > >>> (had heavier bones,
              >
              > >> At least twice as heavy.
              >
              > The skeleton I meant.
              >
              > >>> more muscle mass) -- Bill
              >
              > >> No: chimps are several times stronger than humans.
              > >> Bones that are very heavy are also more brittle.
              >
              > > He was twice as heavy as chimpanzee today?
              >
              > He's bones were. Very dense bones as in seacows are not stronger, but more
              > brittle (calcium/collagen ratio?). H.erectus was very slow on land: heavy
              > skeleton & possibly thick SC fat.
              >


              OK




              > > Some now claim that He was much smaller in terms
              > > of stature than has been generally accepted.
              > > (163 cm instead of 185 cm in the case of the
              > > Nariokotome Boy) -- Bill
              >
              > We've discussed this many times here. WT-15k had remarkably low vertebrae
              > (only 2/3 of ours - why?) + more dorsally projecting processus spinosi (ours
              > are mid-thoracally more caudally oriented, I guess for stabilisation in
              > upright walking), and also otherwise he was different from us postcranially,
              > eg, flaring ilia + longer & more horizontal femoral necks (presumably for
              > femoral ad+adduction, ie, not for running: for swimming?). WT-15k died in a
              > swamp amid reeds, shells, fish & hippo footprints. His (moderate:
              > freshwater?) pachyostosis suggests he dived regularly for sessile foods. I
              > don't think it's wise trying to extrapolate WT-15k's "length" from that of
              > standing Hs adolescents (eg, rel.long legs, but also a remarkably low torso,
              > which was possibly not habitually vertical: for wading &/of diving?).
              > (Note WT-15 might have been +-different from Mojokerto or so, eg, inland vs
              > coastal?)
              >
              > --marc
              >


              Yes, Nariokotome Boy is just one example of He, it may
              be an unrepresentative example of He.



              -- Bill
            • Marc Verhaegen
              Bob, apparently you don t understand it well: - the eccrine gland itself produces a hypertonic solution, - but the glandular duct reabsorbs sodium. IOW, the
              Message 6 of 20 , Oct 2, 2010
              • 0 Attachment
                Bob, apparently you don't understand it well:
                - the eccrine gland itself produces a hypertonic solution,
                - but the glandular duct reabsorbs sodium.
                IOW, the sweat production goes from hyper- to hypotonic.
                Nevertheless, we still lose a lot of salt through sweating.

                --marc

                _____


                >>>>>>>>>>>> Sweat also exudes salts.  The human form could
                >>>>>>>>>>>> never have evolved unless our ancestors lived
                >>>>>>>>>>>> under conditions where those salts were being
                >>>>>>>>>>>> automatically replaced.
                >>
                >>>>>>>>>>> Oh, bloody hell. That's a damn good argument for a
                >>>>>>>>>>> sea-version. The tears argument from AAH also adds
                >>>>>>>>>>> heavily to a salt water notion. It
                >>>>>>>>>>> makes a Mediterrenean region interesting with reference
                >>>>>>>>>>> to Oreopithecus, but other than that I'm left confused.
                >>
                >>>>>>>>>> Afr.apes also have body eccrine sweat glands (although less
                >>>>>>>>>> than humans?), and gorillas are said to shed emotional tears.
                >>>>>>>>>> This suggests a salt- or brackish waterside phase prior to
                >>>>>>>>>> the LCA of chimps, humans & gorillas, ie, probably before the
                >>>>>>>>>> HP/G split c 7 or 8 Ma, ie, before the MSC, but possibly
                >>>>>>>>>> lasting to the MSC or even later. This
                >>>>>>>>>> early waterside phase was apparently different from the
                >>>>>>>>>> coastal dispersal of Homo during the Pleistocene.
                >>
                >>>>>>>>> The human body does not sweat to lose 'salt', as the
                >>>>>>>>> body will normally reabsorb most of the 'salt' from
                >>>>>>>>> the sweat solution back into the sweat duct as we
                >>>>>>>>> sweat.
                >>
                >>>>>>>> Eccrine glands secrete salt, but this is (largely) reabsorbed
                >>>>>>>> in the ductus (double work for a zero result).
                >>
                >>>>>>> To do otherwise, would be to waste 'salt', Marc.
                >>
                >>>>>> If the eccrine glands hadn't secreted salt, the ducti didn't
                >>>>>> have to reabsorb it.
                >>
                >>>>> Marc - As said, 'salt' is present in sweat as sweat is
                >>>>> derived blood plasma, all the body is doing is conserving
                >>>>> that 'salt' by having the glands reabsorb it as we sweat.
                >>
                >>>> Bob, as generally know, sweat excreted by the gland before
                >>>> the reabsorption in the ductus is a lot more concentrated
                >>>> than blood plasma.
                >>
                >
                >>> Sweat is less concentrated than blood plasma, Marc.
                >>> (An salt water is a lot more concentrated than
                >>> blood plasma)
                >>
                >> Again:
                >> - the gland itself produces a hypertonic solution,
                >> - the glandular duct reabsorbs sodium.
                >>
                >
                > Marc - I think you may mean a hypotonic solution a
                > solution weaker than blood plasma, not hypertonic
                > solution.
                >
                > [QUOTE]
                > Hypertonic solution:
                > A Hypertonic solution contains a higher concentration
                > of electrolytes than that found in body cells. If such
                > a solution is allowed to enter the blood stream, the
                > osmotic pressure difference between the blood and the
                > cells will cause water to flow out of the cells, which
                > will then shrink. This may cause serious harm, or
                > even be fatal.
                >
                > _______________________________
                >
                >>
                >>>>>>> 'Salt' is essential for the maintenance of human life.
                >>
                >>>>>> No problem at the coast, to the contrary.
                >>
                >>>>> The 'salt' balance within our bodies is essential
                >>>>> for maintenance of life. (saltwater is too salty
                >>>>> to drink, attempting to do so would result in
                >>>>> dehydration)
                >>
                >>>> No marine mammal drinks sea water.
                >>>> They ingest more than enough salt with their diet.
                >>
                >>
                >>
                >>>>>>> One reason 'salt' is present in sweat is that sweat
                >>>>>>> is derived from blood, specifically blood plasma.
                >>
                >>>>>> It's present in sweat because we have abundant sweat
                >>>>>> glands over our bodies.
                >>
                >>>>> Sweat is 90% water, body fluid is blood, blood plasma
                >>>>> is 90% water, sweat is derived from blood plasma.
                >>>>> "The clear secretion produced by merocrine glands is
                >>>>> termed sweat, or sensible perspiration. Sweat is mostly
                >>>>> water, but it does contain some electrolytes, since it
                >>>>> is derived from blood plasma, although less concentrated.
                >>>>> It therefore contains mainly sodium chloride, but also
                >>>>> other small molecules in the blood. The presence of
                >>>>> sodium chloride gives sweat a salty taste."
                >>
                >>>> Bob, as said, the gland secrete is hypertonic, but the
                >>>> duct reabsorbs sodium.
                >>
                >>> Sodium an other content the body wants to conserve, it is
                >>> the 90% + water content of sensible sweat that is used to
                >>> lose body heat. (sweat is also said to contain a small
                >>> amount of urea)
                >>
                >> Again:
                >> - terrestrial & freshwater mammals try to conserve sodium,
                >> - marine mammals try to get rid of sodium.
                >>
                >
                > We have kidneys, it is a function of the kidneys
                > to get rid of excess sodium.
                >
                > It would probably take you days to secrete the 'salt'
                > through the skin that can be lost spending a few
                > seconds urinating.
                >
                > The 'salt' content of sweat is next to nothing, sweat
                > is more than 90% water
                >
                >>>>>>>> This suggests
                >>>>>>>> a salt or brackish water phase followed by a
                >>>>>>>> freshwater phase.
                >>
                >>>>>>> Unlikely, Marc...
                >>>>>>> As the highest concentration of merocrine sweat glands
                >>>>>>> in humans are in the palms of the hands and the soles
                >>>>>>> of the feet, a pattern that would be expected in an
                >>>>>>> animal who's ancestors once spent time in the trees
                >>>>>>> climbing.
                >>
                >>>>>> Possible, but we differ from most primates in having these
                >>>>>> glands all over our bodies: why?
                >>
                >>>>> Warm blooded mammals sweat, sweat or pant (primates
                >>>>> and horses also have sweaty "armpits").
                >>>>> Humans differ from other primates in having a larger
                >>>>> number of sweat glands,
                >>
                >>>> So far ok.
                >>>> Why?
                >>
                >>> To produce sensible perspiration, the type of sweat
                >>> used to lose body heat.
                >>
                >> No: monkeys nor savanna mammals need body eccrines for
                >> thermoregulation.
                >>
                >
                > It was a reference to why humans sweat, not
                > other primates.
                >
                >> Humans have a rather inefficient & even dangerous (overheating,
                >> salt & water depletion...) method of cooling.
                >>
                >
                > Yes, as sweat is derived from blood plasma excessive
                > sensible sweating can cause problems.
                >
                >>> In the other primates a lower number of sweat glands
                >>> is probably sufficient for insensible sweating and for
                >>> the higher concentration of sweat glands in friction
                >>> surfaces like the palm of the hand and sole of the
                >>> foot (for a better grip while climbing - humans have
                >>> some 500 sweat glands per square cm in the palm
                >>> of the hand).
                >>
                >> This is not about solar & palmar eccrines (which are present
                >> in Primates, Rodentia, Carnivora & Pinnipedia & others AFAIK),
                >> but about body eccrines, which among primates are only seen
                >> in humans, chimps & gorillas (but I don't
                >> know about orangs).
                >>
                >
                > Exact same eccrine sweat glands, but a different function.
                > There is a much higher concentration of the sweat glands
                > in the palms of the hands and the soles of the feet.
                >
                >>>>> a relatively hairless body and their reliance on sweating
                >>>>> to thermoregulate their body temp.
                >>
                >>>> Now used in cooling, but not evolved for cooling, of course:
                >>>> otherwise all mammals had used it.
                >>
                >>>>> "Sweat glands, or sudoriferous glands, are exocrine
                >>>>> glands found under the skin in all mammal species
                >>>>> which are used for body temperature regulation
                >>>>> (thermoregulation). In humans, apocrine and merocrine
                >>>>> sweat glands form the primary method of cooling. Many
                >>>>> other mammals, such as cats, dogs and pigs, rely on
                >>>>> panting or other means as a primary source of
                >>>>> cooling, but still have sweat glands which aid
                >>>>> in thermoregulation. Sweat also serves to increase
                >>>>> friction on the palms of hands or the pads of paws."
                >>
                >>>> Yes, that leaves the question: why did we, as opposed to
                >>>> most other mammals, evolve body eccrines?
                >>
                >>> To lose body heat, humans differ from most mammals in
                >>> having a relatively large brain in a medium sized
                >>> primate body.
                >>
                >> The usual just-so thinking of savanna believers: there's no
                >> evidence for this "explanation".
                >
                > Humans have simply adapted to use sweat, to cool
                > their relatively hairless skin.
                >
                >> Much more efficient protections against overheating of body
                >> & brain are, eg,
                >> - the development of a fur,
                >> - allowing the body Tp to rise during the evening & lower during the
                >> mornings, as in all savanna mammals (eg, oryxes can tolerate a Tp of 45°C),
                >> - loss of SC fat, etc.
                >>
                >
                > The human brain is heat sensitive anything above 40/42.C
                > can be fatal, humans do not have the tiny brain of oryxes.
                >
                > Cooling our relatively hairless skin with sweat is
                > fast and efficient, in most circumstances.
                >
                >> We use our sweat glands for thermoregulation because we had them (for salt
                >> excretion), just like sealions on land: they sweat abundantly thermoactively
                >> through their apo- & eccrine glands on their flippers when overheated on
                >> land.
                >>
                >
                > Our sweat glands are an inefficient way of secreting
                > 'salt' from the body (sweat is more than 90% water
                > with next to no 'salt' content) our kidneys do a
                > far better job.
                >
                >>>>>>> Evidence of how our kidneys evolved would be a better
                >>>>>>> indicator as to how our ancestors adapted to living
                >>>>>>> and foraging on the shore.
                >>
                >>>>>> Than it's clear: human newborns have renculised kidneys
                >>>>>> (typical of marine mammals), which afterwards grow into
                >>>>>> more suid-like kidneys.
                >>
                >>>>> An ancestral adaptation of the human kidneys, as a
                >>>>> result of ingesting large quantise of sea-foods on
                >>>>> the shore?
                >>
                >>>> No doubt IMO.
                >>
                >>>>>>> (as it is our kidneys
                >>>>>>> that deal with excess 'salt' not our sweat glands).
                >>>>>>> Sweat in mammals probably originally evolved to keep
                >>>>>>> the skin from drying.
                >>
                >>>>>> Then why don't most mammals have eccrine skin glands?
                >>
                >>>>> Most mammals subsequently evolved hair, or fur
                >>>>> to protect the skin.
                >>
                >>>> Most furred mammals don't have eccrine skin glands.
                >>>> Horses & camels (furred) sweat thermoactively.
                >>
                >>> Horses sweat, sweat profusely, furred/hairy species like
                >>> dogs pant to lose heat, dogs also have eccrine glands in
                >>> their paws.
                >>> Incidentally horse sweat (an zebra) has an additional
                >>> an unusual ingredient called latherin that acts to
                >>> wet the horses hair when the horse sweats.
                >>> http://eprints.gla.ac.uk/6387/
                >>
                >> Thanks for the link, but the point is that horses sweat
                >> & have furs: the connection between thermoactive sweating
                >> & naked skin is not clear (although furseals sweat
                >> thermoactively through their naked flippers).
                >>
                >
                > Humans have a relatively hairless skin, a bare almost
                > hairless skin makes sweating a pretty effective means
                > of cooling our body.
                >
                >
                >
                >>>>> Merocrine or eccrine skin sweat glands are more
                >>>>> common in primates.
                >>
                >>>> Hominids (HPG) have eccrine glands over the whole body, monkeys &
                >>>> prosimians, like carnivores, rodents etc., don't.
                >>
                >>>>>>> In humans, sweating is
                >>>>>>> primarily a means of thermoregulation.
                >>
                >>>>>>>> The dispersal of Homo to different continents occurred along
                >>>>>>>> the coasts = salt. Pachyostosis (erectus) also is seen in
                >>>>>>>> saltwater habitats, but afterwards we re-evolved thinner
                >>>>>>>> bones again (still slightly heavier than equally large
                >>>>>>>> nonhuman terrestrials). --marc
                >>
                >>>>>>> Would think chimpanzee and gorilla have heavier/denser
                >>>>>>> bones than Modern humans.
                >>
                >>>>>> No, it's He>>Hn>>Hs>apiths>others
                >>>>>> (apiths marginally more, Hs a little bit more, Hn
                >>>>>> considerably more, He very much). --marc
                >>
                >>>>> He was heavier built than chimpanzee today?
                >>>>> (had heavier bones,
                >>
                >>>> At least twice as heavy.
                >>
                >> The skeleton I meant.
                >>
                >>>>> more muscle mass) -- Bill
                >>
                >>>> No: chimps are several times stronger than humans.
                >>>> Bones that are very heavy are also more brittle.
                >>
                >>> He was twice as heavy as chimpanzee today?
                >>
                >> He's bones were. Very dense bones as in seacows are not stronger, but more
                >> brittle (calcium/collagen ratio?). H.erectus was very slow on land: heavy
                >> skeleton & possibly thick SC fat.
                >>
                >
                > OK
                >
                >>> Some now claim that He was much smaller in terms
                >>> of stature than has been generally accepted.
                >>> (163 cm instead of 185 cm in the case of the
                >>> Nariokotome Boy) -- Bill
                >>
                >> We've discussed this many times here. WT-15k had remarkably low vertebrae
                >> (only 2/3 of ours - why?) + more dorsally projecting processus spinosi (ours
                >> are mid-thoracally more caudally oriented, I guess for stabilisation in
                >> upright walking), and also otherwise he was different from us postcranially,
                >> eg, flaring ilia + longer & more horizontal femoral necks (presumably for
                >> femoral ad+adduction, ie, not for running: for swimming?). WT-15k died in a
                >> swamp amid reeds, shells, fish & hippo footprints. His (moderate:
                >> freshwater?) pachyostosis suggests he dived regularly for sessile foods. I
                >> don't think it's wise trying to extrapolate WT-15k's "length" from that of
                >> standing Hs adolescents (eg, rel.long legs, but also a remarkably low torso,
                >> which was possibly not habitually vertical: for wading &/of diving?).
                >> (Note WT-15 might have been +-different from Mojokerto or so, eg, inland vs
                >> coastal?)
                >>
                >> --marc
                >>
                >
                > Yes, Nariokotome Boy is just one example of He, it may
                > be an unrepresentative example of He.
                >
                > -- Bill
              • Marc Verhaegen
                ... Yes, amazing. Within a few months we re going to publish our ebook on AAT (M.Vaneechoutte ed.) with contributions, not only of Elaine Morgan, prof.Tobias
                Message 7 of 20 , Oct 3, 2010
                • 0 Attachment
                  >>> Either way, this IS a bit funky:
                  >>> http://www.youtube.com/watch?v=vF4PN8-2YSk&feature=related

                  >> :-)  Thanks, Engelbrecht.

                  > In general, it's amazing to read about the medical studies of human
                  > freedivers in relation to AAH. During a long breath hold dive, the
                  > human blood vessels constrict to reduce the blood flow to the limbs
                  > and center it to the torso and head.
                  > Also, during a deep breath hold dive (eg. 30+ meters), a bloodshift
                  > phenomenon fills the lung alveoli with blood plasma at increasing
                  > depths, making them expand like balls to minimize the interior volume
                  > of the lungs, preventing the lungs from imploding at these great
                  > depths. (The plasma resumes back into circulation at decent.)
                  > If one watch the above posted freediving video, one notices that the
                  > freediver stops kicking at a point of negative buoyancy and just let
                  > himself drop, exactly as it has been observed in eg. deep diving
                  > dolphins; they kick until they drop by themselves to save energy and
                  > extend the dive. That we with these methods can already reach the same
                  > depths as sea otters is a pretty strong argument in favor of AAH.

                  Yes, amazing. Within a few months we're going to publish our ebook on AAT
                  (M.Vaneechoutte ed.) with contributions, not only of Elaine Morgan,
                  prof.Tobias etc., but also of Erika Schagatay, with the newest data on human
                  diving (eg, the function of the spleen in ejecting RBCs druing repeated
                  dives, eg, for filling the lung alveoli) & on underwater sight.

                  --marc
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