Aquatic Ape Theory resurfaces.

Discussion in 'Human Science' started by siliconshrew, Apr 15, 2008.

  1. siliconshrew Banned Banned

    Messages:
    55
    "But why is the Savannah hypothesis wrong? "

    It was announced on television. There was a surprising doco which stated flatly how the Savannah Hypothesis was now proven wrong. I'll do some searching on it when I get a chance. It was pretty technical as remember but seemed pretty clear cut.

    "You're aware, specifically, that various animals on the savannah benefit from vertical height, including antelopes and giraffes? Bipedalism reduces sun impact (though admittedly not so much for the head) and allows tool carrying."

    Bipedalism is a major change. Not an overnight adaptation. wading makes sense. Monkeys can be seen to walk like humans when wading. There is no example of Savannah animals becoming bipedal. Babboons are not bipedal. Gorilla's aren't bipedal. Not a single other primate or old world monkey or lemur or anything has attempted to become bipedal.
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. (Q) Encephaloid Martini Valued Senior Member

    Messages:
    19,125
    I believe everything announced on TV. Wait, I don't watch TV.

    Can you explain how bipedalism evolved independently across a wide variety of species, some of them now extinct?

    [hint] wading had nothing to do with it.[/hint]
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    I don't think this can be said until we know exactly what point in human evolution we're talking about; I'm sure someone has an idea, but it isn't me. Chimps are able to migrate about - slowly, yes - on the savannah floor, but the first human to do so might not have done so to follow wildebeest or any other beest; as the forest retracted, migration was probably obligatory to avoid exhausting local resources, rather than being for game pursuit (although that isn't impossible). Let's look at it the other way: chimps also wouldn't be too good swimming in the water.

    We need some things for this debate to go on:

    i) at which point did Homo actually come on down out of the trees? What was happening then ecologically? I'm sure I had it in a class at some point, but my brain is tofu at the moment. I'll check the period or something.

    ii) when did Homo get the aquatic features being referred to here? At what point did they enter the water, and why? Does anyone know anything much about their morphology at that point?

    I think the answers will probably be evident when we know the above.

    Ecological retraction of the forests, is usually what's implied. Chimps can hold off single leopards with sticks.

    Yes, but energetically it's probably a lot harder. Most of our weight is lazily borne on our leg bones. Human walking is probably one of the laziest activities in the Mammalia barring watching the Battlestar Galactica.

    I wouldn't call it layers of blubber (but see above). Fangs? Well, compared to a leopards, my response is "so what?" They're puny fangs. You're better off with a banana or a pointed stick. I doubt that four-footed motion is easier, though; I'll see if I can find it somewhere.

    All right: what were the advantages of the aquatic ape? What was so great about the riverbank that, once having got in, he decided "hey, this is all right" and stayed? We have morphological features that suggest it, but why the water?

    Best,

    Geoff
     
    Last edited: May 6, 2008
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. siliconshrew Banned Banned

    Messages:
    55
    Q
    "Can you explain how bipedalism evolved independently across a wide variety of species, some of them now extinct?"
    [hint] wading had nothing to do with it.[/hint]

    We are talking about two different kinds of gait. Actually, several. True bipedalism as seen in humans can only be identified in two existing species that I know of. Penguins are the second one.

    Birds, dinosaurs and various earlier reptiles adopted a two legged posture and it proved an advantage but this wasn't true bipedalism. The body was balanced by a tail. There was no straight posture and the head always hung forwards. I can't explain why so many species evolved that way. I doubt it was to see over the long grass.

    How do you know wading had nothing to do with it? Early reptiles were barely past the aquatic stage. A return to the water in the form of wading seems plausible to me. There are many examples of creatures which have repeatedly changed back and forth from a land existance to an aquatic one. Don't tell me you've never seen a reptile swim. The swimming Iguana's of the Galapagos are a good example.

    Please Register or Log in to view the hidden image!


    Human feet.

    Please Register or Log in to view the hidden image!


    Flippers.


    Please Register or Log in to view the hidden image!


    Ground dwelling Gorilla.
     
  8. (Q) Encephaloid Martini Valued Senior Member

    Messages:
    19,125
    So what? That doesn't explain anything.

    There are a number of reasons, all having to do with evolution. Many had nothing to do with water or tall grass.

    All strawmen arguments. Irrelevant.
     
  9. Asguard Kiss my dark side Valued Senior Member

    Messages:
    23,049
    siliconshrew there is one thing i dont get. If standing up right is such an advantage for an aquatic species why dont elephants do it as i belive they are on there second evolution OUT of the water (at least). This is why there lungs are designed the way they are because if they were like ours and they tried to snorkle under water there chest cavity would explode under the pressure
     
  10. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    Consider this: of most of the savannah species, Homo is the slowest. And stands upright. Wouldn't it make sense to have a little height to see over grass, as you run about as fast as a crippled deer? Coupled with our superior eyesight compared to savannah mammals, we could see trouble ahead more easily this way. African prairie dogs do this opportunistically.
     
    Last edited: May 7, 2008
  11. Roman Banned Banned

    Messages:
    11,560
    Of all the savannah species, Homo can run the longest. Except for maybe dogs. We're endurance animals, not sprinters.
     
  12. Dinosaur Rational Skeptic Valued Senior Member

    Messages:
    4,587
    I am only guessing, but I would expect walking at least partially upright came before primates moved to the Savannah. I can imagine a chimp, gorilla, orangutan, et cetera moving in a jungle environment without walking upright. I cannot imagine such primates wandering out to the Savannah without first evolving at least partially toward upright bipedal walking.
     
  13. Roman Banned Banned

    Messages:
    11,560
    Most mammals have some way of standing on their high legs, if only for a short period of time.
     
  14. siliconshrew Banned Banned

    Messages:
    55
    "So what? That doesn't explain anything."

    You were talking about two legged animals when the conversation was about truly bipedal animals. An easy mistake on your part. You wanted to know how bipedalism evolved independently across a wide variety of species, some of them now extinct. It's a largely irrelevant question as that type of bipedalism is completely different.

    Please Register or Log in to view the hidden image!


    Bird having a quiet ciggy while nobody is looking. Note that it's back is decidedly unvertical.

    "There are a number of reasons, all having to do with evolution. Many had nothing to do with water or tall grass."

    The world is full of theories. What is there to back them up? Neoteny and many other theories only explain the process of change. Not the underlying cause of it. The cause is invariably environmental.

    "All strawmen arguments. Irrelevant."

    I was responding to your supposition that two legged animals didn't become that way because of water. You shouldn't state a possibility as a fact. It's perfectly possible water did have something to do with it. In fact you've raised an interesting line of enquiry. The world was ruled by amphibians for a long time. Seems an interesting topic to search up on. Who knows what I might find.

    "siliconshrew there is one thing i dont get. If standing up right is such an advantage for an aquatic species why dont elephants do it as i belive they are on there second evolution OUT of the water (at least). This is why there lungs are designed the way they are because if they were like ours and they tried to snorkle under water there chest cavity would explode under the pressure"

    There are only two truly bipedal animals and they are both descended from animals either two legged like birds or extremely flexible and with an extremely good sense of balance like chimps. Elephants are the only animal in the world which can't jump. Like Brachiosaurs and Hippo's they are simply too massive. Wading was a useful way for us to repeatedly cross rivers and shallow sea's but elephants developed a snorkel instead.

    Please Register or Log in to view the hidden image!


    Chimp going for a leisurely knucklewalk. Like many other animals including cats and bears it is capable of standing on its back legs and even walking on them. But why assume such a bizarre posture?

    Please Register or Log in to view the hidden image!


    Chimp and baby wading.

    "Consider this: of most of the savannah species, Homo is the slowest. And stands upright. Wouldn't it make sense to have a little height to see over grass, as you run about as fast as a crippled deer? Coupled with our superior eyesight compared to savannah mammals, we could see trouble ahead more easily this way. African prairie dogs do this opportunistically."

    Lots of animals do it. But as soon as they look around they drop back on all fours. Why try and walk on two legs? Four is slow enough. Today we've become better at falling forwards in a controlled way but can you imagine how hard it must have been for our quadrupedal ancestors? Painful too. Wading is a lot easier as the body is buoyant and a wet environment demands such a gait. Besides, our eyesight isn't all that superior. Remember that Baboons have been living on the open Savannah for a very long time indeed and still show no sign of becoming bipedal.

    Roman
    "Of all the savannah species, Homo can run the longest. Except for maybe dogs. We're endurance animals, not sprinters."

    That's very true. Swimming is an endurance sport. Often recommended as a low impact form of calisthenics. When the inland sea vanished and we found ourselves far from the coast we probably went looking for it. Following rivers and settling anywhere vital water resources could be found. We can't survive very long without it. Since we weren't very fast we became creatures of endurance. Even today children in Africa often walk miles to fetch water for their families. We were just too poorly designed for running so we had to rely on weapons, intelligence and stamina.

    The sea levels weren't fixed all the time our ancestors lived in north east africa. Sometimes land bridges formed. So periodically there were waves of new hominids leaving the area. This explains the occurence of so many hominids in Africa. We were the last to leave.

    Dinosaur
    "I am only guessing, but I would expect walking at least partially upright came before primates moved to the Savannah. I can imagine a chimp, gorilla, orangutan, et cetera moving in a jungle environment without walking upright. I cannot imagine such primates wandering out to the Savannah without first evolving at least partially toward upright bipedal walking."

    I think you are correct. That was in the documentary I watched. But if our ancestors were already bipedal before the forests disapeared then why were they?

    Roman
    "Most mammals have some way of standing on their high legs, if only for a short period of time."

    Yes, but not walking.
     
  15. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    True: another reason for the Savannah hypothesis.
     
  16. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    Why would we need to be upright to cross rivers? Most other mammals get by quite easily by dogpaddling.

    Less body surface exposed to high sun and better energetic efficiency.

    I give you that point, but I think our eyesight is quite a bit superior even to a baboon. Plus our processors (brains) are quite a bit better, so we get more out of standing anyway.

    Geoff
     
  17. iceaura Valued Senior Member

    Messages:
    24,070
    Not for the savanna transition, however - the advantages of distance running are even more dependent on being previously and efficiently bipedal.

    A chimp on its hind hands is at even more of a disadvantage to one on three or four, over long distances than short ones.

    Here, among the many advantages of bipedal wading, is one place where the ability to carry something - such as a pry stick or bash rock or small child or bag of gatherings - in a couple of free hands, really pays off.

    But not walking, in the beginning. Not with a chimp brain or smaller.
    It would be much, much worse energetic efficiency for the first thousand generations. And a nice coat of shiny hair, like the stuff humans kept on their heads, is very good protection against high sun.

    You are talking about giving up the ability to run away, while increasing the visibility of the animal in the daylight (high sun), over a transitional phase of maybe a hundred thousand years.
     
  18. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    True - I would expect the Savannah Transition to occur prior to that point. But it would be reinforcement. Heck, possibly a no-return position, what with the hip modifications and so on.

    But running away is pointless for all hominids and primates - a three legged jaguar could catch a chimp without any trouble. But chimps do use sticks and the like to force off predators. Perhaps the bipedalism led to superior tool use and handiness with pointed sticks. This would leave energetic efficiency as the greater fitness/selective issue, which would be superior in the bipedal form. If you're walking, you have more impetus to be using your hands, as there are no pockets to stick them into or Starbucks cups to carry. I note too: in making the transition to the savannah, the ancestral chimpoid might not really have had much choice: with thinning forest, they have to make the best of a bad situation, and bipedalism with tool carrying makes sense. I'm sorry about the overlaying hypotheses, but it's necessarily a multivariate question.
     
  19. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    Oh, also: higher visibility of the hominid also means higher visibility for the hominid. True, they couldn't get away, but they could see trouble coming. And they had pointed sticks.
     
  20. iceaura Valued Senior Member

    Messages:
    24,070
    Like every other argument for a savanna transition that I've heard, that one is backwards.

    We need something that leads to bipedalism, not something that bipedalism leads to.
    And baboons use fangs and cooperation. Both are possible, for quadrupeds. Neither one gives an advantage to being slow, awkward, tired, and visible.
    Again: tripedalism with tool carrying is more efficient for chimps now than bipedalism with tool carrying.

    That's the transition that needs to be explained - the adoption of an initially less efficient mode of tool carrying, baby carrying, getting from A to B over the ground with or without the baggage.

    The only traveling a chimp does more efficiently on its hind hands is walking on tree branches.
     
  21. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    Already told you: tool use. Chimps use tools quite a bit, but are not considered classically bipedal.

    But tool use is easier and more effective and precise with better hand and brain development.

    For chimps now, yes. But millions of years ago as the forests were in decline?

    But bipedalism isn't less efficient in any of these areas. It's more efficient.
     
  22. S.A.M. uniquely dreadful Valued Senior Member

    Messages:
    72,822
    How about hunting? Wouldn't using tools to defend or hunt require standing upright?
     
  23. GeoffP Caput gerat lupinum Valued Senior Member

    Messages:
    22,087
    Sure would make it easier. Do chimps use weapons to hunt larger endotherms also, or just their hands?
     

Share This Page