Hominids First Learned How to Walk in Trees

Discussion in 'Biology & Genetics' started by valich, Jun 1, 2007.

  1. valich Registered Senior Member

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    I don't really find this as groundbreaking news but thought I'd post it just for thought. I had assumed this all along. We learned how to walk in trees, then as the forest thinned out in the Serengeti and savannahs of Africa due to climate change, we took more to the ground. We always had to have trees nearby to run up in for protection. I did not know that the commonly held view is that we first came down from trees and walked on our knuckles? What is the rationale behind this? http://news.bbc.co.uk/2/hi/science/nature/6709627.stm
     
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  3. iceaura Valued Senior Member

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    That isn't logical at all. Orangutans don't show any of the modifications necessary for ground walking, which is much different, for example.

    The logical conclusion is that humans did not become bipedal walkers simply by climbing down from the trees and walking around. That transition would have enforced four legged walking, according to all the evidence we have. Something else intervened.
     
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  5. Wisdom_Seeker Speaker of my truth Valued Senior Member

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    Well, yeah, when the forrest started to dissapear in Africa, due to weather changes. Our ancestors were forced to go search for food on the prairies. Herbal food was in decrease, and they were forced to start eating meat. This is significant.
    Our brain growth in evolution is a combined factor of starting to use our hands for tools and feeding (hunting & collecting) and the meat protein aiding the brain growth.
     
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  7. iceaura Valued Senior Member

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    But you've got a problem: in the "walk out of the trees" scene, the walking had to start before the brain growth - and there is no advantage to bad, slow, vulnerable, bipedal walking in a grassland. All the advantages you list come after the animal is bipedal in some reasonable, efficient manner - after a good long evolutionary transition.

    The initial boost has to be something other than the advantages only gained later. Humans coopted their bipedal walking for its advantages re tools, brain application, etc - but they had to be walking first. A tree ape that wants to carry something a long way over the ground will hold it in one paw and run quickly and with reasonable efficiency on the other three - or use its mouth, like most animals. It will not stagger around on its hind legs using both front paws, wasting time and energy, making itself visible and vulnerable to predators and injury, and in fact not able to carry much more.

    A chimp is no more likely than a raccoon or a bear to set out on its hind legs into a savannah. Baboons came down from trees into the savannah - on four legs, as any animal would.
     
  8. Wisdom_Seeker Speaker of my truth Valued Senior Member

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    You are right, but some chimps do use their hands for tools, after many years of evolution, they would increase their ability to use their hands for each time more efficient tools.

    When the homo-erectus started going down from the trees to the savannah, they went not far from the trees, because as you said, they were vulnerable to predators and injury.

    In the savannah, they needed more and more speed to get away from the predators.

    You can see the evolutionary evidence of "running for our lives" from predators in our basic emotions. When we experience fear, it is a known fact that our heart starts beating stronger in order for more blood to go to our legs, the blood concentrates in the upper part of our legs in order to run faster. That is why we unconsciously feel the need to run when we experience fear.
    But this is an explosive response, it only last for small distances, that is why I say they did not go far from the trees. The trees were the shelter.

    On the other hand, when we experience anger, the heart too beats stronger, but the blood goes to our arms, not our legs, so we feel the unconscious need to hit something (or someone :bugeye: ). This is the evolutionary evidence, that in order to run, our ancestors did not use the arms, but only the legs. The arms were for making tools and fighting.

    Bibliography of the physical responses to our emotions:
    Emotional Intelligence by Daniel Coleman
     
  9. one_raven God is a Chinese Whisper Valued Senior Member

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    I've always thought we started to walk on two legs so we could hold weapons and other tools with our hands.
     
  10. Baron Max Registered Senior Member

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    Well, folks, just remember, the article, the theory, is just the opinion or theory of three individuals. It's not a proven fact by any stretch of the imagination.

    And, Raven, that's exactly what I had always read and heard. And it seems to bear out by watching baboons and other such creatures use sticks and rocks to throw at leopards. It's pretty damned hard to throw a stick at a leopard when you're standing on your hands as well as your feet!

    Baron Max
     
  11. one_raven God is a Chinese Whisper Valued Senior Member

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    Oh, I'm not saying, "I guess I was wrong, and I have to change my mind now." It's more like, "Interesting idea. I think there is good reasion to believe this one, however..."

    Exactly.

    It seems that the developing brain would go hand in hand (no pun intended) with taking up weapons and more advanced hunting/warring techniques etc.
    Which, it seems to me, leads to walking on hind legs, and using weapons/tools with hands.
     
  12. iceaura Valued Senior Member

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    And our chimp-brained, fireless, weaponless, tree-dwelling ancestors invented these things, and spent hours making them without being able to use them, why, exactly?

    Clearly hand weapons are great advantages, if you have free hands. You have to be basically bipedal already, however, and you already have to be out of the trees and walking. Chimps don't get much advantage from hand weapons.

    The problem is not the cascade of adaptations and advantages afterwards, but the initial advantage of bipedal locomotion. The human ancestor that started walking on its back legs exclusively, for long distances and for enough of a reason that their repro success was affected, is not likely to have had pre-adapted tools and weapons for inspiration.

    One possibility more in keeping with circumstance is that the first real tool was a carry bag or baby sling. Gatherers, more than hunters or fighters, need to carry things and gain immediate advantage from free hands.
     
  13. Cortex_Colossus Banned Banned

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    One of the main reasons for the current posture is the reaching and hunting advantage.
     
  14. one_raven God is a Chinese Whisper Valued Senior Member

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    Current chimps use tools and even sometimes weapons.
    It is not they they adapted bipedal motion so they can walk to the hardwae store and buy a hammer, the two very could have developed concurrently and fed off each other with the developing brain.
     
  15. iceaura Valued Senior Member

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    Which they have done in no other ape, or any other animal. For the very good reason that the initial transition involves a severe handicap - a chimp that walks around all day for weeks on its hind legs, carrying in both hands a stick which it can use only with difficulty for some simple tasks, is at a disadvantage, not an advantage. The large handicap of bipedal locomotion far more than cancels the occasional and unpredictable extra opportunites for tool employment. That's why chimps don't do that, and "concurrent" evolution has not happened in chimps despite millions of years of opportunity.

    Or in baboons, gorillas, snow monkeys, etc.

    Again: the initial advantage has to accrue to a tree ape that is incapable of efficient, long distance, bipedal travel. This tree ape has a chimp brain or smaller, no manufactured tools yet, no fire yet, and many enemies. It is probably three or four feet "tall", and weighs about a hundred pounds. We don't know if had fangs, or thick body hair - probably yes. Something has to get this animal on its hind legs, and keep it there long enough and under enough selective pressure to modify its major skeletal structure. Whimsically schlepping two hands worth of rocks and sticks around (rather than one), that it can employ no better than a modern chimp and probably not as well, hardly qualifies as a likely agent.
     
  16. Ophiolite Valued Senior Member

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    Ophiolite waits patiently for someone to mention aquatic ape theory and for the cognicenti of human evolution to jump all over the heretic.
     
  17. Fraggle Rocker Staff Member

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    The Washington Post did a more thorough job of reporting on the original article. More quotes from the scientists give a better context to the argument, without resolving it.

    http://www.washingtonpost.com/wp-dyn/content/article/2007/05/31/AR2007053101372.html

    I always figured that walking upright gave us the ability to see farther, an advantage as both predator and prey.
    I've always found the AAT rather compelling. Three-dimensional environments (air, trees, water) tend to increase intelligence because of the vastly expanded arena of decision making. Coming down out of the trees and adapting to a terrestrial life should have been a damper on our intelligence, or at the very least not caused it to grow. Jumping into the nearest body of water, on the other hand, could have encouraged our brainpower to continue growing, so when we finally came out we would have been smarter than we started. The adaptation of our musculature to swimming might have accidentally caused us to emerge with an upright walking posture.

    Warm-blooded air breathers kick everybody's ass in the water, so we wouldn't have been so vulnerable while waiting to invent tools. And whoever kicks the most ass in the water gets to be the top predator, inviting us to become more carnivorous than the other apes. It's a really nice, neat theory, but of course that's not enough to make it correct.

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  18. iceaura Valued Senior Member

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    Height increases visibility, as well as vision range - and slow, awkward locomotion is a poor companion feature to increased visibility on a grassland of leopards and hyena packs.

    The aquatic ape makes more sense, to me, as a wading ape than a full tilt swimming one.
     
  19. valich Registered Senior Member

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    We have some excellent posts here. I don't think that the increase of standing upright two or three more feet would have given us much more of an advantage for survival predator vs. prey. The main point is that we learned how to walk in trees before we came down to permanently roam and migrate on land in open areas without such protective avenues of escape.
     
  20. Baron Max Registered Senior Member

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    You say that as if it's an established fact??

    I'm also interested in ....exactly HOW does one "walk" in trees?

    Baron Max
     
  21. John J. Bannan Registered Senior Member

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    I had an idea this morning, which maybe new to science. Well, at least it's new to me. Science tells us that man began to walk upright before his brain got bigger. The reason for that maybe that upright walking allowed the skull to rest on a verticle spine greatly increasing the support structure holding up our brains. With greater available support, our brains could grow larger, heavier and smarter. A four legged walker, like a dog, has no underneath support for his head, which hangs out from his body supported by a horizontal spine. Evolution and simple engineering will favor a lighter head where there is no underneath support. Man may have developed a larger brain, because he changed the support structure of his body by walking upright. This also accounts for why man appears to be unique in his intelligence, because man is also unique in his ability to walk upright. Although some animals do walk on two legs, such as an Ostrich, those animals still have only a horizontal spine which is not supporting their skulls from directly below. It maybe that walking upright caused human intelligence by re-engineering the load bearing capability of the body in relation to the head, thus permitting the head to expand greatly in weight. What do you think?
     
  22. iceaura Valued Senior Member

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    Well, that may be the "main point", but it makes little sense as presented and has little evidence behind it so far.

    The treewalking apes are not adapted, structurally, for bipedal walking on land. When they climb out of their trees, they get down on all fours and knuckle walk - because that is much more efficient and much faster and much safer and so forth. That's a serious problem with the hypothesis. According to the hypothesis, the structural modifications for efficient bipedal locomotion on land happened while the animal was tree walking. There is no evidence of that ever happening with any animal, and no particular reason to think it makes sense for early hominids.

    btw: as far as the advantages of height, a long-armed short-legged tree ape doesn't gain that much height by balancing all the way back on its hind hands. Knuckle walking apes are already holding their heads high. Walking in trees is best done and most advantageous with long arms - very long arms, well suited for knuckle walking.
     

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