Why do we walk upright?

Discussion in 'Biology & Genetics' started by Oniw17, Feb 21, 2007.

  1. valich Registered Senior Member

    I stand behind what I posted and also what Spurious posted. Your analysis between humans and horses is very interesting but I'm afraid that I know nothing about equine physiology to comment, although what you did post motivates me to learn more about this. Nice post.

    Again, humans evolved to walk upright as they emerged into the open savannah to maximize cooling efficiency - basic geometry. At noon, an upright horizontally exposed quadraped has 100% of its topside exposed to the sun's rays. If the same quadraped were to be vertical, only about 5 or 10% of the previously exposed upright surface would be subject to the sun's rays. The rest of the body surface is then much more efficiently cooled by horizontal air flow - wind. Tremendous survival advantage.
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  3. iceaura Valued Senior Member

    Again, it's only a survival advantage after it can be accomplished with reasonable speed and efficiency. Until then, it's just a slow and highly visible way of working hard in the sun. A chimp walking on its hind legs in the sun is getting heatstroke, not staying cooler. And savannahs don't just get hot - they get cold. Your biped has to stay warm while walking around on the cold days, too. Then there are insects.

    The point is, there is a transition stage of thousands of years in which our slow, awkward, hairy, highly visible, smallbrained biped is incapable of either speed or efficiency on the ground, and you propose sending that animal out unto a savannah full of predators. Eons from now, that ape may be able to use the heat to its advantage, covering long distances at a jog and leaving the leopards behind in the shade, but right now it's lunch.
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  5. cookie Registered Member

    I believe our ancestors began walking up in response to climate change. More particularlly, to the growing incidence of open spaces and food distribution. Changes in environment means adapting the body temperature and considering how much our ancestors traveled to forage for food makes sense. the amount of body surface a creature is exposed and the intensity of the sun would cause adaptation to want to be further away from the ground and allow the body to have less actual exposure to the sun. Also, freeing your hands for carrying food, tools, and increasing your ability to reach branches to collect fruit would also explain bipedalism. Even when chimps are are one two legs, it is normally when reaching for food. The theory of food and sex is also a great explaination. There are a number of adaptive features that caused our ancestors to become bipeds. Maybe we had less predators and did not have to run as fast? Maybe it was all the traveling? Maybe it was better for reproduction? As climate change occured (and Ardipithecus bring new discoveries to my theory) we began to travel more and needed to bring food back to our home base. Some suggest it was to explore the savannah, but Ardi proves that bipedalism began before the great move because she lived in wooded areas and was an arboreal quadruped and a terrestrial biped
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  7. krazedkat IQ of "Highly Gifted"-"Genius" Registered Senior Member

    Evolution has made us like this. Unfortunately this makes birth extremely painful...
  8. baftan ******* Valued Senior Member

    I was about to say "Natural selection made us", but yours is better. Bio-architecture made us walk like that, it's an adaptation of a species to its environment. Because of food, sex, fight, ground (grass, water, etc.) can be claimed, but in this case which one was dominant reason? Pelvis radically changed within couple of million years, one reason must be dominant among others. Similar biomechanical radical shift happened in bats, they are unique among mammal species as they can fly and use sonar.
    Last edited: Nov 6, 2009
  9. krazedkat IQ of "Highly Gifted"-"Genius" Registered Senior Member

    Yes, for certain tasks, probably hunting reasons, we need to be able to walk upright, so we eventually DID...
  10. Fraggle Rocker Staff Member

    You should all check into the reports on the recent discovery of Ardipithecus, which is about two million years older than Lucy. She is a truly transitional species. The pelvis and feet are fully modified for bipedal walking, yet the big toes are still capable of grasping--an animal that walked upright but could still climb trees far better than later hominids. The hands are also evolved; this creature did not use its knuckles for walking.

    Like all species in our line, the canines are shorter than in the other primates. The males of this species, like us and unlike other apes, did not fight by biting or posture by snarling.

    By correlating the plant fossils from the same time snapshot, they discovered that contrary to the savannah theory, this early hominid evolved in a forest region. It was hypothesized that a key advantage of bipedal walking was that freeing up their hands allowed them to become gatherers, ranging farther from camp and bringing food home. Rather than being impressed by the size of the snarling teeth, these females would have voted for the males who could walk upright and bring back food when they were nursing.

    Incidentally, this drives the splitoff of the hominid line much further back than was previously assumed. Chimpanzees are still our closest relatives, but our common ancestor was not a primitive chimpanzee. It appears now that it looked more like a human, and the chimps have differentiated more from this ancestor than we have.

    BTW, Homo sapiens is a species of Great Ape, a clade that includes us, the two species of gorillas, the two species of chimpanzees, and the orangutans. The Lesser Apes are the various species of gibbons.

    The Discovery Channel ran a very well produced two-hour special on "Ardi," as they call her. A reconstructive artist, working from the bones and the slight indentations that show where muscles attached, created a 3D image. Software used the musculature to figure out how the creature moved, and they made a computer-animated film showing it in action. I'm sure you can find this special on the internet.
  11. Orleander OH JOY!!!! Valued Senior Member

    I do it so I don't break a nail.

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  12. superstring01 Moderator

    What would be the evolutionary advantage of losing prehensile capabilities in our feet? Does it allow us to run faster? I for one think it could come in handy some times.

  13. krazedkat IQ of "Highly Gifted"-"Genius" Registered Senior Member


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    ... I do it so I can reach my microwave easily...
  14. Search & Destroy Take one bite at a time Moderator

    I would have to say that for optimum running and for optimum climbing requires two different types of toes. The evidence would suggest running did become more useful in the Savannah than climbing.

    Maybe it came in handy... but not handy enough.
  15. Search & Destroy Take one bite at a time Moderator

    I think the simple fact is

    Walking takes less energy than climbing.

    edit (unless you're climbing like a sloth. But that's not climbing that's hanging)
    Last edited: Nov 7, 2009
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I.e. they are more evolved than humans.

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  17. Fraggle Rocker Staff Member

    You should watch the two-hour video. I can't recount all of it accurately. The strength and coordination in our foot is distributed more evenly, across all five toes and metatarsals, rather than concentrated on the inside edge as in other primates. This gives us better balance and more sure-footedness on uneven surfaces, and the ability to turn more quickly. It doesn't make us faster but it makes us more nimble and gives us better endurance on long walks.

    I don't remember the program stating that this early species had yet evolved for efficient and skillful running. But she was a sturdy long-distance two-legged walking machine, compared to the other primates who can't carry big loads very far, very fast or very carefully.
    As I mentioned, the program reported the discovery that our ancestors evolved in the forest, not the savannah as was usually assumed. It wasn't running ability they needed, but hands free for carrying food back to camp.
    Only from the neck down. Even Ardi's brain was less than half the size of ours. Chimps are about one-third.

    By the time Homo sapiens appeared, our evolutionary advantage was entirely in our brain. We are no longer adapting to our environment by growing new musculature, dentition and other physical traits. We are adapting our environment to us by inventing technologies that extend our physical (and now mental) power. We have transcended nature and created a new super-organism called civilization. We are its cells.

    Just as the cooperation of multiple single-celled organisms created far more complex multi-celled organisms and ushered in a new era in evolution, the creation of civilization has taken it into the next era.
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Or on an evolutionary time scale, to self-extinction along with other multi-cellular plants and animals? The 10,000 or so years that mankind could write anything is but the blink of an eye by evolution's time scale.

    It far from certain that brains that can reshape nature instead of adapt to its slow changes are a stable invention / development on that longer time scale. It could well turn out that our expanded brain is nature’s greatest mistake in the long run. I am not saying it needs to be that way, but the evidence thus far is mainly how effective that enlarged brain has been in destroying thousands of living systems that once were in slowly evolving mutual harmony. One can very reasonably argue that humans are an “out-of-control” cancer on the biosphere. Let’s see how life forms are going 100,000 years from now before we become too self congratulatory.

    Like Venus, Earth too has two quasi stable thermal states. If humans switch Earth into its hot stable state - a thick, IR-opaque atmosphere of mainly high pressure steam, it will be on the order of a million years before the oceans have boiled off into space and Earth can switch back to the present cooler stable state. As someone once said: "It ain't nice to mess around with mother nature." and I might add: "JUST BECAUSE YOU CAN TO AVOID SOME NEAR TERM INCONVEINENCE (like living on a sustainable energy system).

    For some discussion of how Earth can be switched by man to the hot sterile state see:
    http://www.sciforums.com/showpost.php?p=1473520&postcount=12 and then on to
    http://www.sciforums.com/showpost.php?p=1687196&postcount=32 and on thru
    and in another thread:
    http://www.sciforums.com/showpost.php?p=1693002&postcount=57 and then also

    There are many other posts where I discuss how the Earth can (unfortunately may already have begun to) switch Earth to the hot stable state, making Earth totally sterile but these five posts tell the main points of the mechanism.

    PS what a pity it will be for the innocent, highly-evolved, chimps if the big brained idiots destroy a billion years of evolution - Everything lost on a completely sterile Earth.
    Last edited by a moderator: Nov 8, 2009
  19. Fraggle Rocker Staff Member

    Dubner and Levitt, in their "Freakonomics" books, insist that we can reverse global warming by just "thinking outside the box." It's not that we don't have to change our ways and reduce our carbon footprint; it's that the problem with focusing only on that is: we're doomed! No matter how quickly we scale back our lifestyle, the effect will be so slow that it won't stop us from reaching the tipping point. We need to approach the problem from an engineering perspective, using techniques that will physically alter the atmosphere, while we're waiting for our conservation efforts to alter it biologically.

    Unfortunately "green" has become a religion. The greenies would rather risk civilization regressing to the Stone Age (or perhaps the entire biosphere regressing to a primordial state) rather than admit that the science that caused the problem might also provide the solution.

    With luck, the chimps will survive because our big brains can solve the problems they create. Unfortunately in order for that to happen, humanity now has yet another "religion" to overcome.
  20. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I completely agree with that because the rate and extent of life style changes required to reduce global warming are impossible to achieve.

    For example: As I recall there are 800 cars per 1000 persons in the USA and only 6/ 1000 persons in China, but China is now selling more cars than the US is. Only freezing the number (or total HP) of fossil fuel cars is clearly impossible UNLESS the US were to take about 50% of its cars off the roads so China could have the same ratio of cars to people (400/1000) as the US; but even if that were possible, it would still be a 400% increase in the number of cars as the Chinese population is 4 times larger. (And all this is forgetting about India and Tata's $2500 car for domestic and export, etc.)

    I think there should be a crash program to make thousands of autonomous, floating wind mills, which use a small part of their produced power to "station keep" their assigned location (mainly tropical), but most of their power to spray jets of water to several hundred meters altitude in a full sky covering arc above their locations to form local clouds or fogs during the day time hours, to reflects sunlight. Perhaps during clear night their power is used to heat a coil red hot which is at the focus of a parabolic reflector to send an IR beam into deep space. When local sky is not clear to IR (both day and night) but winds are generating power, there are both chemical processes they could drive to either store energy or make stable, dense (sinking in salt water) compounds from GHG. Alternatively they could use that power to make energy intense compounds like aluminum, for the sea water.*

    *Many years ago, Von Neumann, sort of the founder of AI, proposed (with extensive analysis) that self replicating floating units, made mainly of aluminum, be turned loose on the oceans. After a several decades (perhaps 100 years) some could be periodically and sustainably harvested annually for their aluminum (and some other valuable metals).

    But we are way off thread, except to note that it is good thing that humanoids learned to walk upright (and man can ride bikes) as we will need to do a lot more of that soon (as well as "telecommute" to work from our well insulated, nearly buried, homes or efficiently** cooled apartments.)

    **For several years, I spent part of my profession time developing "CASES" including a detailed study of the US Navy CINCMD base at Norfolk Va.
    (CASES = Community Annual Storage Energy System.) I have been working on energy system for more than 40 years - I see problems coming before most do. (Make that 50 years, if including my fusion related plasma physics Ph.D. research)

    No where until well into Canada is there any net need for heating. Even in the middle of winter, the heat production in larger building (and factories) exceeds the needs of well insulated houses. In CASES, this surplus heat is stored in an Aquifer and used in winter as the heat source for efficient water-source heat pumps.

    Where there is no Aquifer available, then large efficient ice machines*** (they are heat pumps) are used for efficient heat production and the ice is stored in large, well insulated "Quonset hut" type structures for summer cooling. Detailed hour by hour simulations with real weather records were used to evaluate the economics of the CASES approach. It typically had about a 15 year pay-back period. (There are insulated warm and cold water pipes circulating thermal source or sink water for more local heat pumps.) Over all, the annual COP was usually greater than 15 for cooling. (At least five times better than typical air conditioner)Heating is "free" (with zero energy cost) in the model as all electric power was "charged" to cooling in the model. Typically in a reasonably balanced community, there is a net surplus of heat to dump (spray pond) but now with more efficient lighting and motors that surplus would be smaller.

    The US is not socially/politically organized to accept this energy saving system (partly why a US Navy base was modeled in detail) but some of the Scandinavian countries are and closely related ideas are in use there; but as their cooling load is relatively small, these systems tend to be called "district heating system" (hot water, not steam is distributed thru out the community)**** Most of the work was paid for by DoE but the Navy paid for the Norfolk base study.

    *** They have large a rotating drum which is slightly below 0C and continuously scrap off thin ice as it forms. I.e. they do not need to transport heat thru more than ~1 mm of ice film and are very efficient.

    **** Baltimore's BG&E had a small steam district heating systems - sold heat as well as electric power but steam is not suitable for sending more than a few city blocks from the source. Warm / hot water can go miles and feed heat to local very efficient water source heat pumps (which are also cheaper than air source.)
    Last edited by a moderator: Nov 12, 2009
  21. Fraggle Rocker Staff Member

    China is building the infrastructure to convert to electric motors. They've got (ironically) an American company building charging stations all over the country. Once our people see it work there, they might permit the investment to be made here.
    There's no reason that the entire workforce has to transport itself across the landscape twice a day, devoting one-fourth of our petroleum consumption directly to commuting. (Not counting the indirect costs like nannies and fast food.) Except for a small percentage of American workers--psychiatrists, diplomats, chefs, bulldozer operators, janitors, etc.--we spend our entire day talking on the phone, manipulating data that is (or should be) digitized, and attending boring meetings that do nothing except make the manager feel like he's earning his salary. And the meetings can be virtualized, with today's webcams, pass-the-mouse networking software, and multiple monitors.

    While doing the research for my chapter in a book on management a few years ago, I discovered that many Americans actually don't want to go home, either because they're doing penance for being unproductive, or because their family life is dysfunctional.
  22. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Very interesting and I bet quite true.

    Perhaps there should be many local (walk to them) centers where studs and whores provide diversion, one can get cheap drinks and watch sports on TV etc.? That would provide additional jobs too. I.e. open up the zoning laws.

    As I recall BYD sold 400,000 cars in 2008, but only 100 of them were electric hybrids as they cost twice as much as the gasoline version. One thing that may help this is if the Li-ion batteries were leased, not owned. This also removes the car owner's concerns about cost of replacing them.

    Even better idea is to make new cities where there are no cars. I went into some detail about how they should be organized in some old posts. You can greatly reduce the time required to go shopping or sports event too via system's electric "autocars" which are like a 2D horizontal elevator. (I.e. a computer controlled vehicle you cannot get out of before destination traveling in its enclosed "road way" which never needs to stop for any crossing traffic, so is fast and efficient)

    You get a bar code "key" at autocar terminal in the center of each "block building" and tell which "block building" terminal is your desired destination. Each autocar has a "panic button" - hit it and the scheduled destination is cancelled and you are dropped that the closest block building terminal - there you can request a new auto car and destination, if you like. (Autocars come in 2, 4 or 6 passenger versions with rental pricing structure that encourages shared and off peak use.)

    The "block buildings" are stepped pyramids - from high above the city all you see is green plants. The second level, over the enclosed autocar roads is city wide "all weather" bike path system.

    For more on the autocar system see: http://www.sciforums.com/showpost.php?p=2228529&postcount=74
    For more about the city plan see: http://www.sciforums.com/showpost.php?p=2228211&postcount=71
    but there is an earlier more detailed post in some thread aqbout modern cities.
    Last edited by a moderator: Nov 12, 2009
  23. Stryder Keeper of "good" ideas. Valued Senior Member

    Billy, although this is going off topic why not bankroll leasing such batteries yourself, you could make a fair bit of money if you are right. Of course the lease could have cover for theft and damage.

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