Human Evolution: Gain Came With Pain

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Humans are the most successful primates on the planet, but our bodies wouldn’t win many awards for good design. That was the consensus of a panel of anthropologists who described in often-painful (and sometimes personal) detail just how poor a job evolution has done sculpting the human form here Friday at the annual meeting of AAAS (which publishes ScienceNOW). Using props and examples from the fossil record, the scientists showed how the very adaptations that have made humans so successful—such as upright walking and our big, complex brains—have been the result of constant remodeling of an ancient ape body plan that was originally used for life in the trees. “This anatomy isn’t what you’d design from scratch,” said anthropologist Jeremy DeSilva of Boston University. “Evolution works with duct tape and paper clips.”

Starting with the foot, DeSilva held up a cast with 26 bones and said: “You wouldn’t design it out of 26 moving parts.” Our feet have so many bones because our ape-like ancestors needed flexible feet to grasp branches. But as they moved out of the trees and began walking upright on the ground in the past 5 million years or so, the foot had to become more stable, and bit by bit, the big toe, which was no longer opposable, aligned itself with the other toes and our ancestors developed an arch to work as a shock absorber. “The foot was modified to remain rigid,” said DeSilva. “A lot of BandAids were stuck on these bones.” But the bottom line was that our foot still has a lot of room to twist inwards and outwards, and our arches collapse. This results in: ankle sprains, plantar fasciitis, Achilles tendonitis, shin splints, and broken ankles. These are not modern problems, due to stiletto heels; Fossils show broken ankles that have healed as far back as 3 million years ago.

A better design for upright walking and running, DeSilva said, would be a foot and ankle like an ostrich. An ostrich’s ankle and lower leg bones are fused into a single structure, which puts a kick into their step—and their foot has only two toes that aid in running. “Why can’t I have a foot like that?” asked DeSilva. One reason is that ostriches trace their upright locomotion back 230 million years to the age of dinosaurs, while our ancestors walked upright just 5 million years ago.

Turning up the pain threshold a notch, anatomist and paleoanthropologist Bruce Latimer of Case Western Reserve University in Cleveland, Ohio, limped to the podium, dangling a twisted human backbone as evidence of real pain. “If you want one place cobbled together with duct tape and paper clips it’s the back,” said Latimer, a survivor of back surgery.

Written By: Ann Gibbons
continue to source article at news.sciencemag.org

17 COMMENTS

  1. @OP – Turning up the pain threshold a notch, anatomist and paleoanthropologist Bruce Latimer of Case Western Reserve University in Cleveland, Ohio, limped to the podium, dangling a twisted human backbone as evidence of real pain. “If you want one place cobbled together with duct tape and paper clips it’s the back,” said Latimer, a survivor of back surgery.

    Yep! The human back is like a stack of loose-fitting tent-pole sections stuck together with tape! – With pinchable nerves just where the joints move if the tape stretches.

  2. Yep, my aching back. It used to hurt so badly when I had to kneel at church. I recently learned that kneeling is optional. It took them centuries to finally figure this out.

    I’m know I’m poorly “designed.” My smaller jaw may allow for a bigger brain, but has wrecked my TMJ to the point of being arthritic. Not to mention my rusty neck and spine among other parts. Has anyone ever figured out what the appendix does? or why the male nipples? what about being “white”skinned and mostly hairless. Of course we invented clothes, because otherwise, we’d be dead from the snow outside or we would be fried from the sun.

  3. No design awards for the so-called Intelligent Designer then. But then He must be in pretty bad shape Himself, if He designed us in His Image, Poor Thing, I suppose it was the best he could come up with at short notice. He was working to a deadline, remember.

  4. While our 5 million year bipedal evolution has been relatively quick, which has it’s obvious problems, our recent change to an almost sedentary lifestyle over just 1 or 2 generations is even more dramatic.

    A lot has been said about the problem of obesity, and various programmes have been launched to try and deal with that issue, but very little has been said about the problems caused to directly to the musculoskeletal system by spending nearly all day at work, in the car, at home, in a seated position.

    I’ve had problems with my back since I was in my teens and destroyed a lumber disc before I was 40. I’ve no doubt that this is because I’ve spent most of my life hunched over a desk, interspersed with short periods of intense high-impact exercise. It can’t be good to spend your life taking your body from one extreme to another.

    I think government health departments need to start looking urgently at ensuring that people don’t just eat the right foods and avoid smoking, etc, but use their bodies in a healthy way that will keep them fit, strong and supple through their lives. It’s not healthy to sit or stand immobile for hours at a time on a daily basis, as many of us do. We need to revolutionise the way people study and work from a young age to ensure they don’t develop the bad posture and other physiological conditions that sedentary lifestyles cause. As people are living longer and longer it’s even more important that their bodies continue to function well for as long as possible so that they remain productive and pain free.

    • In reply to #6 by Jumped Up Chimpanzee:

      While our 5 million year bipedal evolution has been relatively quick, which has it’s obvious problems, our recent change to an almost sedentary lifestyle over just 1 or 2 generations is even more dramatic.

      A lot has been said about the problem of obesity, and various programmes have been launched to try and deal with that issue, but very little has been said about the problems caused to directly to the musculoskeletal system by spending nearly all day at work, in the car, at home, in a seated position.

      There’s an interesting aspect to this in that there are people around who just can’t be made to sit down and behave themselves for prolonged periods. They have way too much energy for that.

      The reason that some other kinds of people do sit down all day is that they don’t have enough energy. Energy has to be relatively inaccessible metabolically but a crucial proportion of the energy from their food gets stashed onto their waistline and so isn’t readily available to fuel muscle and brain.

      The difference is often age. The younger ones are secreting various hormones that ensure quality sleep and are also growing very fast so their digested energy doesn’t overwhelm their body’s capacity to store this fuel as glycogen. The young ones can even tolerate otherwise extremely attractive, addictive, and toxic foods like biscuits and soft drinks that would eventually kill an older person who is too sleep deprived and tired to exercise. And the less exercise the older ones get the less sleep they get and the less energy they have next day, and the more stress hormone they secrete and the more they crave high energy density food – which again goes straight onto the waistline without doing anything much to fuel the mind and body. So they feel less energetic and get less exercise etc.

      For older sedentary people, who are allowed their own pocket money to buy junk food and hold the keys to the fridge and pantry, appetites firmly established during their youthful growth years can provide more fuel than their body can conveniently store, which causes inconvenient and significant fat accumulation. Middle age spread is evidence of the body’s defense against the toxic impact of excess blood glucose. But as long as the body is accumulating fat to defend itself it is also depriving itself of available energy. We experience this as chronic tiredness.

      So the problem isn’t the need to get people up and moving it’s in understanding why so many people are willing to sit around not moving. Laziness can’t be the answer because kids who won’t sit still and focus and would much rather be running around playing football (where they do focus) are regarded as lazy – but for exactly the opposite reason.

      The examples of poor evolutionary outcomes in human anatomy are probably true, but they aren’t convincing explanations for the misery of present day joint or birthing problems. It’s well known that the younger the mother the better the outcomes for childbirth. And human spines, knees, and ankles get a thrashing during childhood and early adulthood. There are occasional minor and serious injuries. But significant degradation doesn’t normally really kick in until much later in life.

      The problem isn’t the poor evolutionary ‘design’ it’s the inadequate overnight maintenance and regrowth that would otherwise counter inevitable accumulating wear and tear. (Mainly in intra-cellular functional proteins.) Evolution has also provided maintenance workarounds to compensate for its inevitably poor structural design. Just like how a good warranty policy can compensate for design risk. It’s like any factory that produces a poor quality product, but is happy to exchange the failed item for a new one. A product might be less durable than desired, but it’s always cheaper to make a less durable product and the product doesn’t really need to be durable if only you can get hold of the wholesale supplier for a warranty claim when required.

      The ultimate evolutionary warranty work around is to refresh everything by transmitting the crucial genes into a new body and throwing away the previous body along with the worn out bits and the now irrelevant and dysfunctional mind that grew in it.

      The same mechanism that drives food energy into long term fat storage is involved. What the body is attempting to temporarily defend itself (and its brain) against is the chronic onslaught of blood sugars from excess food. Though not so much the excess of food intake as inadequate fuel burning directly by exercise and indirectly by tissue growth and repair that otherwise only occurs with quality sleep – which also depends on exercise. Though tiredness from insufficient sleep and inadequate restoration of bodily wear and tear also drives appetite for energy.

      The cause of inadequate sleep is mostly TV viewing. Though science blogs are probably much more dangerous as they encourage alcohol consumption (which disrupts sleep and growth hormone secretion) and promotes excessively dull and inarticulate posts late into the night.

      Some examples of what a few decades of chronic excess blood sugar can achieve:

      At the extremes there are things like T2 diabetes, alzheimers, cancers, obesity, cardiovascular disease, stroke, high blood pressure. At the nuisance level there are chronic rashes, fungal infections, infertility, myopia, baldness, asthma, skin wrinkling, allergies, tooth decay, frequent colds and upper respiratory infections, and degradation of bone and cartilage.

      A particular problem might be areas of structural tissues under very high mechanical stresses but which are unable to be serviced by blood vessels. The lens of the eye is an example where evolution solves the problem of servicing cells that maintain transparent lens proteins without using blood vessels that would obscure vision. Similar evolutionary problems arises in the knee joints and in the material that contains the spinal disks where capillaries aren’t practical. These shock absorbing and load bearing protein polymer structures, like all functional and structural proteins in the body, are susceptible to being compromised by glucose molecules. Similar to the vulcanisation of rubber polymers by sulphur. It makes the rubber stiff and hard – more durable it some situations but less stretchy and resilient in others: more prone to splitting and it won’t fuse back together after damaging impact. Just like how the lenses in eyes no longer readily change shape after a few decades of marinating in sugar. The affected proteins can be very resistant to normal mechanisms that demolish and recycle proteins. Body temperature and a continual supply of glucose over a long time is sufficient for this to occur. There are mechanisms that mitigate the protein degradation (probably mostly not yet discovered) but they can become overwhelmed when chronic exposure to glucose greatly exceeds what our bodies evolved to experience.

      Blood glucose concentration normally fluctuates between feeds but areas of the body not directly attached to the circulatory system tend to average out the wild fluctuations in the blood. So isolated tissues can become more exposed to relatively high glucose concentrations compared to other better vascularised body tissues. This is why most people get stuffed knees and backs well before they die of a heart attack, stroke, or alzheimers. But it’s basically the same thing. Blood vessels are also becoming stiff, fractured, and inflamed. And neurons are accumulating AGEs that clog everything up – particularly the energy organelles which compromises thinking.

      So the issue isn’t so much poor design. Evolution has produced something that is more or less fit for the purpose. It’s just that some humans aren’t conforming to that purpose. We probably need the kids to teach the adults on this one.

  5. In reply to #6 by Jumped Up Chimpanzee:

    I’ve had problems with my back since I was in my teens and destroyed a lumber disc before I was 40.

    It probably turned right into sawdust.
    ;-)

    (“Lumbar”) Sorry… couldn’t resist! And I’ve got a couple herniated discs myself.

    Steve

  6. What about the shoulder girdle? It’s a cobbled-together suspension system that allows for an amazing range of arm motion, but is delicate and prone to debilitating injury and wear-and-tear dysfunction. The shoulders stick out just right to get hit, slammed, and fallen-on. Walking upright freed our arms for other uses, but it also means you can fall on them from a much greater height; they’ve become more flexible yet less robust, so when you fall, you stand a good chance of dislocating a shoulder, breaking a collarbone, or separating the AC joint. I never knew how much a shoulder injury can screw up your life until I suffered a football-tackle fall onto the point of my shoulder and ended up with a grade 5 AC joint separation. It took two surgeries, lots of hardware, and 18 months of physical therapy to get the use of my arm back. I’ve never heard of a chimp separating a shoulder whilst swinging through the trees.

  7. They should teach how badly we are “designed” in medical school and to many naturalists. I’m sick of hearing just how perfect we are and how “grateful” (to whom?) we should be. Just about anything that goes wrong with our body today can be blamed on a poor diet, lack of exercise or some other stupid thing we shouldn’t have done or could have avoided.

  8. I have ankylosing spondylitis, a chronic spinal disease that in its severest form (mine :( ) eventually ends with all of the vertebrae and connections in the rib cage fusing together. While there may be disadvantages with a spine with too many moving parts, I can testify that one with no moving parts is no picnic either.

  9. I have ankylosing spondylitis, a chronic spinal disease that in its severest form (mine :( ) eventually ends with all of the vertebrae and connections in the rib cage fusing together. While there may be disadvantages with a spine with too many moving parts, I can testify that one with no moving parts is no picnic either.

  10. In reply to #13 by Pete H:

    There’s an interesting aspect to this in that there are people around who just can’t be made to sit down and behave themselves for prolonged periods. They have way too much energy for that.The reason that some other kinds of people do sit down all day is that they don’t have enough energy. Energy has to be relatively inaccessible metabolically but a crucial proportion of the energy from their food gets stashed onto their waistline and so isn’t readily available to fuel muscle and brain.The difference is often age. The younger ones are secreting various hormones that ensure quality sleep and are also growing very fast so their digested energy doesn’t overwhelm their body’s capacity to store this fuel as glycogen. The young ones can even tolerate otherwise extremely attractive, addictive, and toxic foods like biscuits and soft drinks that would eventually kill an older person who is too sleep deprived and tired to exercise. And the less exercise the older ones get the less sleep they get and the less energy they have next day, and the more stress hormone they secrete and the more they crave high energy density food – which again goes straight onto the waistline without doing anything much to fuel the mind and body. So they feel less energetic and get less exercise etc.For older sedentary people, who are allowed their own pocket money to buy junk food and hold the keys to the fridge and pantry, appetites firmly established during their youthful growth years can provide more fuel than their body can conveniently store, which causes inconvenient and significant fat accumulation. Middle age spread is evidence of the body’s defense against the toxic impact of excess blood glucose. But as long as the body is accumulating fat to defend itself it is also depriving itself of available energy. We experience this as chronic tiredness.So the problem isn’t the need to get people up and moving it’s in understanding why so many people are willing to sit around not moving.

    You are undoubtedly correct in saying that for various reasons some people have more energy and are more inclined to move around than other people. My particular concern, born out of personal experience, is that regardless of how much energy some people have, they are required to spend large amounts of time in a sedentary position due to the nature of their schooling and their work. How much this may affect their health (such as the condition of their back) will vary greatly between individuals. It’s why I think it’s very important that we learn how to identify people who are particularly at risk to developing postural problems. (I, for example, was slightly smaller than average height up to about the age of 15, but then suddenly sprouted to well over 6ft in just 2 or 3 years. That undoubtedly helped cause my bad posture.) A lot of people are very fortunate and can spend many hours a day sitting at a desk without it causing them major health problems, so it’s not an easy problem for everyone to appreciate.

    Technology has played a major role in causing many of these problems, and it should play a big role in developing soluttions: alternatives to sitting at a desk or in an armchair for such long periods. It will require a lot of imagination to work out how people can use computers all day without having to sit down or stand still staring at a screen. I saw an article just the other day where a man had built a desk over a treadmill, so he could walk while using his computer. That was a very basic first step in the kind of technological development that we need to introduce.

    A lot of professional drivers also suffer from back problems. That must be an even greater challenge to devise a way people could drive a vehicle for a living without causing those sort of problems.

    • In reply to #14 by Jumped Up Chimpanzee:

      In reply to #13 by Pete H:

      The identification problem is easy. It’s everyone. I don’t think anyone is not at risk from sedentary activity. Unless they are very small and light.

      You might be very similar to myself. I was totally normal (physically at least) until suddenly sprouting to 6’4” and over 200 lbs around age 16.

      All my life I’ve been whacking my knees on the underside of desks. Plus sitting slumped over to somehow perch on the official NZ ministry of education child optimised chairs throughout my academic career. In my first few years at high school (mid 1970s) we still had the single seat desk combinations (with the inkwell and holder for quill pens) that were common in the 17th century. Physically impossible for an adult to actually sit in them. (I was considerably bigger than most adults.)

      They should have been in museums. Unfortunately they all ended up on the bonfire. Some of the graffiti carved into them (back in the days when many kids usually took knives to school) should also probably have ended up in an art gallery.

      I’ve injured my back and knees and just about every possible way over the years. What amazes me is that it actually gets better. It just takes a little longer as age increases. Main factor seems to be quality of sleep. But this can’t be separated from diet and exercise.

      I suspect that a key driver of middle age spread might be having kids – owing to the sleep disruption for the parents which becomes entrenched over the early childhood years. After a while people end up actually believing that they only need 7 hours sleep or whatever.

      There was an appalling court trial recently (in Sydney) where a truck driver defended himself (successfully I think) against manslaughter charges after falling asleep at the wheel and wiping out several people. The defense was that he was obese and suffered from sleep apnoea, along with more than half of all professional drivers, and therefore could not be held responsible for falling asleep at the wheel.

      Seems to be a bit like a physician causing a fatality by prescribing the wrong medication, and then claiming to be illiterate and therefore not liable because he couldn’t know any better. Perhaps lawyers should be arguing that employment selection should favour those who are hopelessly incompetent to perform their jobs – that way there is less liability exposure if things don’t work out. (Actually that might be already happening – it would explain a lot if it did.)

      Here’s an interesting (and very cheap) option for involuntary sedentarists:

      http://spacekat.github.com/blog/2012/07/26/diy-standing-desk/

      It wouldn’t take much to adapt a large truck cab or bus to enable operation from a standing position. And I think that Neil Armstrong landed on the moon while standing up at the controls. So there’s some precedent. Some driver’s cabs already have sufficient room to stand up in. Vehicle controls are already adaptable to paraplegics so they can use hand brakes and throttle.

      • In reply to #15 by Pete H:

        Interesting points.

        You’re right that everyone is at risk, and it’s not only going to be tall or heavy people who are prone to back injury, etc, although having long or heavy levers in your body is going to increase the risk.

        Incidentally, I have an expensive desk at work that can be raised and lowered, which is useful when moving from writing to using a keyboard, as they have different ideal height requirements. I can raise it to stand, too, but find that I get backache from standing still as much as from sitting still. Movement is the key to keeping my joints in the best shape.

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