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The evolution of human running: effects of changes in lower-limb length on locomotor economy.Steudel-Numbers KL, Weaver TD, Wall-Scheffler CM. J Hum Evol. 2007 Aug;53(2):191-6.
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Previous studies have differed in expectations about whether long limbs should increase or decrease the energetic cost of locomotion. It has recently been shown that relatively longer lower limbs (relative to body mass) reduce the energetic cost of human walking. Here we report on whether a relationship exists between limb length and cost of human running. Subjects whose measured lower-limb lengths were relatively long or short for their mass (as judged by deviations from predicted values based on a regression of lower-limb length on body mass) were selected. Eighteen human subjects rested in a seated position and ran on a treadmill at 2.68 ms(-1) while their expired gases were collected and analyzed; stride length was determined from videotapes. We found significant negative relationships between relative lower-limb length and two measures of cost. The partial correlation between net cost of transport and lower-limb length controlling for body mass was r=-0.69 (p=0.002). The partial correlation between the gross cost of locomotion at 2.68 ms(-1) and lower-limb length controlling for body mass was r=-0.61 (p=0.009). Thus, subjects with relatively longer lower limbs tend to have lower locomotor costs than those with relatively shorter lower limbs, similar to the results found for human walking. Contrary to general expectation, a linear relationship between stride length and lower-limb length was not found.
The BBC are reporting: Tendons play key role in running
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It is unclear when humans first started to run
Achilles tendons play a critical role in human running ability, a major conference in York has been told.
A new computer model confirms that skeletons need to store energy in their tendons to be able to run efficiently.
Speaking at the BA Festival of Science, Dr Bill Sellers said further fossil data was needed to shed light on when our ancestors started running.
Running was an important development in human evolution, giving man the ability to chase prey, Dr Sellers explained.
Running is a far more difficult activity than walking.
"It changes your options. If you're an efficient long distance runner then you might be able to run down your prey," the University of Manchester primatologist explained.
"You're not going to walk down your prey."
Dr Sellers created models of a human skeleton with and without tendons, and looked at their running speeds and energy requirements.
If we make a model without tendons, it turns out that it's rubbish
"And what this means is that muscles are attached to bones by tendons at the end and these tendons are big springs that store energy."
"If we make a model without tendons, it turns out that it's rubbish.
"It can't go very fast and it uses an awful lot of food to get from A to B. So you really can't run if you don't have tendons. If you do have tendons you can run a lot faster and you do it for less fuel."
Scientists do not know when humans developed the ability to run.
Studies and models of the bone structure of "Lucy", a 3.2-million-year-old skeleton of a human ancestor from Ethiopia, have shown that she walked upright, but there is no evidence she was a sprinter.
"You look at the Lucy skeleton... and it doesn't look at all like a human. It really is very different, it's got much shorter legs and it's got longer arms and I think there is every chance that Lucy couldn't run," said Dr Sellers.
But, he said he suspected Homo erectus, who lived two million years-ago, could sprint. So the Achilles tendon must have evolved at some evolutionary stage between these two species.
To pinpoint when it evolved, the team now needs to know which fossils show evidence of an Achilles tendon.
But this, said Dr Sellers, was difficult: "The problem with hominid fossils is that the vast majority have no feet. And what you really want, to find evidence of an Achilles tendon, is a nice intact ankle bone."
The University of Manchester researcher said he hoped that future findings would discover evidence of Achilles tendons, allowing scientists to solve the mystery of when humans learnt to run.
Quote (much cut) - "You look at the Lucy skeleton... and it doesn't look at all like a human. It really is very different, it's got much shorter legs and it's got longer arms and I think there is every chance that Lucy couldn't run," said Dr Sellers.
Yes, its accepted world-wide (has been since it was discovered more or less) that Lucy couldn't run, and was much less human-like than either homo habilis or homo erectus.
But, he said he suspected Homo erectus, who lived two million years-ago, could sprint. So the Achilles tendon must have evolved at some evolutionary stage
Well, that's generally accepted too - so really no suprises there at all:p
BTW why would he (the researcher, not homo erectus) need a nice "ankle" bone? Wouldn't tuberosities on othere parts of the lower limb (we have all those - yawn) show what muscles originated where?
The striking variation in limb proportions within the genus Homo during the Pleistocene has important implications for understanding biomechanics in the later evolution of human bipedalism, because longer limbs and limb segments may increase bending moments about bones and joints. This research tested the hypothesis that long lower limbs and tibiae bring about increases in A-P bending forces on the lower limb during the stance phase of human walking. High-speed 3-D video data, force plates, and motion analysis software were used to analyze the walking gait of 27 modern human subjects. Limb length, as well as absolute and relative tibia length, were tested for associations with a number of kinetic and kinematic variables. Results show that individuals with longer limbs do incur greater bending moments along the lower limb during the first half of stance phase. During the second half of stance, individuals moderate bending moments through a complex of compensatory mechanisms, including keeping the knee in a more extended position. Neither absolute nor relative tibia length had any effect on the kinetic or kinematic variables tested. If these patterns apply to fossil Homo, groups with relatively long limbs (e.g. H. ergaster or early H. sapiens) may have experienced elevated bending forces along the lower limb during walking compared to those with relatively shorter limbs (e.g. the Neandertals). These increased forces could have led to greater reinforcement of joints and diaphyses. These results must be considered when formulating explanations for variation in limb morphology among Pleistocene hominins
The evolution of habitual bipedalism is still a fundamental yet unsolved question for paleoanthropologists, and carrying is popular as an explanation for both the early adoption of upright walking and as a positive selection pressure once a terrestrial lifestyle had been adopted. However, to support or reject any hypothesis that suggests carrying efficiency was an important selective pressure, we need quantitative data on the costs of different forms of carrying behavior, especially infant-carrying since reduction in the grasping capabilities of the foot would have prevented infants from clinging on for long durations. In this study, we tested the hypothesis that the mode of load carriage influences the energetic cost of locomotion. Oxygen consumption was measured in seven female participants walking at a constant speed while carrying four different 10-kg loads (a weighted vest, 5-kg dumbbells carried in each hand, a mannequin infant carried on one hip, and a 10-kg dumbbell carried in a single hand). Oxygen consumption was also measured during unloaded standing and unloaded walking. The results show that the weighted vest requires the least amount of energy of the four types of carrying and that, for this condition, humans are more efficient than would be predicted for mammals in general. The balanced load was carried with approximately the predicted energy cost. However, the asymmetrical conditions were considerably less efficient, indicating that, unless infant-carrying was the adaptive response to a strong environmental selection pressure, this behavior is unlikely to have been the precursor to the evolution of bipedalism.
The phalangeal portion of the forefoot is extremely short relative to body mass in humans. This derived pedal proportion is thought to have evolved in the context of committed bipedalism, but the benefits of shorter toes for walking and/or running have not been tested previously. Here, we propose a biomechanical model of toe function in bipedal locomotion that suggests that shorter pedal phalanges improve locomotor performance by decreasing digital flexor force production and mechanical work, which might ultimately reduce the metabolic cost of flexor force production during bipedal locomotion. We tested this model using kinematic, force and plantar pressure data collected from a human sample representing normal variation in toe length (N=25). The effect of toe length on peak digital flexor forces, impulses and work outputs was evaluated during barefoot walking and running using partial correlations and multiple regression analysis, controlling for the effects of body mass, whole-foot and phalangeal contact times and toe-out angle. Our results suggest that there is no significant increase in digital flexor output associated with longer toes in walking. In running, however, multiple regression analyses based on the sample suggest that increasing average relative toe length by as little as 20% doubles peak digital flexor impulses and mechanical work, probably also increasing the metabolic cost of generating these forces. The increased mechanical cost associated with long toes in running suggests that modern human forefoot proportions might have been selected for in the context of the evolution of endurance running.
What We Can Learn About Running from Barefoot Running: An Evolutionary Medical Perspective.
Lieberman DE. Exerc Sport Sci Rev. 2012 Jan 17.
ABSTRACT:
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Barefoot running, which was how people ran for millions of years, provides an opportunity to study how natural selection adapted the human body to run. Because humans evolved to run barefoot, a barefoot running style which minimizes impact peaks and provides increased proprioception and foot strength, is hypothesized to help avoid injury, regardless of whether one is wearing shoes or not.
Quote (much cut) - "You look at the Lucy skeleton... and it doesn't look at all like a human. It really is very different, it's got much shorter legs and it's got longer arms and I think there is every chance that Lucy couldn't run," said Dr Sellers.
Yes, its accepted world-wide (has been since it was discovered more or less) that Lucy couldn't run, and was much less human-like than either homo habilis or homo erectus.
But, he said he suspected Homo erectus, who lived two million years-ago, could sprint. So the Achilles tendon must have evolved at some evolutionary stage
Well, that's generally accepted too - so really no suprises there at all:p
BTW why would he (the researcher, not homo erectus) need a nice "ankle" bone? Wouldn't tuberosities on othere parts of the lower limb (we have all those - yawn) show what muscles originated where?
I for one do not accept that Lucy was bipel in the human sense. My early work on her talus - the only foot bone available, demonstrated it to be non-human, and more similar to African Apes. I have no opinion on the Achilles tendon of Lucy, but do hang on to her talus; so far in the fossil record, the talus has been incredibly predictive of the rest of the foot. To my best guess, Lucy had long toes, and was at least semi-arboreal. (I am just moving sideways to ensure that the lightening bolt from the Lucy camp does not hit me). Rob
I for one do not accept that Lucy was bipel in the human sense. My early work on her talus - the only foot bone available, demonstrated it to be non-human, and more similar to African Apes. I have no opinion on the Achilles tendon of Lucy, but do hang on to her talus; so far in the fossil record, the talus has been incredibly predictive of the rest of the foot. To my best guess, Lucy had long toes, and was at least semi-arboreal. (I am just moving sideways to ensure that the lightening bolt from the Lucy camp does not hit me). Rob
Z-aaaaaap!
Hi Rob,
Don't the phalanges from the right hand show a slight longitudinal curvature to them too, suggestive of an arboreal dwelling mammal?
I only heard this 2nd-hand, but from a reputable source.
What We Can Learn About Running from Barefoot Running: An Evolutionary Medical Perspective.
Lieberman DE. Exerc Sport Sci Rev. 2012 Jan 17.
ABSTRACT:
Quote:
Barefoot running, which was how people ran for millions of years, provides an opportunity to study how natural selection adapted the human body to run. Because humans evolved to run barefoot, a barefoot running style which minimizes impact peaks and provides increased proprioception and foot strength, is hypothesized to help avoid injury, regardless of whether one is wearing shoes or not.
Putting various other issues (of contention) aside here, as I don't want to diversify down other paths (just stick to this topic). The above abstract just seems to me to be nothing more than thinly disguised philosophical naturalism... apparently under the guise of... "An Evolutionary Medical Perspective". Let’s just keep to empirical science... after all, this forum (I presume the journal: Exercise & Sport Sciences Reviews) as well as the underlying context of the research (the assessing of those infamous "impact peaks") should be within the realms of empirical science... not historical speculation (one's world view philosophy), which is the above person's consistent shaky premise when dabbling in this area of barefooting & running.
Let's assess the abstract within the confines of this shaky premise...
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ABSTRACT: Barefoot running, which was how people ran for millions of years, provides an opportunity to study how natural selection adapted the human body to run.
I would think no matter what side of the fence you are on, the above quote is just mere unsubstantiated speculation - period... & questionable, to say the least. Hence, it is not needed in this setting. There are many issues the above content brings up to justify this/my view due to its involvement within a science publication. For starters... "people" (what is the definition of a person - people?) "ran" (what is the definition of running - ran - to at least be bipedal) "for millions of years" (did this happen for millions of years within the evolutionary paradigm). Now, I know some here know my views regarding the Origins discussion but the above view is out of sync within the peer accepted paradigm of evolution... let alone science.
"People"... (people plural of peo·ple (Noun) Noun:
1.Human beings in general or considered collectively.
2.The citizens of a country, esp. when considered in relation to those who govern them.)
... have not existed for "millions of years", hence they have not been running for millions of years.
Now, the above can also be associated to Dr Kidd's comment below (i.e. reference to "Lucy" - aka Australopithecus afarensis & the issue of bipedalism) - of which I have discussed before - of which I agree with (i.e. nature of the Talus bone/foot morphology).
I'm not even going to touch this 'researcher's' likely twisted views on natural selection - particularly in the above context i.e. information gained from within the vast genome or outside (well, being the primate nature of the premise it nullifies this... whoops, I'm not going to go any further).
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Because humans evolved to run barefoot,
Well, did they? Evidence? The above is a hint to the underlying fault... Confirmation bias ... pre-assumed unsubstantiated world view philosophy tainting objectivity - not good science... not good research ethic.
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... a barefoot running style which minimizes impact peaks and provides increased proprioception and foot strength, is hypothesized to help avoid injury, regardless of whether one is wearing shoes or not.
The above was all that was needed... or is scientifically plausible within the abstract.
Quote:
Originally Posted by Rob Kidd
I for one do not accept that Lucy was bipel in the human sense. My early work on her talus - the only foot bone available, demonstrated it to be non-human, and more similar to African Apes. I have no opinion on the Achilles tendon of Lucy, but do hang on to her talus; so far in the fossil record, the talus has been incredibly predictive of the rest of the foot. To my best guess, Lucy had long toes, and was at least semi-arboreal. (I am just moving sideways to ensure that the lightening bolt from the Lucy camp does not hit me). Rob
I agree.
Now... "I am just moving sideways to ensure that the lightening bolt from the Lucy [evolution] camp does not hit me." (ref. Rob Kidd, Podiatry Arena: Evolution of human running: Post 9, 22nd January 2012, 03:47 PM).
Humans didn't evolve to run barefoot.
If we had then the vast majority of us would be, well, running barefoot, and doing little else.
Homo Sap would appear to have evolved along the lines of "survival of the fittest". Part of that premise may have meant being able to move quickly when necessary (I'm pretty sure it did), and that no doubt happened at some stage in the evolutionary process without wearing footgear.
If we accept evolution, and I think I'm right in suggesting you don't B-H (fine by me) then we have to accept that there are many facets to evolving, one of which is our increased cranial capacity, and another is our ability to create more effective surfaces upon which to ambulate.
Homo Erectus was around approx 2 million years ago - we think he could run.
It's kind of difficult discussing human lower limb evolution with a creationist (if you are), but I'm happy to do so if you wish.
Humans didn't evolve to run barefoot.
If we had then the vast majority of us would be, well, running barefoot, and doing little else.
I agree David; humans didn’t evolve to run barefoot. I have seen the following reasoning used a fair bit during barefoot running discussions, however, I have always found this statement nonsensical, regardless of your persuasion on the issue of origins (development of life). Humans are intelligent (to varying degrees) & footgear would/has been developed & used for a means of protection primarily. It has only really been since the 1970’s where the role of running/sports related footgear has taken another role – that of addressing movement related problems to address the incidence of running related/overuse type injuries (we’ll leave the issue of fashion footgear out of the discussion). I personally believe that during this process over the years more problems have been created & the areas it was targeted to resolve has not been efficiently addressed. Yet I also believe that for some, these corrective elements may have been seen to help (depending on the state of one’s lower limb structure) but on the whole I feel the footgear characteristics/gimmicks which have crept into the running shoe market has not been the most effective way to address the issues (i.e. adverse biomechanics relating to genetic entropy -> adverse lower limb forces). Hence the field of Podiatry & the role of orthotic therapy plays in more effectively addressing these issues on an individual basis.
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Originally Posted by davidh
Homo Sap would appear to have evolved along the lines of "survival of the fittest". Part of that premise may have meant being able to move quickly when necessary (I'm pretty sure it did), and that no doubt happened at some stage in the evolutionary process without wearing footgear.
I take it you also mean via natural selection. I believe in "survival of the fittest" & natural selection but in a different context to probably yourself & its driving force role in evolution i.e. natural processes driving speciation - where new species arise from existing species (we also need to keep in mind that "species" is a man made concept thus we are bounded to some degree to the confines of this concept).
I accept the reality of natural selection via the sorting & expressing of existing information already present within the genome (the DNA level) which is then influenced by outside factors i.e. the environment. On the other hand natural selection is not evolution, as it doesn’t create new genetic information... the vast billions of conducive/beneficial pieces of information required for the diversity & complexity we see evident around us in both flora & fauna. Natural selection is not some creative goddess. Natural processes via the likes of random "mutation events" (which have adverse/harmful, neutral & beneficial outcomes – largely adverse though) does not propel the process forward to where new species arise from existing species – which is the driving force needed for evolution to be plausible. Instead, these events are seen to primarily contribute to the loss of information or the degrading of information (rarely beneficial i.e. bacteria resistance to antibiotics – yet there is still a net loss of information here) thus the driving process in heading in the wrong direction. Hence organisms do change; it is the type & direction of change which is the issue here (& subsequently the starting point of the organism in question i.e. humans/Homo sapiens have always been human/Homo sapien).
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Originally Posted by davidh
If we accept evolution, and I think I'm right in suggesting you don't B-H (fine by me) then we have to accept that there are many facets to evolving, one of which is our increased cranial capacity, and another is our ability to create more effective surfaces upon which to ambulate.
You are correct in that I don’t accept evolution but I don’t quite get the above logic. Sure I can understand the need for increased "cranial capacity" under this/your premise but there is a whole lot more elements needed for the hypothesis to work – that is for a speculated arboreal (knuckle walker) ancestor to gain the required millions of pieces of conducive info (from who knows where) to develop bipedalism, erect posture & subsequent running ability we witness today. I have accumulated a fairly large list of the changes that are needed (i.e. inner ear structure for upright movement, spine structure, larger Glutes etc...) which is of prime importance.
I also don’t see the relevance of... "ability to create more effective surfaces upon which to ambulate". The fact is that humans are very efficient running over many types of surfaces. Being a runner myself I do a lot of running over natural surfaces (i.e. trails, bushland etc...) which involves running over rocky terrain & steep inclines. Sure there are likely faster surfaces to run on (i.e. asphalt) but I don’t think this element needs to be in the equation of speculated human development – yet it does for the issue of foot attire/protection.
Quote:
Originally Posted by davidh
Homo Erectus was around approx 2 million years ago - we think he could run.
It's kind of difficult discussing human lower limb evolution with a creationist (if you are), but I'm happy to do so if you wish.
Thanks but I rather spend my attention on how the lower limb functions & the practical implications it has on my patients than dabbling into the historical assumptions of the evolution of its evident design.
Excuse the pun but the evidence is fragmented/disjointed – call me a skeptic but I just don’t have enough faith to take evolution seriously. Sure, I require faith in the Ultimate Cause (of which is uncaused - eternal entity) of events but generally everything following this best fits the evidence; unlike evolution which violates the principle of causation & a string of other factors as the premise evolves from nothing (started by nothing) to the accumulation of information to fulfil today’s diverse fauna & flora gene pool (this requires blind faith in my view). Personally, I feel that concepts invoking history & philosophy should primarily be studied in those areas - not to this degree in science. Sure there at times there may be a cross over but the issues of origins & evolution should not have its degree of current presence in science & in research discussing topics of the above nature i.e. running impact peaks. That said, I can understand its presence here... evolution’s consistent prominence by an evolutionary biologist (from Department of Human Evolutionary Biology, Harvard University) studying barefoot running & impact peaks is present based on confirmation bias & to probably guarantee research funding.
I really don’t want to get into another evolution debate either but felt the need to outline the issues with the... “What We Can Learn About Running from Barefoot Running” abstract. Maybe I should bite my tongue & leave the prevailing religious (naturalism) conjecture alone.
Hi Rob,
Don't the phalanges from the right hand show a slight longitudinal curvature to them too, suggestive of an arboreal dwelling mammal?
I only heard this 2nd-hand, but from a reputable source.
I am not sure, but intuitively, I would expect manual and pedal digits to be curved in the Australopithecus. Rob
Evolution of human running
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