Kuliukas et al 2009; The Relative Cost of BHBK...

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Kuliukas et al 2009; The Relative Cost of BHBK...

Postby AlgisKuliukas » Sun Oct 30, 2011 11:30 am

Kuliukas, A., Milne, N., Fournier, P. The relative cost of bent-hip bent-knee walking is reduced in water. Homo 60:479-488, (2009).
Waterside hypotheses of human evolution assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan. (p118)
Kuliukas, A., Morgan, E. (2011). Aquatic scenarios in the thinking on human evolution: What are they and how do they compare?. In: Vaneechoutte, M., Verhaegen, M., Kuliukas, A. (2011). Was Man More Aquatic in the Past?
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby AlgisKuliukas » Fri Nov 04, 2011 7:53 am

The favourite jibe my detractors have come up with about this paper basically goes like this...

"Algis' wading study demonstrates that wading selects against gait change in the evolution of hominid bipedalism".

I've answered this many times before but let me tackle that disingenuous criticism, again, here as the person who chooses the user name "Recursive Prophet" (I suspect it is not he, because the 'RP' I knew on Dawkins and TR.net was a friendly sort of guy whilst this guy has so far only parroted the arguments of aquaskeptics) has mentioned it at least 3-4 times already.

Ok, first the paper itself...

Kuliukas, A., Milne, N., Fournier, P. The relative cost of bent-hip bent-knee walking is reduced in water. Homo 60:479-488, (2009).

Here's the abstract...

The debate about how early hominids walked may be characterised as two competing
hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip,
bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on
land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing
that the BK gait is 50–60% more energetically costly than a FU human gait on land. We confirm
these findings but show that in water this cost differential is markedly reduced, especially in deeper
water, at slower speeds and with greater knee flexion. These data suggest that the controversy about
australopithecine locomotion may be eased if it is assumed that wading was a component of their
locomotor repertoire and supports the idea that shallow water might have been an environment
favourable to the evolution of early forms of ‘‘non-optimal’’ hominid bipedalism


(I would post the paper itself but I don't want to infringe any copyright rules.)

In a nutshell the paper describes something we've all experienced. Whilst wading in a swimming pool your natural hydrostatic buoyancy makes it easier to move around with a gait that would be harder to do on land. Try walking around like an ape, with bent hips and knees for a couple of minutes and it soon starts to hurt. The greater the knee flexion the harder it gets. The whole dynamics of this changes in water. There, the more you flex your knees - the lower your body, and so after a point, it gets easier. The deeper the water, the quicker the effect sets in. It's a no brainer - walking like an ape is easier in water than on land.

Now, in 2005, a paper was published in the Journal of Human Evolution by Tanya Carey and Robin Crompton which studied the effect of the bent hip bent knee (BHBK) gait on the cost of walking, in humans, on a treadmill. They found that it was about 55% more costly to walk with a BHBK gait than normally. Again, no surprise there. They used this evidence to support their view that australopithecines could not have walked with a BHBK gait but must have walked with fully extended limbs, like we do.

Carey, Tanya Suzanne; Crompton, Robin Huw (2005). The metabolic costs of ‘bent-hip, bent-knee’ walking in humans. Journal of Human Evolution Vol:48(1) Pages:25-44

The costs of different modes of bipedalism are a key issue in reconstructing the likely gait of early human ancestors such as Australopithecus afarensis. Some workers, on the basis of morphological differences between the locomotor skeleton of A. afarensis and modern humans, have proposed that this hominid would have walked in a ‘bent-hip, bentknee’ (BHBK) posture like that seen in the voluntary bipedalism of untrained chimpanzees. Computer modelling studies using inverse dynamics indicate that on the basis of segment proportions AL-288-1 should have been capable of mechanically effective upright walking, but in contrast predicted that BHBK walking would have been highly ineffective. The measure most pertinent to natural selection, however, is more likely to be the complete, physiological, or metabolic energy cost. We cannot measure this parameter in a fossil. This paper presents the most complete investigation yet of the metabolic and thermoregulatory costs of BHBK walking in humans. Data show that metabolic costs including the basal metabolic rate (BMR) increase by around 50% while the energy costs of locomotion and blood lactate production nearly double, heat load is increased, and core temperature does not return to normal within 20 minutes rest. Net effects imply that a resting period of 150% activity time would be necessary to prevent physiologically intolerable heat load. Preliminary data for children suggest that scaling effects would not significantly reduce relative costs for hominids of AL-288-1’s size. Data from recent studies using forwards dynamic modelling confirm that similar total (including BMR) and locomotor metabolic costs would have applied to BHBK walking by AL-288-1. We explore some of the ecological consequences of our findings.  2004 Elsevier Ltd. All rights reserved.

Of course, what they completely ignored was the possibility that these hominids might have moved in water.

If they had, the costs would have been greatly reduced (i.e. instead of 55% greater, with a 50 degree knee flexion, in waist deep water the difference was 18%; in chest deep water there was no difference at all) and the thermoregulatory cost negated completely.

This was the context of my study - to point out that if Carey & Crompton had considered water they wouldn't have been able to make the assumptions they did make.

Now, some aquaskeptic have looked over this and thought they'd spotted a problem: If wading reduces the cost differential between a fully upright gait and a BHBK gait, doesn't this argue that it would reduce the selection for bipedalism? Some have even argued that it would provide selection against bipedalism!

It's absolute nonsense of course.

First of all, it's not that wading eliminates the cost differential (at most depths), it just reduces it. So, as stated above, in waist deep water instead of 55% more costly, it's 18% more costly (50 degree knee flexion at 0.6 m/s). Usually Darwinists invoke methods that work in tiny incremental steps but here, because aquaskeptics think they've found a flaw, they seem to be suggesting that the bigger the step the better. I call this the "elephants might fly" axiom.

Secondly, and most importantly, cost of gait is not the only aspect potentially under pressure from selection. On the contrary, attempting to move quadrupedally in waist deep water would almost certainly be fatal to an ape (see my avatar, it's not rocket science.) The deeper the water, the more having longer legs would be selected for. You cannot get a more clear cut, blatantly obvious, selection pressure for bipedalism than this. None of the other published models come close. I mean, for example, apes sometimes carry food bipedally for short distances, sure. But then they sit down and eat it. They can also carry food quadrupedally (in their mouths) or tripodally. It won't kill them, or reduce their fitness if they do so, unlike wading. Now what "eversbane" picked up on was that I didn't actually address this point in my paper. True, I didn't. I kind of assumed that the reader would take this as a given. In the same way, I didn't address the idea that fat gave you added buoyancy or that water was more viscous than air, either.

It should be stated that the paper was rejected four times before it was eventually accepted by the journal Homo. At no point did any referee make this kind of distorted claim. It is a pure invention of the anonymous web poster who calls himself "eversbane" (I suspect not the same one who came here the other day, but we'll see). The fact that a whole gang of aquaskeptics adopted this as some kind of mantra and repeat it as if it were fact shows to me how desperate they are to believe anything, no matter how tenuous, that can be scratched together against anything remotely in favour of Hardy's idea.

To try to argue that wading does not favour selection for bipedalism in apes is like trying to argue that leaping from trees does not favour selection for having flaps of skin under the forearms of flying foxes.

Algis
Waterside hypotheses of human evolution assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan. (p118)
Kuliukas, A., Morgan, E. (2011). Aquatic scenarios in the thinking on human evolution: What are they and how do they compare?. In: Vaneechoutte, M., Verhaegen, M., Kuliukas, A. (2011). Was Man More Aquatic in the Past?
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby Not RP » Fri Nov 04, 2011 1:59 pm

AlgisKuliukas wrote:The favourite jibe my detractors have come up with about this paper basically goes like this...

"Algis' wading study demonstrates that wading selects against gait change in the evolution of hominid bipedalism".

I've answered this many times before but let me tackle that disingenuous criticism, again, here as the person who chooses the user name "Recursive Prophet" (I suspect it is not he, because the 'RP' I knew on Dawkins and TR.net was a friendly sort of guy whilst this guy has so far only parroted the arguments of aquaskeptics) has mentioned it at least 3-4 times already.

Ok, first the paper itself...

Kuliukas, A., Milne, N., Fournier, P. The relative cost of bent-hip bent-knee walking is reduced in water. Homo 60:479-488, (2009).

Here's the abstract...

The debate about how early hominids walked may be characterised as two competing
hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip,
bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on
land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing
that the BK gait is 50–60% more energetically costly than a FU human gait on land. We confirm
these findings but show that in water this cost differential is markedly reduced, especially in deeper
water, at slower speeds and with greater knee flexion. These data suggest that the controversy about
australopithecine locomotion may be eased if it is assumed that wading was a component of their
locomotor repertoire and supports the idea that shallow water might have been an environment
favourable to the evolution of early forms of ‘‘non-optimal’’ hominid bipedalism


(I would post the paper itself but I don't want to infringe any copyright rules.)

In a nutshell the paper describes something we've all experienced. Whilst wading in a swimming pool your natural hydrostatic buoyancy makes it easier to move around with a gait that would be harder to do on land. Try walking around like an ape, with bent hips and knees for a couple of minutes and it soon starts to hurt. The greater the knee flexion the harder it gets. The whole dynamics of this changes in water. There, the more you flex your knees - the lower your body, and so after a point, it gets easier. The deeper the water, the quicker the effect sets in. It's a no brainer - walking like an ape is easier in water than on land.

Now, in 2005, a paper was published in the Journal of Human Evolution by Tanya Carey and Robin Crompton which studied the effect of the bent hip bent knee (BHBK) gait on the cost of walking, in humans, on a treadmill. They found that it was about 55% more costly to walk with a BHBK gait than normally. Again, no surprise there. They used this evidence to support their view that australopithecines could not have walked with a BHBK gait but must have walked with fully extended limbs, like we do.

Carey, Tanya Suzanne; Crompton, Robin Huw (2005). The metabolic costs of ‘bent-hip, bent-knee’ walking in humans. Journal of Human Evolution Vol:48(1) Pages:25-44

The costs of different modes of bipedalism are a key issue in reconstructing the likely gait of early human ancestors such as Australopithecus afarensis. Some workers, on the basis of morphological differences between the locomotor skeleton of A. afarensis and modern humans, have proposed that this hominid would have walked in a ‘bent-hip, bentknee’ (BHBK) posture like that seen in the voluntary bipedalism of untrained chimpanzees. Computer modelling studies using inverse dynamics indicate that on the basis of segment proportions AL-288-1 should have been capable of mechanically effective upright walking, but in contrast predicted that BHBK walking would have been highly ineffective. The measure most pertinent to natural selection, however, is more likely to be the complete, physiological, or metabolic energy cost. We cannot measure this parameter in a fossil. This paper presents the most complete investigation yet of the metabolic and thermoregulatory costs of BHBK walking in humans. Data show that metabolic costs including the basal metabolic rate (BMR) increase by around 50% while the energy costs of locomotion and blood lactate production nearly double, heat load is increased, and core temperature does not return to normal within 20 minutes rest. Net effects imply that a resting period of 150% activity time would be necessary to prevent physiologically intolerable heat load. Preliminary data for children suggest that scaling effects would not significantly reduce relative costs for hominids of AL-288-1’s size. Data from recent studies using forwards dynamic modelling confirm that similar total (including BMR) and locomotor metabolic costs would have applied to BHBK walking by AL-288-1. We explore some of the ecological consequences of our findings.  2004 Elsevier Ltd. All rights reserved.

Of course, what they completely ignored was the possibility that these hominids might have moved in water.

If they had, the costs would have been greatly reduced (i.e. instead of 55% greater, with a 50 degree knee flexion, in waist deep water the difference was 18%; in chest deep water there was no difference at all) and the thermoregulatory cost negated completely.

This was the context of my study - to point out that if Carey & Crompton had considered water they wouldn't have been able to make the assumptions they did make.

Now, some aquaskeptic have looked over this and thought they'd spotted a problem: If wading reduces the cost differential between a fully upright gait and a BHBK gait, doesn't this argue that it would reduce the selection for bipedalism? Some have even argued that it would provide selection against bipedalism!

It's absolute nonsense of course.

First of all, it's not that wading eliminates the cost differential (at most depths), it just reduces it. So, as stated above, in waist deep water instead of 55% more costly, it's 18% more costly (50 degree knee flexion at 0.6 m/s). Usually Darwinists invoke methods that work in tiny incremental steps but here, because aquaskeptics think they've found a flaw, they seem to be suggesting that the bigger the step the better. I call this the "elephants might fly" axiom.

Secondly, and most importantly, cost of gait is not the only aspect potentially under pressure from selection. On the contrary, attempting to move quadrupedally in waist deep water would almost certainly be fatal to an ape (see my avatar, it's not rocket science.) The deeper the water, the more having longer legs would be selected for. You cannot get a more clear cut, blatantly obvious, selection pressure for bipedalism than this. None of the other published models come close. I mean, for example, apes sometimes carry food bipedally for short distances, sure. But then they sit down and eat it. They can also carry food quadrupedally (in their mouths) or tripodally. It won't kill them, or reduce their fitness if they do so, unlike wading. Now what "eversbane" picked up on was that I didn't actually address this point in my paper. True, I didn't. I kind of assumed that the reader would take this as a given. In the same way, I didn't address the idea that fat gave you added buoyancy or that water was more viscous than air, either.

It should be stated that the paper was rejected four times before it was eventually accepted by the journal Homo. At no point did any referee make this kind of distorted claim. It is a pure invention of the anonymous web poster who calls himself "eversbane" (I suspect not the same one who came here the other day, but we'll see). The fact that a whole gang of aquaskeptics adopted this as some kind of mantra and repeat it as if it were fact shows to me how desperate they are to believe anything, no matter how tenuous, that can be scratched together against anything remotely in favour of Hardy's idea.

To try to argue that wading does not favour selection for bipedalism in apes is like trying to argue that leaping from trees does not favour selection for having flaps of skin under the forearms of flying foxes.

Algis


You really need to provide a facepalm smiley, Algis. On the other hand you might consider putting all this into a phd and seeing if you pass a viva. Remind us why you haven't finished your thesis.
Not RP
 

Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby AlgisKuliukas » Fri Nov 04, 2011 7:49 pm

Recursive Prophet wrote:
AlgisKuliukas wrote:The favourite jibe my detractors have come up with about this paper basically goes like this...

"Algis' wading study demonstrates that wading selects against gait change in the evolution of hominid bipedalism".

I've answered this many times before but let me tackle that disingenuous criticism, again, here as the person who chooses the user name "Recursive Prophet" (I suspect it is not he, because the 'RP' I knew on Dawkins and TR.net was a friendly sort of guy whilst this guy has so far only parroted the arguments of aquaskeptics) has mentioned it at least 3-4 times already.

Ok, first the paper itself...

Kuliukas, A., Milne, N., Fournier, P. The relative cost of bent-hip bent-knee walking is reduced in water. Homo 60:479-488, (2009).

Here's the abstract...

The debate about how early hominids walked may be characterised as two competing
hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip,
bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on
land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing
that the BK gait is 50–60% more energetically costly than a FU human gait on land. We confirm
these findings but show that in water this cost differential is markedly reduced, especially in deeper
water, at slower speeds and with greater knee flexion. These data suggest that the controversy about
australopithecine locomotion may be eased if it is assumed that wading was a component of their
locomotor repertoire and supports the idea that shallow water might have been an environment
favourable to the evolution of early forms of ‘‘non-optimal’’ hominid bipedalism


(I would post the paper itself but I don't want to infringe any copyright rules.)

In a nutshell the paper describes something we've all experienced. Whilst wading in a swimming pool your natural hydrostatic buoyancy makes it easier to move around with a gait that would be harder to do on land. Try walking around like an ape, with bent hips and knees for a couple of minutes and it soon starts to hurt. The greater the knee flexion the harder it gets. The whole dynamics of this changes in water. There, the more you flex your knees - the lower your body, and so after a point, it gets easier. The deeper the water, the quicker the effect sets in. It's a no brainer - walking like an ape is easier in water than on land.

Now, in 2005, a paper was published in the Journal of Human Evolution by Tanya Carey and Robin Crompton which studied the effect of the bent hip bent knee (BHBK) gait on the cost of walking, in humans, on a treadmill. They found that it was about 55% more costly to walk with a BHBK gait than normally. Again, no surprise there. They used this evidence to support their view that australopithecines could not have walked with a BHBK gait but must have walked with fully extended limbs, like we do.

Carey, Tanya Suzanne; Crompton, Robin Huw (2005). The metabolic costs of ‘bent-hip, bent-knee’ walking in humans. Journal of Human Evolution Vol:48(1) Pages:25-44

The costs of different modes of bipedalism are a key issue in reconstructing the likely gait of early human ancestors such as Australopithecus afarensis. Some workers, on the basis of morphological differences between the locomotor skeleton of A. afarensis and modern humans, have proposed that this hominid would have walked in a ‘bent-hip, bentknee’ (BHBK) posture like that seen in the voluntary bipedalism of untrained chimpanzees. Computer modelling studies using inverse dynamics indicate that on the basis of segment proportions AL-288-1 should have been capable of mechanically effective upright walking, but in contrast predicted that BHBK walking would have been highly ineffective. The measure most pertinent to natural selection, however, is more likely to be the complete, physiological, or metabolic energy cost. We cannot measure this parameter in a fossil. This paper presents the most complete investigation yet of the metabolic and thermoregulatory costs of BHBK walking in humans. Data show that metabolic costs including the basal metabolic rate (BMR) increase by around 50% while the energy costs of locomotion and blood lactate production nearly double, heat load is increased, and core temperature does not return to normal within 20 minutes rest. Net effects imply that a resting period of 150% activity time would be necessary to prevent physiologically intolerable heat load. Preliminary data for children suggest that scaling effects would not significantly reduce relative costs for hominids of AL-288-1’s size. Data from recent studies using forwards dynamic modelling confirm that similar total (including BMR) and locomotor metabolic costs would have applied to BHBK walking by AL-288-1. We explore some of the ecological consequences of our findings.  2004 Elsevier Ltd. All rights reserved.

Of course, what they completely ignored was the possibility that these hominids might have moved in water.

If they had, the costs would have been greatly reduced (i.e. instead of 55% greater, with a 50 degree knee flexion, in waist deep water the difference was 18%; in chest deep water there was no difference at all) and the thermoregulatory cost negated completely.

This was the context of my study - to point out that if Carey & Crompton had considered water they wouldn't have been able to make the assumptions they did make.

Now, some aquaskeptic have looked over this and thought they'd spotted a problem: If wading reduces the cost differential between a fully upright gait and a BHBK gait, doesn't this argue that it would reduce the selection for bipedalism? Some have even argued that it would provide selection against bipedalism!

It's absolute nonsense of course.

First of all, it's not that wading eliminates the cost differential (at most depths), it just reduces it. So, as stated above, in waist deep water instead of 55% more costly, it's 18% more costly (50 degree knee flexion at 0.6 m/s). Usually Darwinists invoke methods that work in tiny incremental steps but here, because aquaskeptics think they've found a flaw, they seem to be suggesting that the bigger the step the better. I call this the "elephants might fly" axiom.

Secondly, and most importantly, cost of gait is not the only aspect potentially under pressure from selection. On the contrary, attempting to move quadrupedally in waist deep water would almost certainly be fatal to an ape (see my avatar, it's not rocket science.) The deeper the water, the more having longer legs would be selected for. You cannot get a more clear cut, blatantly obvious, selection pressure for bipedalism than this. None of the other published models come close. I mean, for example, apes sometimes carry food bipedally for short distances, sure. But then they sit down and eat it. They can also carry food quadrupedally (in their mouths) or tripodally. It won't kill them, or reduce their fitness if they do so, unlike wading. Now what "eversbane" picked up on was that I didn't actually address this point in my paper. True, I didn't. I kind of assumed that the reader would take this as a given. In the same way, I didn't address the idea that fat gave you added buoyancy or that water was more viscous than air, either.

It should be stated that the paper was rejected four times before it was eventually accepted by the journal Homo. At no point did any referee make this kind of distorted claim. It is a pure invention of the anonymous web poster who calls himself "eversbane" (I suspect not the same one who came here the other day, but we'll see). The fact that a whole gang of aquaskeptics adopted this as some kind of mantra and repeat it as if it were fact shows to me how desperate they are to believe anything, no matter how tenuous, that can be scratched together against anything remotely in favour of Hardy's idea.

To try to argue that wading does not favour selection for bipedalism in apes is like trying to argue that leaping from trees does not favour selection for having flaps of skin under the forearms of flying foxes.

Algis


You really need to provide a facepalm smiley, Algis. On the other hand you might consider putting all this into a phd and seeing if you pass a viva. Remind us why you haven't finished your thesis.


Note that "Recursive Prophet" did not respond to any of my substantive points against the repeated twisting of my wading paper.

I haven't finished my thesis yet because I have other things on my plate. Is this a problem?

Algis
Waterside hypotheses of human evolution assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan. (p118)
Kuliukas, A., Morgan, E. (2011). Aquatic scenarios in the thinking on human evolution: What are they and how do they compare?. In: Vaneechoutte, M., Verhaegen, M., Kuliukas, A. (2011). Was Man More Aquatic in the Past?
User avatar
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Posts: 443
Joined: Wed Oct 26, 2011 10:24 pm

Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby Iceaura » Sat Nov 05, 2011 12:21 am

AlgisKuliukas wrote:
Recursive Prophet wrote:
AlgisKuliukas wrote:The favourite jibe my detractors have come up with about this paper basically goes like this...

"Algis' wading study demonstrates that wading selects against gait change in the evolution of hominid bipedalism".

I've answered this many times before but let me tackle that disingenuous criticism, again, here as the person who chooses the user name "Recursive Prophet" (I suspect it is not he, because the 'RP' I knew on Dawkins and TR.net was a friendly sort of guy whilst this guy has so far only parroted the arguments of aquaskeptics) has mentioned it at least 3-4 times already.

Ok, first the paper itself...

Kuliukas, A., Milne, N., Fournier, P. The relative cost of bent-hip bent-knee walking is reduced in water. Homo 60:479-488, (2009).

Here's the abstract...

The debate about how early hominids walked may be characterised as two competing
hypotheses: They moved with a fully upright (FU) gait, like modern humans, or with a bent-hip,
bent-knee (BK) gait, like apes. Both have assumed that this bipedalism was almost exclusively on
land, in trees or a combination of the two. Recent findings favoured the FU hypothesis by showing
that the BK gait is 50–60% more energetically costly than a FU human gait on land. We confirm
these findings but show that in water this cost differential is markedly reduced, especially in deeper
water, at slower speeds and with greater knee flexion. These data suggest that the controversy about
australopithecine locomotion may be eased if it is assumed that wading was a component of their
locomotor repertoire and supports the idea that shallow water might have been an environment
favourable to the evolution of early forms of ‘‘non-optimal’’ hominid bipedalism


(I would post the paper itself but I don't want to infringe any copyright rules.)

In a nutshell the paper describes something we've all experienced. Whilst wading in a swimming pool your natural hydrostatic buoyancy makes it easier to move around with a gait that would be harder to do on land. Try walking around like an ape, with bent hips and knees for a couple of minutes and it soon starts to hurt. The greater the knee flexion the harder it gets. The whole dynamics of this changes in water. There, the more you flex your knees - the lower your body, and so after a point, it gets easier. The deeper the water, the quicker the effect sets in. It's a no brainer - walking like an ape is easier in water than on land.

Now, in 2005, a paper was published in the Journal of Human Evolution by Tanya Carey and Robin Crompton which studied the effect of the bent hip bent knee (BHBK) gait on the cost of walking, in humans, on a treadmill. They found that it was about 55% more costly to walk with a BHBK gait than normally. Again, no surprise there. They used this evidence to support their view that australopithecines could not have walked with a BHBK gait but must have walked with fully extended limbs, like we do.

Carey, Tanya Suzanne; Crompton, Robin Huw (2005). The metabolic costs of ‘bent-hip, bent-knee’ walking in humans. Journal of Human Evolution Vol:48(1) Pages:25-44

The costs of different modes of bipedalism are a key issue in reconstructing the likely gait of early human ancestors such as Australopithecus afarensis. Some workers, on the basis of morphological differences between the locomotor skeleton of A. afarensis and modern humans, have proposed that this hominid would have walked in a ‘bent-hip, bentknee’ (BHBK) posture like that seen in the voluntary bipedalism of untrained chimpanzees. Computer modelling studies using inverse dynamics indicate that on the basis of segment proportions AL-288-1 should have been capable of mechanically effective upright walking, but in contrast predicted that BHBK walking would have been highly ineffective. The measure most pertinent to natural selection, however, is more likely to be the complete, physiological, or metabolic energy cost. We cannot measure this parameter in a fossil. This paper presents the most complete investigation yet of the metabolic and thermoregulatory costs of BHBK walking in humans. Data show that metabolic costs including the basal metabolic rate (BMR) increase by around 50% while the energy costs of locomotion and blood lactate production nearly double, heat load is increased, and core temperature does not return to normal within 20 minutes rest. Net effects imply that a resting period of 150% activity time would be necessary to prevent physiologically intolerable heat load. Preliminary data for children suggest that scaling effects would not significantly reduce relative costs for hominids of AL-288-1’s size. Data from recent studies using forwards dynamic modelling confirm that similar total (including BMR) and locomotor metabolic costs would have applied to BHBK walking by AL-288-1. We explore some of the ecological consequences of our findings.  2004 Elsevier Ltd. All rights reserved.

Of course, what they completely ignored was the possibility that these hominids might have moved in water.

If they had, the costs would have been greatly reduced (i.e. instead of 55% greater, with a 50 degree knee flexion, in waist deep water the difference was 18%; in chest deep water there was no difference at all) and the thermoregulatory cost negated completely.

This was the context of my study - to point out that if Carey & Crompton had considered water they wouldn't have been able to make the assumptions they did make.

Now, some aquaskeptic have looked over this and thought they'd spotted a problem: If wading reduces the cost differential between a fully upright gait and a BHBK gait, doesn't this argue that it would reduce the selection for bipedalism? Some have even argued that it would provide selection against bipedalism!

It's absolute nonsense of course.

First of all, it's not that wading eliminates the cost differential (at most depths), it just reduces it. So, as stated above, in waist deep water instead of 55% more costly, it's 18% more costly (50 degree knee flexion at 0.6 m/s). Usually Darwinists invoke methods that work in tiny incremental steps but here, because aquaskeptics think they've found a flaw, they seem to be suggesting that the bigger the step the better. I call this the "elephants might fly" axiom.

Secondly, and most importantly, cost of gait is not the only aspect potentially under pressure from selection. On the contrary, attempting to move quadrupedally in waist deep water would almost certainly be fatal to an ape (see my avatar, it's not rocket science.) The deeper the water, the more having longer legs would be selected for. You cannot get a more clear cut, blatantly obvious, selection pressure for bipedalism than this. None of the other published models come close. I mean, for example, apes sometimes carry food bipedally for short distances, sure. But then they sit down and eat it. They can also carry food quadrupedally (in their mouths) or tripodally. It won't kill them, or reduce their fitness if they do so, unlike wading. Now what "eversbane" picked up on was that I didn't actually address this point in my paper. True, I didn't. I kind of assumed that the reader would take this as a given. In the same way, I didn't address the idea that fat gave you added buoyancy or that water was more viscous than air, either.

It should be stated that the paper was rejected four times before it was eventually accepted by the journal Homo. At no point did any referee make this kind of distorted claim. It is a pure invention of the anonymous web poster who calls himself "eversbane" (I suspect not the same one who came here the other day, but we'll see). The fact that a whole gang of aquaskeptics adopted this as some kind of mantra and repeat it as if it were fact shows to me how desperate they are to believe anything, no matter how tenuous, that can be scratched together against anything remotely in favour of Hardy's idea.

To try to argue that wading does not favour selection for bipedalism in apes is like trying to argue that leaping from trees does not favour selection for having flaps of skin under the forearms of flying foxes.

Algis


You really need to provide a facepalm smiley, Algis. On the other hand you might consider putting all this into a phd and seeing if you pass a viva. Remind us why you haven't finished your thesis.


Note that "Recursive Prophet" did not respond to any of my substantive points against the repeated twisting of my wading paper.

I haven't finished my thesis yet because I have other things on my plate. Is this a problem?

Algis


Not a problem for me, Algis but for someone like yourself who wants to be famoud but can't even understand that his research into demonstrated that wading does not select for morphological gait, not do much. You cannot finish your phd because you have not a shred of evidence to support your watery ramblings. This is why you are no longer registered as a post grad at the UWE.
Eversbane, retract and apologise.
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby RobertRothbury » Wed Nov 23, 2011 10:35 pm

The relative cost of bent-hip bent-knee walking is reduced in water
Algis V. Kuliukas, Nick Milne, Paul Fournier
HOMO—Journal of Comparative Human Biology 60 (2009) 479–488

Algis' personal copy is at: http://www.riverapes.com/Me/Work/200...HBKinwater.pdf

I acquired my copy directly from HOMO. I will be quoting from that subscription copy. It is a pre-press copy, so if there are any discrepancies I depend on Algis to point them out. I assume Algis' personal author's copy is available to everyone as it is openly available on his website. Up front I will say that I have no problem with the methodology or the results, so I will not be going through those sections in detail. I do have a problem with the interpretation of the results. I also have some problems with the interpretation of other work related to the paper.

I begin with the first paragraph.


Even before, but especially after Johanson et al. made the discovery of the fossilised hominid known as ‘Lucy’ (AL288-1) (Johanson and Edey, 1981), there has been debate about how putative ancestors labelled 'australopithecines’ might have moved. Most (e.g. Lovejoy, 2005; Stern and Susman, 1983), but not all (e.g. Sarmiento, 1998), support the notion that generally they moved bipedally but there remains a clear disagreement as to which gait they were likely to have adopted (Ward, 2002; Stern, 2000). Some workers (e.g. Lovejoy et al., 1973; Jungers, 1982; Crompton e tal., 1998) favour a fully upright (FU), very human-like gait, whilst others (e.g. Berge, 1994; Stern, 2000) propose a different, more ape-like, bent-hip, bent-knee (BK) gait. Recently, direct measurements of energy consumption on human subjects (Carey and Crompton, 2005) showed that the BK gait is 50%–60% more costly than FU in humans on land, depending on the speed, and that core body temperature rose by 0.31 C in 30 min by adopting a BK gait, suggesting that it would have been maladaptive in hot, equatorial habitats. This raises the question of whether there are any environments where a BK gait might not have been as maladaptive from a cost of locomotion point of view.

It is important here to point out a distinction between a particular morphology and a gait. The terms fully upright (FU) and Bent-hip, bent-knee (BHBK) are applied to both, often without clearly differentiating between the two. Specifically, the distinction is between a morphology that constrains the individual to a BHBK gait, and a morphology that allows an FU gait but that also allows a BHBK gait.

Here the authors are discussing the former case, reviewing a dispute over the morphology of Australopithecines early in the paragraph (BHBK morphology vs. FU morphology). But once we get to the last few sentences (after the Carey and Crompton 2005 reference) they are talking about the latter case of an FU morphology employing different lower limb arrangements: i.e. straight hip and knee (FU) vs. bent hip and knee (BHBK). This confusion between morphology and behavior is a critical issue that relates to the intent of the Kuliukas et al. paper in contrast to the intent of the Carey and Crompton paper.

Specifically, Carey and Crompton were not considering selection between morphologies in their study. Their study is based on the assessment that AL288-1 possessed a fully upright morphology. That assessment is based on a series of models intended to analyze the Australopithecine morphology, including forward-dynamic modeling based on muscle activation patterns derived directly from Australopithecine morphology, and driven by a genetic algorithm optimization of Australopithecine morphology. The outcome of these analyses is that Australopithecus (and AL288-1 specifically) possessed a morphology that allowed for an FU posture (straight hips and knees), that also allowed for a BHBK posture, but was not constrained to BHBK. These findings are consistent with the studies that indicate that Australopithecine gait was within the range of modern humans.

Carey and Crompton were not investigating selection on morphology. They were testing the likelyhood that a biped with an FU morphology would utilize a BHBK posture. There is nothing in the Carey and Crompton paper about selection or adaptation. In fact, the word 'maladaptive' does not appear in their 2005 paper. That inference is a misinterpretation of the study by Algis et al. Carey and Crompton did not suggest that BHBK would be maladaptive for Australopithecines. They did not discuss adaptation at all. What they conclude is that it is not reasonable to assume that an FU biped would waste energy on a gait posture that was so expensive when they were already morphologically fully upright. Algis et al. contrive the maladaptive argument out of their own desire to discuss adaptation, but adaptation was not the subject of the Carey and Crompton paper.
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby AlgisKuliukas » Wed Nov 23, 2011 10:49 pm

RobertRothbury wrote:The relative cost of bent-hip bent-knee walking is reduced in water
Algis V. Kuliukas, Nick Milne, Paul Fournier
HOMO—Journal of Comparative Human Biology 60 (2009) 479–488

Algis' personal copy is at: http://www.riverapes.com/Me/Work/200...HBKinwater.pdf

I acquired my copy directly from HOMO. I will be quoting from that subscription copy. It is a pre-press copy, so if there are any discrepancies I depend on Algis to point them out. I assume Algis' personal author's copy is available to everyone as it is openly available on his website. Up front I will say that I have no problem with the methodology or the results, so I will not be going through those sections in detail. I do have a problem with the interpretation of the results. I also have some problems with the interpretation of other work related to the paper.

I begin with the first paragraph.


Even before, but especially after Johanson et al. made the discovery of the fossilised hominid known as ‘Lucy’ (AL288-1) (Johanson and Edey, 1981), there has been debate about how putative ancestors labelled 'australopithecines’ might have moved. Most (e.g. Lovejoy, 2005; Stern and Susman, 1983), but not all (e.g. Sarmiento, 1998), support the notion that generally they moved bipedally but there remains a clear disagreement as to which gait they were likely to have adopted (Ward, 2002; Stern, 2000). Some workers (e.g. Lovejoy et al., 1973; Jungers, 1982; Crompton e tal., 1998) favour a fully upright (FU), very human-like gait, whilst others (e.g. Berge, 1994; Stern, 2000) propose a different, more ape-like, bent-hip, bent-knee (BK) gait. Recently, direct measurements of energy consumption on human subjects (Carey and Crompton, 2005) showed that the BK gait is 50%–60% more costly than FU in humans on land, depending on the speed, and that core body temperature rose by 0.31 C in 30 min by adopting a BK gait, suggesting that it would have been maladaptive in hot, equatorial habitats. This raises the question of whether there are any environments where a BK gait might not have been as maladaptive from a cost of locomotion point of view.

It is important here to point out a distinction between a particular morphology and a gait. The terms fully upright (FU) and Bent-hip, bent-knee (BHBK) are applied to both, often without clearly differentiating between the two. Specifically, the distinction is between a morphology that constrains the individual to a BHBK gait, and a morphology that allows an FU gait but that also allows a BHBK gait.

Here the authors are discussing the former case, reviewing a dispute over the morphology of Australopithecines early in the paragraph (BHBK morphology vs. FU morphology). But once we get to the last few sentences (after the Carey and Crompton 2005 reference) they are talking about the latter case of an FU morphology employing different lower limb arrangements: i.e. straight hip and knee (FU) vs. bent hip and knee (BHBK). This confusion between morphology and behavior is a critical issue that relates to the intent of the Kuliukas et al. paper in contrast to the intent of the Carey and Crompton paper.

Specifically, Carey and Crompton were not considering selection between morphologies in their study. Their study is based on the assessment that AL288-1 possessed a fully upright morphology. That assessment is based on a series of models intended to analyze the Australopithecine morphology, including forward-dynamic modeling based on muscle activation patterns derived directly from Australopithecine morphology, and driven by a genetic algorithm optimization of Australopithecine morphology. The outcome of these analyses is that Australopithecus (and AL288-1 specifically) possessed a morphology that allowed for an FU posture (straight hips and knees), that also allowed for a BHBK posture, but was not constrained to BHBK. These findings are consistent with the studies that indicate that Australopithecine gait was within the range of modern humans.



If they were not considering selection, what were they considering? The whole point of the study was to illustrate the implausibility of a BHBK gait in a bipedal hominin compared to a fully upright one. Unfortunately, the only medium they thought worth testing was on dry land - on a treadmill.

RobertRothbury wrote:
Carey and Crompton were not investigating selection on morphology. They were testing the likelyhood that a biped with an FU morphology would utilize a BHBK posture. There is nothing in the Carey and Crompton paper about selection or adaptation. In fact, the word 'maladaptive' does not appear in their 2005 paper. That inference is a misinterpretation of the study by Algis et al. Carey and Crompton did not suggest that BHBK would be maladaptive for Australopithecines. They did not discuss adaptation at all. What they conclude is that it is not reasonable to assume that an FU biped would waste energy on a gait posture that was so expensive when they were already morphologically fully upright. Algis et al. contrive the maladaptive argument out of their own desire to discuss adaptation, but adaptation was not the subject of the Carey and Crompton paper.


Yes, the likelihood on dry land... on a treadmill. Surprise, surprise, it is more likely that human-like bipeds would move fully upright there. In water, though, the situation changes markedly.

If a behaviour is more likely to be practised it is more likely to undergo the rigours of selection for better efficiency, if nothing else. It's implicit in their paper that a BHBK gait would be maladaptive... on land. They neglect water completely.

When you write "they were already morphologically fully upright", you are falling for the "catch 22" self-fulfilling prophesy they advocate. The unstated assumption you make is that this "fully uprightness" was on land. I dispute that. I do not dispute that they might have been fully upright in water but, somehow, aquaskeptics must do so. Why?

Algis
Waterside hypotheses of human evolution assert that selection from wading, swimming and diving and procurement of food from aquatic habitats have significantly affected the evolution of the lineage leading to Homo sapiens as distinct from that leading to Pan. (p118)
Kuliukas, A., Morgan, E. (2011). Aquatic scenarios in the thinking on human evolution: What are they and how do they compare?. In: Vaneechoutte, M., Verhaegen, M., Kuliukas, A. (2011). Was Man More Aquatic in the Past?
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby RobertRothbury » Sat Nov 26, 2011 12:33 am

Paragraphs 2 and 3:


Almost all the theorising by workers in the scientific literature about the possible modes of locomotion of australopithecines to date has been in the context of terrestrial, arboreal or a mixture of the two environs. Serious consideration about how they might have moved in water, or its possible impact on the origins of hominid bipedalism has been conspicuous largely by its absence, although there is a growing body of literature about hydrotherapy and its beneficial effects in exercise regimes for the elderly and post-operatively (see, for example Teramoto et al., 2000; Shono et al., 2001; Fujishima and Shimizu, 2003; Sundelin et al., 2004; Hotta et al., 2004; Barela et al., 2006).

The lack of scientific investigation into the wading hypothesis of bipedal origins is peculiar, considering that the palaeoecological contexts for many of the australopithecine finds have been distinctly ‘‘wet and wooded’’ (WoldeGabriel et al., 2001), climatically variable (Potts, 1998) and dominated by local wetlands (Johanson et al., 1982, p. 391), and that predominantly terrestrial quadrupedal great apes appear to predictably switch to bipedalism in shallow water (Kuliukas, 2002; see discussion this paper).


This portrayal of the palaeolecological context of hominin sites has been augmented recently by a study of more than 1,300 published palaeosol analyses.

Woody cover and hominin environments in the past 6 million years
Thure E. Cerling, Jonathan G. Wynn, Samuel A. Andanje, Michael I. Bird, David Kimutai Korir, Naomi E. Levin, William Mace, Anthony N. Macharia, Jay Quade & Christopher H. Remien
doi:10.1038/nature10306

This study finds that hominin sites were typically dry.


Palaeosols have previously been used to quantify the fraction of C4 biomass in hominin environments, but the relationship between 13C and woody cover (Fig. 2) provides a means to estimate the fraction of woody cover in past environments. Figure 4 shows a summary of reconstructed woody cover for >1,300 palaeosols associated with hominin sites in eastern Africa over the past ~6 Myr. More than 70% of these palaeosols reflect woody cover <40%. Less than 1% of the palaeosols are associated with woody cover >70%; therefore, ‘closed’ forests (>80% woody cover) represent a very small fraction of the environment represented by these palaeosols.



In fact, it matters little to the argument of Algis et al. which palaeoecological context is correct, and this is true for two reasons. First, taphonomic bias does not support water related selection for hominins. In all cases, hominin fossils are associated with a wide variety of terrestrial taxa including Bovids, Cercopithecoids (including Colobids), Suids, Hyenids, Felids, etc. In many instances aquatic taxa are also present, but what is telling is that in some cases hominin fossils are found in a context with terrestrial taxa but no aquatic taxa. While it is not unusual for a terrestrial taxa to be found in association with aquatic taxa, given the peculiarities of taphonomy, it would be highly unusual for an aquatic taxa to be found in a context where there is no other aquatic taxa. It might be argued that the argument is for a hominin that is only slightly aquatic, but what is the use of such an argument when the fossil evidence does not support it.

The second reason that the palaeoecological context is not significantly relevant to the argument of Algis et al. is that Algis et al. (encompassing the entire population of AAT/H/WHHE proponents) have never demonstrated that any hominin ever suffered selection due to association with water, but we will get to that point specifically, later.
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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby JimMcGinn » Sat Nov 26, 2011 8:46 am

For reasons that are obvious it could only have been in an environment that experiences seasonal dessication. Without seasonal dessication the patchiness of the forested habitat would not exist and without seasonal dessication the browsing grazing species would not come flooding in during the dry season, and without seasonal dessication there would be no survival penalty for a communities inablity to perform the behavior.

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Re: Kuliukas et al 2009; The Relative Cost of BHBK...

Postby JimMcGinn » Sat Nov 26, 2011 8:59 am

Another point. If sophisticated tool usage underlies bipedalism then we'd expect head size to have increased at the beginning of hominid evolution. The fact that head size increases later indicates that if tool usage underlies the selective origins of bipedalism then these tools must have been very crude, sticks and stones. And if these tools were very crude then this severely limits the types of scenarios we can envision. The only thing that fits is scenarios in which large communal groups employ sticks and stones to achieve territorialistic ends.

And the only way we can envision such being adaptive is if death is the fate of those that fail to achieve territorialistic ends. And the only scenario that indicates such is one that involves seasonal dessication as being a climatic element in the context of isolated patches of forest from which there would have been no escape.

IMO, an even bigger impediment is the fact that chimps are so plainly ineffective with tools.

Jim
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