Physical fitness and evolution

"Peter Webb" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat). So why
does your body lose these

adaptations

Quoted message said:

to exercise when the exercise stops? What is the
environmental advantage

of

Quoted message said:

becomong unfit when we don't exercise? Why doesn't your
body just

implement

Quoted message said:

the adaptations to exercise even if you aren't exercising?

The responses you describe would seem to increase the
requirement for food. Needing more food is not always
adaptive.

Hi Peter,

I think this is the answer, although it is hard to prove.
When you look at our current metabolism, it has evolved from
times that food wasn't abundant. We humans are build to
survive in harsh conditions, with little food. Our
metabolism is adapted to that: we store energy as fat for
later use.

In our current (western) society we have very much food,
and very little reason to put strain (excercise) on our
body (at least I have little reason, working on computers
the whole day.).

I think your question: "What is the environmental advantage
of becomong unfit when we don't exercise?" is wrong. There
is NO environmental profit. We were just not build in a way
to consume huge amounts of food. The evolution that made us
what we are today only needed a way to store excess
calories. That was an advantage, but in these days you would
be better of have a sloppier metabolism. ;-)

As for your question: "Why doesn't your body just implement
the adaptations to exercise even if you aren't exercising?"

I think the answer is: Because that never needed to
evolves before.

Just my 2 cents. Hope this helps.

Regards, Erwin Moller

Peter Webb said:

People who exercise at the gym primarily do so for one of
two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat). So why
does your body lose these adaptations to exercise when the
exercise stops? What is the environmental advantage of
becomong unfit when we don't exercise? Why doesn't your
body just implement the adaptations to exercise even if
you aren't exercising?

I asked this before in misc.fitness.weights, the best
answer that I saw was that nobody had the opportunity to
be unfit until recent times and so a bad adaptive strategy
has not yet been weeded out. Its not convincing to me,
because the link between exercising and adapting to
exercise seems a deliberate strategy - like it is with
weight training.

Anybody know why not exercising makes you unfit, or has a
plausible theory?

Peter Webb <[email hidden]> wrote or quoted:

Quoted message said:

People who exercise at the gym primarily do so for one of
two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside.

They all have energetic costs to maintain. If you are not
using muscles, they are probably not needed. Maintining them
would be a significant energy drain. That's basically why
muscles that are not used eventually atrophy.

Quoted message said:

Anybody know why not exercising makes you unfit, or has a
plausible theory?

Tissues that are not used represent a drain in terms of the
enegry needed to heat them - and the cost of lugging them
around with you wherever you go. Also the more tissue blood
has to flow through the harder the heart has to work.

Calories were not readily available to most of our ancestors
- they took care to conserve the ones they had, and avoided
wasting them on unused functions.
--
__________
|im |yler timtyler.orgtimtyler.orgOpen ↗ [email hidden] Remove
lock to reply.

in article [email hidden], Peter Webb at
[email hidden] wrote on 6/21/04 4:44 PM:

Quoted message said:

People who exercise at the gym primarily do so for one of
two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat).

Actually, these adaptations generically result in a shorter
lifespan. They improve your performance in the meantime, but
they also cause you to live faster (metabolically) and
senesce sooner.

Quoted message said:

So why does your body lose these adaptations to exercise
when the exercise stops? What is the environmental
advantage of becomong unfit when we don't exercise? Why
doesn't your body just implement the adaptations to
exercise even if you aren't exercising?

You should be careful in your use of the word "unfit" in
this context, because physical fitness and Darwinian fitness
are very different things. I think I basically answered your
questions above. Your Darwinian fitness is improved by
reducing your metabolism to a slow idle when it is not being
used to increase your Darwinian fitness through action.

Cheers,

Guy

Guy Hoelzer said:

in article [email hidden], Peter Webb
at [email hidden] wrote on 6/21/04
4:44 PM:

Quoted message said:

People who exercise at the gym primarily do so for one of
two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat).

Actually, these adaptations generically result in a
shorter lifespan. They improve your performance in the
meantime, but they also cause you to live faster
(metabolically) and senesce sooner.

This is not necessarily true; check out this recent nature
report on a study (1) where mice with sped up metabolisms
live longer:

nature.com040531 2.htmlOpen ↗

E

1: Speakman et al. (2004) Aging cell. 3(3):87

"Tim Tyler" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Peter Webb <[email hidden]> wrote
or quoted:

Quoted message said:

People who exercise at the gym primarily do so for one
of two reasons -

to

Quoted message said:

Quoted message said:

build muscle mass or improve cardio fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of
energy per

Gram

Quoted message said:

Quoted message said:

you carry around, whereas muscle (protein) provides only
4 KCal/gm.

Carrying

Quoted message said:

Quoted message said:

fat around is more energy efficient than carrying
muscle, unless you

have

Quoted message said:

Quoted message said:

some other need for the muscle. Weight training simply
tricks your body

into

Quoted message said:

Quoted message said:

thinking you need muscle for other purposes, so it
alters the balance towards the less efficient storing of
food as muscle.

The adaptations that occur in response to cardio
training are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside.

They all have energetic costs to maintain. If you are not
using muscles, they are probably not needed. Maintining
them would be a significant energy drain. That's basically
why muscles that are not used eventually atrophy.

Yes, the argument as to why muscles atrophy is clear, and I
used it as an example myself above (the energy cost involved
in carrying around muscle is higher than the energy cost in
carrying fat, per gram of energy stored).

But what are the energetic costs of being fit in a cardio
sense? Certainly people who exercise use more energy, but
not because they are fit per se; its because they are
exercising. I have never heard any suggestion that at a
given level of energy expenditure (eg walking 10 kms in two
hours) that a (cardio) fit person uses more calories than
an unfit person - indeed, my personal experience is quite
the opposite.

I stress again that I am talking about cardio fitness. I
understand that a person with huge muscles will use more
energy walking 10 kms in 2 hours than somebody with
normal build.

Given all of the health costs associated with being unfit -
as well as the considerable evolutionary disadavantage of
not being able to run away from sabre toothed tigers - I
cannot see the corresponding benefit in your body reversing
the adaptations to exercise and becoming unfit.

Quoted message said:

Quoted message said:

Anybody know why not exercising makes you unfit, or has
a plausible

theory?

Quoted message said:

Tissues that are not used represent a drain in terms of
the enegry needed to heat them - and the cost of lugging
them around with you wherever you go. Also the more
tissue blood has to flow through the harder the heart has
to work.

But being cardio fit doesn't involve an increase in tissue.

Quoted message said:

Calories were not readily available to most of our
ancestors - they took care to conserve the ones they had,
and avoided wasting them on unused functions.
--

Yes, but I don't see that the adaptations that occur in
response to cardio training involve any additional energy
consumption. (Though the training itself obviously does).
Its not tissue mass - cardio training doesn't increase your
body weight (usually the opposite). Nor have I have ever
heard a theory that fit people need more food than unfit
people at the same level of activity.

So what is the evolutionary advantage of reversing the
adaptations to exercise, which compensates for the huge
disadvantage that unfit people have when confronted by
hungry tigers? What is the hidden (to me) cost of being fit?

"Guy Hoelzer" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

in article [email hidden], Peter Webb
at [email hidden] wrote on 6/21/04
4:44 PM:

Quoted message said:

People who exercise at the gym primarily do so for one
of two reasons -

to

Quoted message said:

Quoted message said:

build muscle mass or improve cardio fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of
energy per

Gram

Quoted message said:

Quoted message said:

you carry around, whereas muscle (protein) provides only
4 KCal/gm.

Carrying

Quoted message said:

Quoted message said:

fat around is more energy efficient than carrying
muscle, unless you

have

Quoted message said:

Quoted message said:

some other need for the muscle. Weight training simply
tricks your body

into

Quoted message said:

Quoted message said:

thinking you need muscle for other purposes, so it
alters the balance towards the less efficient storing of
food as muscle.

The adaptations that occur in response to cardio
training are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike

the

Quoted message said:

Quoted message said:

situation with muscle vs fat).

Actually, these adaptations generically result in a
shorter lifespan.

They

Quoted message said:

improve your performance in the meantime, but they
also cause you to live faster (metabolically) and
senesce sooner.

Really! My understanding was that all else being equal
cardio fit people had a longer life expectancy than cardio
unfit people.

Nor have I heard that cardio fit people age faster.

Even in prehistoric times I would have expected cardio
fit people to live longer than unfit people, if only
because they would be better at hunting food and avoiding
being eaten.

Quoted message said:

Quoted message said:

So why does your body lose these adaptations to exercise
when the exercise stops? What is the environmental
advantage

of

Quoted message said:

Quoted message said:

becomong unfit when we don't exercise? Why doesn't your
body just

implement

Quoted message said:

Quoted message said:

the adaptations to exercise even if you aren't
exercising?

You should be careful in your use of the word "unfit" in
this context, because physical fitness and Darwinian
fitness are very different things.

I

Quoted message said:

think I basically answered your questions above. Your
Darwinian fitness

is

Quoted message said:

improved by reducing your metabolism to a slow idle when
it is not being used to increase your Darwinian fitness
through action.

This would be a very attractive answer if being unfit
increased your life expectancy. However I do not believe
this is true now, and would be even less true of life before
agriculture, cars and supermarkets.

Peter Webb <[email hidden]> wrote or quoted:

Quoted message said:

"Tim Tyler" <[email hidden]> wrote in message

Quoted message said:

Peter Webb <[email hidden]> wrote
or quoted:

Quoted message said:

Quoted message said:

Quoted message said:

The adaptations that occur in response to cardio
training are harder to explain. These include
increased capillaries, more mitochondria, and numerous
others. However, none of these seem to have a
downside.

They all have energetic costs to maintain. If you are
not using muscles, they are probably not needed.
Maintining them would be a significant energy drain.
That's basically why muscles that are not used
eventually atrophy.

Yes, the argument as to why muscles atrophy is clear, and
I used it as an example myself above (the energy cost
involved in carrying around muscle is higher than the
energy cost in carrying fat, per gram of energy stored).

But what are the energetic costs of being fit in a cardio
sense? Certainly people who exercise use more energy, but
not because they are fit per se; its because they are
exercising. I have never heard any suggestion that at a
given level of energy expenditure (eg walking 10 kms in
two hours) that a (cardio) fit person uses more calories
than an unfit person - indeed, my personal experience is
quite the opposite.

I stress again that I am talking about cardio fitness. I
understand that a person with huge muscles will use more
energy walking 10 kms in 2 hours than somebody with
normal build.

Given all of the health costs associated with being unfit
- as well as the considerable evolutionary disadavantage
of not being able to run away from sabre toothed tigers -
I cannot see the corresponding benefit in your body
reversing the adaptations to exercise and becoming unfit.

Why doesn't the heart muscle doesn't behave differently to
all other skeletal muscles in response to lack of exercise?

There are basically two sorts of answer to this:

* The heart muscle is still muscle tissue - and it's
reasonable to expect it to behave in a very similar manner
to all other muscle tissues in response to exercise and
lack of exercise;

* Even something as small and insignificant as a big, strong
heart muscle takes some energy heat and maintain. If the
tissue lies unused for an extended period of time it might
well make good sense to recycle it and utilise the
resources elsewhere.

Quoted message said:

Quoted message said:

Quoted message said:

Anybody know why not exercising makes you unfit, or
has a plausible theory?

Tissues that are not used represent a drain in terms of
the enegry needed to heat them - and the cost of lugging
them around with you wherever you go. Also the more
tissue blood has to flow through the harder the heart
has to work.

But being cardio fit doesn't involve an increase in
tissue.

That's a different question from the one I was answering.

However, it probably does involve increased tissue mass - in
the body of the heart muscle.

Quoted message said:

Quoted message said:

Calories were not readily available to most of our
ancestors - they took care to conserve the ones they
had, and avoided wasting them on unused functions.

Yes, but I don't see that the adaptations that occur in
response to cardio training involve any additional energy
consumption. (Though the training itself obviously does).
Its not tissue mass - cardio training doesn't increase
your body weight (usually the opposite). Nor have I have
ever heard a theory that fit people need more food than
unfit people at the same level of activity.

Heart fitness is associated with a strong and well-exercised
heart muscle, though.

...and there's the issue of the "expense" (in terms of
additional complexity) in making heart muscle behave
differently from all other muscles.

Quoted message said:

So what is the evolutionary advantage of reversing the
adaptations to exercise, which compensates for the huge
disadvantage that unfit people have when confronted by
hungry tigers?

If there were many hungry tigers around, the people in
question would be likely to be getting more exercise - and
the subject would be less likely to come up.

Quoted message said:

What is the hidden (to me) cost of being fit?

As I've mentioned, much of the answer lies in energetic
considerations.

In *practice*, being physically fit has some other
costs as well - e.g. in terms of the other nutrients
needed to rebuild muscle tissue, and the time taken to
perform the exercises which are - in practice - needed
to maintain fitness.

*If* you could somehow magically stay fit without
exercising, then your question would make more sense.
However - in practice - many of the benefits of exercise
come from the process of actually doing it.

E.g. to make sure your tubes stay unclogged you have to pump
fluid through them under pressure. It's all very well
to ask why they don't stay unclogged when you stop
exercising - but it's just in the nature of tubes with
stagnant fluid in them to get clogged up.

So part of the answer to your question as to why a
particular unmaintaned machine tends to go wrong as time
passes - must be of the form: that's just what unmaintaned
complex machinery *does*.

Regular maintenance is needed to keep most complex equipment
with moving parts in good working order.
--
__________
|im |yler timtyler.orgtimtyler.orgOpen ↗ [email hidden] Remove
lock to reply.

Dear Peter,

in article [email hidden], Peter
Webb at [email hidden] wrote on
6/23/04 9:06 AM:

Quoted message said:

"Guy Hoelzer" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

in article [email hidden], Peter Webb
at [email hidden] wrote on 6/21/04
4:44 PM:

Quoted message said:

People who exercise at the gym primarily do so for one
of two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio
training are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat).

Actually, these adaptations generically result in a
shorter lifespan. They improve your performance in the
meantime, but they also cause you to live faster
(metabolically) and senesce sooner.

Really! My understanding was that all else being equal
cardio fit people had a longer life expectancy than cardio
unfit people.

Nor have I heard that cardio fit people age faster.

Even in prehistoric times I would have expected cardio
fit people to live longer than unfit people, if only
because they would be better at hunting food and avoiding
being eaten.

They may indeed have gained a survival advantage in these
ways, which would only compensate the physiological survival
costs I was referring to. Also note that I referred to
"these adaptations" which, following your statement meant
"increased capillaries [and] more mitochondria", not cario
fitness in general.

You may be interested in the following observation (I would
point you to the literature on the metabolic scaling theory
of Brown, West and colleagues). Data spanning many orders of
magnitude in animal size and metabolic rate reveal that
vertebrates are generally allotted about 1 million heart
beats per lifetime. There is plenty of variation around this
rule, but the more data you include in the analysis, the
more robust the rule appears. So, when you work out you use
up your allotment of heart beats faster, but you reduce your
resting heart rate at the same time. You don't get a larger
allotment of heart beats by virtue of working out.

Quoted message said:

Quoted message said:

Quoted message said:

So why does your body lose these adaptations to exercise
when the exercise stops? What is the environmental
advantage of becomong unfit when we don't exercise? Why
doesn't your body just implement the adaptations to
exercise even if you aren't exercising?

You should be careful in your use of the word "unfit" in
this context, because physical fitness and Darwinian
fitness are very different things. I think I basically
answered your questions above. Your Darwinian fitness is
improved by reducing your metabolism to a slow idle when
it is not being used to increase your Darwinian fitness
through action.

This would be a very attractive answer if being unfit
increased your life expectancy. However I do not believe
this is true now, and would be even less true of life
before agriculture, cars and supermarkets.

There is one result from the science of aging that shows up
in virtually every study. The most effective way to maximize
lifespan is to reduce metabolic rate. You can increase your
expected lifespan by something like 30%, for example, if you
lie down, get fed intravenously, and allow your muscles to
atrophy for the rest of your life. It is not a life I would
choose to live, but it is BY FAR the surest way to maximize
your lifespan that we know. I would also argue that, whether
or not there are other effective ways of maximizing lifespan
that we have yet to discover, the existing data are clear
with regard to the effect of metabolic rate.

Guy

Hi Emile,

in article [email hidden], Emile at
[email hidden] wrote on 6/23/04 9:06 AM:

Quoted message said:

Guy Hoelzer said:

in article [email hidden], Peter Webb
at [email hidden] wrote on 6/21/04
4:44 PM:

Quoted message said:

People who exercise at the gym primarily do so for one
of two reasons - to build muscle mass or improve cardio
fitness.

Its easy to see why the body only puts on muscle in
response to weight training. If there is excess food
available, your body is better storing this as fat
rather than as muscle, as fat provides 9 kCal of energy
per Gram you carry around, whereas muscle (protein)
provides only 4 KCal/gm. Carrying fat around is more
energy efficient than carrying muscle, unless you have
some other need for the muscle. Weight training simply
tricks your body into thinking you need muscle for other
purposes, so it alters the balance towards the less
efficient storing of food as muscle.

The adaptations that occur in response to cardio
training are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside. Being
fitter in a cardio sense always seems better than being
unfit (unlike the situation with muscle vs fat).

Actually, these adaptations generically result in a
shorter lifespan. They improve your performance in the
meantime, but they also cause you to live faster
(metabolically) and senesce sooner.

This is not necessarily true; check out this recent nature
report on a study (1) where mice with sped up metabolisms
live longer:

nature.com040531 2.htmlOpen ↗

E

1: Speakman et al. (2004) Aging cell. 3(3):87

Thanks for the reference. Wayne Van Voorhies is actually an
old grad school friend of mine, so it was great to see his
commentary on Speakman's results. I personally think that
there is rather overwhelming evidence, and strong
theoretical reasons, supporting my original statement. My
first interpretation of the Speakman result is that he found
a mutant mouse in which the metabolism of mitochondria is
less constrained by the function of the whole organism.
Because mitochondria are so small they naturally tend to
have a higher metabolic rate than the cells in which they
exist. Speakman noted that these mitochondria produce much
more heat and provide LESS fuel to the cell than normal
mitochondria. Therefore, I would say that the metabolic rate
of the mouse has actually decreased when you discount the
wasted heat production of the mitochondria, which would
explain why these mice live longer. I predict that the
mitochondria of these mice have shorter life spans than
normal mitochondria, and that the general physiological
functioning of the mice and their cells would be compromised
by the degree of independence being expressed by their
mitochondria.

Cheers,

Guy

Peter Webb said:

"Tim Tyler" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

thinking you need muscle for other purposes, so it alters
the balance towards the less efficient storing of food as
muscle.

The adaptations that occur in response to cardio training
are harder to explain. These include increased
capillaries, more mitochondria, and numerous others.
However, none of these seem to have a downside.

They all have energetic costs to maintain. If you are not
using muscles, they are probably not needed. Maintining
them would be a significant energy drain. That's basically
why muscles that are not used eventually atrophy.

Yes, the argument as to why muscles atrophy is clear, and
I used it as an example myself above (the energy cost
involved in carrying around muscle is higher than the
energy cost in carrying fat, per gram of energy stored).

But what are the energetic costs of being fit in a cardio
sense? Certainly people who exercise use more energy, but
not because they are fit per se; its because they are
exercising. I have never heard any suggestion that at a
given level of energy expenditure (eg walking 10 kms in
two hours) that a (cardio) fit person uses more calories
than an unfit person - indeed, my personal experience is
quite the opposite.

You agree that being cardio fit requires maintenance, and
thus energy. Those people spending an hour a day in the gym
definitely spend more energy than couch potatoes. I don't
think though you can simply disregard this investment. It
adds to the costs of being cardio fit.

couch potato: energy spent = a1 * activity cardio freak:
energy spent = a2 * (activity + gymActivity)

I don't think the 10 km walk comparison is fair. One would
assume the body is optimised to perform most efficiently for
a constant given level of activity. If a1>a2 ("fit" person
more efficient), at high activity, the low cardio fitness
individual may perform less efficiently per meter. Below a
certain level of activity, the reverse may also be true.

If the cardio fit person is not blessed with an ability to
be cardio fitter than others at the same level of activity
(with the same rate of expenditure), at that level,
eventually they will become equally cardio fit. In that
sense it is analogous to the muscle-fat example.

There must be a cost to building and maintaining the
structures you describe, like mitochondria and
capillaries. This would increase a2 toward a1. The bulk of
the increase would occur in the muscles, and we're
disregarding that here.

Whether it is really a simple linear relationship remains
to be seen though. My other post in this thread mentions a
study that claims that mitochondria run more efficiently
at higher metabolic rates, resulting in longer life span.
In that case the formula should contain a term with
exponent activity.

E

Quoted message said:

_______________________________________________________
Box 1 The total number of fertile forms reproduced by each
parent within one population.
_______________________________________________________

I also argue that this can be easily proven by reverse
engineering the above definition, i.e. by setting up a
natural population (not just a model simulation) whereby
the total fitness of each parent is artificially kept
equal within one experimental population.
Epistemologically, any unique verification (a verification
only provided by just one theory compared to all the
others on the table) when reversed, must provide a valid
point of refutation for that theory. This principle is
proven, here.

Quoted message said:

snip<

Quoted message said:

JE:- All of us must be much more careful in our use of
"fit" or "unfit", in _any_ evolutionary theory context so
as not to misuse it. Would Dr Hoelzer deny or confirm that
his use of the term "Darwinian fitness" refers to the
definition I provided in Box 1.

GH:- I meant it in a very general way, so it is completely
consistent with the definition in Box 1 without excluding
other definitions.

JE:- "..completely consistent with the definition in Box 1
without excluding other definitions"?

It is ambiguous to leave your statement at just that, unless
you provide a list of at least some of the definitions
included. Clearly, I meant it in a very exact way such that
it has to exclude many other definitions such those provided
by Hamilton et al.

Do you agree or disagree that the only possible way to halt
all natural selection within a growing population in nature
is to perform the experiment above?

Regards,

John Edser Independent Researcher

PO Box 266 Church Pt NSW 2105 Australia

[email hidden]

Quoted message said:

Quoted message said:

_______________________________________________________
Box 1 The total number of fertile forms reproduced by
each parent within one population.
_______________________________________________________

I also argue that this can be easily proven by reverse
engineering the above definition, i.e. by setting up a
natural population (not just a model simulation) whereby
the total fitness of each parent is artificially kept
equal within one experimental population.
Epistemologically, any unique verification (a
verification only provided by just one theory compared to
all the others on the table) when reversed, must provide
a valid point of refutation for that theory. This
principle is proven, here.

Quoted message said:

snip<

Quoted message said:

JE:- All of us must be much more careful in our use of
"fit" or "unfit", in _any_ evolutionary theory context so
as not to misuse it. Would Dr Hoelzer deny or confirm
that his use of the term "Darwinian fitness" refers to
the definition I provided in Box 1.

GH:- I meant it in a very general way, so it is completely
consistent with the definition in Box 1 without excluding
other definitions.

JE:- "..completely consistent with the definition in Box 1
without excluding other definitions"?

It is ambiguous to leave your statement at just that,
unless you provide a list of at least some of the
definitions included. Clearly, I meant it in a very exact
way such that it has to exclude many other definitions
such those provided by Hamilton et al.

Do you agree or disagree that the only possible way to
halt all natural selection within a growing population in
nature is to perform the experiment above?

GH:- You don't really provide enough detail about your
experiment above to make an intelligent response, but I
think I understand it from your previous writings. In fact,
I think that I encouraged you to do your experiment years
ago. It is simple enough to do in a rough way.

JE:- I would answer your question by disagreeing. As you
know, I think that selection can happen at many levels, so
ensuring complete survival and equal reproductive success
among individuals within an experimental population would
not ensure the halting of all sources of natural selection.

JE:- Firstly, why didn't you provide at least a partial list
of these other definitions? I put it to you no such
definitions exist. All you have to do to refute what I
propose is provide at least one other definition of fitness
that is "completely consistent with the definition in Box
1". Please provide it.

All the necessary basics exist within what I wrote to
determine the validity of the proposed experiment. What
missing information do you require before you could make an
"intelligent response"?

Do you agree or disagree that the proposed experiment is a
valid test of a Darwinian _single_ level of selection? If
not, what could possibly constitute another source of
selection using just a single level, within this experiment?

If you think that "selection can happen at many levels" so
the proposed experiment _cannot_ halt "all sources of
natural selection", why hasn't anybody proposed this
experiment as a refutable test of multilevel selection
theory? It appears to me multi level selectionists have been
asleep at the wheel for some time....

Regards,

John Edser Independent Researcher

PO Box 266 Church Pt NSW 2105

[email hidden]

Guy Hoelzer said:

Quoted message said:

Quoted message said:

>>> JE:-
>>> ___________________________________________________-
>>> ____
>>> Box 1 The total number of fertile forms reproduced
>>> by each parent within one population.
>>> ___________________________________________________-
>>> ____
>>>

Quoted message said:

Quoted message said:

Quoted message said:

>> JE:- All of us must be much more careful in our
>> use of "fit" or "unfit", in _any_ evolutionary
>> theory context so as not to misuse it. Would Dr
>> Hoelzer deny or confirm that his use of the term
>> "Darwinian fitness" refers to the definition I
>> provided in Box 1.

Quoted message said:

Quoted message said:

Quoted message said:

>> GH:- I meant it in a very general way, so it is
>> completely consistent with the definition in Box 1
>> without excluding other definitions.

Quoted message said:

Quoted message said:

Quoted message said:

> JE:- "..completely consistent with the definition in
> Box 1 without excluding other definitions"? It is
> ambiguous to leave your statement at just that, unless
> you provide a list of at least some of the definitions
> included. Clearly, I meant it in a very exact way such
> that it has to exclude many other definitions such
> those provided by Hamilton et al. Do you agree or
> disagree that the only possible way to halt all
> natural selection within a growing population in
> nature is to perform the experiment above?

Quoted message said:

Quoted message said:

Quoted message said:

GH:- You don't really provide enough detail about your
experiment above to make an intelligent response, but I
think I understand it from your previous writings. In
fact, I think that I encouraged you to do your
experiment years ago. It is simple enough to do in a
rough way. I would answer your question by disagreeing.
As you know, I think that selection can happen at many
levels, so ensuring complete survival and equal
reproductive success among individuals within an
experimental

population

Quoted message said:

Quoted message said:

Quoted message said:

would not ensure the halting of all sources of natural
selection.

Quoted message said:

Quoted message said:

JE:- Firstly, why didn't you provide at least a partial
list of these other definitions? I put it to you no such
definitions exist. All you have to do to refute what I
propose is provide at least one other definition of
fitness that is "completely consistent with the
definition in Box 1". Please provide it.

Quoted message said:

GH:- "Firstly," another definition of fitness (and a
better one than in the Box above IMHO) is
"reproductive rate."

JE:- How can just "reproductive rate" be " better one than
in the Box" when your definition remains _ambiguous_ as to
what was being reproduced? Because my definition was not
ambiguous, your definition is not "completely consistent
with the definition in Box 1".

Quoted message said:

GH:- Secondly, it is irrelevant whether you think this
definition is consistent with yours. You snipped the start
of this sub-thread above in which you asked me whether I
thought my use of the term "fitness" was consistent with
your definition in a particular statement. I responded
that it was, as is the "reproductive rate" definition.

JE:- Clearly, not all "reproductive rates" when they are
held at just one constant level can halt evolution by
natural selection! If you only hold the number of infertile
forms reproduced by each fertile form within one natural
population to a constant, natural selection cannot be halted
in this way.

It appears to me you are evading the issue of how to test
between your preferred multi level of selection theory and
just a Darwinian single level. One way to separate them is
using verification. If the Darwinian single level can be
experimentally verified using the experimental outline that
I provided that you did suggest "is simple enough to do in a
rough way" then do you agree or disagree that any multi
level theory can be deleted using Occam's Razor because it
is not required?

AGAIN: What extra details do you require to "provide enough
detail about [JE's] experiment above to make an intelligent
response"?

Respectfully,

John Edser Independent Researcher

PO Box 266 Church Pt NSW 2105 Australia

[email hidden]

"Peter Webb" <[email hidden]> wrote in
:"]news:[email hidden]:

Quoted message said:

Quoted message said:

Calories were not readily available to most of our
ancestors - they took care to conserve the ones they had,
and avoided wasting them on unused functions.

Quoted message said:

Yes, but I don't see that the adaptations that occur in
response to cardio training involve any additional energy
consumption. (Though the training itself obviously does).
Its not tissue mass - cardio training doesn't increase
your body weight (usually the opposite). Nor have I have
ever heard a theory that fit people need more food than
unfit people at the same level of activity.

Quoted message said:

So what is the evolutionary advantage of reversing the
adaptations to exercise, which compensates for the huge
disadvantage that unfit people have when confronted by
hungry tigers? What is the hidden (to
me) cost of being fit?

First of all you should be aware that not every aspect of
our physiology is an adaption that is the result of
selection - some are due to drift, especially if there was
no real selective pressure on the trait for our ancestors.
For most of human history, if you didn't get exercise you
didn't eat, so the loss of cardio fitness in the absence of
exercise would never be selected against. Meanwhile, the
general loss of unused muscle mass was (as you have noted
previously) selected for, so the same mechanism that caused
that would also cause the loss of cardio fitness unless our
ancestors routinely were exposed to conditions in which they
were inactive but well fed - and I would guess those
conditions were rare.

Our current problem is that we have two different trends
going on that were both originally adaptive. One is the
tendency to put on additional weight when starvation is not
occurring. For most of human evolution, humans underwent
periods of starvation on a regular basis. So it was
advantageous, during periods of excess food, to add fat.The
second is the tendency to lose muscle and fitness in
response to inactivity, which we have discussed above. Now
people can get lots of calories without expending any
energy, and the result is readily apparent.

Yours,

Bill Morse

Tim,

in article [email hidden], Tim Tyler at
[email hidden] wrote on 6/24/04 10:14 AM:

Quoted message said:

Guy Hoelzer <[email hidden]> wrote or quoted:

Quoted message said:

You may be interested in the following observation (I
would point you to the literature on the metabolic
scaling theory of Brown, West and colleagues). Data
spanning many orders of magnitude in animal size and
metabolic rate reveal that vertebrates are generally
allotted about 1 million heart beats per lifetime. There
is plenty of variation around this rule, but the more
data you include in the analysis, the more robust the
rule appears. [...]

This is "between-species" data.

Quoted message said:

So, when you work out you use up your allotment of heart
beats faster, but you reduce your resting heart rate at
the same time. You don't get a larger allotment of heart
beats by virtue of working out.

...and this is "within-species" data.

The flipside of my point about increasing the scope of the
data in your analysis is that the relationship between
metabolic rate (or number of heartbeats) and lifespan is
that the relationship becomes vague when the data are
limited to a small range of scale (e.g., when limited to
within-species).

Quoted message said:

Using data on the former to make arguments about the
latter doesn't work very well - since for one thing all
the data [1,2,3,4,5] indicates that vigorous exercise
increases mean lifespan.

This observation does not contradict my claim, which was
ambiguous with regard to the net effect of exercise on
lifespan. If we take a naïve approach of counting heart
beats, exercise raises your heart rate temporarily and
depresses it during rest. If we spend more time resting than
exercising, which we do, then your net heart rate may be
reduced by exercise. I think we agreed with respect to the
costs of producing and maintaining more mitochondria and
capillaries, which is a slightly different issue.

Quoted message said:

Quoted message said:

There is one result from the science of aging that shows
up in virtually every study. The most effective way to
maximize lifespan is to reduce metabolic rate. You can
increase your expected lifespan by something like 30%,
for example, if you lie down, get fed intravenously, and
allow your muscles to atrophy for the rest of your life.
It is not a life I would choose to live, but it is BY FAR
the surest way to maximize your lifespan that we know.

The best known and most effective intervention for
extending the lifespan of mammals (or practically anything
else) is calorie restriction - i.e. see:

calorierestriction.orgcalorierestriction.orgOpen ↗

It doesn't work by changing the organism's metabolic rate
- but rather by activating adaptations for dealing with
famine conditions - i.e. see:

cr.timtyler.orgwhyOpen ↗

I will have a look at this web site, but your claim seems
illogical because the rate of calorie consumption is
generally taken as a direct measure of metabolic rate.

Regards,

Guy

Guy Hoelzer <[email hidden]> wrote or quoted:

Quoted message said:

Tim Tyler at [email hidden]

Quoted message said:

Quoted message said:

The best known and most effective intervention for
extending the lifespan of mammals (or practically
anything else) is calorie restriction - i.e. see:

calorierestriction.orgcalorierestriction.orgOpen ↗

It doesn't work by changing the organism's metabolic
rate - but rather by activating adaptations for dealing
with famine conditions - i.e. see:

cr.timtyler.orgwhyOpen ↗

I will have a look at this web site, but your claim seems
illogical because the rate of calorie consumption is
generally taken as a direct measure of metabolic rate.

Metabolic rate itself - in terms of raw energy consumption -
is not a very useful measure when comparing organisms of
different size - since it takes no account of body size.

A mouse has a much smaller body than an elephant - and while
the mouse burns far fewer calories, it is normally regarded
as having a metabolism that burns through them much faster
than an elephant's metabolism does.

There are various ways to adjust metabolic weight for body
size. In particular there is the notion of "specific
metabolic rate".

This is desribed on:

webusers.xula.eduMetabolism3.htmlOpen ↗

Once you factor weight into the equation somehow (as you
obviously must if you want to claim any negative correlation
between metabolic rate and longvity) then it is no longer
clear that dieting organisms have reduced specific metabolic
rates, since - while they burn energy more slowly - they
have fewer metabolically demanding tissues to support.

There are empirical studies of the issue - e.g.:

``Controlled trial of the metabolic effects of a very-low-
calorie diet: short- and long-term effects''

- calorierestriction.orgpmidOpen ↗

...shows an initial energy deficit - followed by weight loss
and a recovery of the original specific metabolic rate.

There are several explanations of why this happens.

One is that the body of the dieting organism is pumped full
of stress hormones, and it is thus encouraged into activity
in the hope that activity will result in food.

Also - on a longer term basis - the non-restricted animals
normally tend to become increasingly sleepy and sedentary
- compared to the restricted subjects - due to the onset
of old age.

There's a nice 1:43 minute video of this on:
biomarkerinc.compress.htmOpen ↗ that provides a
dramatic demonstration of the effect.
--
__________
|im |yler timtyler.orgtimtyler.orgOpen ↗ [email hidden] Remove
lock to reply.

Tim,

in article [email hidden], Tim Tyler at
[email hidden] wrote on 6/25/04 9:56 PM:

Quoted message said:

Guy Hoelzer <[email hidden]> wrote or quoted:

Quoted message said:

Tim Tyler at [email hidden]

Quoted message said:

Quoted message said:

The best known and most effective intervention for
extending the lifespan of mammals (or practically
anything else) is calorie restriction - i.e. see:

calorierestriction.orgcalorierestriction.orgOpen ↗

It doesn't work by changing the organism's metabolic
rate - but rather by activating adaptations for dealing
with famine conditions - i.e. see:

cr.timtyler.orgwhyOpen ↗

I will have a look at this web site, but your claim seems
illogical because the rate of calorie consumption is
generally taken as a direct measure of metabolic rate.

Metabolic rate itself - in terms of raw energy consumption
- is not a very useful measure when comparing organisms of
different size - since it takes no account of body size.

For most questions, it turns out that this is a good thing.
I recognize that it has been conventional to control for
body size until recently, but dropping that convention has
allowed many (see the papers of the extended group of Brown
and West) to make extraordinary progress.

Quoted message said:

A mouse has a much smaller body than an elephant - and
while the mouse burns far fewer calories, it is normally
regarded as having a metabolism that burns through them
much faster than an elephant's metabolism does.

Only on a per mass basis, as predicted by metabolic
scaling theory.

Quoted message said:

There are various ways to adjust metabolic weight for body
size. In particular there is the notion of "specific
metabolic rate".

This is desribed on:

webusers.xula.eduMetabolism3.htmlOpen ↗

Once you factor weight into the equation somehow (as you
obviously must if you want to claim any negative
correlation between metabolic rate and longvity) then it
is no longer clear that dieting organisms have reduced
specific metabolic rates, since - while they burn energy
more slowly - they have fewer metabolically demanding
tissues to support.

Right; when you control for mass many things become unclear.
They become clear again when you stop artificially
controlling for mass.

Quoted message said:

There are empirical studies of the issue - e.g.:

``Controlled trial of the metabolic effects of a very-low-
calorie diet: short- and long-term effects''

- calorierestriction.orgpmidOpen ↗

...shows an initial energy deficit - followed by weight
loss and a

recovery of the original specific metabolic rate.

There are several explanations of why this happens.

One is that the body of the dieting organism is pumped
full of stress hormones, and it is thus encouraged into
activity in the hope that activity will result in food.

Also - on a longer term basis - the non-restricted animals
normally tend to become increasingly sleepy and sedentary
- compared to the restricted subjects - due to the onset
of old age.

There's a nice 1:43 minute video of this on:
biomarkerinc.compress.htmOpen ↗ that provides a
dramatic demonstration of the effect.

Thanks for all the pointers.

Guy

in article [email hidden], John Edser at [email hidden]
wrote on 6/24/04 10:14 AM:

Quoted message said:

Quoted message said:

_______________________________________________________
Box 1 The total number of fertile forms reproduced by
each parent within one population.
_______________________________________________________

I also argue that this can be easily proven by reverse
engineering the above definition, i.e. by setting up a
natural population (not just a model simulation) whereby
the total fitness of each parent is artificially kept
equal within one experimental population.
Epistemologically, any unique verification (a
verification only provided by just one theory compared to
all the others on the table) when reversed, must provide
a valid point of refutation for that theory. This
principle is proven, here.

Quoted message said:

snip<

Quoted message said:

JE:- All of us must be much more careful in our use of
"fit" or "unfit", in _any_ evolutionary theory context so
as not to misuse it. Would Dr Hoelzer deny or confirm
that his use of the term "Darwinian fitness" refers to
the definition I provided in Box 1.

GH:- I meant it in a very general way, so it is completely
consistent with the definition in Box 1 without excluding
other definitions.

JE:- "..completely consistent with the definition in Box 1
without excluding other definitions"?

It is ambiguous to leave your statement at just that,
unless you provide a list of at least some of the
definitions included. Clearly, I meant it in a very exact
way such that it has to exclude many other definitions
such those provided by Hamilton et al.

Do you agree or disagree that the only possible way to
halt all natural selection within a growing population in
nature is to perform the experiment above?

You don't really provide enough detail about your experiment
above to make an intelligent response, but I think I
understand it from your previous writings. In fact, I think
that I encouraged you to do your experiment years ago. It is
simple enough to do in a rough way.

I would answer your question by disagreeing. As you know, I
think that selection can happen at many levels, so ensuring
complete survival and equal reproductive success among
individuals within an experimental population would not
ensure the halting of all sources of natural selection.

Regards,

Guy Hoelzer