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I ended ordering Rose's book, and found the story about frogs =
interesting. Amazon has the 1st chapter on their site if one wants to =
read the whole chapter. =20
http://www.amazon.com/exec/obidos/ASIN/0195120353/002-4411775-2437049
Lifelines : Biology Beyond Determinism
by Steven P. R. Rose
Our Price: $21.00
You Save: $9.00 (30%)
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Hardcover - (March 1998) 304 pages
FIVE WAYS OF LOOKING AT FROGS
Once upon a time, five biologists were having a picnic by a pool, when =
they noticed a frog, which had been sitting on the edge, suddenly jump =
into the water (Figure 1.2.). A discussion began between them: why did =
the frog jump?=20
Says the first biologist, a physiologist, `It's really quite =
straightforward. The frog jumps because the muscles in its legs =
contract; in turn these contract because of impulses in the motor nerves =
arriving at the muscles from the frog's brain; these impulses originate =
in the brain because previous impulses, arriving at the brain from the =
frog's retina, have signalled the presence of a predatory snake.'=20
This is a simple `within-level' causal chain: first the retinal image of =
the snake; then the signals to the brain; then the impulses down the =
nerves from the brain; then the muscle contraction -- one event =
following the other, all in a few thousandths of a second (Figure 1.3). =
Working out the details of such causal sequences is the task of =
physiology.=20
`But this is a very limited explanation,' says the second, who is an =
ethologist, and studies animal behaviour. `The physiologist has missed =
the point, and has told us how the frog jumped but not why it jumped. =
The reason why is because it sees the snake and in order to avoid it. =
The contraction of the frog's muscles is but one aspect of a complex =
process, and must be understood in terms of the goals of that process -- =
in this case, to escape being eaten. The ultimate goal of avoiding the =
snake is essential to understanding the action.'=20
Such goal-directed explanations, which are known as teleonomic, have =
given more trouble to philosophers than almost anything else in biology; =
they are sometimes regarded as bad form, yet they make more everyday =
sense than most other explanations. They insist that an organism, a =
piece of behaviour or of physiology, can be understood only within an =
environmental context which includes both its physical surroundings and =
other living, socially interacting neighbours. (Indeed, when the =
organism is a member of that very peculiar species, Homo sapiens, then =
further complexities, those of personal and collective history, come =
strongly into play.) This type of explanation is a `top-down' one (it is =
sometimes called a holistic explanation, a dangerously ambiguous word, =
which I shall avoid). But notice that, unlike the physiologist's =
explanation, it is not causal in the sense of describing a temporal =
chain of events in which first one thing, the nerve firing, and then =
another, the muscle contraction, happen one after the other in time. The =
jump inevitably precedes achieving the goal towards which it is =
directed. Thus when animal behaviourists -- ethologists -- talk of =
causes, they do so quite differently from physiologists.=20
`Neither the physiologist's nor the ethologist's explanations are =
adequate,' says the third biologist, who studies development. `For the =
developmentalist, the only reason that the frog can jump at all is =
because during its development, from single fertilized egg through =
tadpole to mature animal, its nerves, brain and muscles have become =
"wired up" in such a way that such sequences of activity are inevitable =
-- or at least, the most probable given any set of starting conditions.' =
The process of wiring is an aspect of ontogeny, the development of the =
organism from conception to adulthood, and is addressed by genetics and =
developmental biology. Unlike the first two explanations, the =
ontogenetic approach introduces a historical element into the account: =
the individual history of the frog becomes the key to understanding its =
present behaviour. Ontogeny is often seen as a dialogue -- even a =
dichotomy -- between nature (genetics) and nurture (environment). There =
have even been attempts to mathematicize this split, and to ask how much =
is contributed by genes and how much by environment. As will become =
clear in later chapters, this is a spurious dichotomy and I shall =
endeavour to transcend it.=20
`None of these three explanations is very satisfactory,' counters the =
fourth biologist, an evolutionist. `The frog jumps because during its =
evolutionary history it was adaptive for its ancestors to do so at the =
sight of a snake; those ancestors that failed so to do were eaten, and =
hence their progeny failed to be selected.'=20
This type of explanation presents problems of defining just what is =
meant by terms like `adaptive' and `selected', problems which have been =
raised most sharply in the polemical debate over sociobiology, and which =
I shall examine rather critically in later chapters. One might contrast =
the developmentalist and the evolutionist by regarding the first, like =
the physiologist, as asking how and the second, like the ethologist, as =
asking why-type questions. The evolutionary explanation combines the =
historical -- though now with regard to an entire species rather than =
one individual -- with the goal-directed. Perhaps because of this, some =
sociobiologists argue that it is the fundamentally causal question and =
dismiss other causal claims as merely `functional'.=20
The fifth biologist, a molecular biologist, smiles sweetly. `You have =
all missed the point. The frog jumps because of the biochemical =
properties of its muscles. The muscles are composed largely of two =
interdigitated filamentous proteins, called actin and myosin, and they =
contract because the protein filaments slide past one another. This =
behaviour of the actin and myosin is dependent on the amino acid =
composition of the two proteins, and hence on chemical properties, and =
hence on physical properties.' This is a reductionist programme, and is =
the way in which biochemists seek to describe living phenomena.=20
But note again that this is not a causal chain in the sense in which the =
physiologist uses the phrase. It is not a question of first one thing =
happening (the actin and myosin sliding across each other), then another =
(the contraction). If the word `cause' is used at all here, it must mean =
something quite different from how it is used in physiology. The =
confusion about the several ways in which `cause' is used has bedevilled =
scientific thinking since the days of Aristotle. Perhaps we would see =
things more clearly if we restricted our use of the word to clear =
temporal sequences in which first one and then another event occurs. =
Each of these events -- the image on the frog's retina, the processing =
in the brain, the transmission down a motor nerve and the muscle =
contraction itself -- can be translated into the language of =
biochemistry. And of course it is possible to describe this biochemical =
sequence in temporal terms too, in which one set of biochemical =
processes (the molecular events in the nerve), produces another (the =
sliding actin and myosin filaments). At issue, then, is the relationship =
between the two temporal sequences, that of the physiologist and that of =
the biochemist. In later chapters I shall explain why I use the term =
`translation, to describe how the description of the phenomenon of =
muscle contraction in the language of (at the level of) physiology may =
be replaced by a series of presumed identity statements in the languages =
of biochemistry, chemistry, and so on.=20
Nate Schmolze
http://www.geocities.com/~nschmolze/
schmolze who-is-at students.wisc.edu
People with great passions, people who accomplish great deeds,
People who possess strong feelings even people with great minds
and a strong personality, rarely come out of good little boys and girls
L.S. Vygotsky=20
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Once upon a time, five biologists were having a picnic by a pool, = when they=20 noticed a frog, which had been sitting on the edge, suddenly jump into = the water=20 (Figure 1.2.). A discussion began between them: why did the frog jump?=20
Says the first biologist, a physiologist, `It's really quite = straightforward.=20 The frog jumps because the muscles in its legs contract; in turn these = contract=20 because of impulses in the motor nerves arriving at the muscles from the = frog's=20 brain; these impulses originate in the brain because previous impulses, = arriving=20 at the brain from the frog's retina, have signalled the presence of a = predatory=20 snake.'=20
This is a simple `within-level' causal chain: first the retinal image = of the=20 snake; then the signals to the brain; then the impulses down the nerves = from the=20 brain; then the muscle contraction -- one event following the other, all = in a=20 few thousandths of a second (Figure 1.3). Working out the details of = such causal=20 sequences is the task of physiology.=20
`But this is a very limited explanation,' says the second, who is an=20 ethologist, and studies animal behaviour. `The physiologist has missed = the=20 point, and has told us how the frog jumped but not why it jumped. The = reason why=20 is because it sees the snake and in order to avoid it. The contraction = of the=20 frog's muscles is but one aspect of a complex process, and must be = understood in=20 terms of the goals of that process -- in this case, to escape being = eaten. The=20 ultimate goal of avoiding the snake is essential to understanding the = action.'=20
Such goal-directed explanations, which are known as teleonomic, have = given=20 more trouble to philosophers than almost anything else in biology; they = are=20 sometimes regarded as bad form, yet they make more everyday sense than = most=20 other explanations. They insist that an organism, a piece of behaviour = or of=20 physiology, can be understood only within an environmental context which = includes both its physical surroundings and other living, socially = interacting=20 neighbours. (Indeed, when the organism is a member of that very peculiar = species, Homo sapiens, then further complexities, those of personal and=20 collective history, come strongly into play.) This type of explanation = is a=20 `top-down' one (it is sometimes called a holistic explanation, a = dangerously=20 ambiguous word, which I shall avoid). But notice that, unlike the = physiologist's=20 explanation, it is not causal in the sense of describing a temporal = chain of=20 events in which first one thing, the nerve firing, and then another, the = muscle=20 contraction, happen one after the other in time. The jump inevitably = precedes=20 achieving the goal towards which it is directed. Thus when animal = behaviourists=20 -- ethologists -- talk of causes, they do so quite differently from=20 physiologists.=20
`Neither the physiologist's nor the ethologist's explanations are = adequate,'=20 says the third biologist, who studies development. `For the = developmentalist,=20 the only reason that the frog can jump at all is because during its = development,=20 from single fertilized egg through tadpole to mature animal, its nerves, = brain=20 and muscles have become "wired up" in such a way that such sequences of = activity=20 are inevitable -- or at least, the most probable given any set of = starting=20 conditions.'=20
The process of wiring is an aspect of ontogeny, the development of = the=20 organism from conception to adulthood, and is addressed by genetics and=20 developmental biology. Unlike the first two explanations, the = ontogenetic=20 approach introduces a historical element into the account: the = individual=20 history of the frog becomes the key to understanding its present = behaviour.=20 Ontogeny is often seen as a dialogue -- even a dichotomy -- between = nature=20 (genetics) and nurture (environment). There have even been attempts to=20 mathematicize this split, and to ask how much is contributed by genes = and how=20 much by environment. As will become clear in later chapters, this is a = spurious=20 dichotomy and I shall endeavour to transcend it.=20
`None of these three explanations is very satisfactory,' counters the = fourth=20 biologist, an evolutionist. `The frog jumps because during its = evolutionary=20 history it was adaptive for its ancestors to do so at the sight of a = snake;=20 those ancestors that failed so to do were eaten, and hence their progeny = failed=20 to be selected.'=20
This type of explanation presents problems of defining just what is = meant by=20 terms like `adaptive' and `selected', problems which have been raised = most=20 sharply in the polemical debate over sociobiology, and which I shall = examine=20 rather critically in later chapters. One might contrast the = developmentalist and=20 the evolutionist by regarding the first, like the physiologist, as = asking how=20 and the second, like the ethologist, as asking why-type questions. The=20 evolutionary explanation combines the historical -- though now with = regard to an=20 entire species rather than one individual -- with the goal-directed. = Perhaps=20 because of this, some sociobiologists argue that it is the fundamentally = causal=20 question and dismiss other causal claims as merely `functional'.=20
The fifth biologist, a molecular biologist, smiles sweetly. `You have = all=20 missed the point. The frog jumps because of the biochemical properties = of its=20 muscles. The muscles are composed largely of two interdigitated = filamentous=20 proteins, called actin and myosin, and they contract because the protein = filaments slide past one another. This behaviour of the actin and myosin = is=20 dependent on the amino acid composition of the two proteins, and hence = on=20 chemical properties, and hence on physical properties.' This is a = reductionist=20 programme, and is the way in which biochemists seek to describe living=20 phenomena.=20
But note again that this is not a causal chain in the sense in which = the=20 physiologist uses the phrase. It is not a question of first one thing = happening=20 (the actin and myosin sliding across each other), then another (the=20 contraction). If the word `cause' is used at all here, it must mean = something=20 quite different from how it is used in physiology. The confusion about = the=20 several ways in which `cause' is used has bedevilled scientific thinking = since=20 the days of Aristotle. Perhaps we would see things more clearly if we = restricted=20 our use of the word to clear temporal sequences in which first one and = then=20 another event occurs. Each of these events -- the image on the frog's = retina,=20 the processing in the brain, the transmission down a motor nerve and the = muscle=20 contraction itself -- can be translated into the language of = biochemistry. And=20 of course it is possible to describe this biochemical sequence in = temporal terms=20 too, in which one set of biochemical processes (the molecular events in = the=20 nerve), produces another (the sliding actin and myosin filaments). At = issue,=20 then, is the relationship between the two temporal sequences, that of = the=20 physiologist and that of the biochemist. In later chapters I shall = explain why I=20 use the term `translation, to describe how the description of the = phenomenon of=20 muscle contraction in the language of (at the level of) physiology may = be=20 replaced by a series of presumed identity statements in the languages of = biochemistry, chemistry, and so on.