Switch. Hmh.
There is a thing called Periodic System of Elements,
in chemistry. Wisest scientist say that the Periodic
System of Elements has never been directly proven,
that it is just a hypothesis which has survived all
the tests of something like two centuries. That there
has not (yet) been found a flaw in fundament of that
hypothesis. That its essential content has never (yet)
been needed to revised...
No direct proof. Only an immense load of indirect
evidence....
So, Todd, you argue that everything related to
behavioral differences between human males and
females, if genetic, comes from the switch, and not
from any direct gene in Y chromosome.
The switch looks very much like a hypothesis to me. Is
there any direct proof of the validity of THAT
hypothesis?
Is its believed validity based only upon indirect
evidence?
How vast is the amount of such indirect proofs? Is it
less-well proven than the Periodic System of Elements?
or better-proven?
I am not questioning the possibility that the, or a,
mechanism may be through such switch. I am only saying
that it is a convenient explanation - how to prove it
false?
I am also invoking the Occam's Razor - if a direct
mechanism could be possible, an indirect, at least two
stages mechanism should not be needed...
How exhaustively have all the possibilities that
direct genetic determinants of male-like behaviors
could reside in Y chromosome, been checked and proven
non-existent?
____________________________________________________________________________________
PS the Googlegroups option of this list appears to be
somewhat capricious in these days. It allows only some
posts through, while other posts fail, and are
available only in the rootsweb version.
____________________________________________________________________________________
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What was a king anyhow? (was Re: Granada - king or Emir ?)
Moderator: MOD_nyhetsgrupper
-
Gjest
Re: What was a king anyhow? (was Re: Granada - king or Emir
On Jan 29, 12:33 pm, "M.Sjostrom" <[email protected]> wrote:
And gravity and the germ theory of infectious disease and
heliocentrism and spheroterism, and, while we are at it, the existence
of genes.
All of human knowledge is hypothesis, by this definition, even things
you think you know by personally witnessing them (which relies on
hypotheses about light transmission, perception, and cerebral
processing, uniformitarianism, etc., etc. It thus becomes pointless
to draw a distinction between fact and really well supported
hypothesis, and in science, the word 'fact' applies to such things.
The alternative is intellectual nihilism - we can never know anything,
which makes for decent if oft-repeated philosophical discussions, but
doesn't get you very far in the real world.
No, I only present the scientific consensus. God-did-it is another
common explanation, but not as popular in the scientific community.
See above.
We have just disproved the concept of proof, so no. If you mean
observations that support it, yes.
Almost everything we think we know about genes is based on indirect
evidence (Plus, our theory of genes involves molecules of DNA that are
made up of atoms, or so the hypothesis goes).
Probably not, in fact, almost certainly not. After all, we only
discovered the gene involved about 15 years ago.
Well, you could remove the gene in question and see what happens.
What happens is that you get a female - a completely normal female,
except with a funny Y chromosome. Nature actually did this experiment
for us.
You are misapplying it. The simplest explanation is perhaps most
likely in the absence of evidence, but in application, it is the most
simple explanation for the evidence that it most likely. An
alternative phrasing of it is, if it walks like a duck and it quacks
like a duck and it flies like a duck, it's probably a duck.
Well, it's probably a duck.
They haven't. Didn't I just tell you that most of the genes on the Y
chromosome were completely unknown until a handful of years ago. That
being said, the same is true of every characterized genetic
association. Diabetes, Huntingdon's disease, Cystic Fibrosis. In no
case has every other gene been eliminated systematically.
Now for some more hypotheses based on indirect evidence. The gene in
question, SRY, has a structure similar to other proteins known to bind
DNA and to regulate genes . . . there I go again. The DNA that is
mutated in these sex reversal individuals surrounds an open reading
frame which one would predict to make a protein, predict based on
direct sequence correlation between DNA and amino acid sequece of
other proteins with known genes - 'known' because putting that piece
of DNA into a species that does not have it (or even into a test tube
containing the right mix of enzymes) results in the appearance of a
new protein with the corresponding sequence. From this process the
genetic code was determined. By applying these rules to the SRY gene,
we predict an amino acid sequence similar to the amino acid sequence
of other proteins that bind DNA. How do we know they bind? because
you can drive a piece of DNA through a slab of Jello and it will
migrate a distance inversely proportional to its cross-section area.
If you put a protein in with it, it now migrates much more slowly,
consistent with it now being part of a larger complex with the
protein. If you modify the protein in a critical position predicted
to be important in DNA binding, then you get no shift in migration
(and hence apparent size). Further, you can form a crystal made up of
protein and DNA and fire X-rays through it, and the X-rays scatter in
a pattern induced by the presence of those hypothetical atoms. From
this pattern you can extrapolate back the position of the atoms in the
crystal, and compare that to the pattern of atoms that make up the
cosntituent members of the crystal. What you see is a pattern
consistent with the protein binding to the DNA. Given the similarity,
it seems reasonable to conclude that the SRY protein also binds DNA,
so the same experiments can, and at least in the first case, have been
completed with it. It binds DNA (or so the hypothesis goes). OK, next
you can put the sequence that it binds to next to a gene-regulatory
region controling a reporter gene - something easy to detect and
quantify, not normally found in the system being studied, and it
causes that gene regulatory region to make more of its product. This
suggests that the protein binding to that DNA sequence can regulate
transcription. You can then turn up the levels of SRY in a cell and
see some genes turned up, and some genes turned down. You can remove
the SRY protein and see them change in the opposite directions. When
you identify the individual genes being turned up or turned down, you
find them spread across the entire genome (as is typical with proteins
that regulate the transcription of other genes). I could go on, but
it is off-topic, and I am boring myself. (And believe it or not, this
is a simplified explanation of what has been studied: EMSA, GeneChip
arrays, ChIP assays, supershifts, FISH, . . . . , and every last one
of them based on indirect evidence and hypotheses.)
Now it is your turn. What evidence do you have for your mechanism?
Men have Y and women don't?
Switch. Hmh.
There is a thing called Periodic System of Elements,
in chemistry. Wisest scientist say that the Periodic
System of Elements has never been directly proven,
that it is just a hypothesis which has survived all
the tests of something like two centuries. That there
has not (yet) been found a flaw in fundament of that
hypothesis. That its essential content has never (yet)
been needed to revised...
No direct proof. Only an immense load of indirect
evidence....
And gravity and the germ theory of infectious disease and
heliocentrism and spheroterism, and, while we are at it, the existence
of genes.
All of human knowledge is hypothesis, by this definition, even things
you think you know by personally witnessing them (which relies on
hypotheses about light transmission, perception, and cerebral
processing, uniformitarianism, etc., etc. It thus becomes pointless
to draw a distinction between fact and really well supported
hypothesis, and in science, the word 'fact' applies to such things.
The alternative is intellectual nihilism - we can never know anything,
which makes for decent if oft-repeated philosophical discussions, but
doesn't get you very far in the real world.
So, Todd, you argue that everything related to
behavioral differences between human males and
females, if genetic, comes from the switch, and not
from any direct gene in Y chromosome.
No, I only present the scientific consensus. God-did-it is another
common explanation, but not as popular in the scientific community.
The switch looks very much like a hypothesis to me.
See above.
Is
there any direct proof of the validity of THAT
hypothesis?
We have just disproved the concept of proof, so no. If you mean
observations that support it, yes.
Is its believed validity based only upon indirect
evidence?
Almost everything we think we know about genes is based on indirect
evidence (Plus, our theory of genes involves molecules of DNA that are
made up of atoms, or so the hypothesis goes).
How vast is the amount of such indirect proofs? Is it
less-well proven than the Periodic System of Elements?
or better-proven?
Probably not, in fact, almost certainly not. After all, we only
discovered the gene involved about 15 years ago.
I am not questioning the possibility that the, or a,
mechanism may be through such switch. I am only saying
that it is a convenient explanation - how to prove it
false?
Well, you could remove the gene in question and see what happens.
What happens is that you get a female - a completely normal female,
except with a funny Y chromosome. Nature actually did this experiment
for us.
I am also invoking the Occam's Razor - if a direct
mechanism could be possible, an indirect, at least two
stages mechanism should not be needed...
You are misapplying it. The simplest explanation is perhaps most
likely in the absence of evidence, but in application, it is the most
simple explanation for the evidence that it most likely. An
alternative phrasing of it is, if it walks like a duck and it quacks
like a duck and it flies like a duck, it's probably a duck.
Well, it's probably a duck.
How exhaustively have all the possibilities that
direct genetic determinants of male-like behaviors
could reside in Y chromosome, been checked and proven
non-existent?
They haven't. Didn't I just tell you that most of the genes on the Y
chromosome were completely unknown until a handful of years ago. That
being said, the same is true of every characterized genetic
association. Diabetes, Huntingdon's disease, Cystic Fibrosis. In no
case has every other gene been eliminated systematically.
Now for some more hypotheses based on indirect evidence. The gene in
question, SRY, has a structure similar to other proteins known to bind
DNA and to regulate genes . . . there I go again. The DNA that is
mutated in these sex reversal individuals surrounds an open reading
frame which one would predict to make a protein, predict based on
direct sequence correlation between DNA and amino acid sequece of
other proteins with known genes - 'known' because putting that piece
of DNA into a species that does not have it (or even into a test tube
containing the right mix of enzymes) results in the appearance of a
new protein with the corresponding sequence. From this process the
genetic code was determined. By applying these rules to the SRY gene,
we predict an amino acid sequence similar to the amino acid sequence
of other proteins that bind DNA. How do we know they bind? because
you can drive a piece of DNA through a slab of Jello and it will
migrate a distance inversely proportional to its cross-section area.
If you put a protein in with it, it now migrates much more slowly,
consistent with it now being part of a larger complex with the
protein. If you modify the protein in a critical position predicted
to be important in DNA binding, then you get no shift in migration
(and hence apparent size). Further, you can form a crystal made up of
protein and DNA and fire X-rays through it, and the X-rays scatter in
a pattern induced by the presence of those hypothetical atoms. From
this pattern you can extrapolate back the position of the atoms in the
crystal, and compare that to the pattern of atoms that make up the
cosntituent members of the crystal. What you see is a pattern
consistent with the protein binding to the DNA. Given the similarity,
it seems reasonable to conclude that the SRY protein also binds DNA,
so the same experiments can, and at least in the first case, have been
completed with it. It binds DNA (or so the hypothesis goes). OK, next
you can put the sequence that it binds to next to a gene-regulatory
region controling a reporter gene - something easy to detect and
quantify, not normally found in the system being studied, and it
causes that gene regulatory region to make more of its product. This
suggests that the protein binding to that DNA sequence can regulate
transcription. You can then turn up the levels of SRY in a cell and
see some genes turned up, and some genes turned down. You can remove
the SRY protein and see them change in the opposite directions. When
you identify the individual genes being turned up or turned down, you
find them spread across the entire genome (as is typical with proteins
that regulate the transcription of other genes). I could go on, but
it is off-topic, and I am boring myself. (And believe it or not, this
is a simplified explanation of what has been studied: EMSA, GeneChip
arrays, ChIP assays, supershifts, FISH, . . . . , and every last one
of them based on indirect evidence and hypotheses.)
Now it is your turn. What evidence do you have for your mechanism?
Men have Y and women don't?