>see below for my responses .
>
>Best,
>
>Michael
>On Oct 23, 2004, at 5:52 AM, José F. Morales wrote:
>
>>>My understanding of evolutionary theory is that only actual genes and
>>>not recombinations can be selected for; thus the genes that are
>>>recombined to give rise to the immune system's immense variability are
>>>selected for as a whole, not combinations by combination.
>>
>>While this is not my area, i don't think this is
>>true. At least somatically, there is something
>>called "clonal selection" . This selection is
>>not on a species evolution, level but rather by a
>>selection process in a single organism.
>but we are talking about evolution, at least evolutionary psychology is
OK. I THINK I UNDERSTAND. YOU BROUGHT
RECOMBINATIONS INTO THE DISCUSSION PERHAPS
BECAUSE I TALKED ABOUT ALTERNATIVE SPLICING. I'M
NOT SURE WHY OTHERWISE. ANYHOW, IN TERMS OF
ALTERNATIVE SPLICING, THAT IS INDEED SELECTED FOR
IN A SPECIES EVOLUTIONARY MANNER. THIS IS AS
OPPOSED TO THE IMMUNE SYSTEM RECOMBINATION. THE
RESULTS OF GENOMIC RECOMBINATIONS OCCURRING IN
MEIOSIS CAN ALSO BE SELECTED FOR. THAT IS ONE OF
THE MECHANISMS WHEREBY NOVELTY IS GENERATED.
>>Even so, the machinery to enable recombination in
>>the immune system IS selected for on a species
>>level.
>Exactly, but not each individual recombinant, so you can't arrive at
>more evolutionary adoptations that way
SO I GUESS WE HAVE TO PROPOSE WHETHER BRAIN
DEVELOPMENTS ARE THE RESULT OF A)
MUTATION-->SELECTION --> ADAPTATION B) NEUTRAL C)
SPANDRALS (SP?) ALA GOULD. I WOULD SUSPECT
MOSTLY A AND A LITTLE B AND C.
AS FOR THE MECHANISM WHEREBY THE ADAPTATIONS
ARISE, THERE ARE MANY WAYS MUTATION CAN ARISE,
RECOMBINATION BEING ONLY ONE. I SEE NO REASON
WHY THE DNA THAT IS INVOLVED IN THE GENERATION OF
NEURAL STRUCTURES SHOULD BE SPECIAL AND NOT BE
SUBJECT TO MUTATION -SELECTION -ADAPTATION.
THEREFORE I DON'T SEE A BIOLOGICALLY BASED
ARGUMENT TO INSIST THAT MOST EXISTENT NEURAL FORM
DOES NOT ARISE FROM MUTATION -SELECTION
-ADAPTATION.
>>
>>>The hypothesis of Evolutionary Psychology is that there are many
>>>different
>>>adaptations that lead to cognitive or affective outcomes; while the
>>>outcomes are expected to vary widely according to environmental
>>>circumstances,
>>
>>Most polymorphisms in the genome arise from
>>random drift not selection. Maybe the EP crew
>>thinks that these adaptations arise in pre-homo
>>sapiens.
>
>Random drift is not an adaptation; an adaptation is a genetic change of
>whatever orginin that increases fitness enough to be inherited in
>larger numbers in subsequent generations. The EP crew argues quite
>specifically that most "mental" adaptations arose after the chimp-human
>split
PROBABLY SOME DID AND SOME DIDN'T. I SEE NO
REASON WHY AT LEAST SOME IF NOT MOST "MENTAL"
ADAPTATIONS ARISE VIA MUTATION -SELECTION
-ADAPTATION.
>>
>>>each of the adaptations must correspond in some
>>>manner to a specific gene or genes that can
>>>reliably be inherited individually.
>>
>>Clearly novel features of the brain arise due to
>>natural selection that involves the genetic
>>level. I would say its probably not one to one
>>gene<->brain feature. Any brain feature is
>>probably under multi-genic control. I would be
>>quite surprised if anyone on this list would
>>think that that novel brain features arise
>>WITHOUT the involvement of genes.
>well I certainly do. Our brains both have the feature, incorporated in
>neurophysiology of being able to read and write and type English. No
>human brain a thousand years ago had quite this feature. It arrived by
>culture, not genes. Of course SOME genetic endowment, but perhaps only
>a very general one must underlie tiis capapbility.
SO ARE YOU SAYING THAT NOVEL BRAIN STRUCTURES
ARISE FROM INTERACTIONS HUMANS HAD AMONGST EACH
OTHER? I GUESS YOU DON'T HAVE A PROBLEM BEING
NON-DARWINIAN. OK.
I WOULD BE INTERESTED HOWEVER IN HEARING YOUR
DESCRIPTION OF THE BIOLOGICAL MECHANISM HOW A
NOVEL NEURAL STRUCTURE COMES INTO BEING BY VIRTUE
OF CULTURE. I MUST ADMIT I FIND THAT UNLIKELY.
I'M ALL EARS.
>>
>>>A trait that is only the result of a
>>>recombination out of many possible
>>>recombinations could hardly be reliably
>>>inherited, and therefore could never have been
>>>selected evolutionarily.
>>
>>I'm not sure I know what you mean. you mentioned
>>recombination in regards to immune system --->
>>then we switched to brain ---> then we went back
>>to recombination. I would comment that the
>>mechanism of recombination is inherited, the
>>starting material of recombination is inherited,
>>and the various results of recombination are also
>>inherited. What gets selected for is another
>>matter.
>You were the one who originally brought up recombination, I thought.
I DON'T THINK SO UNLESS YOU THINK THAT
ALTERNATIVE SPLICING IS RELATED TO RECOMBINATION.
>We know it works for immunity, but the point is specific immunities cannot
>be inherited, only the general capacity.
I DON'T THINK THE IMMUNE SYSTEM IS EXACTLY
PERTINENT TO THE DISCUSSION OF GENOMIC EVOLUTION.
>Likewise, if some sort of
>recombination were responsible for mental functions, the individual
>functions could not be inherited, but EP claims they are, by the
>hundreds certainly, or even by the hundreds of thousands, according to
>Phil.
>>
>>>Supporters of EP definitely would have some explaining to do if the
>>>number of genes has been correctly counted as only 25,000 or fewer,
>>>especially considering that it is presumably still the case that 98%
>>>of our genes are shared with chimps.
>>
>>That assumes total number of genes directly
>>correlates with number of traits. Probably not
>>true. Especially because of alternative splicing
>>and post-translational modification to name a few.
>But that's recombinatation, isn't it, which I was just discussing? See
>above.
>>
>>>That would leave only 500 or so to account for
>>>anatomical and physiological differences as well
>>>as all the "modules" in our much more complex
>>>brains.
>>
>>As I said, this comment bears a big assumption
>>that is not justified. Therefore, one cannot use
>>it as evidence in proof against someone's views.
>>Unless they are equally holders of an unjustified
>>assumption. Any proof of that?
>Ignoring my entire argument, you repeat yours. I think a s "splicing"
>or other forms of recombination are concerned, I've made a case that
>you haven't refuted.
OK HERE YOU SAY IT PLAINLY SAYING THAT SPLICING
IS RECOMBINATION. IT ISN'T. ITS PRECISELY
SELECTED FOR. EVERY GENE HAS ALTERNATIVE SPICE
FORMS THAT ARE TEMPORALLY AND TISSUE SPECIFIC.
THAT IS ONE WAY THE COMPLEXITY OF THE GENOME IS
INCREASED WITHOUT INCREASING THE GENE COUNT.
EACH GENE COMES IN PARTS CALLED EXONS THAT ARE
MIXED AND MATCHED IN VARIOUS WAYS TO GENERATE
VARIOUS TRANSCRIPTS WITH SLIGHTLY AND SOME TIMES
WIDELY DIVERGING FUNCTIONS. KINDA LIKE MANY FROM
ONE.
>I have since learned that for some reason , when
>genome students count genes, the count only protein-coding ones. There
>may be RNA coding genes not counted that affect development.
THEY ARE USUALLY COUNTED IN WHAT I READ.
>the
>problem is that different specialties may have different definitions of
>genes.
CERTAINLY THERE IS SOME DISCUSSION OF PRECISE
DEFINITIONS, BUT NOT COMPLETELY DIFFERENT
VERSIONS OF WHAT A GENE IS.
>Certainly in the sense used on the basis of selection, a gene
>need not be protein coding.
SURE SMALL RNA'S, RIBOSOMAL RNA'S LOTS OF
DIFFERENT RNAS. THEY STILL ARE SELECTED FOR THO.
>Ow much of a miscount this might lead to, I
>don't know.
ACTUALLY, THE MISCOUNT COMES FROM THE PRECISE SET
OF CHARACTERISTICS THAT ALL GENES HAVE THAT
VARIES GREATLY. IE. GC RATIO, SPLICE SITE
JUNCTIONS, TRANSCRIPTION START AND STOP SITES,
ETC.
>But I suspect that it may prove to be a significant
>difference. Take faces. They have pretty much uniform protein content,
>but different structure resulting from heritable developmental
>sequences (e.g.,. some bones or fat deposits grow proportionately more
>in some people than in others, and this must be inheritable, accounting
>for facial resemblances between close relatives). If brain
>developmental timing affects functions, which is certainly plausible,
>then maybe EPers would have a way out.
I GUESS MY MAIN POINT IS THAT WHILE I DON'T
ENDORSE THE EP SOCIAL AGENDA, I DON'T THINK THAT
IS JUSTIFIABLE TO SAY CATEGORICALLY THAT BRAIN
STRUCTURES DON'T ARISE FROM INTERACTIONS OF
SPECIFIC SETS OF GENES AND THEIR GENE PRODUCTS.
--
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Jose Morales Ph.D.
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