Despre o conversatie esuata

Sonata a mentionat o dezbatere video pe care nu am postat-o din cauza ca nu am putut urmari o structura disciplinata. Am propus sa ne reintalnim cu un moderator care sa impuna punctele de discutie, si propunerea ramane in picioare. Nu are rost sa contrazic impresiile lui care, fireste, difera de a le mele, atata vreme cat nu puteti urmari emisiunea, pe care am sters-o din lipsa de spatiu pe SSD. Voi raspunde doar la acele obiectii in care Sonata nu citeaza impresii ci afirmatii concrete. Nu imi amintesc exact fiecare cuvant si reactiile descrise de Sonata, dar ii ofer beneficul indoielii pentru a continua conversatia.

Pe parcursul discutiei l-am intrebat daca a auzit de Haldane’s Dilemma. “Nu”, mi-a raspuns.

Deci nu mi-am facut bine lectia. Ca unul gata sa invete oricand si de la oricine, am dat un google cu Haldane si prima pagina s-a umplut imediat cu situri ID si YEC. Nici o lucrare stiintifica. Am trecut la Wikipedia, si dupa primul paragraf am inteles de ce nu am auzit de Haldane.

Haldane’s dilemma is a limit on the speed of beneficial evolution, first calculated by J. B. S. Haldane in 1957, and clarified further by later commentators. Some creationists and proponents of intelligent design claim it remains unresolved. Today, Haldane’s Dilemma is raised mostly by creationists opposed to evolution, who claim it is evidence against large-scale evolution, and a supposed example of negligence on the part of the scientific community.
Haldane stated at the time of publication „I am quite aware that my conclusions will probably need drastic revision”, and subsequent corrected calculations found that the cost disappears. He had made an invalid simplifying assumption which negated his assumption of constant population size, and had also incorrectly assumed that two mutations would take twice as long to reach fixation as one, while sexual recombination means that two can be selected simultaneously so that both reach fixation more quickly.

Mai jos este raspunsul din TalkOrigins:

Haldane’s „cost of natural selection” stemmed from an invalid simplifying assumption in his calculations. He divided by a fitness constant in a way that invalidated his assumption of constant population size, and his cost of selection is an artifact of the changed population size. He also assumed that two mutations would take twice as long to reach fixation as one, but because of sexual recombination, the two can be selected simultaneously and both reach fixation sooner. With corrected calculations, the cost disappears (Wallace 1991; Williams n.d.).

Haldane’s paper was published in 1957, and Haldane himself said, „I am quite aware that my conclusions will probably need drastic revision” (Haldane 1957, 523). It is irresponsible not to consider the revision that has occurred in the forty years since his paper was published.

ReMine (1993), who promotes the claim, makes several invalid assumptions. His model is contradicted by the following:
The vast majority of differences would probably be due to genetic drift, not selection.
Many genes would have been linked with genes that are selected and thus would have hitchhiked with them to fixation.
Many mutations, such as those due to unequal crossing over, affect more than one codon.
Human and ape genes both would be diverging from the common ancestor, doubling the difference.
ReMine’s computer simulation supposedly showing the negative influence of Haldane’s dilemma assumed a population size of only six (Musgrave 1999).

Imi recunosc lacunele in literatura tip ID si YEC, dar Sonata ar fi trebuit sa admita totusi ca in emisiunea Ceasuri moleculare am spus ca notiunea conform careia majoritatea mutatiilor au fost selectate pozitiv este depasita. Acesta este de fapt si unul din argumentele din TalkOrigins:“The vast majority of differences would probably be due to genetic drift, not selection” (3,a).

“Dar de Muller’s Ratchet?” “Nu, nici de asta”.

Sa ne intoarcem la Wikipedia.

In evolutionary genetics, Muller’s ratchet (named after Hermann Joseph Muller, by analogy with a ratchet effect) is a process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner.[1][2] Muller proposed this mechanism as one reason why sexual reproduction may be favored over asexual reproduction. The negative effect of accumulating irreversible deleterious mutations may not be prevalent in organisms which, while they reproduce asexually, also undergo other forms of recombination. This effect has also been observed in those regions of the genomes of sexual organisms which do not undergo recombination.

Atunci cand ma acuza ca nu am auzit nici macar de Mueller’s Rachet, Sonata ignora faptul ca in emisiunea Deus sex machina am prezentat chiar teza lui Mueller mentionata in citatul de mai sus, si ca el m-a contrazis cu privire la validitatea ei. In conversatia noastra, Sonata nu s-a referit la teoria lui Mueller despre evolutia meiozei (pe care eu o sustin si el o respinge) ci la lucrari apologetice din genul ID care, in maniera devenita clasica, mentioneaza termenul “Muller’s Ratchet” intr-un context care lasa impresia ca teza: “the genomes of an asexual population accumulate deleterious mutations in an irreversible manner” ar dovedi ca mutatiile nu pot duce la evolutie. Ca aici. Cu alte cuvinte, Sonata m-a contrazis cu privire la teza numita Mueller’s Rachet dar ma acuza ca nu sunt familiar cu ea asa cum este rastalmacita in literatura creationista.

Ceva mai tarziu l-am intrebat daca este familiar cu dogma centrala a biologiei moleculare. Aici a sarit ca ars cu fierul rosu: “Cine a spus ca este dogma? Cine a venit cu prostia asta”? “Stai linistit omule”, i-am spus, “nu am inventat-o eu si nici vreun alt creationist. Este expresia lui Francis Crick”. “Cum? Crick?? A spus Crick dogma???”

O sa iau caricatura de portret. Cum sa nu sari in sus? Sa-l lasm mai intai pe Crick sa ne explice ce a vrut sa spuna.

I called this idea the central dogma, for two reasons, I suspect. I had already used the obvious word hypothesis in the sequence hypothesis, and in addition I wanted to suggest that this new assumption was more central and more powerful. … As it turned out, the use of the word dogma caused almost more trouble than it was worth. Many years later Jacques Monod pointed out to me that I did not appear to understand the correct use of the word dogma, which is a belief that cannot be doubted. I did apprehend this in a vague sort of way but since I thought that all religious beliefs were without foundation, I used the word the way I myself thought about it, not as most of the world does, and simply applied it to a grand hypothesis that, however plausible, had little direct experimental support.

Sonata vrea sa credem ca “dogma” lui Crick este o dogma in sens religios, cand Crick a vrut sa spuna „ipoteza centrala”. Cu alte cuvinte, pana si Crick ar fi recunoscut ca TE nu este stiinta ci credinta. Reactia mea (pe care Sonata si-o aminteste viscerala) are de a face cu lipsa de onestitate. Atunci cand il intreb pe Sonata daca are alta explicatie decat selectia naturala pentru culoarea verde a brostelor comune dar viu colorata a celor veninoase, nu astept sa schimbam subiectul pe analiza semantica a cuvantului “dogma” la Crick. Astept un raspuns pe care inca nu l-am primit.

Mai departe Sonata pledeaza impotriva emisiunii Ceasuri moleculare si a articolului Algebra evolutiei. Intrucat acestea sunt la indemana oricui, nu simt nevoia sa raspund. Internetul ne ofera acces la surse stiintifice. Oricine poate cauta termeni ca: parsimony, molecular clock, molecular philogenetics, convergent evolution, molecular computational evolution, si sa vada daca bat campii. Cand argumentul cel mai preferat este „se stie”, astept macar o referire la Wikipedia. Nu toata lumea stie ce scrie in literatura ID.