AverageMan wrote:А потом - по каким критериям вы собираетесь различать Давида от кучи мусора? Где универсальная система мер - что есть сложно/просто, красиво/безобразно и т.д?
В нашем примере критерием вполне может быть эстетическое чувство пинающих мусор рабочих
Statistics: Posted by Melkor — 02 Sep 2004 20:58
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А потом - по каким критериям вы собираетесь различать Давида от кучи мусора? Где универсальная система мер - что есть сложно/просто, красиво/безобразно и т.д?
Statistics: Posted by AverageMan — 02 Sep 2004 20:35
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AverageMan wrote:
Существуют мутанты - у которых признак-мутация может оказаться очень к месту именно в условиях изменения среды. Например травоядное с более длинной шеей(результат мутации) сможет лучше приспособится в условиях когда на некой территории начнет пропадать трава. Животное с такой мутацией успешно будет поедать листву с деревьев, в то время когда "нормальные" представители класса начнут вымирать. Соответственно и шанс встретить полового партнера с подобной мутацией у выживших больше. Это упрощенное, конечно описание. Но суть соответствует...
Melkor wrote:Т.е., в популяции в каждом поколении (или, на худой конец, в промежутке нескольких поколений) всегда существуют мутанты, способные выжить в любых условиях, сколь угодно сильно отличающихся от текущих?
Существуют мутанты - у которых признак-мутация может оказаться очень к месту именно в условиях изменения среды. Например травоядное с более длинной шеей(результат мутации) сможет лучше приспособится в условиях когда на некой территории начнет пропадать трава. Животное с такой мутацией успешно будет поедать листву с деревьев, в то время когда "нормальные" представители класса начнут вымирать. Соответственно и шанс встретить полового партнера с подобной мутацией у выживших больше. Это упрощенное, конечно описание. Но суть соответствует...
Что я хотел сказать. Возможных изменений среды очень много (изменение температуры, химического состава, уровня радиации, появление/исчезновение хищников/добычи и т.д.). Поскольку, как Вы утверждаете, сами мутации с ними никак не коррелируют, для выживания вида необходимо, чтобы регулярно рождались мутанты, приспособленные ко всем возможным изменениям. При этом часто (если не всегда) эволюционно продвинутые изменения должны появляться "в комплекте", что еще сильнее снижает вероятность того, что это произойдет случайно. Например, животное с длинной шеей, но недостаточно сильными ногами, или пищеварительным трактом, не приспособленным для переваривания веток деревьев вместо травы, никакими преимуществами перед своими обычными собратьями обладать не будет (а, скорее всего, просто погибнет). И еще раз подчеркну, что при случайных мутациях требуемой для приспособляемости к изменениям среды силы на одну особь с конструктивными нововведениями (пусть даже не для данной среды) будут приходиться миллионы откровенно нежизнеспособных.
"Melkor wrote:В нашем примере можно добавить рабочих, которые, проходя мимо, пинали ногой случайное скопление мусора, если оно им не нравилось - убедительней он от этого не станет.
Melkor. С непредвзятой точки зрения - что высшее животное, что кусок мусора (носитель мультимиллиардных изменений в результате множественных пинков рабочих) - не отличаются. Ваш взгляд строго субъективен (человечен) на этот вопрос. Это как лотерея - тот кто выиграл в лотереи (1 шанс на миллиард) - будет плакать от счастья и считать это чудо или проведение в отношение его. А для организатора лотереи - само собой разумеющая вещь – ведь кто-то должен выиграть...[/quote]
А откуда уверенность, что кто-то обязательно выиграет? Я считаю, что кучу мусора сколько не пинай, "Давидом" Микеланжело она не станет.
Statistics: Posted by Melkor — 02 Sep 2004 19:43
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Melkor wrote:Т.е., в популяции в каждом поколении (или, на худой конец, в промежутке нескольких поколений) всегда существуют мутанты, способные выжить в любых условиях, сколь угодно сильно отличающихся от текущих?
Существуют мутанты - у которых признак-мутация может оказаться очень к месту именно в условиях изменения среды. Например травоядное с более длинной шеей(результат мутации) сможет лучше приспособится в условиях когда на некой территории начнет пропадать трава. Животное с такой мутацией успешно будет поедать листву с деревьев, в то время когда "нормальные" представители класса начнут вымирать. Соответственно и шанс встретить полового партнера с подобной мутацией у выживших больше. Это упрощенное, конечно описание. Но суть соответствует...
"Melkor wrote:В нашем примере можно добавить рабочих, которые, проходя мимо, пинали ногой случайное скопление мусора, если оно им не нравилось - убедительней он от этого не станет.
Melkor. С непредвзятой точки зрения - что высшее животное, что кусок мусора (носитель мультимиллиардных изменений в результате множественных пинков рабочих) - не отличаются. Ваш взгляд строго субъективен (человечен) на этот вопрос. Это как лотерея - тот кто выиграл в лотереи (1 шанс на миллиард) - будет плакать от счастья и считать это чудо или проведение в отношение его. А для организатора лотереи - само собой разумеющая вещь – ведь кто-то должен выиграть...
Statistics: Posted by AverageMan — 02 Sep 2004 01:32
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AverageMan wrote:
Дело в том, что изменение окружающей среды наносит удар по основной массе представителей той или иной популяции, позволяя выжить лишь "генетическим уродам". Про активищзацию мутаций тут речи не идет (хотя тоже тема интересная и неоднозначная). Просто модуль естественного отбора по тому или иному признаку в популяции меняется вслед за изменением среды.
Melkor wrote:Изменение окружающей среды - это вообще не причина
Дело в том, что изменение окружающей среды наносит удар по основной массе представителей той или иной популяции, позволяя выжить лишь "генетическим уродам". Про активищзацию мутаций тут речи не идет (хотя тоже тема интересная и неоднозначная). Просто модуль естественного отбора по тому или иному признаку в популяции меняется вслед за изменением среды.
Т.е., в популяции в каждом поколении (или, на худой конец, в промежутке нескольких поколений) всегда существуют мутанты, способные выжить в любых условиях, сколь угодно сильно отличающихся от текущих?
По-моему, высшие формы жизни больше похожи на идеально выполненную скульптуру, которую строитель Иванов обнаружил на стройке и объяснил случайным накоплением мусора
Почему случайно? Эволюция как раз и осуществляет строгий отбор. И как раз настаивает на строгих причинно-следственных связй развития живого.
Отбор отбором, но речь шла о возникновении изменений. В нашем примере можно добавить рабочих, которые, проходя мимо, пинали ногой случайное скопление мусора, если оно им не нравилось - убедительней он от этого не станет.
Statistics: Posted by Melkor — 01 Sep 2004 22:40
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Melkor wrote:
Ну, мы же уже обсуждали это. Во-первых, для объяснения всего многообразия видов изменений среды явно не достаточно.
Ну, мы же уже обсуждали это. Во-первых, для объяснения всего многообразия видов изменений среды явно не достаточно.
Почему? Что ето за термин такой - "явно"?
Statistics: Posted by Koza — 01 Sep 2004 03:31
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Melkor wrote:Изменение окружающей среды - это вообще не причина
Дело в том, что изменение окружающей среды наносит удар по основной массе представителей той или иной популяции, позволяя выжить лишь "генетическим уродам". Про активищзацию мутаций тут речи не идет (хотя тоже тема интересная и неоднозначная). Просто модуль естественного отбора по тому или иному признаку в популяции меняется вслед за изменением среды.
[quote] По-моему, высшие формы жизни больше похожи на идеально выполненную скульптуру, которую строитель Иванов обнаружил на стройке и объяснил случайным накоплением мусора [quote]
Почему случайно? Эволюция как раз и осуществляет строгий отбор. И как раз настаивает на строгих причинно-следственных связй развития живого.
Statistics: Posted by AverageMan — 30 Aug 2004 02:55
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AverageMan wrote:Melkor. Я скромно не претендовал на заявление что "всего многообразия видов изменений среды явно не достаточно", потому свое сообщения начал с "Одна из причин прозаична". Эта причина имеет место быть. Вторая причина - вирусная эволюция - уже указывалась недавно уважаемым Noskov[ым] Sergey[ем]. Повторюсь - это лишь только то выведено и подтверждено на практике (прямо или косвенно). Если сюда добавить массу теорий (недостатки каждой, имхо, в том что их разработчики тянут одеяло на себя в попытке все объяснить лишь с собственной колокольни) - получится коктейль способный изменять во времени геном достаточно продуктивно. Это без учета еще не открытых механизмов (без привлечения божественных сущностей, есно...) которые объективно существуют (или существовали), наверняка.
Изменение окружающей среды - это вообще не причина, т.к. нужно еще объяснить, почему в этих условиях организмы вдруг начинают мутировать. Ретровирусы - причина произвольных изменений, а не полезных (насколько я понял). Т.е. те же случайные бесцельные перестановки генов, "только в профиль".
Я не специалист (обыватель) - но, имхо, голоса тех которые с кондачка заявляют (имея на руках результаты и сам механизм) - что самой цепи развития не могло быть - очень сильно походит на заявление что "не мог кирпич упасть на голову строителю Иванову без вмешательства некой высшей разумной сущности". И действительно? "Почему именно на голову и именно Иванову?"
По-моему, высшие формы жизни больше похожи на идеально выполненную скульптуру, которую строитель Иванов обнаружил на стройке и объяснил случайным накоплением мусора. Согласитесь, сравнивать их с падением кирпича просто нелепо.
Хотя кирпичи действительно случайно на голову не падают. Это называется Карма.
Statistics: Posted by Melkor — 29 Aug 2004 22:30
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Statistics: Posted by AverageMan — 28 Aug 2004 15:25
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Melkor wrote:
Ха, я помню, что лет в 16 я сам думал точно так же.
Felicie wrote:Elsewhere Dawkins has asserted that "if you meet
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)."
Ха, я помню, что лет в 16 я сам думал точно так же.
Я тоже
Еще я думал что Бога придумали попы для запугивания простого народа и наука доказала что Бога нет... как молоды мы были...
Statistics: Posted by Dmitry67 — 28 Aug 2004 11:44
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AverageMan wrote:
Одна из причин прозаична. "Прогрессивная" мутация - на то и "прогрессивная" (например морозоустойчивость) что бы обеспечит выживание в условиях изменения среды (например - ледниковый период). В то время как "среднестатистические" носители признака выбывают из гонки естественным путем - смерти. То есть - первопричина - изменение среды. Закрепление признака - естественное статистическое следствие этой первопричины.
Melkor wrote:Кроме того, почему особи с "прогрессивными" мутациами успешно выживают и обладают достаточными преимуществами перед остальными, чтобы суметь существенно распространить свой генофонд (по сравнению со среднестатистической особью)
Одна из причин прозаична. "Прогрессивная" мутация - на то и "прогрессивная" (например морозоустойчивость) что бы обеспечит выживание в условиях изменения среды (например - ледниковый период). В то время как "среднестатистические" носители признака выбывают из гонки естественным путем - смерти. То есть - первопричина - изменение среды. Закрепление признака - естественное статистическое следствие этой первопричины.
Ну, мы же уже обсуждали это. Во-первых, для объяснения всего многообразия видов изменений среды явно не достаточно. Во-вторых, образование нового "фичера", который позволит пережить допустим даже изменившиеся условия среды - очень маловероятная вещь и серьезное изменение генофонда. При форсированной мутации на одну удачную особь должны приходиться десятки и сотни миллионов неудачных, с несовместимыми с жизнью дефектами. А т.к. эта продвинутая особь будет в единственном числе (по крайней мере, локально), ее удачная мутация еще и должна уметь передаваться по наследству поверх обычного генотипа.
Statistics: Posted by Melkor — 28 Aug 2004 10:25
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Melkor wrote:Кроме того, почему особи с "прогрессивными" мутациами успешно выживают и обладают достаточными преимуществами перед остальными, чтобы суметь существенно распространить свой генофонд (по сравнению со среднестатистической особью)
Одна из причин прозаична. "Прогрессивная" мутация - на то и "прогрессивная" (например морозоустойчивость) что бы обеспечит выживание в условиях изменения среды (например - ледниковый период). В то время как "среднестатистические" носители признака выбывают из гонки естественным путем - смерти. То есть - первопричина - изменение среды. Закрепление признака - естественное статистическое следствие этой первопричины.
Statistics: Posted by AverageMan — 27 Aug 2004 22:05
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Noskov Sergey wrote:За себя скажу, что есть идеи вирусных эволюций (озвучивались уже), т.е. большую часть генома, составляет ретро-вирусный вариант, который при активации вполне может давать безобразные, ну или прекрасные последствия вплоть до изменения числа хромосом. Кстати у коняшек разное число хромосом между разными видами. Average Man довольно внятно бытописал лоцальные изменения геномов, происходящие гораздо быстрее последовательного отбора и т.д.
Вопрос (как я его понял) был не о том, как могут происходить изменения в принципе, а от том, как могут происходить полезные и работающие изменения, привносящие принципиально новые черты. Очевидно ведь, что при случайном распределении нерабочих вариантов изменений будет несоизмеримо больше, чем рабочих. Кроме того, почему особи с "прогрессивными" мутациами успешно выживают и обладают достаточными преимуществами перед остальными, чтобы суметь существенно распространить свой генофонд (по сравнению со среднестатистической особью), а особи с дефективными мутациами (которых должно быть в миллионы раз больше) не вымириют массово, а лишь носят в себе свои дефекты в более или менее скрытой форме.
Noskov Sergey wrote:Хватать Докинса за разные места можно и нужно наверное, но сперва тщательно его изучив.
CBI как-то постил линк на "Selfish Gene". Его теория (ну или его интерпретация дарвинизма) остроумно обясняет некоторые детали, но вещей, которые она не объясняет, намного больше.
Statistics: Posted by Melkor — 27 Aug 2004 19:51
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Идей что может вызывать быструю эволюцию систем вагон и телега. В куске рецензии цитированном выше, было много откровенных перлов, особенно в рассуждениях о фолдинге и прочих радостях жизни. Видно, что писавший чего-то не допонимает, в общем то и не обязан.
За себя скажу, что есть идеи вирусных эволюций (озвучивались уже), т.е. большую часть генома, составляет ретро-вирусный вариант, который при активации вполне может давать безобразные, ну или прекрасные последствия вплоть до изменения числа хромосом. Кстати у коняшек разное число хромосом между разными видами. Average Man довольно внятно бытописал лоцальные изменения геномов, происходящие гораздо быстрее последовательного отбора и т.д.
Хватать Докинса за разные места можно и нужно наверное, но сперва тщательно его изучив. Вопрос эволюции зрения, в общем то там совсем не ключевой, а скорее одна из иллюстраций. Как уже говорил не Доукинсом единым. Я Вас не записываю в креационисты, не пугайтесь
. Это так ,ремарки к прошедшим спорам. В реалиях схватки идут между популизаторами и полемистами типа Доукинса и Берлинского, тогда как наука потихоньку идет себе вперед.
Statistics: Posted by Noskov Sergey — 26 Aug 2004 22:16
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Noskov Sergey wrote: Поскольку факт эволюции зрения, и конкретно белковых систем отвечающих за ту или иную функцию прекрасно известен, то мне не понятно в чем проблема. Эволюция родопсина прослеживается аж от бактерий до позвоночных. Как Вы и написали к креационизму это отношения не имеет.
Объясню Вам в чём проблема для меня. Мне не даёт покоя не сам вопрос эволюции (его я даже и не обсуждаю), а почему она произошла так быстро. Мне, биологически непосвящённому человеку, кажется поразительным, что столько завязанных между собой изменений произошли за такой короткий промежуток времени. Традиционная теория учит нас, что мутации происходят методом проб и ошибок. И к тому же никто не говорит, что мутации должны происходить постоянно. Ну и что, что существует selection pressure? Из этого же не следует, что организм должен слушаться и выдавать новые полезные мутации на ура? Ведь жизнь спокойно могла и вымереть. Вы и сами писали в этом разделе, что те мутации, которые мы наблюдаем на сегодняшний день обычно смертельны для организма. Поэтому для меня существование компьютерной или математической модели, симулирующей эволюцию и доказывающей, что она действительно могла бы произойти за короткий срок, служило бы, ну если бы не абсолютным доказательством правоты традиционной Дарвиновской модели, то, по крайней мере, доказательством того, что мои сомнения по поводу временной шкалы не имеют под собой основания.
Поэтому мне было интересно прочитать возражения Берлинского. Если я его правильно поняла, его возражения сводятся к тому, что, во-первых, глаз был рассмотрен "в вакууме", без учёта других сопутствующих изменений, а во-вторых, авторы взяли с потолка скорость эволюционных изменений и решили, что каждый полезный шаг (1%) будет происходить в каждом поколении. Но ведь это и есть под большим вопросом, если эволюция происходит спонтанно. Если он прав, то их расчёт в нескольно сотен тысяч лет - неоправданно оптимистичный. "Nilsson and Pelger assume but do not prove the existence of 'a smooth gradient of change, from flat skin to full camera eye, such that every intermediate is an improvement'". А также "the original light-sensitive patch in Nilsson and Pelger's paper was never allowed to undergo 'localized random mutations of its refractive index'". Плюс компьютер они не использoвали. Так что нехорошо получилось, как Докинс переврал их результаты. И этот человек обвиняет других в being wicked. Но это уже другая тема.
Ещё раз для нервных повторяю, что на позициях креационизма я не стою и эволюцию не отрицаю.
Statistics: Posted by Felicie — 26 Aug 2004 21:30
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Когда речь заходит о моделировании эволюции систем, состоящих из миллиардов молекул, тут уже идет упрощение на таком уровне, что найти ряд спорных постулатов проблем особых не вызывает. Т.е. спор идет о пути эволюции и это нормально. А уж когда начинается оценка времени эволюции из построений подобных Сандерсоновскому, вообще тушите свет. Причем ребята часто использую классическую термодинамику для оценок энтропий, средней температуры по палате и прочего, некоторые особенно продвинутые используют неравновесную, но результат в общем то одинаков.
Поскольку факт эволюции зрения, и конкретно белковых систем отвечающих за ту или иную функцию прекрасно известен, то мне не понятно в чем проблема. Эволюция родопсина прослеживается аж от бактерий до позвоночных. Как Вы и написали к креационизму это отношения не имеет.
Statistics: Posted by Noskov Sergey — 25 Aug 2004 21:48
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Модераторы, извините за такую длинную цитату. Этот журнал не в public domain. Поскольку я привожу не всю статью, то надеюсь, что правила форума и копирайта не нарушаю. Здесь Дейвид Берлински критикует компьютерную симуляцию глаза.
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... biologists have long wished for a direct demonstration that something like a functional eye could be formed in reasonable periods of time by means of the Darwinian principles of random variation and natural selection.
Just such a demonstration, I noted in my essay, is what the biologists Dan-Erik Nilsson and Susanne Pelger seemed to provide in a 1994 paper. (1) Given nothing more than time and chance, a "light-sensitive patch," they affirmed, can "gradually turn into a focused-lens eye," and in the space of only a few hundred thousand years--a mere moment, as such things go.
Nilsson and Pelger's paper has, for understandable reasons, been widely circulated and widely praised, and in the literature of evolutionary biology it is now regularly cited as definitive. Not the least of its remarkable authority is derived from the belief that it contains, in the words of one of its defenders, a "computer simulation of the eye's evolution."
If this were true, it would provide an extremely important defense of Darwin's theory. Although a computer simulation is not by itself conclusive--a simulation is one thing, reality another--it is often an important link in an inferential chain. In the case of Darwin's theory, the matter is especially pressing since in the nature of things the theory cannot be confirmed over geological time by any experimental procedure, and it has proved very difficult to confirm under laboratory conditions. The claim that the eye's evolution has been successfully simulated by means of Darwinian principles, with results falling well within time scales required by the theory, is thus a matter of exceptional scientific importance.
And not just scientific importance, I might add; so dramatic a confirmation of Darwinian theory carries large implications for our understanding of the human species and its origins. This is no doubt why the story of Nilsson and Pelger's computer simulation has spread throughout the world. Their study has been cited in essays, textbooks, and popular treatments of Darwinism like River Out of Eden by the famous Oxford evolutionist Richard Dawkins; accounts of it have made their way onto the Internet in several languages; it has been promoted to the status of a certainty and reported as fact in the press, where it is inevitably used to champion and vindicate Darwin's theory of evolution.
In my essay, I suggested that Nilsson and Pelger's arguments are trivial and their conclusions unsubstantiated. I also claimed that representations of their paper by the scientific community have involved a serious, indeed a flagrant, distortion of their work. But in a letter published in the March issue of COMMENTARY, the physicist Matt Young, whom I singled out for criticism (and whose words I have quoted here), repeated and defended his characterization of Nilsson and Pelger's work as a "computer simulation of the eye's evolution." It is therefore necessary to set the matter straight in some detail.
I hope this exercise will help to reveal, with a certain uncomfortable clarity, just how scientific orthodoxy" works, and how it imposes its opinions on the faithful.
HERE IN their own words is the main argument of Nilsson and Pelger's paper:
Theoretical considerations of eye design allow
us to find routes along which the optical structure
of the eye may have evolved. If selection
constantly favors an increase in the amount of
detectable spatial information, a light-sensitive
patch will gradually turn into a focused-lens
eye through continuous small improvements in
design. An upper limit for the number of generations
required for the complete transformation
can be calculated with a minimum number
of assumptions. Even with a consistently pessimistic
approach, the time required becomes
amazingly short: only a few hundred thousand
years.
And here is how they arrived at their conclusions. The setting is "a single circular patch of light-sensitive cells"--a retina, in effect--"which is bracketed and surrounded by dark pigment." A "protective layer" lies above these light-sensitive cells, so that the pigment, the light-sensitive cells, and the protective layer form a kind of sandwich. Concerning the light-sensitive patch itself, Nilsson and Pelger provide no further details, indicating neither its size nor the number of cells it might contain.
What they do assume, if only implicitly, is that changes to the initial patch involve either a deformation of its shape or a thickening of its cells. The patch can be stretched, dimpled, and pulled or pushed around, and cells may move closer to one another, like bond salesmen converging on a customer.
So much for what changes. What is the change worth? Assuming (reasonably enough) that an eye is an organ used in order to see, Nilsson and Pelger represent its value to an organism by a single quantitative character or function, which they designate as "spatial resolution" or "visual acuity"--sharp sight, in short. Visual acuity confers an advantage on an organism, and so, in any generation, natural selection "constantly favors an increase in the amount of detectable spatial information."
There are two ways in which visual acuity may be increased in an initial light-sensitive patch: a) by the "invagination" of the patch, so that it becomes progressively more concave and eventually forms the enclosed interior of a sphere; and b) by the constriction of the sphere's aperture (the two rounded boundaries formed as the flat patch undergoes invagination). These changes may be represented on sheets of high-school graph paper on which two straight lines--the x and y axes of the system--have been crossed. On the first sheet, representing invagination, visual acuity moves upward on one axis as invagination moves to the right on the other; on the second sheet, visual acuity moves upward as constriction moves to the right. The curves that result, Nilsson and Pelger assert, are continuous and increasing. They do not hurdle over any gaps, and they go steadily upward until they reach a theoretical maximum.
The similar shape of the two graphs notwithstanding, invagination and aperture constriction exercise different effects on visual acuity. "Initially, deepening of the pit"--i.e., invagination--"is by far the most efficient strategy," Nilsson and Pelger write; "but when the pit depth equals the width, aperture constriction becomes more efficient than continued deepening of the pit." From this, they conclude that natural selection would act "first to favor depression and invagination of the light-sensitive patch, and then gradually change to favor constriction of the aperture."
THE RESULT is a pin-hole eye, which is surely an improvement on no eye at all. But there exists an aperture size beyond which visual acuity cannot be improved without the introduction of a lens. Having done all that it can do, the pin-hole eye lapses. Cells within the light-sensitive sphere now obligingly begin to thicken themselves, bringing about a "local increase" in the eye's refractive index and so forming a lens. When the focal length of the lens is 2.55 times its radius--the so-called Mattiessen ratio--the eye will have achieved, Nilsson and Pelger write, the "ideal solution for a graded-index lens with a central refractive index of 1.52." (2)
Thereafter, the lens "changes its shape from ellipsoid to spherical and moves to the center of curvature of the retina." A flat iris "gradually forms by stretching of the original aperture," while the "focal length of the lens ... gradually shortens, [until] it equals the distance to the retina ... producing a sharply focused image." The appearance of this spherical, graded-index lens, when placed in the center of curvature of the retina, produces "virtually aberration-free imaging over the full 180 degrees of the visual field."
The same assumptions that governed invagination and aperture constriction hold sway here as well. Plotted against increasing lens formation, visual acuity moves smoothly and steadily upward as a graded-index lens makes its appearance, changes its shape, and moves to center stage. When these transformations have been completed, the result is a "focused camera-type eye with the geometry typical for aquatic animals."
One step remains. Nilsson and Pelger now amalgamate invagination, constriction, and lens formation into a single "transformation," which they represent by juxtaposing, against changes in visual acuity, changes to the original patch in increments of 1 percent. The resulting curve, specifying quantitatively how much visual acuity may be purchased for each 1-percent unit of change, is ascending, increasing, and straight, rising like an arrow at an angle of roughly 45 degrees from its point of origin. Transformations are "optimal" in the sense that they bring about as much visual acuity as theoretically possible, with the "geometry of each stage [setting] an upper limit to the spatial resolution of the eye."
It is the existence and shape of this fourth curve that justify their claim that "a light-sensitive patch will gradually turn into a focused-lens eye through continuous small improvements in design" (emphasis added). This is not the happiest formulation they could have chosen.
HOW MUCH does the initial light-sensitive patch have to change in order to realize a focused camera-type eye? And how long will it take to do so? These are the questions now before us.
As I have mentioned, Nilsson and Pelger assume that their initial light-sensitive patch changes in 1-percent steps. They illustrate the procedure with the example of a flat one-foot ruler that also changes in l-percent steps. After die first step, the ruler will be one foot plus 1 percent of one foot long; after the second step, it will be 1-percent longer than the length just achieved; and so forth. It requires roughly 70 steps to double a one-foot ruler in length. Putting the matter into symbols, [1.01.sup.70] [congruent to] 2.
Nilsson and Pelger undertake a very similar calculation with respect to their initial light-sensitive patch. But since the patch is a three-dimensional object, they are obliged to deal with three dimensions of change. Growing in steps of 1 percent, their blob increases its length, its curvature, and its volume. When all of these changes are shoe-horned together, the patch will have increased in magnitude along some overall (but unspecified) dimension.
The chief claim of their paper now follows: to achieve the visual acuity that is characteristic of a "focused camera-type eye with the geometry typical for aquatic animals," it is necessary that an initial patch be made 80,129,540 times larger (or greater or grander) than it originally was. This number represents the magnitude of the blob's increase in size. How many steps does that figure represent? Since 80,129,540 = [1.01.sup.1,829], Nilsson and Pelger conclude that "altogether 1,829 steps of 1 percent are required" to bring about the requisite transformation.
These steps, it is important to remember, do not represent temporal intervals. We still need to assess how rapidly the advantages represented by such a transformation would spread in a population of organisms, and so answer the question of how long the process takes. In order to do this, Nilsson and Pelger turn to population genetics. The equation that follows involves the multiplication of four numbers:
R = [h.sup.2] x i x V x m
Here, R is the response (i.e. visual acuity in each generation), h is the coefficient of heredity, i designates the intensity of selection, V is the coefficient of variation (the ratio of the standard deviation to the mean), and m, the mean value fur visual acuity. These four numbers designate the extent to which heredity is responsible for visual acuity, the intensity with which selection acts to prize it, the way its mean or average value is spread over a population, and the mean or average value itself. Values are assigned as estimates to the first three numbers; the mean is left undetermined, rising through each generation.
As for the estimates themselves, Nilsson and Pelger assume that [h.sup.2] = .50; that i= 0.01; and that V = 0.01. On this basis, they conclude that R = 0.00005m. The response in each new generation of light-sensitive patches is 0.00005 times the mean value of visual acuity in the previous generation of light-sensitive patches.
Their overall estimate--the conclusion of their paper--now follows in two stages. Assume that n represents the number of generations required to transform a light-sensitive patch into a "focused camera-type eye with the geometry typical for aquatic animals." (In small aquatic animals, a generation is roughly a year.) It, as we have seen, the mean value of visual acuity of such an eye is [1.01.sup.1,829] = 80,129,540, where 1,829 represents the number of steps required and 80,129,540 describes the extent of the change those steps bring about; and if [1.00005.sup.n] = [1.01.sup.1,829 ] = 80,129,540, then it follows that n = 363,992.
It is this figure--363,992--that allows Nilsson and Pelger to conclude at last that "the time required [is] amazingly short: only a few hundred thousand years." And this also completes my exposition of Nilsson and Pelger's paper. Business before pleasure.
NILSSON AND Pelger's work is a critic's smorgasbord. Questions are free and there are second helpings.
Every scientific paper must begin somewhere. Nilsson and Pelger begin with their assumption that, with respect to the eye, morphological change comes about by invagination, aperture constriction, and lens formation. Specialists may wish to know where those light-sensitive cells came from and why there are no other biological structures coordinated with or contained within the interior of the initial patch for--example, blood vessels, nerves, or bones. But these issues may be sensibly deferred.
Not so the issues that remain. Nilsson and Pelger treat a biological organ as a physical system, one that is subject to the laws of theoretical optics. There is nothing amiss in that. But while theoretical optics justifies a qualitative relationship between visual acuity on the one hand and invagination, aperture constriction, and lens formation on the other, the relationships that Nilsson and Pelger specify are tightly quantitative. Numbers make an appearance in each of their graphs: the result, it is claimed, of certain elaborate calculations. But no details are given either in their paper or in its bibliography. The calculations to which they allude remain out of sight, if not out of mind.
The 1-percent steps: in what units are they expressed? And how much biological change is represented by each step? Nilsson and Pelger do not say. Nor do they coordinate morphological change, which they treat as simple, with biochemical change, which in the case of light sensitivity is known to be monstrously complex.
Does invagination represent a process in which the patch changes as a whole, like a balloon being dimpled, or is it the result of various local processes going off independently as light-sensitive cells jostle with one another and change their position? Are the original light-sensitive cells the complete package, or are new light-sensitive cells added to the ensemble as time proceeds? Do some cells lose their sensitivity and get out of the light-sensing business altogether? We do not know, because Nilsson and Pelger do not say.
Biologists commenting on Darwin's theory have almost always assumed that evolution reflects what the French biologist Francois Jacob called bricolage--a process of tinkering. Biological structures are put together out of pieces; they adapt their function to changes in their circumstances; they get by. This suggests that in the case of eye formation, morphological change might well purchases less visual acuity than Nilsson and Pelger assume, the eye being tinkered into existence instead of flogged up an adaptive peak. But if, say, only half as much visual acuity is purchased for each of Nilsson and Pelger's 1-percent steps, twice as many steps will be needed to achieve the effect they claim. What is their justification for the remarkably strong assertion that morphological transformations purchase an optimal amount of visual acuity at each step?
Again we do not know, because they do not say.
More questions--and we have not even finished the hors d'oeuvres. The plausibility of Nilsson and Pelger's paper rests on a single number: 1,829. But without knowing precisely how the number 1,829 has been derived, the reader has no way of determining whether it is reasonable or even meaningful.
If nothing else, the number 1,829 represents the maximum point of a curve juxtaposing visual acuity against morphological transformation. Now, a respect for the ordinary mathematical decencies would suggest that the curve is derived from the number, and the number from various calculations. But all such calculations are missing from Nilsson and Pelger's paper. And if the calculations are not given, neither are any data. Have Nilsson and Pelger, for example, verified their estimate, either by showing that 1,829 1-percent steps do suffice to transform a patch into an eye, or by showing that such an eye may, in 1,829 1-percent steps, be resolved backward into an initial light-sensitive patch? Once again, we do not know because they do not say.
Still other questions suggest themselves. Although natural selection is mentioned by Nilsson and Pelger, it is a force that plays no role in their reasoning. Beyond saying that it "constantly favors an increase in the amount of detectable spatial information," they say nothing at all. This is an ignominious omission in a paper defending Darwinian principles. An improvement in visual acuity is no doubt a fine thing for an organism; but no form of biological change is without cost.
Let us agree that in the development of an eye, an initial light-sensitive patch in a given organism becomes invaginated over time. Such a change requires a corresponding structural change to the organism's anatomy. If nothing else, the development of an eye requires the formation of an eye socket--hardly a minor matter in biological terms. Is it really the case that an organism otherwise adapted to its environment would discover that the costs involved in the reconstruction of its skull are nicely balanced by what would initially be a very. modest improvement in sensitivity to light? I can imagine the argument going either way, but surely an argument is needed.
Then there is Nilsson and Pelger's data-free way with statistics. What is the basis of the mathematical values chosen for the numbers they use in assessing how rapidly transformation spreads in a population of eye patches? The coefficient of variation is the ratio of the standard deviation to the mean. The standard deviation, one might ask, of what? No population figures are given; there are no quantitative estimates of any relevant numerical parameter. Why is selection pressure held constant over the course of 300,000 years or so, when plainly the advantages to an organism of increasing light sensitivity will change at every, step up the adaptive slope? Why do they call their estimates pessimistic (that is, conservative) rather than wildly optimistic?
Finally, Nilsson and Pelger offer an estimate of the number of steps, computed in 1-percent (actually, 1.00005-percent) intervals, that are required to transform their initial patch. At one point, they convert the steps into generations. But a step is not a temporal unit, and, for all anyone knows, each step could well require half again or twice the number of generations they suggest. Why do Nilsson and Pelger match steps to generations in the way they do? I have no idea, and they do not say.
WE ARE at last at the main course. Curiously enough, it is the intellectual demands imposed by Darwin's theory of evolution that serve to empty Nilsson and Pelger's claims of their remaining plausibility.
Nilsson and Pelger assert that only 363,992 generations are required to generate an eye from an initial light-sensitive patch. As I have already observed, die number 363,992 is derived from the number 80,129,540, which is derived from the number 1,829--which in turn is derived from nothing at all. Never mind. Let us accept 1,829 pour le sport. If Nilsson and Pelger intend their model to be a vindication of Darwin's theory, then changes from one step to another must be governed by random changes in the model's geometry, followed by some mechanism standing in for natural selection. These are, after all, the crucial features of any Darwinian theory. But in their paper there is no mention whatsoever of randomly occurring changes, and natural selection plays only a ceremonial role in their deliberations.
At the beginning of their paper, Nilsson and Pelger write of their initial light-sensitive patch that "we expose this structure to selection pressure favoring spatial resolution" (emphasis added), and later that "[a]s the lens approaches focused conditions, selection pressure gradually appears to ... adjust its size to agree with Mattiesen's ratio" (emphasis added). But whatever Nilsson and Pelger may have been doing to their patch, they have not been exposing it to "selection pressure." The patch does only what they have told it to do. By the same token, selection pressures play no role in adjusting the size of their lenses to agree with Mattiesen's ratio. That agreement is guaranteed, since it is Nilsson and Pelger who bring it about, drawing the curve and establishing the relevant results. What Nilsson and Pelger assume is that natural selection would track their results; but this assumption is never defended in their paper, nor does it play the slightest role in their theory.
And for an obvious reason: if there are no random variations occurring in their initial light-sensitive patch, then natural selection has nothing to do. And there are no random variations in that patch, their model succeeding as a defense of Darwin's theory only by first emptying the theory, of its content.
An example may make clearer both the point and its importance. Only two steps are required to change the English word "at" to the English word "do": "at" to "ao" and "ao" to "do." The changes are obvious: they have been designed to achieve the specified effect. But such design is forbidden in Darwinian theory. So let us say instead, as Darwin must, that letters are chosen randomly, for instance by being fished from an urn. In that case, it will take, on average, 676 changes (26 letters times 26) to bring about the same two steps.
Similarly, depending on assessments of probability, the number of changes required to bring about a single step in Nilsson and Pelger's theory" may range widely. It may, in fact, be anything at all. How long would it take to transform a light-sensitive patch into a fully functioning eye? It all depends. It all depends on how likely each morphological change happens to be. If cells in their initial light-sensitive patch must discover their appointed role by chance, all estimates of the time required to bring about just the transformations their theory demands--invagination, aperture construction, and lens formation--will increase by orders of magnitude.
If Darwin were restored to pride of place in Nilsson and Pelger's work, the brief moment involved in their story would stretch on and on and on.
FINALLY, THERE is the matter of Nilsson and Pelger's computer simulation, in many ways the gravamen of my complaints and the dessert of this discussion.
A computer simulation of an evolutionary process is not a mysterious matter. A theory is given, most often in ordinary mathematical language. The theory's elements are then mapped to elements that a computer can recognize, and its dynamical laws, or laws of change, are replicated at a distance by a program. When the computer has run the program, it has simulated the theory.
Although easy to grasp as a concept, a computer simulation must meet certain nontrivial requirements. The computer is a harsh taskmaster, and programming demands a degree of specificity not ordinarily required of a mathematical theory. The great virtue of a computer simulation is that if the set of objects is large, and the probability distribution and fitness function complicated, the computer is capable of illustrating the implications of the theory in a way that would be impossible using ordinary methods of calculation. "Hand calculations may be sufficient for very simple models," as Robert E. Keen and James Spain write in their standard text, Computer Simulation in Biology (1992), "but computer simulation is almost essential for understanding multi-component models and their complex interrelationships."
Whatever the merits of computer simulation, however, they are beside the point in assessing Nilsson and Pelger's work. In its six pages, their paper contains no mention of the words "computer" or "simulation." There are no footnotes indicating that a computer simulation of their work exists, and their bibliography makes no reference to any work containing such a simulation.
Curious about this point, I wrote to Dan-Erik Nilsson in the late summer of 2001. "Dear David," he wrote back courteously and at once,
You are right that my article with Pelger is not
based on computer simulation of eye evolution.
I do not know of anyone else who [has]
successfully tried to make such a simulation either.
But we are currently working on it. To
make it behave like real evolution is not a simple
task. At present our model does produce
eyes gradually on the screen, but it does not
look pretty, and the genetic algorithms need a
fair amount of work before the model will be
useful. But we are working on it, and it looks
both promising and exciting.
These are explicit words, and they are the words of the paper's senior author. I urge readers to keep them in mind as we return to the luckless physicist Matt Young. In my COMMENTARY essay of last December, I quoted these remarks by Mr. Young:
Creationists used to argue that ... there was
not enough time for an eye to develop. A computer
simulation by Dan-Erik Nilsson and Susanne
Pelger gave the lie to that claim.
These, too, are forthright words, but as I have just shown, they are false: Nilsson and Pelger's paper contains no computer simulation, and no computer simulation has been forthcoming from them in all the years since its initial publication. Sheer carelessness, perhaps? But now, in responding to my COMMENTARY article, Matt Young has redoubled his misreading and proportionately augmented his indignation. The full text of his remarks appears in last month's COMMENTARY; here are the relevant passages:
In describing the paper by Nilsson and Pelger ...,
I wrote that they had performed a computer simulation
of the development of the eye. I did not
write, as Mr. Berlinski suggests, that they used
nothing more than random variation and natural
selection, and I know of no reference that
says they did.
... The paper by Nilsson and Pelger is a sophisticated
simulation that even includes
quantum noise; it is not, contrary to Mr.
Berlinski's assertion, a back-of-the-envelope
calculation. It begins with a flat, light-sensitive
patch, which they allow to become concave
in increments of 1 percent, calculating
the visual acuity along the way. When some
other mechanism will improve acuity faster,
they allow, at various stages, the formation of
a graded-index lens and an iris, and then optimize
the focus. Unless Nilsson and Pelger
performed the calculations in closed form or
by hand, theirs was, as I wrote, a "computer
simulation." Computer-aided simulation might
have been a slightly better description, but not
enough to justify Mr. Berlinski's sarcasm at my
expense....
And here is my familiar refrain: there is no simulation, "sophisticated" or otherwise, in Nilsson and Pelger's paper, and their work rests on no such simulation; on this point, Nilsson and I are in complete agreement. Moreover, Nilsson and Pelger do not calculate the visual acuity" of any structure, and certainly not over the full 1,829 steps of their sequence. They suggest that various calculations have been made, but they do not show how they were made or tell us where they might be found. At the very best, they have made such calculations for a handful of data points, and then joined those points by a continuous curve.
There are two equations in Nilsson and Pelger's paper, and neither requires a computer for its solution; and there are no others. Using procedures very. much like Nilsson and Pelger's own, Mr. Young has nevertheless deduced the existence of a missing computer simulation on theoretical grounds: "Unless Nilsson and Pelger performed the calculations in closed form or by hand, theirs was, as I wrote, a computer simulation." But another possibility at once suggests itself: that Nilsson and Pelger did not require a computer simulation to undertake their calculations because they made no such calculations, their figure of 1,829 steps representing an overall guess based on the known optical characteristics of existing aquatic eyes.
Whatever the truth--and I do not know it--Mr. Young's inference is pointless. One judges a paper by what it contains and one trusts an author by what he says. No doubt Matt Young is correct to observe that "computer-aided simulation might have been a better description" of Nilsson and Pelger's work. I suppose one could say that had Dan-Erik Nilsson and Susanne Pelger rested their heads on a computer console while trying to guess at the number of steps involved in transforming a light-sensitive patch into a fully functioning eyeball, their work could also be represented as computer-aided.
MATT YOUNG is hardly alone in his lavish misreadings. The mathematician Ian Stewart, who should certainly know better, has made virtually the same patently false claims in Nature's Numbers (1995). So have many other prominent figures. (3) But misreadings are one thing, misrepresentations another. More than anyone else, it has been Richard Dawkins who has been responsible for actively misrepresenting Nilsson and Pelger's work, and for disseminating worldwide the notion that it offers a triumphant vindication of Darwinian principles.
In a chapter of his 1995 book, River Out of Eden, Dawkins writes warmly and at length about Nilsson and Pelger's research. (4) Here is what he says (emphasis added throughout):
[Their] task was to set up computer models of
evolving eyes to answer two questions ... [:] is
there a smooth gradient of change, from flat
skin to full camera eye, such that every intermediate
is an improvement? ... [and] how
long would the necessary quantity of evolutionary
change take?
In their computer models, Nilsson and Pelger
made no attempt to simulate the internal
workings of cells.
... Nilsson and Pelger began with a flat
retina atop a flat pigment layer and surmounted
by a flat, protective transparent layer. The
transparent layer was allowed to undergo localized
random mutations of its refractive index.
They then let the model transform itself at random,
constrained only by the requirement that
any change must be small and must be an improvement
on what went before.
The results were swift and derisive. A trajectory
of steadily mounting acuity led unhesitatingly
from the flat beginning through a shallow
indentation to a steadily deepening cup, as
the shape of the model eye deformed itself on the
computer screen.... And then, almost like a conjuring
trick, a portion of this transparent filling
condensed into a local, spherical region of
higher refractive index.
... This ratio is called Mattiessen's ratio.
Nilsson and Pelger's computer-simulation model
homed in unerringly on Mattiessen's ratio.
How very remarkable all this is--inasmuch as there are no computer models mentioned, cited, or contained in Nilsson and Pelger's paper; inasmuch as Dan-Erik Nilsson denies having based his work on any computer simulations; inasmuch as Nilsson and Pelger never state that their task was to "set up computer models of evolving eyes" for any reason whatsoever; inasmuch as Nilsson and Pelger assume but do not prove the existence of "a smooth gradient of change, from flat skin to full camera eye, such that every intermediate is an improvement"; and inasmuch as the original light-sensitive patch in Nilsson and Pelger's paper was never allowed to undergo "localized random mutations of its refractive index."
And how very remarkable again--inasmuch as there are no computer "screens" mentioned or cited by Nilsson and Pelger, no indication that their illustrations were computer-generated, and no evidence that they ever provided anyone with a real-time simulation of their paper where one could observe, "almost like a conjuring trick," the "swift and decisive" results of a process that they also happen to have designed.
And yet again how very remarkable--inasmuch as Nilsson and Pelger's "computer-simulation model" did not home in unerringly on Mattiessen's ratio, Nilsson and Pelger having done all the homing themselves and thus sparing their model the trouble.
Each and every one of these very remarkable assertions can be explained as the result of carelessness only if" one first indicts their author for gross incompetence.
...
(1) "A Pessimistic Estimate of the Time Required for an Eye to Evolve," Proceedings of the Royal Society, London B (1994) 256, 53-58. In my essay I twice misspelled Susanne Pelger's name, for which I apologize.
(2) A graded-index lens is a lens that is not optically homogeneous; the figure of 1.52 is "the value close to the upper limit for biological material."
(3) Among those who, by contrast, have raised (on the Internet) points similar to my own, I would single out especially Brian Harper, a professor of mechanical engineering at Ohio State University.
(4) A version of the same material by Dawkins, "Where D'you Get Those Peepers," was published in the New Statesman (July 16, 1995).
Statistics: Posted by Felicie — 25 Aug 2004 20:57
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Felicie,
Хо (это она) биохимик, занимавшийся всю жизнь био-энергетикой и потом немного генетикой. Я была на ее лекции в Корнелле по поводу страшной угрозы ГМ продуктов и вообще всякой такой социальной деятельностью около науки. Яркая личность, с ее трудами в области эволюционной теории не знаком, Саундерсовская статья попадалась давно (95???), ответ попался позднее.
Дело было так: Саундерс предложил ряд уравнений (разработанных впрочем до него), описывающих эволюцию био-системы как результат изменений внешней среды (средняя темперетура по моему evolution by physics not by species biology). Там было много всяких фенек, типа температура каждой специи, альбедо планеты и прочей дребедени.
В итоге выяснилось , что ребята забыли внести довольно важную поправку, в исходной модели считалось что планета способна адаптировать био-мир под любые внешние условия. При введение разумных ограничений все возвращается на круги Дарвиновской эволюции. Почему температура важна? В модели Сандерса были белые и черные ромашки, которым считалась температура, черные были всегда теплее. Модель почистили очень просто, взяли известные данные по максимальным температурам стабильности липидов-мембран (50 С) Итоговая модель получилась вполне Дарвиносвской. За деталями надо лезть в статьи.
Я лично к подобным упрощенческим схемам отношусь скорее отрицательно. У меня был пример классного стат. механика и прекрасного физика который попытался применить аппарата стат.механики неравновесных процессов к анализу фондового рынка, конечно он написал пару статей в Nature на эту тему, но аппарат не фига не работал как надо.
Statistics: Posted by Noskov Sergey — 25 Aug 2004 14:32
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KYKAH wrote:Подпишусь под каждым словом:
К сожалению, Наука и Жизнь на Привете, похоже, это правило подтверждает.
Code:
Elsewhere Dawkins has asserted that "if you meet
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)." Such
shrill, juvenile reactions suggest not a scientific but a quasi-religious
sensibility threatened by any challenges to its orthodoxy. К сожалению, Наука и Жизнь на Привете, похоже, это правило подтверждает.
А Вы книги Dawkinsa читали? Или подпишитесь, судя по тому что о нем думает неизвестный автор (как и полагается начинающему фундаменталисту
) Можете привести ссылку на то место, где Ричард Докинс утверждает то, что ему приписывают выше?
Statistics: Posted by CBI — 25 Aug 2004 13:25
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Felicie wrote:Elsewhere Dawkins has asserted that "if you meet
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)."
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)."
Ха, я помню, что лет в 16 я сам думал точно так же.
Statistics: Posted by Melkor — 24 Aug 2004 22:23
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Code:
Elsewhere Dawkins has asserted that "if you meet
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)." Such
shrill, juvenile reactions suggest not a scientific but a quasi-religious
sensibility threatened by any challenges to its orthodoxy. К сожалению, Наука и Жизнь на Привете, похоже, это правило подтверждает.
Statistics: Posted by KYKAH — 24 Aug 2004 22:02
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Noskov Sergey wrote: В общем то было несколько статей, которые показывали что ограничения самой модели вполне себе определяли развитие системы. Так бывает...
Не могли бы Вы в двух словах пояснить?
Statistics: Posted by Felicie — 24 Aug 2004 21:47
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Имена многих дебатирующих я знаю и примерно знакома с их позицией. Следила за дебатом Дейвида Берлинского и его оппонентов в Комментари, и мне его аргументация показалась обоснованной. Он довольно подробно отвечал на контр-аргументы оппонентов и парировал их. Это всё, что я, как неспециалист, могла оценить. Книжку я эту обязательно достану и прочитаю. Меня лично интригует теория интелледжент дизайна, потому что она снимает вопрос, каким образом мутации могли происходить за такое короткое время - например домашняя свинья одичала на островах за какие-то 100 лет (про компьютерную модель эволюции зрения я читала, но её критиковали). Мне представляется вполне возможным, что может существовать в природе некий ещё неоткрытый процесс информационного обмена. Может быть биологические системы работают, как компьюторы и просчитывают всякие варианты. Любой обмен мнений на эту тему буду читать с большим интересом.
Прo Petera Saundersa я значит перепутала. Думала, что он биолог. Но его соавтор, Mae-Wan Hо точно биолог. Книга, которую они редактировали - Beyond Neo-Darwinism - уже второй или даже третьей свежести - аж 84 года, но её до сих пор часто цитируют (в философской литературе). Так что Вы, Сергей, наверняка знаете куда больше моего про последниe модели. Мне бы было очень интересно Ваше мнение о дебате Берлинского.
Но очень важный вопрос, который также поднят в этой статье - это вопрос научной этики. Я твёрдо верю, что учёные должны keep an open mind, а не превращать научное yчение в догму. То, что Докинс сказал, как там цитируется - это просто несерьёзно. Когда критики пишут, что такой подход близок к религии, я с ними согласна. (Я вообще скептически отношусь к радикальному редукционизму. Но будущее покажет).
Statistics: Posted by Felicie — 24 Aug 2004 21:40
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Сандерс (Sounders PT?) не биолог, он математик. Речь очевидно идет о его "daisyworld " модели, крайне примитивной и работающей без механизма естественного отбора. Его читали и мы (закоренелые Дарвинисты) даже читали :
Lenton TM, Lovelock JE
Daisyworld is Darwinian: Constraints on adaptation are important for planetary self-regulation
JOURNAL OF THEORETICAL BIOLOGY 206 (1): 109-114 SEP 7 2000
В общем то было несколько статей, которые показывали что ограничения самой модели вполне себе определяли развитие системы. Так бывает...
Т.е. создать пару уравнений "описывающих" отношения на гипотетической 1-D (2-D??) планете с гипотетическими взаимодействиями вещь классная, но она не соответствует самой эволюции напрямую. Возможно, что у Вас имеются какие либо другие данные, был бы очень рад их узнать.
Кстати искуственных моделей эволюции вагон и телега, даже более обоснованных чем названные Вами.
В некоторых топиках ниже, обсуждались вероятные пути "эволюции", отличные от дарвиновского или "нео-Дарвинского = Доукинсовского пути". Они вполне вероятны, но противостояние в основном идет между креационистами и не, а уж внутри эволюционной теории столько под-теорий.
Statistics: Posted by Noskov Sergey — 24 Aug 2004 18:44
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Felicie wrote:Вообще-то хорошо бы прочитать вначале книгу прежде, чем делать подобные заключения.
А Вы какие-нибудь современные научные или научно-популярные книги по эволюции читали?
Statistics: Posted by CBI — 24 Aug 2004 16:42
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Statistics: Posted by OtecFedor — 23 Aug 2004 20:17
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August 17, 2004
Challenging Darwinian Fundamentalism
by Bruce Thornton
Book review for Private Papers
Uncommon Dissent. Intellectuals Who Find Darwinism Unconvincing, ed. William
A. Dembski (ISI Books)
If you believe what you hear in the mainstream media, the critics of
Darwinian evolution are all wild-eyed creationists who believe that Genesis
literally describes the origins of life, and so are equivalent, as William
Dembski says in his Introduction, to a "holocaust denier, a flat-earther, or
a believer in horoscopes." Arrayed against them are those presumed paragons
of rational thought who simply believe what the facts of science have
established as the truth. It doesn't take much to figure out who the media
thinks wears the white hat-- all those enlightened sophisticates who are
protecting us from the narrow-minded fundamentalists itching to take us and
our children back to the dark ages of ignorance and superstition.
As usual, the media have it backwards. Although creationists use the work of
Darwin's critics, most of the latter are not advancing the creationist or
any other religious view of life's origins. Instead, they are doing what
scientists and intellectuals are supposed to do: exercise "a hungry mind and
a willingness to question received opinion," as John Wilson says in his
Foreword. After all, isn't that how science works, through a relentless
skepticism that subjects each and every theory to the questioning of its
assumptions and claims, not to mention the evidence that is supposed to
support both? As this collection of essays shows, the best critics of
Darwinian evolution are precisely that: intellectuals and scientists
scrutinizing the claims of Darwinian theory, and pointing out its flaws and
weaknesses. As Edward Sisson says in "Teaching the Flaws in Neo-Darwinism,"
"The proponents of intelligent design whom I find persuasive do not argue
that evolution must be suppressed because of some conflict with the Bible.
Instead, they argue that unintelligent evolution should be questioned
because the scientific evidence offered to support it is weak."
In fact, frequently it is the Darwinians who display an intolerance of
dissent and impatience with criticism more typical of the fundamentalist
mentality, as evidenced by the readiness with which some Darwinians resort
to ad hominem attacks and personal disparagement of their critics. One
tactic is simply to avoid any argument and label a critic with the
scare-epithet "creationist," as arch-Darwinist-popularizer Richard Dawkins
did in response to David Berlinksi's article in Commentary magazine
(reprinted in Uncommon Dissent along with other readers' responses and
Berlinski's replies). Elsewhere Dawkins has asserted that "if you meet
somebody who claims not to believe in evolution, that person is ignorant,
stupid, or insane (or wicked, but I'd rather not consider that)." Such
shrill, juvenile reactions suggest not a scientific but a quasi-religious
sensibility threatened by any challenges to its orthodoxy.
Another tactic used to dismiss critics of Darwinism is to smugly assert that
all criticisms have been answered and so should no longer be taken
seriously. For example, Michael Behe's idea of "irreducible complexity"
argues that the finely calibrated biochemical mechanisms regulating cell
function could not have been created by the accumulation of incremental
random mutations selected for survival value, since the many parts that
perform the function must be present at the same time. As Behe says in the
current volume, "Irreducibly complex systems are headaches for Darwinian
theory because they are resistant to being produced in the gradual,
step-by-step manner that Darwin envisioned."
Yet according to Andrea Bottaro, writing for the National Center for Science
Education, the idea of irreducible complexity has been "delivered a fatal
blow" by a computer simulation that used "undirected random mutation and
selection" to create an "irreducibly complex" outcome. This assertion is
supported by two references, yet when these are analyzed, as Dembski does in
his essay, the "fatal blow" turns out not even to be a flesh wound. The
first reference, as Dembski notes, merely points "the reader to the
rationalizations employed by the biological community for sidestepping the
challenge posed by irreducible complexity." The second refers to the
computer simulation that "built into the simulation what they [the authors]
thought evolution needed to make it work" and so "presupposed the very point
at issue."
For many defenders of evolution, Darwinism indeed is part of a religious
system whose tenets are as much a consequence of faith as of reason. This
religion is atheism, a belief that arises not from evidence but from faith,
as any sophomore philosophy major can tell you. The first principle of
atheism is materialism: the belief, equally unproven by science, that all
reality is material and so everything must be explained by material causes
and forces blindly following the laws of physics. In other words, as Robert
C. Koons notes, "Darwinism has been part of a metaphysical attack on the
very idea of agency, both human and superhuman, that has been ongoing for
two hundred years."
Thus Darwinism, like Freudianism and Marxism, is another example of
modernity's attack on the very idea of the human, a reduction of people to
mere things in the world completely determined by the brute forces of
nature. Needless to say, to dismiss free will and spiritual reality is to
make not a scientific claim, but rather a philosophical or a religious one:
"What the science educators propose to teach as 'evolution," Phillip E.
Johnson notes, "and label as fact, is based not upon any incontrovertible
empirical evidence, but upon a highly controversial philosophical
presupposition." God, however, has not been done away with by evolution; all
his creative and purposive powers have now been bestowed on "random
mutations" and "natural selection."
Recognizing the non-scientific roots of a commitment to Darwinism helps
explain the reluctance of many to deal with the problems with the theory.
Some of these problems are logical, such as the circular reasoning of
Darwinian evolution: "Time and time again," David Berlinski writes,
"biologists . . . explain the survival of an organism by reference to its
fitness and the fitness of an organism by reference to its survival." It
reminds me of Pangloss's belief that noses were designed to support
spectacles. Or consider the problems created by a commitment to a
purposeless universe. The evolutionary process is driven by random mutations
that by sheer accident improve a creature's fitness for survival and
reproductive success. But isn't the drive to survive and reproduce a
goal-driven purpose supposedly impossible in the Darwinian scheme? "What is
it," James Barham asks, "about living matter that makes it care about its
own self-preservation?" There might be a scientific answer to this question,
but evolutionary theory so far hasn't provided it.
Then there is the uncomfortable lack of fossil evidence supporting
evolution: "The fossil evidence," Johnson notes, "is very difficult to
reconcile with the Darwinist scenario. If all living species descended from
common ancestors by an accumulation of tiny steps, then there once must have
existed a veritable universe of transitional intermediate forms linking the
vastly different organisms of today, such as moths, trees, and humans, with
their hypothetical common ancestors." Yet when forced to acknowledge the
appearance in the fossil record of numerous species already fully formed, as
in the "Cambrian explosion" of species 600 million years ago, apologists for
evolution advance a variation of the "dog ate my homework" argument: there
is a gap in the fossil record because for some reason the fossils didn't
survive. The issue is not that a few apparently transitional fossils like
that of archaeopteryx, the feathered dinosaur, exist, but that millions more
don't.
Darwinian evolution increasingly resembles the old Ptolemaic picture of the
universe, in which all the planets revolved around a stationary earth. Over
the years those committed to it on the basis of faith in biblical authority
adjusted the model to account for new evidence, until finally the evidence
against the model became so overwhelming that its core assumption, a central
stationary earth, had to be discarded. A new instrument, the telescope,
provided the new evidence that did in the geocentric cosmos. So too today:
new observational instruments have revealed the biochemical and genetic
bases of life whose remarkably intricate complexity pose powerful challenges
to the Darwinian picture of gradually accumulated random changes.
Proteins, for example, must "fold" into a particular shape before they can
perform a function in the cell. But as Roland F. Hirsch observes, "This
folding process is possible only because it is guided. A process of folding
in which the protein chain bends entirely in random ways could not achieve
the functional fold of that protein in any useful period of time." When one
considers the incredible number of proteins necessary just for one cell to
function, not to mention their interconnections, then one is faced with the
question Hirsch raises: "How could a function requiring multiple proteins in
a cellular machine ever arise through the required random mutations that
developed, one protein molecule at a time and in a stepwise manner;
mutations that provided no intermediate product with any function that would
allow Darwinian natural selection to work?"
So too with the DNA that encodes the pattern of about 250 amino acids that
make up a protein. An estimate cited by Berlinksi puts the number of viable
proteins at ten to the fiftieth power-the raw material of all life that has
ever existed. Yet the number of "all possible proteins of a fixed length
(250 [amino acid] residues, recall) is computed by multiplying twenty by
itself 250 times (twenty to the 250th power)." Yet we are supposed to
believe that the tiny subset of proteins that makes possible all living
things arose by accident out of that vast ocean of possibility. This is
about as likely as thousand monkeys randomly pounding typewriter keys and
producing even one line of Shakespeare, which cannot happen unless something
can save the right letters when they are accidentally hit upon, because that
"something" knows what the target line is. In evolution, that "something" is
natural selection, which is now given the powers of purpose, intention, and
design once reserved for God.
The point ultimately of this valuable collection is not, contrary to what
the media would have you believe, that the biblical account of creation
should be taught in schools. Rather, it is that scientists should behave as
scientists and be willing to question their own assumptions and meet
criticism with reasoned debate rather than with insult, caricature, and
appeals to authority. Skepticism is science's most valuable tool; its
absence among too many advocates of Darwinian evolution suggests that
something other than science is driving their beliefs.
2004 © Bruce Thornton
Statistics: Posted by Felicie — 23 Aug 2004 00:36
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