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a review of Reinventing Darwin by Gert Korthof
updated: 27 Jul 2013 (first published: 8 Feb 1998)
 updated 27 Jul 2013 |
Reinventing Darwin has refreshing ideas to offer for those who enjoyed a traditional neo-Darwinistic education and thought that the theory of evolution exists irrespective of who explains it. I learned from Niles Eldredge that scientists such as Maynard Smith, Williams and Dawkins (geneticists) are in fact ultra-Darwinists. He himself, Gould, Stanley and Vrba are presented as the naturalists, all being paleontologists.This book is well written and centres on the conflicting views on evolutionary theory of those naturalists and ultra-Darwinists. There is indeed debate in the book. Niles Eldredge does not recognise 'Normal Darwinists', but probably he would classify evolutionists as Dobzhansky, Mayr and Simpson in that group. Anyway they are neither in the ultra-Darwinist group nor in the naturalist group. Eldridge is a critic of neo-Darwinism. Neo-Darwinism is a 'gene-centered and essentially reductionist approach to evolutionary explanation' and a 'distortedly oversimplified view of the natural world' (page 4). Next we encounter a criticism well-known to creationists: the unjustified extrapolation from generation-by-generation change to change on a geological time-scale. Neo-Darwinism is OK in its proper domain, but when extrapolated outside its proper domain things go wrong. Ultra-Darwinians transform natural selection from a filter to a creative force that shapes organic form. Naturalists however take the existence of large-scale ecosystems seriously. They can't be reduced to changes in gene-frequency. 'Ultra-Darwinians are strangely silent about why adaptive change occurs when it does and why adaptive change does not seem to occur' (p.6). If evolutionary change is inevitable, why do 'living fossils', like Limulus, stay unchanged for 200 million years? Naturalists suggest as a possible explanation in some of such cases 'habitat tracking', that is species move to a suitable environment, in stead off changing their anatomy. I placed Eldredge in the category 'Non-religious critics of orthodox neo-Darwinism' (in fact: 'anti-ultra-Darwinism') and 'pro-evolution', because he does not doubt evolution (common descent).
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 new paragraph 27 Jul 13 |
SexIn the last chapter Eldredge discusses 'Paradoxes in Ultra-Darwinism':"The second paradox is the very existence of sex. If the very name of the game of life is to leave as many copies of your genes behind, why on earth do so many organisms reproduce sexually, thereby limiting themsleves to contributing only half of the genes that go into each descendant? ... the paradox of sex has not yet been resolved. Nor will it just go away." (p. 205)and further down the chapter: "... it is pure folly to mix them with someone else's on a 50–50 basis" (p. 217)Eldredge solution is: "Once we admit that nature might not be so dogmatic about the reproductive imperative, sex ceases to loom as such an intractable problem." (p. 219)It seems to me that individuals and species which are 'not so dogmatic about the reproductive imperative' will soon be outcompeted by species which are very dogmatic about reproduction. Precisely that is what we are seeing in nature: sexually reproducing species outnumber asexually reproducing species. So Eldredge doesn't have a solution... Nine years later, in Why we do it. Rethinking Sex and the Selfish Gene, Eldredge reaffirms the problem of sex: "that sexual reproduction cuts in half the rate at which individuals can spread their genes". "Why didn't the world stay asexual? Why didn't parthenogenesis (production of offspring from a singe, maternal diploid parent) drive sexual reproduction off the game-of-life board?" (p. 47–49). Amazingly, he then states: "But consider this: there is a problem only if we assume that the struggle for existence is really all about the spread of an individual organism's genes. ... then sexual reproduction is no more costly to the individual than asexual reproduction. (p. 49)Well, apparently, the problem has just gone away. But, then why offer DNA repair or any other hypothesis as an explanation for sex at all? And if sexual and non-sexual reproduction are equally costly, then we should predict as many sexual as non-sexual species. But this prediction fails: the majority of species have sexual reproduction. Whether that fact is a big or a small or no problem, it is a fact that demands explanation. Why sex? | |||
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| Copyright © 1998 G.Korthof | First published: 8 Feb 1998 | Update: 27 Jul 2013 F.R.: 27 Aug 2004 |
"Reinventing Darwin. The Great Evolutionary Debate."