tag:blogger.com,1999:blog-264226589944705290.post7552482875316047471..comments2023-11-05T03:45:25.001-08:00Comments on God Plays Dice: Some probabilistic ramblings on evolutionMichael Lugohttp://www.blogger.com/profile/15671307315028242949noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-264226589944705290.post-20536071683703743732008-01-30T22:10:00.000-08:002008-01-30T22:10:00.000-08:00Basically, evolution is made up of a ridiculously ...<I>Basically, evolution is made up of a ridiculously large numer of random decisions, each with a very small effect. There are a lot of classes of combinatorial structures for which we can generate members of the class uniformly at random (or according to some other probability distribution; the details don't matter here) and they'll all basically look the same. Why shouldn't evolution be like that?</I><BR/><BR/>Because evolution <I>isn't</I> like that at all. <BR/><BR/>Evolution <I>is not random</I>.<BR/><BR/>Evolution is literally <I>descent</I> with <I>modification</I>.<BR/><BR/>Evolution is not random, because natural selection (the thing that makes evolution "work") is decidely nonrandom.<BR/><BR/>To an extent the modification part is random - <BR/>for example, mutation is random BUT NOT IID - critical genes are much more carefully conserved than ones we can mostly manage if they don't work so well.<BR/><BR/>Also, sexual reproduction in terms of crossover is random (i.e. in animals, after sperm fertilizes egg there's a random crossover), but at the organism level, it's to a large extent about selection (mate selection, for example) - and the pool of potential reproducers is only going to include the individuals that survive long enough to even try.<BR/><BR/>That's the modification part (how genes change). But the descent part is all about how important the genes were in contributing to the survival and reproduction of the organisms they came from. <BR/><BR/>Now it seems that at the molecular level, there is quite a bit of random drift goes on - mostly with minor effects on the phenotype, and this may turn out to be more important than previously understood - but the nonrandomness and importance of selection is quite well established. I can privide links.<BR/><BR/>It's a bit like noticing the dealer shuffles the cards before dealing a hand of poker, and thereby concluding that the winner at a winner-take-all game will be selected randomly from the participants.Efriquehttps://www.blogger.com/profile/08526031804261484547noreply@blogger.comtag:blogger.com,1999:blog-264226589944705290.post-82401090031109993122008-01-30T19:13:00.000-08:002008-01-30T19:13:00.000-08:00I wonder if you've seen this little exercise in ra...I wonder if you've seen <A HREF="http://www.ted.com/index.php/talks/view/id/146" REL="nofollow">this little exercise</A> in random evolution? Will Wright talks (in this TedTalk) about the soon-to-be-released video game "Spore" which is based on the process of evolution. Can't wait... looks like it's got lots of mathematical underpinnings.Maria H. Andersenhttps://www.blogger.com/profile/04686325011770339309noreply@blogger.com