I don’t think anybody here has said that mutations are not random and not by accident. Mutations are random. Natural selection is not. Mutations simply add to the pool of possibilities on which natural selection acts.
Mutations are random in the sense that they are unpredictable, but not in the sense that they are all equaly likely. There is usually a finite number of ways in which a gene can vary.
Selection upon this variation, upon these mutations, is not random, however. Selection is “guided” by the prevailing conditions in which an organism finds itself; some of those mutations will prove harmful, some may prove beneficial, and some may have no real affect on the organisms one way or the other. In general, those that prove to be beneficial will be favored by selection – meaning, those individuals who possess such mutations will be more likely to survive and reproduce, thereby allowing that mutation to continue on in the gene pool. Eventually, that mutation may become commonplace in the population, to the point that it is now considered a “normal” trait within it.
All the while, however, there is variation of previously “normal” traits. Some animal moves a little bit faster, some predator is just a little better at hunting, some prey is just a little better at hiding, and so on. Each of those variations acted upon by selection to filter out those that do not work as well, while favoring those that work better.
None of this happens “by accident”, however. Selection is non-random, while mutations are more likely to occur in certain situations, and only along certain paths. Humans will probably never grow feathers, for example, because we do not possess the genes, or even the precursors which might eventually serve as a building block for a future feather gene, to produce them.
Darwin’s Finch
Thanks for that explanation. It seems like it would be like the mess we have in the Drosophila genus now. It is split into a number of subgenera, it is hugely polyphyletic, etc. One of the subgenera is Drosophila, so not all Drosophilids are Drosophilidae as I take it. For instance, melanogaster is in another subgenus, Sophophora, so I suppose it would be a Sophophorid. All Drosophilids are in Drosophilinae, though. Adding to insult, another subgenus is actually called Dorsolipha. Freakin’ nomenclature. As I say, phylogeny isn’t my strong point.
The Church might not have killed anybody over this (my professor said something to the otherwise), but they did force Galileo to recant his support for the Heliocentric model.
I expressly noted that there have been periods when the church has demonstrated hostility toward some scientific thought. I deny the broad assertion that the church has tortured and killed scientists for practicing science. (Even the case of Hypatia, in which a pagan scholar was murdered by monks whom the Christian authorities never brought to justice–a genuinely shameful act–was killed as much over city politics in Alexandria as for her “science.”)
While it took the RCC 353 (not 453) years to reopen Galileo’s 1631 trial and declare that he had been shafted, it took fewer than 100 years for the RCC to publicly recogize that the heliocentric model was correct.
Random walk is a reasonable way to desribe it. At each generation, there’s a large chance of introducing a small variation, and a small chance of introducing a large variation. After a sufficiently large number of generations, it’s possible to get just about anywhere from any starting point. Including humans with feathers.
It’s the external influence of the environment that governs what actually does happen.
Note that I’m not disagreeing with you, just trying to help with the explanation.
** Ah, so slaughtering people for practicing the wrong religion is so much better… especially when they’re educated females.
The RCC should never have recognized any model of the universe as correct.
At least it’s more consistent.
You should note that tomndebb used the word “politics”, not “religion”. And I doubt that the words “a genuinely shameful act” were meant to imply your sarcastic “so much better”.
With the benefit of a couple of millenia of hindsight, that may be correct. So what?
I’m tempted to post a few pages of rolleye smileys.