This is an archive of past discussions about Natural selection. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.
As a visitor to this page, I found the opening paragraph to be confusing:
Natural selection is the process by which biological individuals that are endowed with favorable or deleterious traits end up reproducing more or less than other individuals that do not possess such traits. Differential reproduction imposed by random factors is normally not considered to be an instance of natural selection because natural selection requires that differential reproduction be caused by differences between individuals. When a superior trait is heritable so that in the next generation one observes more individuals displaying the trait, one speaks of adaptive evolution by natural selection. Evolution, therefore, can involve changes not driven by natural selection; and natural selection is not sufficient for evolutionary change to take place, let alone for adaptive evolutionary change (since the latter requires that the selected traits be heritable). In general, however, adaptive evolution requires natural selection because the possibility that favorable traits become more frequent across generations due to random fluctuations in trait occurrence, is negligible (see genetic drift). Favorable traits that owe their occurrence in a population to the fact that the genes encoding them were enriched in the population through evolution by natural selection are called adaptations.
What does "Differential reproduction" mean?
What "factors" does "random factors" refer to?
What does "adaptive evolution" mean? Is this somehow different from "regular" evolution?
Is the line, " requires that differential reproduction be caused by differences between individuals", tautological?
Why does it start discussing Evolution when its role in evolution hasn't even been raised?
What is a "superior trait"? (It seems to me that an audience that knows these terms wouldn't be reading an introductory article on NS.)
How do you "enrich" a gene?
Couldn't it be (alot) shorter?
In any case, it is virtually opaque, and mostly incoherent. I tried to edit it but was reverted. Which is fine, but at least replace it with something readable. Limbo socrates20:00, 30 December 2005 (UTC)
if you read the text carefully you will see that all your questions are already answered.
nobody will mind if you make the english more precise but please do not change the content unless you are fully positive that there is an error or omission. same regarding succintness, but do not forget that often repeating something in technical terms is not "redundant". Marcosantezana04:33, 31 December 2005 (UTC)
Some observations
First, I agree that the Wikipedia:Lead section is too long, it attempts to be rigorous and exhaustive rather than introducing material to come. I suggest deleting the second paragraph, the history is better covered in the section lter on, and the rest doesn't pay it's rent. The second paragraph, the one that deals with levels of selection, is a topic that deserves to be expanded to a section in the main body (and eventually an article unto itself). The fourth, fifth & sixth paragraphs need to be tightened up if they are to stay in the lead section, or merged into the appropriate sections of the main article. The last paragraph of the lead section is redundant, repeating what is in the initial paragraph. I think that would bring the introduction closer to the Wikipedia:Manual of Style and make it do the job of introducing better.
I believe Marcos intends "adaptive evolution" to mean "evolution that is not mere genetic drift", ambiguous. Certainly could use cleaning up.
The sentence "requires that differential reproduction be caused by differences between individuals" isn't tautological because a huge amount of variance in reproductive success has more to do with stochastic environmental effects than individual variation.
pete is right about the imbalance but that conclusion assumes that the remaining parts of the article are done deals. i consider instead that the remaining parts need to be expanded a lot. once they will be the intro will not feel that long anymore. the article should be considered under construction. another possibility would be to consolidate the whole thing into a single piece of text without repetitions and then subdivide, etc (or not). also, i tried to mention in a very quick way the main issues related to selection to make sure they are there right away so that the reader gets the punch line immediately and can then choose to look for in-depth treatment in the remaining of the article or via links. that's why darwin is still there (i found it there btw before i started contributing and i thought it made sense when i saw it albeit i wanted to have a merely conceptual abstract intro), not as exhaustive treatment of the history but as a express teaser and as context that stresses why evolution by natural selection was so well received when it was proposed Marcosantezana15:14, 31 December 2005 (UTC)
I do not think anyone is suggesting changing the content of the article itself. But I think we should consider changing the content of the opening paragraph - NOT to make it inaccurate, but to make it more accessible. I am well-versed in evolutionary theory, and while I understand the opening paragraph I can easily see how non-specialists would find it confusing and daunting. I think the problem with the contents of the opening is it is a summary or abstract of the whoole article. My suggestion is to see the first paragraph as a real "introduction," stating in the simplest of terms what natural selection means, who developed the theory, and why it is importnt - and leave it to the body of the article to go into all of the details. I do not think I am disagreeing with any of the participants in this discussion, just adding another angle. Slrubenstein | Talk18:43, 31 December 2005 (UTC)
good intentions won't eliminate the fact that the article is not done and won't be for a while. so one should avoid talking about what the best introduction to a finished article would be when the article is not finished. on the other hand one has to make sure the the content is correct and complete for people who are using the article as reference right now. the intro part as it is now is complete regarding the crucial issues, but the following parts are quite "narrative". of course if the first part is daunting it should be clarified and made more reader-friendly. please let's all try to rephrase things so the text becomes clearer. however, do think that when people find a long article they often read only the beginning so one should not give them a sense that things are easy since in that case they tend to let their prejudices fill the gaps. a complete summary-like "introduction" will function both as a summary for readers and as guidance for further expanding the article. but it does not have to be written in obscure sentences or like a children's encyclopedia. Marcosantezana19:28, 31 December 2005 (UTC)
I'd like to point out that the WP style guide suggests 2-3 paragraphs of lead section. It's just too long now, and much of the material that is in there is simply not introductory. I'm under no illusions that the rest of the article is done. Marcos has put a lot of work into this, but clearly there's a lot more to do. Some of this will be accomplished by moving stuff out of the lead section into the rest of the article. As for the rigour vs. simplifiying/"dumbing down" of the lead section, I'd just like to point to the style guide.
"It is even more important here than for the rest of the article that the text be accessible, and some consideration should be given to creating interest in reading the whole article"
"Begins with a definition or clear description of the subject at hand. This is made as absolutely clear to the nonspecialist as the subject matter itself will allow."
"The purpose of an encyclopedia is to codify human knowledge in a way that is most accessible to the most people, and this demands clear descriptions of what the subject matter is about. So we aren't just dropped into the middle of the subject from the first word"
I think the aim should be to say nothing *wrong* in the lead section, but to say less. Following that Saint Exupery "perfecton is not acheived when there's nothing more to add, but when there's nothing more to be taken away" kind of a way. Everything in the lead section has to pay it's rent, otherwise it goes into the main body, or gets the chop. Best Regards, Pete.Hurd19:48, 31 December 2005 (UTC)
citing the high standards of wiki won't make the article any better or make it any more useful to the people who will use it as reference. so let's see who can write the wonder intro paragraph. it has to mention differential reproduction due to differences in biological performance which are themselves the result of phenotypic differences between the relevant units of selection. it is wrong to commit to individuals, to adaptation, and to genetic differences as the cause of the trait and fitness differences. furthermore i do not see where in the remaining paragraphs a lot of crucial intro stuff could fit. it's up to you to propose where you want to put it. and remember that an article that looks good cannot be the only goal since wiki is about knowledge for others rather than about pleasing our esthetic senses or adhering to wiki's revealed standards of presentation (which are only meant as flexible quidance, btw). finally with the exception of the historical stuff, my personal opinion is that the stuff after the introduction is superfluous. if i did not get rid of it it's only because i did not want to break any eggs. Marcosantezana00:20, 1 January 2006 (UTC)
I think the opening is much clearer now (I am not arguing that it cannot be improved upon) but I think the question now is, how much of the material in the opening can be moved into the body? Slrubenstein | Talk23:12, 4 January 2006 (UTC)
great job. some word choices are awkward, some content got lost, etc, but these are small details. congratulations. however, the too-long-intro argument may come back but i think one should simply accept that the following sections have not yet reached their full length. Marcosantezana02:10, 5 January 2006 (UTC)
Aye, nice work. I don't think the intro too long problem went away at all... but I'd say that the too long intro problem isn't the biggest problem. I do think that keeping the intro down to 2-3 paragraphs will improve the article as a whole as the problems with the rest of the article incorporate stuff now in the intro. Pete.Hurd03:24, 5 January 2006 (UTC)
clap, clap, clap Nice job! It is a longer opening but it hits the real important stuff right off. By the third paragraph I felt I had the gist of it. --Limbo socrates23:03, 6 January 2006 (UTC)
Thanks! And thanks for calling attention to it. Wikipedia is always a work in process, but it helps when people such as yourself can pinpoint places that need more attention. I'm sure as other editors keep working on this it will get even beter, Slrubenstein | Talk23:14, 6 January 2006 (UTC)
Criticisms of Natural Selection
I've noticed that the pages dealing with creationism enjoy a healthy representation of critiques and opposing viewpoints, which this page does not. I think including a section that deals with this issue is important for a couple reasons.(Or--better yet--relocate one of the better articles dealing with the point I'm about to make as a section of this article or--failing that--at least link to one of them. BTW, there are at least two or three of those articles and someone should probably erase the lesser quality ones.)
First, from a philosophical perspective, the concept of natural selection seems to be a tautology or truism. As this article states, natural selection represents the view that nature presents the most adaptable (and most likely to produce thriving offspring) specimens with the carrot of survival and the least adaptable(and the less likely to produce offspring) with the carrot of extinction in order to ensure the survival of the fittest. But what places one in the category of "fittest"? It seems that the fittest would have to be those that successfully reproduce. In essence, we say that natural selection is the device that ensures that the fittest will reproduce while identfying the fit as those that reproduce. Given this, it seems that natural selection is the secularist counterpart to the Cartesian circle.
Secondly, Darwin made this point:"For I am well aware that scarcely a single point is discuss in this volume on which facts can be adduced, often apparently leading to conclusions directly opposite to those which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on each side of the question." On this point, I agree with the man. We need a discussion of substance on this issue. Today, the debate concerning evolution is mainly carried out by narrow-minded assholes like Steven Pinker and Pat Robertson. Let's not be like them. Let's give each view representation and debate the resulting positions on their merits--the view that creationists are idiots and that evolution is an errorless and universally accepted explanation for the origin of the species is lazy and cartoonish.Eskatos13:21, 21 January 2006 (UTC)
the fallacious tautology "argument" (advanced in 1976 by the shrewd rh peters and later by many other conceptuologists) is demolished in the article text indirectly (in the way it was done by elliot sober). i made sure to cover it since it's quite loved among naive "conceptual" people. you should please reread the article and consider to start thinking before delivering stale lines that have already been debunked in the literature and even under your own nose. but if everybody wishes explicit treatment of this idiocy i can provide it, but i personally do not think it belongs in the article. Marcosantezana16:25, 21 January 2006 (UTC)
I can think no other criticisms than the thoughoughly debunked "tautology" argument that belong in Natural Selection. Your second point pertains more to Evolution, not Natural Selection. Natural Selection was identified as a mechanism for maintaining Platonic ideal types under a creationist view before Darwin came along (natural selection removed the forms which deviated excessively from the true form). It might be worthwhile to have a section framing and debunking the "tautology" hoo-haw, just to make it super-easy to find by those who need educating on the point. But let me add that calling people "narrow-minded assholes" just makes me want to ignore everything you have to say. You may find people respond better to editors who act more like educated adults. Pete.Hurd17:44, 21 January 2006 (UTC)
Todo list
I've just added a todo list to this talk page. I'd like to invite you all to write down any suggestions you may have for the improvement of the article, and work on any of the items already suggested. I hope this will help us make better progress. - Samsaracontribtalk16:37, 24 January 2006 (UTC)
Suggestions for Lead Section
It seems that those of you who have been working on this article for a while may be too attached to the Lead Section to be able to trim it down. I don't want to go in straight away and start hacking away at it after you've all put so much work into it, so I'll just post a few suggestions here for debate.
The first paragraph starts off as an excellent introduction, but breaks down starting with the "Before Darwin..." sentence. For the first paragraph, it is not necessary to describe the pre-Darwin philosophies, and while the remainder of the paragraph contains useful information, it is far too technical. I'm a biologist, and even I have to focus to get through those sentences. It almost seems as if someone wanted it to be hard for non-biologists to read. So, take out the historical reference (or move to the history section), and replace the jumble of science-speak with a plain english explanation of the genetic basis of variation and selection.
The second paragraph belongs in the history section - so much so that it's already there in a slightly different form.
In the third paragraph, the second and third sentences could use some simplifying, and the whole paragraph could be moved to the Mechanisms section.
Items of debate, such as the issue of whether natural selection functions at levels other than the individual level (as discussed in the fourth paragraph), do not belong in the lead section unless they are integral for the basic understanding of the subject (which this is not). Move to Mechanisms, or make a new section for "Current Issues" (or somesuch). By now, I think I've made my point about everything being too complex and technical, so I'll stop mentioning it now.
Paragraph 5: Non-biologists won't know what "fecundity" is. This paragraph makes a good point about the two realms of natural selection, but could stand to be clarified a bit. I might take a stab at it later when I have time.
I like paragraph 6 and think it should stay.
Paragraph 7: Avoid classifying some traits as "better" than others in an absolute sense; use "better adapted" or "better suited to environmental pressures", for example.
The final paragraph is good.
Cheers! --Barefootmatt 21:13, 1 February 2006 (UTC)
Marcosantezana 19:23, 3 February 2006 (UTC)
Yeah, agreement on most your points (I've made a few of them before myself, pulling out history paragraphs from lead, for instance). For a start, let me suggest you place a draft 1st paragraph replacement here on the talk page. I think a "levels of selection" section could pretty much be dropped into the article now. Pete.Hurd21:47, 1 February 2006 (UTC)
the main thing here is that this is reference article, so removing content because it feels like this or feels like that, is frivolous. this article is supposed to allow anybody to get the best and most important punch lines about a topic. this is not only about about letting people feel that they already know what they are reading/seeing (that's american tv) or about introducing recalcitrant youngsters to a new fish oil.
ever read britannica's nat.selection article? it's not for children although it's bad quality sometimes because the author does not always know well what he/she is talking about.
"i am a biologist"... means little. i know many *evol*biologists who do not know well what natural selection means and implies, especially not regarding what people need to know about the concept (which often requires knowing how people tend to misundertand the concept).
just an example, you two are challenging the unit of selection part. well that part is really very important in order to let people understand that ascribing things to natural selection is a very complex task, and also to expose them to what the criteria are to do so (causality dissection).
if people knew that, nobody would be panting and jumping around poor richard dawkins. (mostly non-specialists actually, duh).
furthermore causality dissection is what allows one to debunk the circularity fallacy. but of course knowing that a base can mutate is soooo much important, right?
so the unit thing is there for a few very good reasons.
i often have to look up words when i use encyclopedias and i do it with joy. certainly i won't fault the encyclopedia for my not knowing them. should we adopt the vocabulary of fox news ?
now, if you guys want to challenge content it cannot be out of whim or esthetics or feelings. let's work on the "technical" words (although i see none that are not defined right away, and all are very easy to understand).
"this does not belong here". please if you know why think first. or i ask about it.
"The second paragraph belongs in the history section". are you kidding? don't you realize that the purpose of the paragraph is not so much darwin etc but stressing the fact that the questions of adaptation and speciation are central not only to biology but to any persons's weltanschauung and that selection explains both quite cogently and that for that reason the idea was and is extraodinarly important? furthermore this passage also presents indirectly the central question of speciation with depth that few specialists could convey (but rc lewontin can).
neither of these two things are "current topics", believe me. this is knowlegge about selection everybody should have.
i initially was against the conceptual history part (but did not say it) because i thought the article should be about natural things. but i reconsidered. there will for sure many be readers who will profit from getting a lead and the gist about the conceptual history, and now they get it.
besides, it is very short and tells people something very important about how great ideas originate. (yes, it normally happens against the will of people who want to see and read only what they already know).
but this is such a waste of time. why don't you guys contribute to the body of the article better? it is in pretty bad shape, full of boring common places. once the body will be ripe, let's go back to fret about the holy leading part, about declaring what is a "current topic" (sic), etc. Marcosantezana04:09, 2 February 2006 (UTC)
I'm not saying that all of those things you mention aren't important to the article, they're just not important to the lead section. You're entirely right that the article should not avoid important issues in order to make it accessible, but in my opinion, the lead section should give a clear, concise overview of what natural selection is. After that has been established, the body of the article can go on to talk about the specifics with regards to its history, how it works, and what mechanisms are involved. Keep in mind that anyone who's trained in biology and knows enough about natural selection to understand this article as it currently stands probably doesn't need to read it. The purpose of encyclopedia articles is to educate people who lack a background in the subject, because those who have the background don't need the article. That means it has to be accessible.
I apologize, I seem to have skipped over the definition of fecundity the last time I read the article. I maintain, however, that the lead section is too technical. Even if there is no one word that a layperson could not understand, the section is packed so tightly with long words in long sentences that it just gets overwhelming.
With respect to the "unit of selection" issue, I agree that gene-based selection is a well-established theory. Group selection, however, is not. I think that needs to be made clear. I also still don't think it's essential for the lead section, although I don't feel too strongly about it.
What do you mean by demeaning my status as a biologist? Your argument about why that is meaningless does not relate in the slightest to the context in which I stated it. I was using that to indicate that despite knowing about natural selection and understanding all the words being used, the way in which the sentences were constructed made the article hard to process. You turned that around and told me that people like me know nothing about the subject and need everything explained to us. Please, be civil. I don't mind you criticizing my arguments, but don't attack my intelligence. --Barefootmatt16:43, 2 February 2006 (UTC)
so let's play a game. let's make a *list* of what should be in the intro and why?
and let's come up with ideas on how to avoid that people read the pleasant, inviting thing and leave without reading other important stuff. (my trick so far was not to allow anybody to avoid the important stuff)
it's not about intelligence. expertise does equate with intelligence.
"gene-selection"? how about re-reading the useless intro? it's individual selection ;)
and it's not "well-established" for many traits that are very important. human altruism was evolved via group selection (read the useless intro to see why and also the kin selection article)
see why being a "biologist" does not always help with everything biological?
being civilized when it comes to knowledge implies first and foremost not being overly confident about one's knowledge. smiles and pleasantries and bon mots are welcome but not required.
If Marcos is still completely opposed to holding the lead section down to 2-3 paragraphs then I'll continue to direct my efforts to other things. Pete.Hurd04:40, 3 February 2006 (UTC)
we are exchanging ideas
the three main problems:
i) to agree on what is fundamental for an educated person to know about selection.
ii) how to avoid that the intro, if shortened, be felt as sufficient by people who cannot know better and who will then leave thinking, wrongly, that they got the basics (and then go buy dawkins books), which would mean doing a disservice to them and going against the raison d'etre of wiki.
iii) why cannot be the intro the teaser to the reader and catalist and guide to continue expanding the main body of the article.
i propose that we finish, at the highest level of content and readability, the main body of the article, and that we make more readable the intro where needed. Marcosantezana06:08, 3 February 2006 (UTC)
You misunderstood me. In the part about units of selection, I wasn't saying that the article already specifically mentions gene selection. It mentions individual selection, and that there are other levels as well, and it was those other levels that I was discussing. Individual selection and gene selection have, from my POV, been well proven as generalizable models of selection. The consensus seems to be shifting from individual to gene as the basic, universal mechanism, as gene selection explains altruism better than individual selection. Group selection, on the other hand, is generally considered, at least by the people I've talked to, as being "the easy way out" of explaining the real mechanisms of selection. It is fallacious and is supported by not a shred of evidence that is not better explained by gene selection.
Having now read the kin selection article you directed me to, I can only conclude that we can't possibly be talking about the same thing. What I know of as "group selection" is not used at all in that article. Group selection (read that article) is the theory that members of a population have traits that were selected for the survival or benefit of the population as a whole, rather than the fitness of any individual. Kin selection, on the other hand, is explained by the concepts of gene selection and inclusive fitness. Genes are selected for which increase an individual's inclusive fitness, despite a decrease in its direct fitness; i.e. the gene enhances the survival of close relatives by an amount equal to or greater than the resulting decrease in survival of the individual (taking into account the degree of relatedness as the probability that the individual's genes, especially the altruism gene in question, are found in a given relative). That has nothing to do with "group selection", because none of the effects of the trait are explained solely on the group level. The trait may also increase the overall survival of the population, but stopping there and assuming that the individual is acting purely for the benefit of the group is just lazy.
I agree entirely with your statement of the problems at hand. Those are exactly the things that need to be addressed, and I'd say that's what we're doing. --Barefootmatt18:00, 3 February 2006 (UTC)
unfortunately you cannot only work with what's here in wiki. and i cannot expect you to be a specialist: the sentence "that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the fitness of individuals within that group" should give you a hint if you compare that to the first sentence in "kin selection". you could read elliott's sober's book "the nature of selection" if you really care about this. it gives the proof that "kin-selection" is a case of group selection Marcosantezana18:16, 3 February 2006 (UTC)
The sentence you just quoted and the first sentence in kin selection are not the same thing! What you quoted says that for the alleles in question, the group is the unit of selection. The first sentence in kin selection essentially says that individuals act to ensure the replication of their genes, whether through themselves or through the survival of their relatives. Kin selection generally acts on small family groups, as the degree of relatedness quickly diminishes the inclusive fitness gained with progressively distant relatives. Group selection, on the other hand, is often said to act on the level of whole species.
Would you please stop trying to criticize my expertise? I have done extensive reading on kin selection and eusociality. Don't assume I know less than you just because we disagree. As for "proof", need I direct you to the classic writings of Sherman (1977) and Hamilton (1964)? There's some "proof" for the gene-level basis of kin selection. --Barefootmatt18:56, 3 February 2006 (UTC)
"Elliott Sober in his book "The Nature of Selection" has stressed that natural selection can entail the differential reproduction of many things ("selection of") but that it is the cause of the differences in reproductive output what points to the target of selection and thus defines what the level and the unit of selection are."
this from the horrible intro should have given you the cue. more in sober's book. see, sober became famous among philosophers of science bcse of his solution to this "unit of selection" mess, a mess that had lasted for decades. read the book or the few web pages that present his arguments clearly. reading naive biologists' puerile attempts at analytical philosophy just won't do. yes that includes lewontin, maynard smith, gould, williams, you name them. Marcosantezana19:23, 3 February 2006 (UTC)
Perhaps you're right about Sober, but I'm not convinced, and other readers won't be either. Readers of an encyclopedia shouldn't have to go find another book to find the reasoning behind your arguments. I'm not sure what the sentence you quoted is trying to say (is the "what" after "reproductive output" supposed to be "that"? Even then it doesn't really make sense), but it seems like it's trying to say that Sober believes that selection can take place at different levels. That's fine, but it should also say why he thinks that. Giving the name of an expert on the subject does not excuse us from explaining why that perspective is the right one. --Barefootmatt20:16, 3 February 2006 (UTC)
the cause of the differences in reproductive output is what points to the target of selection and thus defines what the level and the unit of selection are... and this cause is not to be confused, if i may add, with whatever caused each individual involved to become different as it developped from egg to adult Marcosantezana20:36, 3 February 2006 (UTC)
Call for action
Guys, whatever happened to being bold? We've had lengthy discussions like the one above over at evolution and they actually resulted in very little change. I think we all agree on a few things, e.g. the material in the lengthy introduction must be dispersed to other, possibly new sections and articles. Can we just go ahead and do this? - Samsaracontribtalk11:52, 9 February 2006 (UTC)
Samsara, please go do it. I think the consensus is close to but not quite at unanimity on what needs to be done. I'm up to my eyeballs in midterms, various manuscript deadlines (and an infant that appears to be member of some sort of cult opposed to any and all sleep on anyone's part), but I'll be checking in a couple of times a day at least to lend help on details and other issues. Bold on! Pete.Hurd15:31, 9 February 2006 (UTC)
i think the critical issue here is to agree on what is important for people to read first. be bold, go for action, say what it is important for people to read first before messing things haphazardly. in other words be bold but be also serious. i alredy wrote this before but people prefer "action". what's this futurism? fascism? Marcosantezana06:08, 10 February 2006 (UTC)
Well, I am particularly in favour of changing things that are factually inaccurate, such as the statement that Darwin was the first to discover NS. The introduction is meant to be just that, an introduction to the article and its different sections. The introduction is still trying to be an article unto itself, as you've pointed out yourself. However, it is clearly not sufficient as an article, so let's go and shake out the dirt, and return to the talk page if disagreements happen - I take it they haven't happened yet? If so, please say. - Samsaracontribtalk11:38, 10 February 2006 (UTC)
don't see where in the intro darwin is said to be the discoverer. however, what matters is both intellectual impact and primacy. darwin's impact cannot be denied, primacy is often important for the celebratory phase of a community. nothing against it, but primacy without impact belongs best in the history part.
btw, i think that your idea of reallocating things is sound as long as we manage to get a very short intro paragraph that won't allow people to walk away misinformed (like that in muller's ratchet, or the first sentence in kin selection). however, some people like it quick so the intro stuff could become a kind of executive summary/overview (like a micropedia article in britannica albeit with more substance) that precedes the table of contents. Marcosantezana16:25, 10 February 2006 (UTC)
The introduction is waaaaaay too long and way outside the boundaries of our Manual of Style. The intro should contain: 1. a very, very brief (one, two sentence max) definition of what natural selection is; 2. a super-brief history of the term (Darwin, theory of evolution, wasn't popular, then with modern synthesis became important again). The rest of the article should deal with these two issues (defining it, the history of it). Simple as that. --Fastfission01:09, 12 February 2006 (UTC)
As an aside, the list of tasks above says merging from the 1911 EB is still needed. I'm highly suspicious that it is. For one thing, the theory of natural selection was in a vastly different position in 1911 than it was by the end of the 1930s, much less today. I would be highly suspicious that an entry on the subject made in 1911 would be accurate today. --Fastfission02:14, 12 February 2006 (UTC)
I felt it was a good idea, in the light of our attempt to bring down the size of the intro and get this article to FA standard, to move a section dealing with Elliott Sober's contribution to the unit of selection debate to that more specific article. I have noticed that my change has been reverted. The section now exists in duplicate, once at unit of selection and once here. Can we reach a consensus on where it belongs? Let's hear your views. Thanks. - Samsaracontribtalk13:28, 12 February 2006 (UTC)
I really like the idea of having an article to cover this topic, the coverage in this article is a bit opaque and a lucid treatment of the issue would be really valuable. I'm not totally opposed to having some dupication here in Natural selection, but not in the lead section (as I've said a here a couple of times before). I think a brief (one short paragraph) section or subsection with a link to the main article is the way to go. Cheers, Pete.Hurd16:52, 12 February 2006 (UTC)
i'd recommend that you all truly reflect on this issue. if that does not help, i think that you should read sober's book. this is not a side-issue, this is about the very essence of what selection is and what is not, and is very important because grasping this allows one to avoid confusing selection and evolution by selection and the many confusions that arise when people do that (e.g. group vs. kin "selection") Marcosantezana18:43, 12 February 2006 (UTC)
I'm with Samsara; the material should be moved. The paragraph that remained still described the issue briefly and provided a link to unit of selection for elaboration. On a side note: Marcosantezana, please make use of the "Edit Summary" feature. This is especially important when you're reverting changes someone else has made. To indicate a reversion, include the word "revert" or "rv" in the edit summary, preferably with a section heading and/or some indication of what is being changed and why. --Barefootmatt02:13, 14 February 2006 (UTC)
i do use that edit summary thing, dear barefoot, and i did not "revert". i edited the passage. do yo want me to lie? :(
furthermore, i'd like to read your arguments rather than learn how much and/or strongly you agree with others. ever read sober's book? do you know why he has gotten so many prizes? do you know his main arguments? anything to say about why his arguments deserve or not to be included in the article ? sober's identification of the causation of fitness differences as the sole criterion to decide on units of selection/level of selection issues is the major advance of the last 50 years in the analytical philosophy and epistemology of natural selection and, as a i wrote above, provides the foundation to avoid common and pernicious misunderstadings about selection by both aficionados and professionals. ;) 03:24, 14 February 2006 (UTC)
Does that mean you are going to try writing a short, lucid exposition of this critically important point? ... or does this mean that you don't think such an attempt ought to be made? Pete.Hurd06:04, 14 February 2006 (UTC)
Origin of species does not afaik make a link between NS and speciation
Hi there, the header says it all: if I remember correctly, the irony of the Origin was that it does not make a link between natural selection and speciation. Hence, we can shorten the intro from
Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments and the origin of new species.
to
Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments.
be this as it may, darwin did not "forget" the origin. it is obvious that he knew that one needn't be a rocket scientist to figure out that populations would diverge adaptively and become different species. are we kidding here? are we all bookish sophists? to the very least one should write that the origin followed from his treatment of adaptation. and the mere title justifies one saying that he proposed selection as the driver of speciation. Marcosantezana18:51, 12 February 2006 (UTC) 18:50, 12 February 2006 (UTC)
My understanding of Origin is that the mechanism CD proposed that the combination of NS with natural variation and lots and lots of time was indeed what brought about new (that is, divergent from previous and other) species. But he was fuzzy about whether NS brought about new species or whether it merely selected them for survival. One line from Origin which I hope is not too much of a quote out of context: "...I think it inevitably follows, that as new species in the course of time are formed through natural selection, others will become rarer and rarer, and finally extinct."[1] (emp. mine) --Fastfission21:20, 12 February 2006 (UTC)
It seems like that quote is addressed more to chronospecies than what we would now call allopatric speciation. Also, I think it was implicitly acknowledged by the founders of the modern synthesis that Darwin really didn't solve the problem of the origin of species more generally (which is why there are so many books entitled something and the origin of species). And yet, as that quote shows, Darwin certainly made some connections between natural selection and speciation.--ragesoss22:27, 12 February 2006 (UTC)
I believe this is not in keeping with the times. Modern evolutionary biologists are not concerned with chronospecies; they are far more interested in the process of speciation, and the "origin of species" is widely considered synonymous with speciation. However, as I said before, Darwin is concerned with adaptation through selection, not with the branching of species that is speciation. Fastfission's quote shows that Darwin was thinking about the effect of extinction, not that of speciation. - Samsaracontribtalk13:27, 15 February 2006 (UTC)
first sentence
I have changed the first sentence because it was wrong. Darwin's natural selection is not a mechanism that leads animals to adapt. This as the opposite of what natural selection is and thoroughly distorts Darwin. Slrubenstein | Talk11:02, 14 February 2006 (UTC)
you are wrong in your reading of the existing text: being the "driver" of a process does not make you into a *sufficient* factor/cause. furthermore, genetic variation is already mentioned in the same paragraph and appropriately so. 20:33, 15 February 2006 (UTC)
Well, apart from not understanding now what you mean by "driver." Be that as it may, you mis understand my point. The theory of natural selection does not "drive" "the adaptation of organisms to their environments. The phrase "adaptation of organisms to their environment" is at best poorly worded. What are you trying to say? Slrubenstein | Talk15:17, 16 February 2006 (UTC)
You still haven't explained to me what you mean by "driving adaptation of organisms to their environment." I know of no definition or synonym for "driving" that would render this a correct statement. As I read it, it is flatly wrong. Slrubenstein | Talk15:37, 16 February 2006 (UTC)
for organisms adapted or adapting see lewontin's article "Adaptation," Scientific American, vol. 239, (1978) 212-228. btw, no *theory* can adapt anybody to anything. theories are mental constructs 69.209.238.5004:43, 17 February 2006 (UTC)
How about
How about:
Natural selection is the name Charles Darwin used in 1859 for the process which he suggested led both to organisms adapting to their environments, and to produce new species.
Natural selection is the term Charles Darwin used in 1859 to refer to the process he postulated was responsible for producing organisms adapted to their environments and the origin of new species.
Natural selection is the term Charles Darwin used in 1859 to describe the process whereby species adapt to their environments, and by which new species originate.
acquired characteristics, Darwin's pangenesis
"Darwin, moreover, had also to overcome the then dominant view that individual organisms can transmit to their progeny modifications elicited in them by environmental factors. In contrast, Darwin argued that adaptation is the result of the culling by nature of inheritable variation that arises without directionality."
As far as I know, Darwin did accept the transmission of "somatic" modifications, he proposed pangenesis, his own idea of that. Thus accepting then that the modification could arise directionally.
But with natural selection taken in consideration, acquired characteristics, by itself, were not the main mechanism driving the evolution of adaptations. Along with that, there was the point that the environment is limited (Malthus influence), and those who are better adapted would succeed reproductively with more ease, outnumbering the lesser adapted variants, and eventually only the better adapted ones would exist.
Only with the rediscovery of Mendel's works with heredity that the inheritance of acquired characteristics was finally abandoned. Initially Mendel's genetics were also seen as a trouble for natural selection, by some. However, nowadays there's the myth resulting from oversimplification and historical incorrectness that Lamarckism and Darwinism conflict each other in the sense of "natural selection of non-acquired characteristics" versus "transmission of characteristics acquired by individual effort".
Even though Darwin received a letter of Mendel himself, as I've read it or heard it, he never opened, for some reason. Mendel's genetics remained unknown for some more time, and were never defended by Darwin. (I guess I've read that on Carl Zimmer's "at the water's edge", but I've also read something that makes me suspicious, I guess that was in wikipedia, about Darwin citing some of Mendel's papers.
"Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments."
This may sound like I'm just disagreeing to be disagreeble, but I swear it is not. Even though Darwin accepted the inheritance of acquired characteristics, natural selection doesn't make an organism better adapted to its environment, but a population. English is not my first language, but I guess that by "organism" we would more likely understand "an individual organism", the living body, than "a population of a certain species of organisms".... I'm not trying to be sarcastic, I don't change it myself because I don't trust my english (but in this case..... maybe would be just replace "organisms" for "populations"?.... well.... I guess I'll do it then, and here's the explanation why... if someone disagrees, can always be reverted to the earlier version... --Extremophile23:05, 16 February 2006 (UTC)
The change I did, switching "organisms" for "populations" was readily altered to "species" with the justification "(semi rv of previous edit (which wasn't really minor) deserves discussion on talk page)"... which I think is a bit odd, because I guess that the right then would be to revert back to "organisms", no to "species" that wasn't there when I edited. Probably was just a mistake.
Anyway, arguing in this specific case, the evolution of populations/species, I stick defending that populations are more appropriate. Species doesn't evolve as a whole, orchestratedly, but local populations that evolve, independently from each other (and it doesn't have anything to do with a defense of punctuated equilibrium over anything else). And is because populations evolve, and not species, that speciation occurs. If species (somehow) evolved only as a whole, it would never diverge in two species, only "chronospeciation" would occur. Now I will not change anything, it's all here anyway to discuss. --Extremophile00:22, 17 February 2006 (UTC)
Species, however, do in as far as there is a taxonomic description of each species listing its characteristics, and (like some populations) they have characteristics that distinguish them from other species. - Samsaracontribtalk00:41, 17 February 2006 (UTC)
Populations do have their own, unique, adaptations. Human races, for example. Different degrees of melanin, adaptations to different degrees of exposition to sunlight; different body shapes, dipersing or "storing" heat; and even different degrees of oxygen absorption, evolved in different ways, in populations living in higher lands. More details and examples at "Human biological adaptability". There are also differences between populations of other species too. Starting from simple differences, like pesticide resistance in some locals, to the degree that a certain population is technically called an ecological species (surprisingly there's no entry of that in this wikipedia, so here's an external short description) (although often referred just as a "species"), which is, they're adapted to somewhat different "lifestyles", even though they still can perfeclty have fertile offspring, i.e., they're not different biological species yet. Ring species is also another example of populations of a certain species varying gradually, geographycally (adaptivelly or not). --Extremophile13:07, 17 February 2006 (UTC)
Extremophile, ring species exemplify the point that there is variation within populations, most of which (in a qualitative sense) is likely shared with other populations of the same species. The concept of species, on the other hand, requires that some variation is unique to each species. So to be completely botheringly precise, while you may talk about the adaptation of a population (as a process), it is troublesome to talk about adaptations of populations (referring to particular characteristics). - Samsaracontribtalk13:51, 17 February 2006 (UTC)
To be honest, I don't quite get your point mentioning that what you said until the last sentence. I don't want to enter in any personal conflict here, believe me when I say that if I sound provocative or sarcasitc it was acidental. Anyway, to me, "species" is better than "organism", although not yet strictly correct. To avoid conflict, I'll not argue more on that, just a last time, so, for your last sentence and my main point altogether: what about the earlier example, of different adaptations in human races? By mentioning ring species my point wasn't to give an example of different adaptations occuring between populations (as they're most often differ by traits that are probably of little adaptative value on these differences, or at least these are the most known differences). The point there, was that populations of a species evolve, adaptatively or not, independently, not a species as a whole. There's no reason why a species could vary geographicaly only in non adaptative manners. When populations live in diferent localities, there are different selective "pressures" (and there will be, eventually), they will diverge adaptativelly. They can't avoid that just because we can classify the many populations as constituints of a single species. Of course, the divergence will not happen not all of a sudden, at the degree that biological species differ from each other (my point was never to equate populations with species, just because both can vary adaptatively). And simple there is no way a species (except for species composed by just one or a few extremely reduced populations, with enough genetic flow, living in the same habitat) could evolve adaptatively as a whole. So, resulting of the process of a population adapting, there would be populations with different adaptations; the adaptation of a single population of a species will not necessarely spread through all the populations. Even because some adaptations are mutually exclusive. Although in some cases can by viable mid-terms between the extremes, between the "adaptive peaks", the "peak adaptations" will still be in advantage in the "peak situations". Eventually this may lead to speciation, but not necessarely. (and anyway, the point that there would be different adaptations between different populations, remains, with or without adapted intermediates). --Extremophile14:53, 17 February 2006 (UTC)
Most of your comment refers to the classic Fisher-Wright debate (we need an article about this), which remains unresolved. The debate, very crudely speaking, is about whether favourable mutations spread from subpopulation to subpopulation (Wright), or spread to the entire species in one (continuous and slow) go ("panmixis"; Fisher). The current state of the debate is that Fisher wins, as not enough convincing evidence in favour of Wright's "shifting balance theorem" (I believe I wrote an article on this, but it seems to have been deleted) has accumulated. - Samsaracontribtalk16:14, 17 February 2006 (UTC)
Wow, I've never thought that would go that far. Anyway, I believe that Fisher-Wright debate has more to do with subpopulations, not populations with more stabilished isolation of some kind (I might be mistaken). I've said I wouldn't argue anymore, but now I'll try to be very concise: let's see again one example of human populations, varying melanin degrees. Black skin is an adaptation to sunny environments, whiter skin, is another adaptation, to another environment where protection against sunlight isn't that crucial. That's it. In populations of "black" and "white" people these adaptative traits evolved, instead of a general, intermediate, adaptation of the whole species. Was not the whole species that evolved orchestratedly, but isolated populations with respect with the selective pressures of their respective environments (although of course NS doesn't need to happen in already isolated populations, but can be the isolation barrier itself). We still can phrase it as "the species adapted to different climatic conditions", but NS acted upon the different populations that compose this species, differently, and independently. It's not very different, in this sense, than saying that NS drives the adaptation of genera, or of the sum of all life on Earth. It does, as the "final" result, but the process happens on populations. Populations simply can't avoid evolving (including diverging adaptively) independently if there's not enough genetic flow between them, doesn't matter that we classify them all as a single species. How could, a sum of isolated populations, manage to always be adaptatively equal, all over it's geographic distribution? Only if all over its geographic distribution the environment is also ideally equal, without other different species, climate, diseases, etc; and if never arises new, more fit, variants in one of those populations without equivalents arising at the same time in the other populations. (I failed a bit being concise, but I tryed.)--Extremophile17:40, 17 February 2006 (UTC)
Now, let's be clear on this. It seems that you have defined "population" as a unit of individuals that is so far separated from any other such unit in geographical or genetic terms that it inevitably diverges from it. That is not how "population" is usually used. Normally, when using the word, we are not assumed to imply anything about the level of gene flow between populations, other than that it is less than would be expected "by chance". Most likely, using your definition, your ring species do not contain populations at all, or the populations are of recent origin.
What we should also be clear on is that for any given degree of gene flow between two populations, there is a corresponding level of sequence divergence (mutation-gene flow balance). Such divergence may also be increased by selection. With low gene flow or strong selection, populations may diverge sufficiently for hybrids to be unfit and traits that decrease the frequency of hybrid matings may then be selected for - the beginning of parapatric speciation. To me, there do not seem to be different sets of ideas attached to "population" vs. "subpopulation". I think subpopulation is generally used to emphasise that there is more than one. A similar term is "population subdivision". - Samsaracontribtalk18:10, 17 February 2006 (UTC)
That's not my definition of a population; altough in that situation a group of individuals would still be a population. That would be a "extremely isolated" population, whereas "normal" populations can have genetic flow with other populations, but, IMHO, at a significantly lesser degree than the "gene flow within" the same population. Otherwise would be equally valid say that a given group of individuals is one, two or ten populations (or at least populations wouldn't have much to do with gene flow).
And to make things shorter, could you please adress to the example of adaptative differences in human popupulations, such as varying degrees of melanin? Isn't that populations with their own adaptations, evolved independently by NS? By which we could conclude that NS affects populations, and not species orchestratedly? And that then populations will have their own adaptations, not necessarely shared with the rest of the species?
It doesn't mean that will always occur with any and all populations, since populations aren't necessarely isolated enough, nor necessarely have sufficiently different environments, but it also means that isn't only a population that is a species itself, or only the sum of populations that compose a species, somehow united, that is able to evolve adaptatively. (And implicitly opens more space to cladogenesis.) --Extremophile20:38, 17 February 2006 (UTC)
I liked the "organisms" language (but then I understood that it was obviously not intended to imply that any specific individual evolved). The sentence talks about Darwin's views, "species" seems more appropriate than "populations" in this context. Pete.Hurd02:55, 17 February 2006 (UTC)
you guys are truly hilarious. how about stopping aplitting hairs or reading an evolutionary biology textbook ? it is deplorable that so much time gets lost with these sophistries while important work is still to be done for the article (and by that i mean work in the main body of the article). is this a self-experiencing therapy group? ;) Marcosantezana04:14, 17 February 2006 (UTC)
Marcosantezana, I have read a good many books on population genetics and evolutionary theory, not just college textbooks. Your sentence about organisms adapting is simply wrong. It is a misinterpretation of Darwin. Granted, it is a popular misinterpretation of Darwin. Darwin's simple, subtle, and brilliant idea is one that most people in the general public misunderstand and do not appreciate. His theory is not about organisms "adapting," or "the adaptation of organisms." It doesn't matter whether you like the language or not. It is a false claim, if made about the theory of natural selection. Do not call this splitting hairs or sophistry (especially when you keep reverting to your sentence, which certainly seems like you are splitting hairs). The sentence is just wrong. It misrepresents Darwin and science. Slrubenstein | Talk09:25, 17 February 2006 (UTC)
We should always make explicit that populations, not individual organisms evolve because of the potential for a lay audience to misunderstand. — Dunc|☺10:46, 17 February 2006 (UTC)
I agree that populuations or sub-populations evolve but I think it's ok for Marcosantezana to say 'organisms are adapted to their environments'. I think this is understood to mean [all instances of] organisms tend to become more adapted over generations and not that an individual orgainsm adapts during its own lifetime. Axel147
I like the current solution. It says what is needed to say, at the same time that avoids the population/species issue. And make less room to misunderstand that individual organisms adapt by natural selection (which, anyway, can be made even clearer later in the article). I also apologise by being nearly a troll making such a case on that detail. Gosh. Look at the size of this discussion... --Extremophile23:24, 18 February 2006 (UTC)
Nice progress
I like the edits you are making to the intro. Good to see that you're managing to keep it short. Ideally, we want it even shorter. I think we should aim for four paragraphs (currently nine). - Samsaracontribtalk17:35, 18 February 2006 (UTC)
Marcosantezana, I don't think you are quite right, but maybe it's my turn to split hairs. Natural selection is not just the 'selection' part of evolution in the sense of fit individuals being selected to reproduce ahead of less fit individuals. It is more than that. Quoting Darwin:
This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection.
But if variations useful to any organic being do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterised. This principle of preservation, I have called, for the sake of brevity, Natural Selection.
The key element to any definition is the 'preservation' of favourable traits in a population. Preservation requires more than just selection: it requires inheritance. As a result I think it is very difficult to distinguish 'natural selection' from 'evolution by natural selection', so I have reverted to my definition. What are other people's opinions? — Axel14721:39, 18 February 2006 (UTC)
wrong and short is not sufficient. it's simply wrong. darwin is talking about the case in which the stuff is heritable because he cares about evolution by natural selection. however the definition of natural selection has nothing to do what darwin thinks about how evolution by natural selection takes place. ever taken a logic class? furthermore i) in evolutionary biology this distinction is crucial, standard, and widely exploited when measuring natural selection in the wild; and ii) this distinction is also crucial to avoid that people mix up the two things and come with all kind of messes when thinking "conceptually" about selection. finally don't you know that the fitness-wise most important phenotypic variation is either genetic but not heritable in the narrow sense or is not genetic at all? Marcosantezana22:53, 18 February 2006 (UTC)
Dear Marcosantezana, I understand all the things you are talking about individually very well. I cannot understand the connection you are trying to make between them. Most of all, I would appreciate if you could explain exactly how your version of said paragraph differs from Axel147's paragraph and why you believe your version is more befitting of this encyclopaedia. Many thanks, Samsaracontribtalk23:30, 18 February 2006 (UTC)
Maybe better but I think we've lost the sense of definiton, in a crisp sentence or two: 'Natural selection is ....'
I (unsuprisingly) prefer my defintion!
According to Darwin, natural selection is the process by which heritable characteristics or traits conferring survival and reproductive advantage to an individual tend to be passed on to succeeding generations and preserved in a population, whereas other less favourable traits tend to become eliminated.
I think people are confused by 2 possiblities for Natural Selection:
1) Selection of fit individuals to reproduce.
2) Selection of favourable traits over time.
It is clear from the extract in my previous comment that Darwin is talking about 2), the [selection and] presevation of favourable variations.
2) requires 1) plus inheritance.
Now, if the words means something different in evolutionary biology we should say so in the article. I still think we should change the definition — Axel14700:19, 10 February 2006 (UTC)
I am now reverting it once more. This definition is consistent with other definitions on the internet: try Googling 'Natural selection is the process by which'. Also consistent with the Origin of Species. More (abridged extract) from Darwin to hopefully convince Marcosantezana:
I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection. And in two countries very differently circumstanced, individuals of the same species, having slightly different constitutions or structure, would often succeed better in the one country than in the other, and thus by a process of 'natural selection,' as will hereafter be more fully explained, two sub-breeds might be formed. That natural selection will always act with extreme slowness, I fully admit.
Just to add a bit more grist to the mill, Ernst Mayr's very simple definition of NS from his monumental history, The Growth of Biological Thought. (Among the founders of the Modern Synthesis, he was probably the most Darwin-centric).
"...the differential reproduction of individuals that differ uniquely in their adaptive superiority..."
In describing the way Darwin conceived of it, he said "Darwin's theory consisted of three inferences based on five facts," which I will reproduce in abbreviated form:
Inference 1: Struggle for existence, survival of only a part of each generation's offspring
Fact 4: No two individuals are exactly the same
Fact 5: Much of this variation is heritable
Inference 2: Survival in the struggle for existence is not random, but depends in part on heriditary constitution. "This unequal survival constitutes a process of natural selection."
Inference 3: "Over the generations this process of natural selection will lead to a continuing gradual change of populations, that is, to evolution and to the production of new species."
My attempt to solve the "just natural selection" versus "evolution by natural selection" issue, at the sime I try to make the definition of the process a bit clearer:
1 Darwin called "natural selection", the process by which individuals on the wild will have different survival abilities according to their physical and behavioural traits. From that process results that some traits are "selected" by nature over others, in analogy with traits humanly selected in artificial selection.
or something like
1 Darwin called "natural selection" the process that results in some specific individual traits being "selected" by nature, in analogy with traits humanly selected in artificial selection, but according with the different levels of survival abilities that are conferred by these traits.
and directly followed by something in the sense of
2 When the selected traits are heritable, they will increase or decrease in frequency over the generations, as a consequence of the number individuals possessing such traits being able to survive until the reproductive age, passing it to the next generation or not. The heritability of selected traits causes adaptativeevolution by natural selection.
Well, that's just the general idea, consider these as sketches of proposals (or totally disregard, that's an option, anyway).
Another point I think that should be made is that, I guess, the distinction between "just natural selection" and "evolution by natural selection" is post-Mendelian. Darwin, by deffending pangenesis, supposed that (again I guess) that nearly any physical trait would be passed to the next generation by reproduction.
So, even though the distinction actually exists, we probably can't support that by quoting Darwin. I think the fact that he is the coiner of the term, doesn't implies that then "natural selection" is a synonym with "evolution by natural selection", even though for him it would be, with the knowledge he had at that time.
And making the distinction doesn't seems that hard to do. I guess that something in the sense I suggested does that, without causing a much contrast with Darwin's views and the modern views, it's something that work for both instances, differing only that the in last phrase, "when selected traits are heritable", is a parameter that to Darwin, would be filled with "nearly all the time".
Guys, can you please stop edit-warring? We're going to have a vote on this. I propose two versions, one by Marcosantezana and one by Axel147.
Marcosantezana reads (proposal 1):
Darwin realized both that i) organismic traits that are functionally superior given the context defined by the biological and physical environment, can boost the reproduction of the individuals displaying such traits, and ii) that when such selected-for traits are heritable they should become more common over the generations. In other words, Darwin realized that natural selection can result in adaptive evolutionary change.
Axel147 reads (proposal 2):
According to Darwin, natural selection is the process by which heritable characteristics or traits conferring survival and reproductive advantage to an individual tend to be passed on to succeeding generations and preserved in a population, whereas other less favourable traits tend to become eliminated. Furthermore Darwin realized that traits which increase the reproductive success of related individuals, sharing the same trait, could also become more common over the generations.
Votes will be counted in three days' time, that's on Wednesday morning. You will accept the outcome of that vote. No editwars until then please. - Samsaracontribtalk01:32, 19 February 2006 (UTC)
Proposal 1 support:
Proposal 2 support:
Comments:
I don't find either one very satisfying; both seem to dance around a simple definition without ever getting to it. The language in proposal 2 is definitely cleaner and the first sentence is pretty good, but the second sentence seems evasive. I'm not quite comfortable with the "Darwin realized that" sentences in either; only in retrospect can we say "realized". In contemporary terms, it was more like "inferred that" or "thought that" or "argued that". For Darwin, the place of natural selection in evolution was something that was never simply a given; he was always considering it in conjunction other factors and grappling with alternate explanations. For now, I say stick with Axel's, but I don't exactly support it.--ragesoss02:21, 19 February 2006 (UTC)
First, thanks Samsara for initiating this constructive attempt. I'm not going to vote because Voting Is Evil (see WP:VIE). A discussion ought to be more productive than a poll. So here's my thoughts. I don't particularly like either of the options' phrasing, but intellecually I think option one is clearly preferable. If you can ignore his usual need to dish out the insults, this diff makes (or I think tries to make, I find it hard to separate the signal from the noise) the following points 1) this page is about natural selection, not evolution, or evolution by natural selection. They have different names because they refer to different things. Traits can evolve through other processes, genetic drift, sexual selection whatever, and it isn't really useful to try to shoehorn evolution into this NS page, in fact, it might be of pedagogic value to do exactly the opposite, to clarify the distinction. 2)If S>0 then selection happens, even if heritability (and therefore response to selection, R) is zero Natural selection is still natural selection if the trait shows no response to selection (ie is not strongly heritable, or even not heritable at all). I suspect Axel147's response would be (here I apologise for putting words in your mouth, but I'm soon going to be away from the web for some days and anticipate missing your response) something to the effect that Darwin didn't talk about heritability or response to selection etc, and what he *did* say justifies version 2. To this I would suggest putting what Darwin thought in a paragraph (or page) of historical items and make the second paragraph be about more current view, or explaining the concept behind this disagreement. Best regards to you all. Pete.Hurd04:45, 19 February 2006 (UTC)
The idea that this paragraph should outline the modern perception, and leave Darwin to later section, looks worthwhile. However, Darwin was a very good but wordy explainer, and I humbly suggest this alternative paragraph:
In The Origin of Species, Darwin saw an endless number of slight heritable variations occurring in organisms. As a farmer can "preserve and accumulate" such variations by selection, so in the "infinitely complex and close-fitting... mutual relations of all organic beings to each other and to their physical conditions of life" where "many more individuals are born than can possibly survive... individuals having any advantage, however slight, over others, would have the best chance of surviving and procreating their kind... any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable individual differences and variations, and the destruction of those which are injurious, I have called Natural Selection". ...dave souza, talk10:22, 19 February 2006 (UTC)
Ok, my turn to comment.
To Marcosantezana — I agree with your sentence but don't think it's a definition.
To Regesoss — I agree with point about 'realized'. Maybe we should agree conceptually and then get the phraseology right!
To Pete.Hurd — I never used the word 'evolution' in my defintion.
To dave souza — What do you think is the 'modern perception'?
To Extremophile — I don't think it's fair to say Darwin thought nearly any trait would be heritable. The laws governing inheritance are quite unknown; no one can say why the same peculiarity in different individuals of the same species, and in individuals of different species, is sometimes inherited and sometimes not so. (Perhaps not the best quote to support the argument but I think the point still holds).
I think conceptually the debate is around the question....'If a trait is not heritable is it still natural selection?
(Correct if I have misrepresented anyone.) If we accept Darwin's definition, 'this preservation of favourable variations and the rejection of injurious variations, I call Natural Selection', in my view, inheritance should be part of the definition, not a special case. This is the way it is defined in the 'evolution' article of this encyclopedia! — Axel14716:33, 19 February 2006 (UTC)
I'm far more familiar with sexual selection studies than natural selection, but if one does a mate choice experiment and demonstrates that females prefer males with more of trait X, then one concludes that trait X is sexually selected. One does not go and measure the response to selection before concluding that there is sexual selection for the trait. You are telling me that studies of natural selction in the wild do not follow a similar use of the language? Do studies in the Grant/Schluter/Endler tradition reserve the use of "natural selection" for cases on which there is a measurable response to selection? Pete.Hurd16:59, 19 February 2006 (UTC)
It is still natural selection if the trait is not heritable. Besides, all actual traits are at least mildly heritable, so the question doesn't even arise. - Samsaracontribtalk17:19, 19 February 2006 (UTC)
Maybe we are being distracted by the word 'trait' and should use 'characteric' or 'variation' instead which isn't by definition heritable. — Axel14717:38, 19 February 2006 (UTC)
That traits are defined as heritable is news to me. I note that trait (biological) says that the same is true of "characteristic" and "phenotype" (I'd like to see some standard references before agreeing). I find it hard to believe that readers will be confused by this paragraph because they assume that the trait being discussed must be heritable and therefore natural selection and evolution are synonymous. Pete.Hurd19:42, 19 February 2006 (UTC)
Generally I prefer Axel's definition, with one qualification. Although I disagree, strongly, with Marcosantezana's claim that there is, in principle, a distinction between natural selection in and of itself and natural selection vis a vis evolution (I disagree because "natural selection" has no meaning outside of evolutionary theory. It is like asking what a spark plug does, but being told that you can't answer by refering to engines or carburators (er, fuel injectors)), I do think it is important to distinguish between "the evolution of species" and "evolution" more abstractly. This distinction is important because one of the things that makes Darwin such a towering genious and influential scientist is that "natural selection" can be applied to the evolution of other things besides species - scientists in different fields have applied it to explain the development of neural pathways in the brain, and the evolution of different cultures. For this reason I do not think it is appropriate, let alone wise, to limit the definition of natural selection to its role in the evolution of species.
That said, I do agree with Axel about two things. First, it is most definitely the seclection of traits that is at issue. Second, I do think we should privilege the meaning of natural selection in its original context because (1) this is still where it is most robust and (2) it was this original context that provided a model for its use elsewhere. So maybe wa can say something like, "According to Darwin, natural selection ..." and then have some sentence like " Since Darwin, scientists have argued that natural selection can explain the evolution (change, or development) of many other things besides heritable traits." Slrubenstein | Talk11:43, 20 February 2006 (UTC)
Another proposal
To answer the question above, I'm a layman interested in Darwin but not a biologist, and would hesitate to define the modern perception or understanding of natural selection. Darwin clearly sees "the strength of the hereditary tendency" as part of his definition: the analogy with preservation and accumulation of varieties in "domestic productions" depends on the relevant variations being heritable. He uses "characteristics" but not "traits". I thought traits might imply heritability, but my dictionaries give "a stroke, touch, a characteristic" and "a distinguishing feature or quality, especially of a person's character". Presumably it means something more to biologists, as does "organismic" which isn't in my dictionaries – please avoid that term, and use characteristic rather than trait. The following aims to present Darwin's essential points more concisely:
In nature, all organisms produce more offspring than those that will in turn succeed in reproducing, and all offspring show variations in characteristics which can affect their chance of surviving and reproducing in the prevailing conditions. Successful heritable variations can accumulate over generations. Darwin called this process natural selection in an analogy with a farmer choosing variations with characteristics he desires for breeding stock, which Darwin called artificial selection. ...dave souza, talk20:09, 19 February 2006 (UTC)
(minor modifications to clarify the above).. Note that this statement shows the culling effect of natural selection operating without heritable variations, in the same way as a farmer will select characteristics whether or not they are heritable, but the useful effect in both cases only occurs when the variation is heritable. Natural selection will cull an animal with a broken leg or may favour an animal that has exercised and developed its muscles for non heritable reasons, but these cases are irrelevant for the breeding which is the point of Darwin's analogy. ....dave souza, talk01:34, 20 February 2006 (UTC)
rephrase proposal to show natural selection on nonheritable "traits":
In nature, all organisms produce more offspring than will in turn survive to successfully reproduce, and all offspring show variations in characteristics which can affect their chance of surviving and reproducing in the prevailing conditions. Darwin called this process natural selection in an analogy with a farmer choosing variations with characteristics he desires for breeding stock, which Darwin called artificial selection. In both cases if selected variations are heritable and the selective preference continues, the population of descendants will have the favoured characteristic as an evolvedadaptation. ...dave souza, talk02:15, 20 February 2006 (UTC)
I like it works for me. I think the last sentence is unnecessary, and detracts from the flow into what is now the 3rd paragraph. I suggest using this, drop the last sentence and join the 3rd para to this second one. Pete.Hurd02:46, 20 February 2006 (UTC)
I couldn't support this so I'll try to put my case once again. Natural Selection as intended by Darwin and in common use today is not just the selection of fit individuals and the rejection of bad ones. I thought this was the kind of laypersons misunderstanding we were trying to avoid. Darwin's title is 'On the Origin of Species by Means of Natural Selection'. What is profound is that Natural Selection explains the origin of species. The principle of inheritance is absolutely key to that. Darwin does not use the word evolution. Natural Selection is a theory, a principle, a process, which embraces both selection and inhertance. This is self-evident in any other dictionary or encyclopeidic definition of the term. So I say again, Natural Selection is not merely 'selection'. — Axel14704:36, 20 February 2006 (UTC)
Natural selection is a process to explain the origin of species.
Charles Darwin proposed natural selection theory based on the fact that organisms are adapted to their environments. Along with the rules of inheritance discovered by Gregor Mendel at about the same time, natural selection provides the fundamental mechanistic foundations for modern evolutionary theory.
The previous version read:
Natural selection is the phrase Charles Darwin used in 1859 for the process he proposed to explain the origin of species and the fact that organisms are adapted to their environments. Along with the rules of inheritance discovered by Gregor Mendel at about the same time (but unknown to Darwin then and rediscovered only at the turn of the twentieth century), natural selection provides the fundamental mechanistic foundations for modern evolutionary theory.
I object to the new version on several grounds:
A bit of historical tragedy helps set the context: Darwin was unaware of Mendel's discovery. This is an important fact that even a person who reads only the introduction should not go away without.
Natural selection is not in the first instance about speciation at all, although, as Marcosantezana has pointed out, Darwin does hint at the implications by putting it in the title. In the first instance, the book is about explaining adaptation in a non-teleological way.
Darwin did not propose natural selection on the basis of adaptation. He proposed it on the basis of artificial selection because this was the only "fact" he had. Everything else was speculation. His very purpose was to predict adaptation, not take it as a prima facie fact!.
"Natural selection is the phrase Charles Darwin used in 1859 for the process he proposed to explain the origin of species and the fact that organisms are adapted to their environments." Is this accurate? Natural selection as I understand it does not explain "the fact" that organisms are adapted to their environment. On the contrary, it assumes that some organisms are more and others less fit ("adapted?" "Fit" is better because it describes a relative quality; "adapt" is a verb), and explains why the traits that render an organism more fit surivive over time. Slrubenstein | Talk12:10, 20 February 2006 (UTC)
My first thought: " and the multiplicity of different organisms each closely adapted to its environment." ....dave souza, talk
I wouldn't say that he was talking about diversity per se. I suggest:
Natural selection is the phrase Charles Darwin used in 1859 for the process he proposed to explain the origin of species and why organisms appear adapted to their environments.
Natural selection does not explain why organisms appear adapted to their environments. It takes for granted that some organisms are less fit, and others more fit. It does not explain why they are more or less fit. It does explain why the traits that render an organism more fit become more widespread over time, maybe. Slrubenstein | Talk16:23, 20 February 2006 (UTC)
Organisms appear adapted to their environments as heritable traits that render an organism more fit become more widespread over time due to natural selection. "Why" can be misunderstood as implying a higher purpose: "how it is that" might be better. ...dave souza, talk17:46, 20 February 2006 (UTC)
I agree "how it is that" or just a simple "how" is better than "why", but thought the original "the fact that" was ok. — Axel14719:41, 20 February 2006 (UTC)
There's also a lot of mathematics that can be done with natural selection, in relationt o heterozygosity and variation. should some of these equations perhaps be included?
I have several objections to Slrubenstein's edit, the main one of which is still that exposing the origin of species as the main objective of either the Origin of Species, or natural selection as originally conceived, is wrong. It was always about explaining the apparent adaptedness that had previously attracted teleological lines of argument. The main point in the book was to illustrate how artificial and natural selection are analogous.
Lamarckism should also be regarded a deprecated link until the concerns from the Michael Ghiselin article have been investigated. The article argues that Lamarck is being used as a straw-man for the commonplace attitude of his day, and his role in the history of science is both overly maligned and generally exaggerated.
I have suggested another edit that puts the meat of what natural selection is in the first sentence. If someone could fix the syntax a bit, I'd be grateful.
I do not understand Samsara's objections. Natural selection was indeed proposed to explain the evolution of species. This fact is in no way contradicted by Samsara's claim that it was an alternative to teleological arguments - because those teleological arguments were meant to explain the differences between species. These themes are linked, and Samsara is putting the cart before the horse. There is a need to define natural selection, which my edit accomplished. I do not undertand what a "depricated link" is, but I see no reason to delete the reference to Lamark. I do think that it would be appropriate to add that Darwin's model has displaced teleological explanations as well. Slrubenstein | Talk13:55, 21 February 2006 (UTC)
Speciation is a branching process that the Origin of Species is not explicitly concerned with. When you say "origin of species", this branching process is what a modern audience will be thinking of. Hope that makes it clearer. - Samsaracontribtalk13:57, 21 February 2006 (UTC)
You mistake quantity for centrality. You are correct that much of the book treats similarities between natural and artificial selection. This is because Darwin wanted the evidence to be effectively irrefutable. That does not mean that this similarity is his main point. By the way, what do you think Darwin meant by "origin of species?" I hope this is clearer to you, cheers, Slrubenstein | Talk14:10, 21 February 2006 (UTC)
Seeing that people in his day were interested in the fossil record, Darwin was probably talking about chronospecies, that is, species changing into different "species" through time. However, this is not consistent with the modern usage, which is why we make the distinction and say "chronospecies" instead. - Samsaracontribtalk16:49, 21 February 2006 (UTC)
I don't like the word 'fecudity'. Maybe technically correct but makes the introduction less accessible to the layman. — Axel14715:43, 21 February 2006 (UTC)
Yes of course survival is required. That's why it's worth mentioning. A lot of traits influence survival directly and fecundity indirectly. It helps understanding. Darwin asks which individulas would have 'the best chance of surviving and of procreating their kind?' and talks about the 'struggle for life'. — Axel14716:53, 21 February 2006 (UTC)
Samsara, I do not understand your point. Yes, one cannot be fecund unless one survives. But the fact that one survives does not make one fecund. These are two different things and both are important to natural selection. How can you say the distinction is nonsense? It is a crucial one for biologists and demographers, with good reason - and it was an important distinction to Darwin too. Slrubenstein | Talk18:16, 21 February 2006 (UTC)
Anyway whether survival [of the individual possessing the characteristic] is required brings me back to another point. I think there is a temptation to try to rephrase to Darwin's basic defintion of natural selection and a risk of losing some of its meaning. 'The principle of preservation of favourable variations' has the advantage that it does not exclude the following possibity: characteristics that have the property of being able to create copies of themselves through any means could be preserved, even if it is not by the reproduction of the individual 'displaying' the characteristic. Although this 'kin selection' idea is more of a subtlety I think this is something the opening definition should try not to exclude. — Axel14722:17, 21 February 2006 (UTC)
I agree with you, Axel. As for Samsara, I am sorry that you do not find the distinction useful. But that does not matter. It is important to Darwin and to scientists today who rely on natural selection as a causal mechanism. As Axel suggests, kin-selection leads in another direction, but this doesn't change the fact that survival and fecundity (which is in no way included in survival), as Axel himself noted above, are still important. Slrubenstein | Talk11:30, 22 February 2006 (UTC)
I removed most of Marcosantezana's changes because they were both awfully written and wrong. First, "to underly" is not a verb and to write "to underly the origin of species" is both poor English usage and meaningless. Second, I see no value in using the metaphor "negotiate" which implies a consciousness and active role on the part of individual organisms that is just antithetical to the whole idea of natural selection. Third, natural selection in no way causes differential reproduction. I find it hard to believe anyone would think these edits improve the article, in fact they are so bad they verge on vandalism, although I want to take Marcosantezana as acting in good faith. Can you explain and justify these changes? Slrubenstein | Talk11:38, 22 February 2006 (UTC)
This affair is getting increasingly queer. For a reference about your claims about underlying: [2]. It is perfectly valid to say that organisms negotiate their surroundings, i.e. they move around in them and go about their daily business. To discuss the concept of consciousness of organisms is beyond this article. I refer to to cognition. I see no antithesis.
Third, differential reproduction IS natural selection. That is what we have been debating for so long, that is what it is. Marcosantezana may at times be crude in his words towards other editors, but I cannot but strongly defend this edit. - Samsaracontribtalk11:47, 22 February 2006 (UTC)
What does "underlying" mean in this case? Underlie as a verb means "support" but the theory of natural selection does not "support" the origin of species, it is used to explain the origin of species. I stand firm on its being poor English usage in this case. Moreover, I stand irm in saying that "negotiate" is a poor metaphor. But my point is not just that it is a poor metaphor, but one that is inappropriate for natural selection. I will back down on differential reproduction - however, Samsara, if you agree that differential reproduction is involved, then fecundity is important. Differential reproduction is NOT the same thing as differential survival. The former is predicated on the latter, but it is by no means the necessary outcome of the latter. Slrubenstein | Talk11:52, 22 February 2006 (UTC)
You can undeprecate any Lamarckism links: I've reviewed Ghiselin's article, and it's a bit hyperbolic, understates Lamarck's importance, but has interesting material on some false history. He wrongly states the "doctrine, the one with which Lamarck's name is most famously associated, had been widely accepted since antiquity and was taken for granted by most 19th-century biologists." - some in France and Edinburgh, but certainly not the English establishment - see the inception of Darwin's theory and linked articles for examples. I've tweaked the article a bit, and there's no conflict with G's article now. ...dave souza, talk15:01, 22 February 2006 (UTC)
I remain sceptical, since the wikipedia article you cite likewise acknowledges only a single source, and one I am less familiar with than Janet Brown's biography of Darwin, which is a more recent source and widely acclaimed as the definitive treatment to date. Unfortunately, I don't recall any commentary on Lamarck from her book. - Samsaracontribtalk16:00, 22 February 2006 (UTC)
Regarding importance, "Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801" : Charles Darwin, intro to 5th edn of Origin; and if Lamarck's doctrine was taken for granted, why any fuss about Chambers' Vestiges of the Natural History of Creation and Darwin's Origin? Richard Owen#Owen and Darwin's theory of evolution gives an establishment example. Brown's book sounds interesting, Desmond and Moore are well regarded. ...dave souza, talk20:34, 22 February 2006 (UTC)
Let's not confuse Larmarck's theory of evolution with Lamarckism in the sense of inheritance of acquired characters (which is definitely not original with Lamarck). At no time was the former generally accepted, but the latter was, in England as well as the continent. As for the biographies, Browne's is now considered the definitive one (well, two technically); having read Browne and D&M, it's pretty obvious why. Desmond and Moore focus more intensely on aspects of religion and Darwin's psychology, as well as the relevant social history of England, but Browne's really integrates the broader scientific context as well as covering the social and cultural factors. (Browne is also the editor of the Darwin papers).--ragesoss21:23, 22 February 2006 (UTC)
Moore was an editor for the Darwin papers too -- he's just not as creative as Browne. ;-) I don't think that Browne and D&M's book contradict each other in any obvious sense, do they? I thought it was a difference of emphasis, synthesis, and, frankly, writing ability. --Fastfission23:13, 22 February 2006 (UTC)
Regarding "fecundity" - the distinction between fecundity and survival is clearly an important one. Compare humans with mosquitos, the former with relatively low mortality before reproductive age but very low fertility rates, the latter with extremely high mortality but compensatory absurdly high fertility. These are important differences in evolutionary strategy that deserve at least the brief, two-word mention SLR gave 'em. If these don't seem the correct terms, that's a different matter - the words are of course subject to change, but the underlying idea is sound. Graft15:48, 22 February 2006 (UTC)
So? Who said anything about life history strategies or comparative studies? The subject of this article is Natural Selection. As Graft points out, the distinction between fecundity and survival is crucial to understanding natural selection.Slrubenstein | Talk15:57, 22 February 2006 (UTC)
I too withdraw as a contributor to this article. Clearly not that much intelligent design. Wilkipedic Selection is the process by which variations which appease the most persistent editors and those with most time on their hands tend to be preserved unless those variations differ wildly from concensus. — Axel14718:08, 22 February 2006 (UTC)
I am surprised you are leaving, Axel147. I assumed you agreed about the distinction between survival and fecundity, as you yourself emphasized both "'the best chance of surviving and of procreating their kind." I certainly do not object to anyone finding a synonym for fecundity or finding another way to make the point. Slrubenstein | Talk09:26, 23 February 2006 (UTC)
Natural selection versus the outcome of natural selection
I have tried to read the article, failed and I am not happy about it. I have the strong feeling that natural selection (which is a process) is confused with the outcome of natural selection (who survived) and the variation in crucial components that contribute to this outcome (aka what contributes to survival). Variation in components, such as life-history traits, change the likelihood of an individual to survive and reproduce, it does not change the process itself although it can change the mechanism along which the process operates. --KimvdLinde04:35, 23 February 2006 (UTC)
Slrubenstein, just to be clear I am withrawing because I feel I have made the main points I wanted to make and don't have time to constantly monitor this article, and because we're having diffculting getting a stable version. Please continue to revert Marcosantezana changes if they are added without respecting the discussion. The main point I have been arguing in these pages is, as it happens, the opposite of the one above by KimvdLinde. I believe strongly that natural selection, as defined by Darwin and used today, is the selection of good traits which is a consequence of the selection of fit individuals, and that it is not simply the selection of fit individuals by itself. But it looks like we will never reach concensus on this point. — Axel14716:51, 23 February 2006 (UTC)
I've said all along in this discussion page that natural selection is a process, a process that can be defined in terms of its result: the preservation of favourable variations. The selection of fit individuals and reproduction are part of that process. — Axel14719:08, 23 February 2006 (UTC)
Ok, that clarifies your idea. I disagree with you that a process can be defined by its result as many different processes can lead to the same result. Therefore, the process needs to be defined by itself. I prefer a clear distinction between the process, the results of that process, and the actuall mechanisms how those results are obtained. --KimvdLinde19:23, 23 February 2006 (UTC)
I agree that to define a process only in terms of its result is not sufficient but all I really meant was that the result should be part of the defintion. The process is 'differential reproduction' generation after generation (where 'fit' individuals reproduce more frequently on average). The result of the process is that favourable characteristics become more common. That was the part that wasn't understood and needs to be emphasized. The understanding of the result is key so perhaps it is better to view natural selection as a principle or theory rather than as a process. — Axel14720:48, 23 February 2006 (UTC)
I have the impression that if I were to seriously restructure this article, you would be perfectly happy with it as it would make both the process as well as the results perfectly clear. I agree with you that the results can be very convincing, and need to have a place in the article. --KimvdLinde01:15, 24 February 2006 (UTC)
