What is the mechanism that prevents microevolution to become macroevolution?

What good points would those be? Well, again, parents don't have random offspring, they have offspring determined by whatever genetic payload they wind up passing on.We define "species", scientifically, as a reproductive community. Obviously, offspring and their parents must be part of the same reproductive community because there's gene flow between them (in one direction anyway.)Speciation - the creation of a new species from an old one - occurs when a portion of a population is split from the whole. Subject to different pressures and isolated, genetic differences accrue until genetic incompatibility is too great to allow interfertile hybridization. That's the gist of it, anyway. You've never had a tan? You don't think that the darkening of your skin in response to sunlight is just coincidence, do you?Ever have a sunburn, though? Pretty painful, right? If you were going to be out in the sun all day, having skin that was already tan would have been a considerable advantage, right? So is it really so surprising to find that the people who live in hot, sunny Africa have dark skin?Now, I'm not saying that the sun makes people black (although you may get a tan from the sun, it's not a tan you pass on to your children.) What I'm saying is that people who had been born with genetics that programmed them to produce a certain amount of melanin in advance would have had an advantage over those who didn't, or who had much less.I don't know. Doesn't seem that complicated to me, I guess. Maybe I don't understand what you're asking?

black people get sunburns too, crash.

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Just the usual statistic that says that most mutations are not beneficial. Most do nothing recognizable, many do something lethal or produce diseases. So? Since when is a feeling of offense the standard for truth? Because it proves nothing that it happens once in a while. What must happen in order to offset the trend of allele loss or reduction of genetic diversity is LOTS of beneficial mutations. (This isn't relevant to humans since humans have never speciated according to the ToE formula -- that is, we don't have human groups who can't interbreed. The only point here is that beneficial mutations in humans should demonstrate that the rate is insufficient in any case).I'll take your word for it at this point that this Italian thing is a mutation -- until I read more and get another angle on it or something.

Well it depends on what your definition of "human" is. There is some support to classifying every species in the genus Homo as "human", and if this is true then humans have speciated. Of course you can declare that "human" only refers to H. sapiens and you wouldn't be alone in that position. My point: There is no monolithic "ToE formula" that declares that humans have never speciated.and also: to steal your arguement, maybe there is a new human species out there but we haven't found them.Edited by DrJones*, : reworded a bitEdited by DrJones*, : added a sentance.Edited by DrJones*, : cause I'm an editing fool.

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Just a monkey in a long line of kings.
If "elitist" just means "not the dumbest motherfucker in the room", I'll be an elitist!
*not an actual doctor

Oh, just to let you know, I AM Black But...I actually accept the vast majority of the evolutionary theory. But the only thing that I don't agree with is the time periods that associated with it, as well as what is referred to as "speciation." Something to support this:"Biologists studying evolution do a variety of things: population geneticists study the process as it is occurring; systematists seek to determine relationships between species and paleontologists seek to uncover details of the unfolding of life in the past. Discerning these details is often difficult, but hypotheses can be made and tested as new evidence comes to light. This section should be viewed as the best hypothesis scientists have as to the history of the planet. The material here ranges from some issues that are fairly certain to some topics that are nothing more than informed speculation. For some points there are opposing hypotheses -- I have tried to compile a consensus picture. In general, the more remote the time, the more likely the story is incomplete or in error."Intro to Evolutionary BiologySorry for posting such a large segment, but I did cite my source.Don't get me twisted, man. I probably agree with you on the majority of things, but I want your take on this.Also, what about Tragopogon and T. mirus and T. miscellus? What do you think about that? And how do you propose that it supports the common ancestry theory supported by many evolutionary biologists?Also, do you mind explaining "common ancestry" and "speciation" to me? I would like to know what you think.|the kidEdited by TheNewGuy03, : grammar.

Environment and geographical division.1.The pigment is an adaption to the environment in which they live. Vitamin D plays a large part in this. Human skin color - Wikipedia2.The formation of distinct races was aided by limited movement between populations (most especially in the pre-industrial era) - local traits were reinforced.Edited by RickJB, : No reason given.Edited by RickJB, : No reason given.Edited by RickJB, : No reason given.

This has to do with "Noticing a Mutation" how exactly?It is helpful for the browsers or those looking for a particular point if the post titles are a bit meaningful.I think it also helps you to focus your thoughts.Thanks.

My apologies for being caucaso-normative. A rude oversight on my part. The time periods are confirmed by the convergence between geologic and genetic data. Maybe you could elucidate your concerns? If speciation is false then where do all the new species come from? On what? The fact that the conclusions of science are tenative and based on the best evidence we have at the time?I don't see that as a contentious point, or even a significant one. It's never been asserted that science always gets it right. Science is mostly right, and getting righter; things like creationism never change no matter what evidence is found and so are completely and eternally wrong. What? Elaborate, please. Speciation I explained. Common ancestry seems obvious. What's to explain?

I think we can afford a short diversion to explain this term (even if Crash thinks it is utterly obvious).Going back to Darwin's "Origin of Species" we find him saying that life's diversity arose from "one or a few".He was saying that all of the wide diversity of life can arise from only a small number of earlier forms through the evolutionary process.The question then becomes: "Is it a few or one?"That is does all life have one form as the "common ancestor" way back there or are there several lineages with several starting points?How would you settle this? You'd have to both look at what the fossil record tells us and what life forms alive today are like.Obviously, if you pick a restricted group you find that there is lots of good evidence that all members of it arose from a very narrow base.Let's look at the mammals. The exhibt a set of characteristics that are most easily explained by accepting that they came from a single branch. This is from both the body form we see and, very strongly, from the shared genetics.From the fossil record we see that this common ancestor would have been about 200 some odd million years ago. The genetics happens (surprise!) to agree with such a date.We also see that all mammals share some deep biochemistry and genetics for which there is no good reason that we should think they all arose independently (especially with the fossil evidence pointing the same way).From this we conclude that not only could mammals share a common ancestor based on evolutionary processes but that they, in fact, do.It gets trickier and more complex to be sure that this can be extended further and further but so far it looks like the "few" is actually "one".This is not to say that life didn't arise more than once. It does suggest, though, that either only one branch made it through or the descendants of the other branchs are as yet unfound or unrecongnized or that there was an interchange of chemistry between the separate branchs to merge them into an apparent single one very, very early on. (by early I mean sometime before 3 billion years ago).

Sorry Nosy. I really am hopeless at remembering to use those!

Almost everyone is. I'm going to go on occasional rampages to try to remind everyone because I do think it is helpful.

Hi New Guy, I'm one of the Biblical Creationists here and will give you my angle on these terms.Common ancestry in the most ordinary sense refers to any ancestor you have in common with other people, someone you all can trace your genealogy back to, such as a grandparent or great-great-great grandparent you all have in common.Common ancestry to evolutionists means all living things can be traced back through many other forms of life to some beginning, say in the primordial ooze as a one-celled creature; and it is often used to refer to some supposed pre-ape/pre-human creature who is said to be the common ancestor of all the apes and all us human beings together.From a Biblical point of view all human beings have Adam as our common ancestor; Noah too.As for speciation, there was a time when creationists wouldn't own the term because it seemed to have been so completely taken over by the evolutionists it was useless to us. Gradually it's been accepted to define what we always have recognized as the way you can breed plants and animals to develop different forms of them. Evolutionists define speciation as the point at which these new breeds lose their ability to interbreed with the former population of which they were a part. To creationists this is an artificial distinction, since the ability to interbreed may be lost just because the genetics change too much, although the creature is not a new species, simply a new variation or breed.So I freely use the term speciation to describe this ordinary process of variation. It occurs in nature and it occurs most dramatically when you aim to get a new breed of, say, dogs and cats.On this thread I've been arguing that speciation occurs all the time, but that if you examine what brings it about, it ultimately involves the loss of genetic information -- that is, you get a new breed of dog by eliminating the genetic information that produces the characteristics you don't want in your new breed. The same thing happens in nature when a small population of an animal goes off on its own.The "races" of human beings developed when people split the same way, small groups going off on their own and no longer mixing with the previous groups. They would then mix together only the alleles they had among them, which would eventually develop their own distinctive characteristics.About skin color, the usual idea that it was an adaptation to the amount of sun in an environment implies that a lot of people had to die for the adaptation to develop, the ones who didn't have that adaptation. I'm not sure that explains it, but if it doesn't that leaves something Lamarckian, along the lines of genes changing in response to the environment.Hope this is clear.Edited by Faith, : No reason given.Edited by Faith, : No reason given.

So essentially you use the word speciation in a way that makes it completely meaningless to anyone else?TTFN,WK

I believe I use it to describe exactly what you use it to describe, only I disagree with you that it implies anything beyond the usual variation in a kind. As far as the genetics and other facts go, I use it the same way you do. I try to be careful to make distinctions when it seems necessary to set off the different interpretations.{edit: I see I wasn't that careful in my post to New Guy, though, so maybe you have a legitimate complaint there. All the changes that are in the direction of speciation as evos describe it I guess I sometimes call speciation, though for the sake of clarity I suppose I should always make distinctions along the way.This simply reflects the arbitrariness of the word to my mind, as evos use it, it seems to me. Inability to interbreed is an artificial standard from a creationist point of view, especially when you consider that by the time "speciation" by that definition has been arrived at, the genetic diversity is so decreased any further variation is just about impossible.Edited by Faith, : No reason given.

Seems to me I've made my case that all the processes of population genetics, with the exception of mutation, that lead to a change in allele frequencies in populations, either merely shuffle alleles or eliminate alleles, reducing genetic diversity, and that over time elimination of alleles is the slowly accumulating trend in changing populations -- faster if drastic events like bottleneck occur; and that mutation is the only thing that could possibly add alleles and increase genetic diversity in populations.That being the case, I'd really love to see the DATA that so many refer to, that support the oft-repeated claim that mutation occurs frequently enough and beneficially enough to offset this inexorable trend to genetic depletion. Data, evidence. LOTS of GOOD mutations. Edited by Faith, : No reason given.Edited by Faith, : No reason given.Edited by Faith, : No reason given.