Poll: Do you believe in speciation?
- Thread starter dnnydllr
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The problem here is that there's a very finite science to the matter which you seem to be missing. For one, humans never had any relation to bacteria (saying that we evolved from them is a misconception to say the least). We may share a common ancestor (the simplest single-celled organisms in this case), but that's it. Also, you call mutations 'random'; they're not. Sure, some may occur due to replication errors, but most mutations should be classified as 'adaptations' instead. Giraffes have long necks due to the height of the trees that produce their food; this didn't happen accidentally, but over millenia of constant strain, their DNA adapted. Bacteria, on the other hand, mostly adapt through random mutation, but again, their composition is markedly different from complex organisms.dnnydllr said:
As for speciation, in my opinion it's a proven phenomenon. Separate two groups of the same animals, place 'em in different environments, and you'll indeed get two different end results.
As for your question regarding why we don't see speciation on a large scale; we've only been around for a few thousand years, and detailed records have existed for what, a hundred of those? Genetically, that's a modicum of time for any huge changes to happen.
But at random? No. In fact, what a lot of creationists fail to understand is that with the infinite expanse of the universe, with a bigger number of stars and planets than could even be numerically comprehensible to any of us, and with all the possibilities for various conditions and chemical reactions a planet like Earth was pretty much bound to come about somewhere in the universe. I say "like Earth" in the sense of having many distinctly developed species living on it. Theoretically, there could be other planets exactly like ours somewhere, at a distance so hugely far away that we may never even be aware of them.Steven Kyzburg said:
When probability is literally unlimited by the grand scale of the universe it's really myopic to call something like evolution improbable or impossible.
But say one in every hundred of these interbreedings leads to offspring that are fertile. If they continued breeding for long enough, their DNA may have mutated in such away (as it is being selected for) that they can breed.dnnydllr said:
Ermm... you have heard of a guy called Einstein, right?dnnydllr said:
To be clear, you're not actually implying that it was the giraffes straining their necks that led to them having long necks? It is merely the fact that the giraffes with longer necks were more likely to pass on their genes, as they had more likelyhood of being well fed and hence being fit enough to breed.CuddlyCombine said:
The thing about bacteria is the fact that they are highly mobile, are easily interchangeable with one another, and they reproduce faster than rabbits. Another thing that the thread poster seems to have forgotten or doesn't understand about the evolutionary process, is the fact that it is SLOW. So, no, bacteria could not have evolved into a human being (or something that resembled a human being) overnight. In fact, bacteria didn't even evolve into fish overnight either. Cellular tissue started to develop as new species of bacteria started appearing and competing with each other. Cellular tissue started to develop when different types of bacteria started banding together for survival. Over a tremendously long period of time, bacteria started to evolve into fish. Meanwhile, on land, other groups of bacteria that had either started off on land or come out of the water, started to evolve and change in a similar, yet different manner; and thus land animals came into being.
Well, this isn't completely correct, either.CuddlyCombine said:
The different mutations were random, but the situation (i.e. leaves only on tall trees because of, say, a drought) led to a selection.
So, say, there were several families of giraffes with long necks as well as many with short necks.
A drought hits and there's a food shortage.
All the other animals consume the leaves on the lower branches and when the giraffes finally get to the trees, only those with long necks can reach and eat.
They are the ones with higher chances of survival in this specific situation (they are "the fittest" under these circumstances), which also means they have a higher chance of reproducing.
Therefore, over several generations, the numbers of giraffes with short necks dwindled until only those with long necks remain.
It is an adaption of the species as a whole, but it did not happen through "directed mutation" but through random mutation and (after the fact) selection via enviromental influences.
The DNA of the species did adapt but it did so through a form of trial-and-error.
I'll give you that, I guess. Random mutation leads to adaptation. However, mutation can be caused directly by some events or situations. Of course, I can't say I know this from experience, seeing as I've only been alive for 18 years and haven't ever mutated...Skeleon said:
http://mwclarkson.blogspot.com/2008/04/rapid-evolution-of-lizards-in-adriatic.html
http://www.youtube.com/view_play_list?p=019F146277A3EDFD
The first link leads to a blog that talks about some lizards who were removed from their home island and moved to another. The lizards' diet in their original habitat was <10% vegetation, but their diet on the new island consisted of a lot more. Over a period of about fourty years, the lizards developed an altered jaw morphology and a cecal valve.
The second link will direct you to a playlist of videos explaining how evolution works; perhaps you can find something to interest you there.
http://www.youtube.com/view_play_list?p=019F146277A3EDFD
The first link leads to a blog that talks about some lizards who were removed from their home island and moved to another. The lizards' diet in their original habitat was <10% vegetation, but their diet on the new island consisted of a lot more. Over a period of about fourty years, the lizards developed an altered jaw morphology and a cecal valve.
The second link will direct you to a playlist of videos explaining how evolution works; perhaps you can find something to interest you there.
I wasn't saying a bacteria goes straight to a human, I was saying that it couldn't climb all the way up the evolutionary ladder to be a human. I may seem stupid, but I do realize that evolution is alleged to take millions of years to occur.TheDoctor455 said:
With regard to how random it is i'm refferring to evolution. Although perhaps random is a bad choice of word since it is misleading. In either case, evolution is down to chance, down to the possibility that a situation will favour one particular allele, or, in an extreme case, that vast proportions of alleles will be wiped out like it was with humanity when we were back in Africa.CaptainEgypt said:
Random's a bad choice of word, chance is the correct one in terms of evolution. So perhaps I'm in the wrong since i read into your statement incorrectedly.
I wasn't so much as reffering to you, I was just picking up on that one statement of dnnydllr's (which i've left un cut) which as far as i'm aware is incorrect.dnnydllr said:
It can and as far as we know it did.dnnydllr said:
Firstly I noticed that you think that the earth is only a few hundred million years old (correct me if you don't think this) But for your information a technique called carbon dating can date samples of rock rather "accuratly" (When your looking back by the billions the margin of error get's bigger) Some of the oldest rocks available are tens of billions years old.
And that's not taking into the account rocks which are naturally pushed underneath the earths crust by tectonic movements. The planets surface is relativly young.
But, back to the bacteria evolving. It took tens of billions of years to go from a simple slow sluggish cell to a cell that could harness light, then even more millions to get bacteria that produce carbon shells (they do, chalk is also a by product) and then time crawls on for millenia as we probably get a few simple celled slug like things untill we get to the fossil record.
Remember with the fossil record that it only preserves thigns that have skeletons or other hard parts. So unfortunatly most things beyodn the Cambrin explosion (look it up if your not familiar) are unknown to us.
Evolution is slow and due to chance. Evolution isn't a ladder that goes up, it goes wheve is best. Bacteria can survive and reproduce better than us and so from an evolutionary stand poitn are superior, but there are benefits to being big and multi cellular.
With humans though, well, our intelligence is due to chance. It's due to chance that we are the only survivors from our family when all our other "species relatives" died off. It's a chance that we weren't all killed and left a few thousand survivors to repopulate the earth.
It's a chance we survived and got here. This is where peopel pull the god card but hay, if theres a chance, it's goign to happen sooner or later.
I'll go through this bit by bit.dnnydllr said:
"but rather that all species came from a common ancestor through the process of speciation. I quite frankly don't see how this could possibly make any sense. Even through billions of random mutations, I don't think bacteria could turn into something as complex as a human."
First, the reason that bacteria can (over millions and millions of years) evolve to a human is that species branch and split as time goes on. The "path" of evolution isn't a straight line. Different species branch off over time. Take, for example, cats and dogs. Scientists believe that they had a common ancestor. However, over time, proto-cats or dogs split off from the ancestor, and both eventually evolved into what we now know as a cat or dog. The split happened, but it happened millions of years ago.
"Also, is it not true that because species can only reproduce with members of the same species that whenever a new species did arise through a mutation it would immediately die off as it had no other organisms to reproduce with, because no other organisms would have that exact mutation turning it into that species?"
The reason that animals with mutations can still reproduce with their species is because the mutations are, well, just mutations. They become a different species when the mutation becomes a trait. If a fish had three eyes (as a natural mutation) it could still reproduce. When the trait shows up in all fish descended from it, then the mutation is a trait, and eventually, the offspring's DNA becomes different enough so that the "other" fish cannot reproduce with normal fish.
"And why don't we see any animals changing species today? You'd think that at least one or two should be crossing over around now.
The reason we don't see animals changing left and right is because evolution happens incredibly slowly. Any traits that are favorable to survival are passed down and eventually become the traits of a separate species.
Though the Theory of Evolution does have some holes in it, it is nearly universally believed (among scientists) because it has the most scientific evidence on it's side. You can believe whatever you want, but I hope this cleared things up for you.
No, though the image is humorous at least. It's not like he's willing his neck to grow longer, but the repetitive strain of having to reach up (possibly higher than normal) will select that group of mutations to prevail (since, as the previous poster said, those giraffes will survive more easily than the rest). I'm no biologist, so I'm probably using wholly incorrect terms.Lukeje said: