Quote: Original post by Anonymous Poster

Quote: Original post by owl
The probabilities for a mutation to be exactly what a species needs to survive in a specific moment of it's evolution, and particulary for ants where the reproduction rate of the population is so low in comparision with other species (like cockroachs) is so improbable that I felt like saying it was infinite.

Evolution doesn't provide an improvement that the population needs to survive, it provides some improvement over what the population had before.

If the improvement isn't for survival, what's the improvement then?

Quote: Original post by Anonymous Poster
If one population of ants was significantly better at surviving than some other population, it would reproduce at a faster rate and competition for survival would result in the better population becoming more prevalent.

Indeed. What we are discussing here is the means by which a population becomes better. You stand that it is purely accidental. I propose it is because the matter that compose the creature has a tendency to be arranged in direct relation to the enviroment it exist, and that those changes are passed onto the next generation.

Quote: Original post by Anonymous Poster
Significant mutations do not happen frequently.

Read the case of the cockroach in the post above.

Quote: Original post by Anonymous Poster

Quote: Original post by owl
If adaptations are "convenient accidents", why technical/planned breading of animals such as cows or horsed works as expected and doesn't mutate into something else "randomly" ?

Selective breeding does not rely on mutations during the breeding process. Natural variation already exists in the genetics of the species (caused by mutations which occured during the evolution of the species). Selective breeding selects individuals to breed based on the desired traits. The traits may be caused by the genetics of the individuals, and so some of the offspring may possess similiar traits. The offspring that possess the traits are used for futher breeding.

Yes, I regret to have pointed this out. It's a pointless case of study.

There is lots of research done on cancer. Here's a wikipedia article that explains some of the mutations that cause cancer, and it has some references if you're interested in following them to verify what the article says: http://en.wikipedia.org/wiki/Carcinogenesis

As for cockroaches developing immunity to poison: The theory that an animal's experiences can be written back into its genetics doesn't explain this one either, because the cockroach that eats poison would die. If it has some way of surviving the poison, the mechanism for survival must have existed before the poison was eaten.

Cockroaches able to survive the poison are the only ones able to reproduce, and the result is that the next generation of cockroaches is decended from cockroaches that survived the poison. The resistance wasn't developed in a single generation, the poisoning merely eliminated the individuals that didn't have resistance.

It doesn't take a high mutation rate for such a mutation to occur when the population is large.

Quote: Original post by owl

Quote: Original post by Anonymous Poster

Quote: Original post by owl
The probabilities for a mutation to be exactly what a species needs to survive in a specific moment of it's evolution, and particulary for ants where the reproduction rate of the population is so low in comparision with other species (like cockroachs) is so improbable that I felt like saying it was infinite.

Evolution doesn't provide an improvement that the population needs to survive, it provides some improvement over what the population had before.

If the improvement isn't for survival, what's the improvement then?

The improvement might help the animal to survive, but it isn't necessary for survival. Even if the beneficial mutation didn't occur, the animal would still have survived. And mutations can result in variation without any noticable benefits. The variation itself can be beneficial because some members of the population may be better able to survive a climate change or a new predator or a new disease, or the variations may be elaborated on by further mutations resulting in something that is useful.

Quote: Original post by owl
Well, if you consider adaptation as part of evolution, cockroachs are able to become resistant to poison from one generation to another (and that period of time may be months). What's going on there? Mutation?

No, its not post-poisoning mutation over a single generation. Its pre-poisoning mutations over many ancestors.

Quote: Original post by owl
Cancer is caused by the inability of certain cells to produce a particular component that inhibits the process of reproduction. That's a very specific kind of malfunction, can you name any other cell malfunction caused by mutation?

Yes.

Quote: Original post by owl
Cells perform lots of activities apart from reproduction. Besides, is there some proof that cancer is the result of an accidental mutation? Or is it just an assumption too? :)

When I make an assumption during a discussion, I usualy point out that it is an assumption. I don't try to hide them in an air of confidence. There are people who so often argue from assumption but fail (or refuse) to admit it, that they (ahem) assume that everyone else is presenting assumptions too.

Quote: Original post by owl
Again, what evidence supports that cancer is the ramification of a mutation?

All of the evidence ever collected on the subject supports it because that is infact what it is.

Quote: Original post by owl
I mean, to know that you need a copy of the DNA right before reproduction and the resultant mutated DNA that shows a new element which happens to be the cancer code. Is there such a proof?

They can tell you exactly which genes are responsible for the different forms of cancer, and even which genes are responsible for its migration.

- Rockoon (Joseph Koss)

okey. The wikki article on cancer is really good and explains a lot about how different changes (mutations) in the DNA can lead to cancer. This would prove without doubt that DNA mutations occurs in cells.

Anyway I haven't found information about other kind of mutations that don't lead to cancer or that may have "benign" consecuences. So, I still won't take that mutations are the basis for evolution. :)

But I accept that it's cientifically proved that mutation is one of the most important causes of sickness and death in many life forms.

Let me "invent" an analogy:

Say we have a couple of billons of personal computers. We proceed to "randomly" add and remove different electronic parts of them. From the resulting set of computer that are still able to run (say Quake) without problems we build 10 copies of each and we continue adding and/or removing croping and re-ensambling parts (including hardisk/ram's blocks, any little bit that confoms it). We repeat this process from one generation to another like if it were a GA.

EDIT: Obviously we will destroy the working ones from the prior generation to simulate natural death.

What are the probabilities that we will be able to continue this process forever because there will always be at least one computer that will be able to run quake?

To make it more interesting why don't we start with just one?


[Edited by - owl on November 27, 2005 10:39:13 PM]

The computer analogy is not valid. Its biological equivalent would be like taking arms, legs, various organs, etc, and randomly assembling them together. Then we throw away all the chimeras that cannot climb some stairs, and we shuffle the parts of the remaining monsters. This is not what mutations in the genetic code generally do.

Here's some simple examples of known beneficial mutations: A mutation in a bacteria may alter a protein on its exterior membrane, causing an antibiotic to no longer react to that protein and thus granting resistance to that antibiotic. A poison that interferes with an enzyme involved in an insect's metabolism by binding to it might not bind with a slightly altered enzyme, so the mutated enzyme would provide resistance to the poison.

Biological systems work in intricate, interconnected ways. Most mutations may indeed be harmful, but such mutations tend not to survive in the population since their carriers will be unable to produce offspring. But those mutations that are not harmful contribute to genetic diversity and may even be beneficial.

Also it seems that there is evidence that some single celled organisms, when placed in a stressful situation, may have a mechanism for increasing their mutation rate. And there are mechanisms by which single celled organisms can share parts of their genetic code, which is useful for sharing immunities to chemicals.

Quote: Original post by ketek
You should elaborate a bit on yourself, if your first impulse was to kill,
next time before killing a bug or a small animal, or you when you feel the impulse to do some experimenting on something alive, slam an hammer on your hand and see if it hurts

He was in his bathroom, as he said you moron. Ants do not belong in your bathroom.
Little disease carrying rodents, get poisoned if they come in the house. Do you want your house infested with bite-stinging ants and disease carrying rodents? I don't think so.

Idiot.

Quote: Original post by Anonymous Poster
This is not what mutations in the genetic code generally do.

We actually don't really know for sure how and why mutations occur in all cases. We know they may be caused by radiation and by some substances in little dossis and others by overdose and that they may vary depending on the subject metabolism.

Almost all the mutations that derivate from this causes are proven to be detrimental (probably because they are mostly studied in the case of deseases). Whatever the reason is, there are no solid statistics to say for sure that "aleatory mutations" in DNA are the path taken by evolution.

According to dictionary.com the definition of genetic mutation is this: A change of the DNA sequence within a gene or chromosome of an organism resulting in the creation of a new character or trait not found in the parental type

As I understand it, parent do not (or none of both parents in case of sexual reproduction) carry the trait that suddently apears on a child.

Following the evolution of mankind (for example) based on the information we have today, it becomes very hard to me to belive that the homo-sapiens evolved it's capabilities of building tools in a lapse of, say, 500-300 thousands years with such a small a population as it is tought there was at that time, just by accident.

As you say, if mutations are aleatory, not so frequent, and they may happen in any place of a DNA that happens to be huge, how is that humans evolved so technically both in morphology as mentally in such a "short" period of time (from monkeys to "engineers" in about... 1.000.000 millon years?) with such a short population?

I stand that these "mutations" are not casual, that they are in direct relation to the eviroment in which they apear, and that they may be "forced to happen" by the organism in question in order to survive.

Quote: Original post by owl

Quote: Original post by Anonymous Poster
This is not what mutations in the genetic code generally do.

We actually don't really know for sure how and why mutations occur in all cases. We know they may be caused by radiation and by some substances in little dossis and others by overdose and that they may vary depending on the subject metabolism.

Almost all the mutations that derivate from this causes are proven to be detrimental (probably because they are mostly studied in the case of deseases). Whatever the reason is, there are no solid statistics to say for sure that "aleatory mutations" in DNA are the path taken by evolution.

According to dictionary.com the definition of genetic mutation is this: A change of the DNA sequence within a gene or chromosome of an organism resulting in the creation of a new character or trait not found in the parental type

As I understand it, parent do not (or none of both parents in case of sexual reproduction) carry the trait that suddently apears on a child.

Following the evolution of mankind (for example) based on the information we have today, it becomes very hard to me to belive that the homo-sapiens evolved it's capabilities of building tools in a lapse of, say, 500-300 thousands years with such a small a population as it is tought there was at that time, just by accident.

As you say, if mutations are aleatory, not so frequent, and they may happen in any place of a DNA that happens to be huge, how is that humans evolved so technically both in morphology as mentally in such a "short" period of time (from monkeys to "engineers" in about... 1.000.000 millon years?) with such a short population?

I stand that these "mutations" are not casual, that they are in direct relation to the eviroment in which they apear, and that they may be "forced to happen" by the organism in question in order to survive.

I thought mutations where caused by errors in dna replication when cells divide, given the sheer number of cell you go through in your life everything must have mutations, most of them just result in cells that die iirc.

Evolution happens very fast really, I think there must be more to it than we know. Obviously really, there are so many unexplained things. Classic example: echolocation in bats, you can't really explain how bats evolved the two organs necessary for it via short steps. If evolution does work by advantageous mutations surviving, you have to wonder about the intervening steps. An elephant evolving a trunk really has an advantage. But what use is an elephant with an inch long half evolved trunk?

The ancestors of elephants were smaller and would not have needed a trunk as long as an elephant's for it to be useful. A half inch long trunk? That's called a snout. Some animals have one. A short trunk is still useful for picking up things from the ground (for a smaller animal) and for swimming (point the trunk up towards air to breathe).

For echolocation mechanisms, it is known that whales first evolved improved hearing. The mechanism for hearing high pitched sounds is useful without the mechanism for creating them. It is possible that the same thing happened with bats. There is no need for the ability to receive high pitched sounds and the ability to create them to evolve at the same time.

A genetic mutation that causes a protein to have a slightly different amino acid is a mutation. The parent did not have the altered protein and the child did. The new trait can just be a slightly different protein.

It is believed that one mechanism for the creation of new proteins is that during replication a gene may be duplicated, and thereafter it appears in the sequence twice. Now one copy can mutate, and even if the mutated version is not as effective the organism still has the other copy which works fine. This provides some more freedom for the genetic code to diverge.

Your main hypothesis is that animals can somehow affect their evolution so that their experiences can be conveyed in some way to their decendants, that the insect that learns to escape may in some way confer knowledge of what to do in that situation to its decendants. It is very well known that engineers are capable of doing this. If an engineer solves a problem, then not only can the solution be shared with the engineer's decendants, it can be communicated to other engineers. This level of intelligence provides a huge advantage over animals that can't share high level knowledge. Intelligent animals are more likely to survive, so there was actually significant evolutionary pressure to evolve intelligence.

Quote: Original post by owl
Following the evolution of mankind (for example) based on the information we have today, it becomes very hard to me to belive that the homo-sapiens evolved it's capabilities of building tools in a lapse of, say, 500-300 thousands years with such a small a population as it is tought there was at that time, just by accident.

As you say, if mutations are aleatory, not so frequent, and they may happen in any place of a DNA that happens to be huge, how is that humans evolved so technically both in morphology as mentally in such a "short" period of time (from monkeys to "engineers" in about... 1.000.000 millon years?) with such a short population?

Generally, I agree with you on this point - the rate of human evolution seems to outstrip that of other animals, given the small population and reproduction rate. I am inclined to think that there is another factor in there. However, don't forget the role of cultural transmission in humans - the ability to pass down knowledge from one generation to the next without explicitly encoding it within the human. This amplifies the abilities of any single human within a society. Most of the tools we use today are only usable because of cultural information telling us how to recreate and operate those tools.