What actually causes the adaptations behind evolution to manifest? No creationist nutters please!?

Answer 1

Nearly nobody so far has answered the question as I understand it. I think what wesellbunny wants to know is not how evolution works (I'm assuming they know that), but how the mutations occur.

I think that whenever cells reproduce, there is a chance of mutation. When one cell splits to become two, it doesn't necessarily make an exact copy, it might be different in a very small way, i.e. where there should have been an A-T in the DNA there is actually a C-G. Also other factors can cause mutation. Cancer is caused by mutated cells which reproduce rapidly, causing a growth to occur. Cells can be mutated by light to become skin cancer cells, or by cigarette smoke to become lung cancer cells.

As far as evolutionary mutation goes: if a mutation happens in a cell which is destined to split into two and become gametes (eggs or sperm, or the equivalent in other species) then any offspring from that egg/sperm will have every cell in its body as the mutated form, as every cell is a copy of the original fertilised egg.

Hope that was the answer you were looking for.

Edit: While I was writing this, someone else gave a pretty good answer. Graham I said: "DNA copying is not actually perfect, but only nearly so." I think thats what drives the mutation.

Answer 2

Adaptations are usually very small changes in structure or behavior. They manifest for exactly the same reasons that any structure or behavior manifests, because the DNA that codes for that structure or behavior gets expressed during development.

The following quote is from NatureWorks (see link):
"All organisms have adaptations that help them survive and thrive. Some adaptations are structural. Structural adaptations are physical features of an organism like the bill on a bird or the fur on a bear. Other adaptations are behavioral. Behavioral adaptations are the things organisms do to survive. For example, bird calls and migration are behavioral adaptations.
Adaptations are the result of evolution. Evolution is a change in a species over long periods of time. Adaptations usually occur because a gene mutates or changes by accident! Some mutations can help an animal or plant survive better than others in the species without the mutation. This doesn't happen overnight. It takes thousands of years for a mutation to be found in an entire species. Over time, animals that are better adapted to their environment survive and breed. Animals that are not well adapted to an environment may not survive. The characteristics that help a species survive in an environment are passed on to future generations. Those characteristics that don't help the species survive slowly disappear."

I also recommend any book by Stephen J. Gould (especially "Wonderful Life" or any of the Natural History magazine essay collections, such as "Ever Since Darwin") and Richard Dawkins ("The Selfish Gene", "The Blind Watchmaker"), both of whom write books about evolution for the non-scientist. For those who want more technical information, Ernst Mayr is an excellent choice (" Evolution and the Diversity of Life", "One Long Argument", "What Evolution Is").

Answer 3

Darwin proposes that environment may have an effect on the sexual reproductive systems, thus children will mutate in some way.

That causes the first instance of change. If the changes are in anyway beneficial to the child - getting more food, fending of attackers - then the child lives and propogates its genetic code. More and more descendants are born with the advantage, thus becoming more widespread. Darwin says that the fight for survival is more intense for beings of the same type because they want the same food, environment, hunted by the same predators, therefore those with the advantage should take hold, whereas those without are lost.

Darwins book on evolution can be found in any bookshop for about £5. It's written in a fairly easy style - there aren't loads of mathematical equations etc to worry about! The laws of variation are probably the hardest bit to get through.

The interesting thing is, that creationists say this is just a theory and not proven, but Darwin illustrates the book with examples from farming. Basically, if farmers improve animals through selected breeding then this must happen in the wild too.

Answer 4

Sex.
Every animal reproduced by sexual reproduction is different from both it's parents (indeed it is unique).
Most of the changes are small, sometimes they are visible or obvious.
If a change benefits the animal it will be more successful than it's peers and therefore more likely to reproduce. Once it has reproduced, it's offspring will be more likely to have the characteristic that benefitted it's parent. Eventually enough of this type of creature will be produced to be a distinct species.
All changes are small, and many factors may come together.
But every change takes it further and further away from the beginning. Like breeding types of domestic animal.

eg.
A group of Islands on the limit of habitable range.
The most northerly of these Islands is un-vegetated and therefore uninhabitable.
One good year means that Island blooms with new growth.
Birds colonise island.
Next year back to normal, birds die (they cannot go back, as all land is claimed by others).
A few birds survive because seals happen to breed on the beach, birds eat afterbirth.
Seals don't breed all year round - starvation.
Birds with slightly sharper beaks peck at wounds of seals.
All the rest die of starvation. Sharp beaks breed.
Next generation, those with slightly sharper beaks are more successful and outcompete others, they breed.
A few more years, a few more generations.
Then a new species.
And that's how a common seed eating finch changed into the 'Vampire Finch' in 20yrs., on the Galapogas Islands.

Although this is fact, Evolution still cannot account for other types of change and adaptation (viruses for example are only now being understood, and they seem to follow the rules of Evolution but all the facts are still not in).

Answer 5

Right, well, evolution is based on mutation. Without that, evolution cannot happen. Within a group of organisms, mutations occur which make some organisms different to others. Some are bad mutations- just like what happens in all organisms, even humans- which cause the organism to die either before birth or very young because it is easier for predators or it is outsted of food by other organisms. 'Advantageous' mutations- which are advantageous at that time, in that environment- mean that this organism is more likely to survive because of this adaptation, eg. a rabbit has longer legs and is able to run faster to escape prey. This rabbit will then breed and pass on this advantageous gene to it's babies who, again, have more chance of survival and they themselves will breed and eventually the number of organisms with this advantageous adaption will grow while the others without it will die out because, in this case, they are more likely to be caught by the prey than the faster-running rabbits.

Answer 6

There is a theory that adapting is not an entirely random process; that a life form reacts to change or pressure in some way. Animals can see their environment, they make decisions about survival.
The moths that changed colour is a good example; as the industrial revolution produced pollution the moths found themselves living in an environment that was darker than before.
Their eyes picked up that info and it was registered by their brain. Its possible that the stress of 'knowing' that you're the wrong colour for the background and therefore less well camouflaged provoked a response to change the offspring.
Before you write this off as sci fi, remember that the cuckoo can change the colour of the egg it is about to lay to make it match the colour of the eggs in the nest it is about to invade.
So its possible that the moths brains ordered a change or 'randomise colour pattern' in the eggs that the parents were producing.
Evolution is not an entirely random or passive process, its probably down to a number of factors that all work together.

Answer 7

Basically genes mutate randomly. Some mutations will have no real impact on adaptation, but will cause us to, for example, look different from one another. Some mutations will lessen the chances of survival, and therefore this line of genes is likely to die out. Some mutations will increase the chances of survival, and therefore this line of genes will tend to be successful. Successful adaptations of course often are a result of a whole series of random mutations over generations which had no significant impact in themselves, but arrive at a seemingly sudden advantageous adaptation.

The mutation itself is a simple matter of biochemistry - DNA copying is not actually perfect, but only nearly so. Once in a while a bit gets copied wrongly, causing a mutation.

Answer 8

That's a v interesting question and its more than survival of the fittest. although that is important..
There is a theory that severe stresses in the environment can kick start adaptions and compartively rapid evolution, but to understand what the mechanism is requires someone of scientific expertise to explain and is beyond my knowledge. Read anything by Stephen J Gould or Richard Dawkins.
What fascinates me is animals like the fishing owl in Africa somewhere.
It's the wrong shape for a diving bird (chunky, not streamlined), was originally a dusk or night hunter, presumably ate something else, and its beak is the wrong shape (curved not pointed) for spearing fish yet it thrives in its niche. How did it get to the complete change of diet, hunting methods and so on? How come it was not out competed by the species who evolved for that environment?

Answer 9

Animals adapting 2 changing surroundings.
A moth adapted 2 the Brit Industrial Age, it's wings appeared 2 take on a shade darker, 2 blend in2 the Dusty/Smog residue covered trees & buildings.
It's the only 1 I can think of right now.

From that Darwin expanded his theory of Evolution.
Shame 4 him that Carbon-dating in the 70s disproved most of his skeletons.
1 had the skeleton of a human but the skull of a Ape!

Answer 10

As I understand it, a particular animal may have any number of slight variations compared with another of the same species. But if one, say had slightly darker colouring, and this suited the environment better, that specific animal would have a slightly better chance of survival than a lighter animal. And therefore would have a slightly better chance to reproduce. From then on its just genetics at work.