A question was asked two pages ago about why animals would consciously decide to live in the water.
The questions is not valid, because the premise of the question is not accurate. No one here is suggesting that an animal might look at the water, think to itself "I think I'll live there now. All I need is gills, but those will evolve with time!", and proceed into the water.
There is no conscious effort required here!
Rewording the question with the fewest basic assumptions as possible, you might get something more like this:
"Why and how would a land animal move into the water, and become aquatic?"
This question, I can largely answer, because it is not assuming intelligence on the part of the animal in question.
The first thing I think we can all agree on is that it wasn't a simple transition. No animal simply walked into the water and lived the rest of it's life there. If you are I tried that right now, with no technology to help us, we would shortly drown, and not pass on any of our genes.
However, if we were to purposely banish any technology from our society (for the purposes of this example, I will get back to technology later. For now I want you to put the humans in this thought experiment into the role of any other animal - in need of food, shelter, water, a method for reproduction, etc. And no tools to help us out), and then attempt to live next to the water, we would have a situation ripe for evolutionary effects to take place.
Those in the population who are better swimmers would more readily be able to procure food for themselves and their families, raising the chances that their genetic line would continue. Similarly, those who are better foragers would have the same advantage, but for different reasons.
We would have two groups in this society, based on their abilities - a forest gathering group, and a water-gathering group. Niether is better than the other, if everyone in the population remains fed and healthy, there is no driving force to push change. Some people will be better foragers, and their children will most likely be good at foraging, too (though, giving social factors, they may not follow in their parents footsteps)
The forest gathering group benifits most from good eyesite (for spotting food), good manual dexteriaty (for picking berries), endurance in walking (for travelling long distances over long periods of time) which is helped by strong legs, but a light body frame, and strenth & speed for hunting with their bare hands (remember, no technology, this includes spears, etc).
The swimming group benifits from good lung capacity, good strength over shorter distances, good eyesute underwater (with less, and bluer light), dexterity. If the majority of the food is on the bottom of the ocean/lake, then a denser frame (help the individual sink) will help their ability to gather food underwater with their bare hands.
We are now at a population which Flores seems to believe populates the world. Differences in population, passed from parents to child, but without evolution. There is no reason to change from the exsisting population of genes - everyone is eating.
Now, let add seom environmental pressures to this situation. Let's say that a new species of lion comes into the area, and starts eating the gatherer group when they are out and about collecting food. Those gatherers who have better eyessight already will be able to spot the lions sooner, and have a better chance to get away from the lion w/o getting eaten. Similarly, the faster runners will be more likely to survive their lion encounters, even if they don't have better eyesight. Those individuals who are slow runners, and *also* have poor eyesight are going to be lion snacks.
The genes which gave them the traits of slow and near-sighted are now less in number in the possible reproductive population now, because the guy who had 4 of those genes (two per trait in question for this simple example) is now dead.
The next generation of kids has a slightly lower chance to be slow and near-sighted, simply because there are fewer slow and near-sighted genes to be had.
Note that I have not introduced mutation yet. This change in the overall population genotype and phenotype is due simply to the reduction of available genes in the reproductive population.
Now let's continue. These lions happen to do very well in the area, and begin not only to hunt people out in the forest, but also in the village itself, at random times.
With this change in the environment, now both the foragers and the swimmers are put under preditory pressure by the lions. Those foragers who have better eyesight, those who are fast, and those who are both will continute to have a better chance for survival than their slower, near-sighted brothers. However, now, the slower, and also the near-sighted swimmers are more likely to be killed, thus reducing the slow and near-sighted genes in the swimming population.
But wait, things are not so clear-cut. Didn't I suggest above that those individuals who are more dense might do better as swimmers, but those with lighter frames would do better as foragers? What might make indiduals slow, and more likely to be eaten by a lion?
A dense frame, which requires more effort to get up to speed when running. So a dense frame, which is a good thing in the water, is now a bad thing out of the water.
So how do people survive lion attacks, and therefore have an opurtunity to pass their genes onto the next generation? Well, the lions attack int he forest still, so not being in the forest is a good thing. However, if you are a gatherer, and are good enough at swimming to gather food from the water, you *must* go into the forest for food in order to survive. (this is a metaphore, and such, I'm spicifically removing the chance of food sharing between the swimmer and gatherer group, just like I'm ignoreing technology. I'll deal with this later on). therefore, once in the forest, being able to run fast and being able to see the lions sooner are advantages.
However, the lions are *also* attacking in the village. People could either spot the lion sooner, run fast, or both in order to survive these randomly timed lion attacks. Or they could not be in the village, where the attacks are occuring.
The swimmer have a distinct advantage here - the less time they spend in the village, and the more time they spend out in the water gathering food, the less the chance that they end up eaten by the lions.
Therefore, overall, all slow, near-sighted gatherers will have a pretty good chance that they will be eaten. All fast or better-sighted gatherers will have a smaller chance of being eaten (a fast/good eye-sight gatherer may still be eaten in his sleep, where good eyesight and speed are of no use. We are only talking about relative *chances* of being eaten, here).
In the Swimmers population, however, the faster runners with good eyesight will have a low chance of being eaten, but so will those who have very good endurance at swimming, and are not in the lion's hunting area for longer stretches of time.
Let say that the lions continue to do well in the area, and their population increases year over year. The number of deaths due to lion attack increase year after year, and soon, being fast isn't good enough. Running from one lion simply puts you in the jaws of another. The chances of being eaten are now even for fast/good eye sight indiviuals and slow/bad eyesight individuals. The only people who are less likely to be eaten are those outside of the lion's hunting area, the long-endurance swimmers. So (again, without any mutation), you will have a shift in the population towards survival of of the swimmers.
Look! evolution of the *population*! This is what I think Flores is talking about. No mutation, no new genes, just a selection of which exsisting genes are available. Functionaly different than the evolution of the species, however. The population has changed, and the genes available to create good gatherers have largley been lost (given enough time, and the right combination of lion kills, you may lose all the gatherers, and only have swimmers left). If gatherers were to suddenly appear again (say by god/allah simply creating more, the swimers would still be able to reproduce with members of the gatherers group, and would therefor still be part of the same species as thet were from the begining, by definition of the classification 'species.'
However, these swimmers are, as a population, different than the original swimmers. Some are still better than others at swimming just like before, some are worse. No new genes which hinder or help swimming exist. However, the population median for swimming - ie, how quantitativly good the average swimmer is at swimming, has changed. *This,* the evolution of the average individual in a population, is evolution of the species. we still have the same species as before, but the average member of that population is different now than before the lions arrived.
Now, lets continue. As time goes on, the lion population stays stable, randomly, swimmers are killed, randomly, they are out at sea collecting food, and don't get killed. The more time you spend out in the water, the better your chances are to live. Those who prefer living on land as much as possible (say, 12 hours a day) are more likely to be eaten than those who like being in the water more (say, 18 hours a day). As more of these "land-lubbers" are eaten, their genes are removed from the reproductive population, making it less likely for individuals in the next generation to want to spend time on land. Eventually, given enough of this trend, you will end up with a populaiton with nearly identical genes -all favoring nearly the best suited gene combination for this environment - those who can spend as much time as possible in the water (18 hours). all the people with shorter-time genes will, given enough time, be eaten, and prevented from reproducing.
However, we don't have aquatic people, yet, we just have very good swimmers. No new species, just the extreme of the old species. Evolution, but only for a population, not for the creation of new species.
Now, lets add in mutation to the puzzle. God suddenly decides to flip the "mutation occurs" switch to on, and our swimmers gene begin to mutate in a random fasion, but at a regular rate. In other words, some sort of mutation that can be passed to the individuals offspring will occur every 20 years, but what that mutaion will be will be random.
Based on the link you provided before, Flores, most genome mutations don't show up in the pheontype, because many alleles code for the same amino acid. Making a substitution in the genome will most offen do nothing to the population's abilities to swim. however, other mutations will show up in the individuals which receive them.
and 90% of the time, it will be bad. Individuals may be born with a mutation which causes them to be allergic to salt water. they die as soon as they are born into their parent's mostly ocean environment. Individuals may be born unable to digest seaweed at all, they may very well starve to death. Some will simply end up with mutations breaking the entire zygote process, and will never develop into a baby at all.
However, one time, a gene mutates in one individual such that his body is able to produce more of a particulaer molecule which stores oxygen. This mutation occurs in one of their reproductive cells, and so their offspring may have a chance to inherit this gene, which will then exsist in every cell in their body.
This offspring, if it is born, can now take the same large breath as everyone else in the swimmer's group, but he can stay down longer. He may be able to avoid drowing for another 5 seconds, which may happen to save his life one day, which some other die.
This individual, due to a *random* mutation, has now been selected for by non-random environmental pressures. He, randomly can hold his breath longer. He also, due to the determining (non-random) factor that he spends most of his day in water, is better suited to his environement.
He now also may be able to spend 18 hours and 5 minutes in the water, added 5 more minutes to the time that he isn't being threatened by lions. He is therefor more likely to survive, and that gene is more likely to be passed on to his offspring, who will all have a good chance of inheriting that gene (read up on punett squares to understand the idea of "chance of inheritance").
Over time, more people will get bad mutations, and every once in a while a good mutation will pop up. For the situation, anything which allows the individuals to avoid going onto land is a good thing. slightly larger lung capasity, thicker skin, larger fat layer, larger ammounts of of webbing for better swimming ability, etc.
This is evolution. Nothing nore, nothing less. these people aren't thinking "I better spend more time int he water, in order to survive," its those individuals who spend time the water that *do* survive, through no aware choice of their own.
Now, lets cover those items I ignored above.
1)technology. The idea here was to huminise this example for those arguing against evolution at all. I remove the chance of technology because I wanted the "people" to FAIAP, act as simple animals. If we were to add technology to the idea, then you have different driving factors. Instead of fast/good eye shight being benificial, it's "good at not being eaten by lions". This may push for the advantage of more complex brains, or better ability to make tools, or maybe the ability to yell really loud, and scare the lions off. Maybe people can invent a little box which drives the lions away with a high-pitched whine. There is still those who are better suited to not be eaten by lions; their genes will be more likely to survive to the next generation.
2)social interaction. Now, if one person did invent a Lion-Away 2000 sound-making box, and the village that he lived in was a social one, then he might want to make more than one. He might make one for everybody in the town. Suddenly, the threat of lions has been eliminated, and the drive for the population to evolve towards faster and better eye-sight individuals is gone. The population will not change toward faster runners anymore, as they are just as likely to have kids as a slower individual.
Same goes for food sharing. If the swimmers begin sharing food with the gatherers, then the gatherers don't need to spend as much time in the forest, and are more likely to survive, at least until the lion begin entering the village.
Technology and, more significatly social networks between individuals, have reduce environmental factors, reducing the evolutionary push. There is, in fact, an entire school of though based around the idea that by having advanced social networks, humans as a genetic species are slowing down our evolution. By shaping our environement to suit our current phenotype, we may end up driving the evolution of other species, while removing the pressure for our gene set to evolve. A few hundred thousand years ago, we may be competing for the same technological reasources we are creating now with species that we today consider dumb, and unable to use technology. If they survive better by using the technology that we make (say monkeys learning how to use and make new stick tools by watching things that we do with them, or even more simple, pigeons leanring how to make nests in the nooks of concrete buildings), then those individuals more likely to be able to use those technologies may be more likely to survive in our technological world. There mkids will be more likely to be able to have that ability as well.
This, however, also brings in another question, the evolution of knowledge. Seperate from physical evolution, the collective knowledge of a population changes as well. Good, usefull ideas come, and are passed between individuals, gain most common use, and become part of the population as a whole. Non-usefull ideas come about, but are left behind as the are used less and less frequently. Over time, the entire knowledge of the population of any social species can have an effect on their physical evolution - those squirels who learn how to hide nuts more effectively by their parents and who *also* recieved a gene for being better at digging will have twice the chance to not starve to death. They can *really* hid food well.
Now, take the entire swimmer/gatherer example, and apply it to a population of large land based mammels who spend some time swimming for their food. You know have a full *possible theory* on how whales may have evolved. In fact, teh fossil evidence seems to support just such a path of evolution. This is in no way proof that whales evolved from land-based animals. It still could be that God created everything as it is noww. However, if he did, then he also created non-useful features in whale, and fossils of whale-like creatres were created with the intent of confusinf people who like to dig up bones - if these creatures do not exsist now, and whales didn't evolve from them, then the fossil record of 'no wales, but whale-like creatures' to 'no whale-like creatures, but whales' must be a forgery, as these whale-like creatures certainly didn't exist. God created everything at once. These things may have exsisted, but no longer do. That's fine. But if god did create everything at the same time, then there should be whale skeletons in tandom with the whale-like skeletons, as they would have co-exhisted in the begining. No whale skeletons in the same strata as whale-like skeletons suggests that they did not live together.
Not to mention that if only a small percentage of living beings are ever fossilized, we can then say that for every one fossil, there were a much larger number of living individuals of the same species. If this is the case, an all living things were created together at the begining, then the number of living things which exsisted in the first instant would most likely have been more than could have effectivly fit o the surface of the earth at once.
Flores:
I am quite miffed by the fact that after James R defined evolution for you, and seperated random mutation and non-random selection, you actually "disagreed* with him!
How do you ever expect to learn anything if you refuse to even understand the definition of other people's words? how can you even communicate?
If I define the word "xxwer" to mean "happy like I just ate cake," then you cannot argue the statement "I feel so xxwer right now" by telling me that I'm wrong in my definition of the word "xxwer." Feel free to disagree with the definition of the word "xxwer" if you wish, but until we agree on the definition, it is logisitcally impossible to argue the entire statement.
If you wish to argue the idea of evolution, you first must accept the defined idea of evolution. you can't argue both the definition and the idea at the same time - no one will have any method for communicating their ideas to you if you words are not clearly defined.
If you want to argue creationsm vs evolution, then go back, and accept James R's defnintion of evolution. We can then argue the merits of that idea. *Then* we can re-define evolution to what ever you want, and argue the merits of *that* idea. We won't be arguing the scientific community's idea of evolution anymore, but at least we'll both know what's on the table to be discussed.
I did not say or indicate that I had evidence contrary to the ape to man theory, only that it is still a theory. Why do you want it to be a fact so badly? If you believe it is a fact, that is respectable. I happen not to. If it is ever proven, however, it will not upset me at all. How's that?
