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Originally posted by begoodbees
The vestigial organ thing has already been addressed and dismissed. Every part has a purpose. I know you were probably taught in school that they do not but that part of the indoctrination has been proven false. You can google it if you like.
The concept of vestigiality applies to genetically determined structures or attributes that have apparently lost most or all of its ancestral function in a given species. Assessment of the vestigial status must generally rely on comparison with homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to positive selection pressures when it loses its value in a changing environment. More urgently the feature may be selected against when its function becomes definitely harmful. Typical examples of both types occur in the loss of flying capability in island-dwelling species.
Originally posted by begoodbees
reply to post by paradox
I have been proven wrong about nothing. Again I suggest you see the difference between proof and evidence.
Show me one example of a vestigial organ in any species that you can prove (not speculate) has no purpose whatsoever.
Your rebuttal is just a recitation of theory.edit on 18-12-2012 by begoodbees because: (no reason given)
Fake Sex in Virgin Whiptail Lizards (Vestigial Behavior)
Only females exist in several species of the lizards of the genus Cnemidophorus, which might seem like a problem when it comes time to propagate the species. The females don't need the males though, they reproduce by parthenogenesis, a form of reproduction in which an unfertilized egg develops into a new individual. So basically, the females don't need the males; they just produce clones of themselves as a form of reproduction. Despite the fact that it is unnecessary and futile to attempt copulation with each other, the lizards still like to try, and occasionally one of the females will start to "act like a male" by attempting to copulate with another female. The lizards evolved from a sexual species and the behavior to copulate like a male -- to engage in fake sex -- is a vestigial behavior; that is, a behavior present in a species, but is expressed in an imperfect form, which in this case, is useless.
The Sexual Organs of Dandelions
Dandelions, like all flowers, have the proper organs (stamen and pistil) necessary for sexual reproduction, but do not use them. Dandelions reproduce without fertilization; they basically clone themselves, and they are quite successful at it. Look at any lawn for the proof. If dandelions were to revert to sexual reproduction, they might not retain whatever traits they have that allow them to be pests to gardeners everywhere. If flowers can begin reproducing in this manner, does that mean animals, even humans could too? Asexual reproduction can be a good strategy in an environment that is constant if a species is well suited to those conditions. It doesn't take a scientist to figure out that humans wouldn't last long if the condition set forth was no sexual contact with others. Therefore, the human sexual organs are probably in no danger of becoming vestigial.
Wisdom Teeth in Humans
With all of the pain, time, and money that are put into dealing with wisdom teeth, humans have become just a little more than tired of these remnants from their large jawed ancestors. But regardless of how much they are despised, the wisdom teeth remain, and force their way into mouths regardless of the pain inflicted. There are two possible reasons why the wisdom teeth have become vestigial. The first is that the human jaw has become smaller than its ancestors -and the wisdom teeth are trying to grow into a jaw that is much too small. The second reason may have to do with dental hygiene. A few thousand years ago, it might be common for an 18 year old man to have lost several, probably most, of his teeth, and the incoming wisdom teeth would prove useful. Now that humans brush their teeth twice a day, it's possible to keep one's teeth for a lifetime. The drawback is that the wisdom teeth still want to come in, and when they do, they usually need to be extracted to prevent any serious pain.
The Blind Fish Astyanax Mexicanus
In an experiment designed by nature, the species of fish known as Astyanax mexicanus, dwelling in caves deep underground off the coast of Mexico, cannot see. The pale fish has eyes, but as it is developing in the egg, the eyes begin to degenerate, and the fish is born with a collapsed remnant of an eye covered by flap of skin. These vestigial eyes probably formed after hundreds or even thousands of years of living in total darkness. As for the experiment, a control is needed; and luckily for us, fish of the same species live right above, near the surface, where there is plenty of light, and these fish have fully functioning eyes. To test if the eyes of the blind mexicanus could function if given the right environment, scientists removed the lens from the eye of the surface-dwelling fish and implanted it into the eye of the blind fish. It was observed that within eight days an eye started to develop beneath the skin, and after two months the fish had developed a large functioning eye with a pupil, cornea, and iris. The fish were blind, but now they see.
The concept of vestigiality applies to genetically determined structures or attributes that have apparently lost most or all of its ancestral function in a given species. Assessment of the vestigial status must generally rely on comparison with homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to positive selection pressures when it loses its value in a changing environment. More urgently the feature may be selected against when its function becomes definitely harmful. Typical examples of both types occur in the loss of flying capability in island-dwelling species.
1proof noun \ˈprüf\
Definition of PROOF
1
a : the cogency of evidence that compels acceptance by the mind of a truth or a fact
b : the process or an instance of establishing the validity of a statement especially by derivation from other statements in accordance with principles of reasoning
Originally posted by begoodbees
reply to post by paradox
You are absolutely right, you have proven without a doubt that your brain is a vestigial organ.
You have proven nothing. You are demonstrating variation. If the fish swims out of the cave, a few generations later the eyes will regain their strength.
Evolution
Definition
noun, plural: evolutions
(1) The change in genetic composition of a population over successive generations, which may be caused by natural selection, inbreeding, hybridization, or mutation.
(2) The sequence of events depicting the evolutionary development of a species or of a group of related organisms; phylogeny.
Variation
Definition
noun, plural: variations
(1) A difference or deviation (e.g. in structure, form, function) from the recognized norm or standard.
(2) A modification in structure, form or function in an organism, deviating from other organisms of the same species or group.
(3) Mutant; an organism possessing characteristic(s) as a result of mutation.
Without genetic variation, some of the basic mechanisms of evolutionary change cannot operate.
There are three primary sources of genetic variation, which we will learn more about:
Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations.
Gene flow is any movement of genes from one population to another and is an important source of genetic variation.
Sex can introduce new gene combinations into a population. This genetic shuffling is another important source of genetic variation.
The statement of the truth of a theory has essentially the same meaning as that of a simple factual judgment: we refer to some experience which justifies, or will justify, the decision-making on the basis of this statement. When this experience is in the past we say that the truth is established. When it is expected in the future we say it is hypothetical. There is no difference of principle between factual statements and theories: both are varieties of models of reality which we use to make decisions. A fact may turn out to be an illusion, or hallucination, or a fraud, or a misconception. On the other side, a well-established theory can be taken for a fact. And we should accept critically both facts and theories, and re-examine them whenever necessary. The differences between facts and theories are only quantitative: the length of the path from the statement to the production of predictions.