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Hmmm, thoughts on evolution?(no, not vs religion)

#101
I recently took a philosophy course in which we compared the methods of science and those of religion. It seems that in recent years many Christian scholars have begun to use scientific reasoning and the scientific method when attempting to solve religious problems. Of course, the subject matter often makes it more difficult to get reproducible results and there will always be certain assumptions that have to be made, but they are trying which I think is a good sign.

Nonsqtr, I am curious - I had heard about those experiments done on fruit flies but as far as I know they have not managed to produce any beneficial mutations (or any mutations that make the product more adapted than the original), I could definitely be wrong though - do you know anything about the specific mutations? Not that I would necessarily classify that as an evolutionary experiment though. To me the theory of evolution has to do (roughly) with the idea of one species changing into another completely different species over time. It is obvious that small changes can occur within a given species through breeding or as a result of a climate change. The experiments also do not help solve the problem of why or how these changes occur in nature randomly. In the experiment the answer to both why and how is 'the scientists intentionally mutated them in a lab'.
 
#102
Hi Lloyd, as far as I know, scientists have been deliberately "selecting" the desired traits in lab organisms for a long long time. They've come up with several ways of deliberately creating mutations, like for instance in plants they use colchicine and colcimid, and in animals they typically use similar mutagens, and even intense ultraviolet light (in those cases where they can isolate, mutate, and replace the desired cells). In the case of fruit flies and lab rats, the effort has been to create "typed" strains with particular desirable properties. For instance, in lab mice, there are well catalogued mutations involving "behaviors". Like, you have your "reeler" mice that have a particular genetic mutation that causes the nerve fibers in the cerebellum to connect differently. You have your "fat rats" that have a hormonal mutation that affects the homeostatic centers in the hypothalamus. Scientists have deliberately bred these creatures so they could study the underlying internal processes. These mutations don't exist in nature, or if they do, they'd be immediately selected out, 'cause there's no "advantage" for those kinds of things in the real world. However in the laboratory there is, and you're right, it's an "artifical" selection instead of a "natural" one (and to cast that in evolutionary terms, all we're saying is that the "environment" is different, therefore the factors that are used in the "selection" process are different).

Another really interesting area of study is developmental biology. If you stick a pin in a frog embryo at the right time and in the right place, you can get frogs with legs where their eyes are supposed to be, and vice versa. Lately they've been trying to figure out why that is, and it turns out that the "chemical gradients" in the developing cells are vitally important in "polarizing" the organism (in other words, determining which end is the head and which end is the tail). Even the cells themselves are polarized, so as the frog embryo develops and the cells continue to divide, each cell itself has a concept of "which end is up". The pin disrupts the chemical gradients inside the cells, so they get confused about "which end is up", and so you get legs where the eyes are supposed to be. Lately they've managed to accomplish exactly the same thing using chemical means.

As you say, I'm not aware of any direct results involving the mutation of one "species" into another. However, it's important to take a high-altitude view of that concept. In other words, let's say you did the pin experiment, and you came up with a wierd frog. Would that still be "a frog"? Or, if someone didn't know you'd done that experiment, and just saw the result, would they classify that organism as a different "species"? Hard to say. I don't know very much about how taxonomy is done through observation. I'm guessing they classify the major features of the organism, and then use statistics to figure out where the "groupings" are. I also know that things change, so what used to be considered a "species" unto itself, might now be considered just a "sub-species" of some other grouping. I'm not entirely sure how useful that concept really is. To me, it's one of those things like "race", no one can really define what it means, although operationally and observationally, one can say that there's "a difference". What I see, personally, is that there's a "spectrum" of life, and that spectrum has pieces that are successful (ie where there's a lot of coverage), and pieces that aren't. According to the concept of evolution, those differences would be determined by the niches that the environment allows. So to me, the difference between mutating a lab rat into a "fat rat", and mutating a lab rat into a monkey, is just one of degree. But, that would be conjecture on my part, and I have absolutely no evidence to support that statement. :)
 
#105
Well, there's a flip side to that coin too. It's interesting to study the way "natural mutations" occur. In the context of an organism based on DNA, that replicates by "copying" its DNA (and possibly sharing it with some other organism), people have studied the "types" of mutations that occur, and how "frequently" they occur. The most common type of mutation is a "point mutation", which generally results in the creation of an "incorrect" entry in the DNA sequence. Point mutations can be caused by many factors, including light (especially UV), radiation (X-rays and the like), chemicals (like colchicine), and physical processes (like mechanical stress). Then there are other types of mutations. Some actually result in the "duplication" of an entire segment of DNA, into a place where it wouldn't ordinarily occur in the DNA sequence. People have postulated that it is these types of mutations that underlie the "punctuated equilibrium" concept. Then there is the "frequency" issue, and without going into detail, I'll just say that mutations occur "surprisingly frequently". The interesting thing about mutations is, that the DNA tends to be highly protected in the more advanced organisms, and in those organisms even a point mutation is often fatal. In primitive organisms though, where the DNA isn't as highly protected, mutations are quite common and regularly result in robust new organisms. This would be the penicillin-resistant bacteria example. Mutations occur all the time. In humans, all you have to do is sit out in the sun for a long time, and the chances are good you'll get skin cancer. But the reproductive systems generally tend to be more highly protected. Nevertheless, there are plenty of pharmaceuticals that are known to cause mutations (among them some of the new anti-viral drugs), and even some widely used drugs are now becoming suspect in that regard. In humans and other advanced organisms, the chances are that 99% or more of the possible mutations will be fatal. Of the remaining one percent, 99% of those are detrimental in some way, and would be considered "harmful" to the success of the organism. But the remaining .01% might give rise to some useful new traits or capabilities. People are still arguing about what those numbers really are, but there's general agreement that the chances of getting a useful mutation are "very small". That's why, the people who do genetic engineering on vegetables and that kind of thing, generally do it on single cells in the lab, and then find some way to re-insert the result back into the strain. By the way, did you know that "most" of the tomatoes you get in the supermarket these days (or at McDonald's it would be "all" the tomatoes) have been genetically engineered?

Edit: oh, and, wouldn't that be an example of "intelligent design"?
 
#108
Hey, I know this is an old thread but I enjoyed reading it after stumbling across it. I noticed that there is a lot of confusion about the definition of some terms, particularly what makes a scientific theory, so I thought I would excerpt this:





The scientific community has developed a vocabulary to describe the various aspects of the scientist's work. Although individual scientists are not always careful in their use of that vocabulary, a rigorous set of definitions can help to prevent confusion about what a scientific theory is. . . .

The grist for the mill of scientific inquiry is an ever increasing body of observations that give information about underlying "facts." Facts are the properties of natural phenomena. The scientific method involves the rigorous, methodical testing of principles that might present a naturalistic explanation for those facts. To be a legitimate scientific "hypothesis," an explanatory principle must be consistent with prior and present observations and must remain subject to continued testing against future observations. An explanatory principle that by its nature cannot be tested is outside the realm of science.

The process of continuous testing leads scientists to accord a special dignity to those hypotheses that accumulate substantial observational or experimental support. Such hypotheses become known as scientific "theories." If a theory successfully explains a large and diverse body of facts, it is an especially "robust" theory. If it consistently predicts new phenomena that are subsequently observed, it is an especially "reliable" theory. Even the most robust and reliable theory, however, is tentative. A scientific theory is forever subject to reexamination and -- as in the case of Ptolemaic astronomy -- may ultimately be rejected after centuries of viability.

Every scientific discipline embraces a body of facts and one or more theories to explain them. . . . . facts and theories are not interchangeable: An explanatory principle is not to be confused with the data it seeks to explain. - excepted from AMICUS CURIAE BRIEF OF 72 NOBEL LAUREATES, 17 STATE ACADEMIES OF SCIENCE, AND 7 OTHER SCIENTIFIC ORGANIZATIONS

http://talkorigins.org/faqs/edwards-v-aguillard/amicus1.html






Furthermore, a scientific "law" is a concise and specific description, made in verbal or mathematical form, of a relationship that always applies under the same conditions. This is distinct from a "theory" in that a law does not include a model or explanation; it is simply an observation

Example:

The theory of gravity is a description of the tendency of objects with mass to attract one another. It includes explanations about how a force can act at a distance from simple accelerating bodies to field theory to general relativity to quantum mechanics and much more.

The law of gravity simply states that the gravitational force between two objects is proportional to the mass of the first object times the mass of the second object divided by the square of the distance between them.
(F = G* m1*m2 / r^2)


The concept of "proof" is different in science than in everyday usage. Usually, scientists prefer the word "evidence", which is observational data that is used to support a theory.
 
#109
I have some doubts about the periodic table. I just don't see how all of the different stuff we see around us can be made of only about a hundred so-called "elements". There must be more to it than that. Anyway, that's my opinion and because I'm entitled to one, then it must be as valid as anyone else's. I just hate it when people who've studied chemistry in detail assume they know more about it than us regular folks.
 
#110
Why must you bring this back, i was reading through and was very happen because i thought some of the old people came back, only to disappoint myself when i saw the year. JMX and Nick were cool peeps.


Listening to: Living Legends - Nothing less
 
#111
bassybill said:
I have some doubts about the periodic table. I just don't see how all of the different stuff we see around us can be made of only about a hundred so-called "elements". There must be more to it than that. Anyway, that's my opinion and because I'm entitled to one, then it must be as valid as anyone else's. I just hate it when people who've studied chemistry in detail assume they know more about it than us regular folks.
Click to expand...

People who say that kind of thing should be forced to treat all their own ailments and injuries by googling sites on medicine ...:p

And they shouldn't be allowed on a plane until they have worked out how to fly it from reading magazines!! ;)
 
#112
Davidoc said:
I've been thinking, I'm not sure if I totally buy the whole concept of natural-selection being the cause of evolution, which implies that all changes and development of lifeforms stems from the deaths of prvevious lifeforms with undesirable traits. There's gotta be something more. I have no ideas, and no suggestions as to what that something/somethings would be, but I kinda doubt that it's just natural-selection that causes evolution.

It just seems hard to believe that all the variety in life comes from traits that were already there. I've been reading that more and more people are being born without wisdom teeth. Does this mean that wisdom teeth were causing the death/inability to reproduce? No. It just seems that many adaptions we see in today's living world come from things that would not effect the organism's ability to reproduce or survive to be able to reproduce.

Something's fishy with that theory. I think there's something more going on. Does anyone here know what I'm talking about?
Click to expand...

No, it doesn't focus on those with "less desireable" traits. It focuses on those who survive to reproduce, and who are most successful at reproducing.

Also, not all mutations are harmful or helpful. Some aren't either, but if they occur in individuals who are good at surviving to reproduce, they stay. For example, if a mutation caused someone to randomly have purple hair (I'm simplifying things a ton, but just roll with it), but did not affect any other part of them and they survived to reproduce and carry on that gene, it would be seen in later generations, as though it had not helped them, it had not hurt them either.
 
#114
bassybill said:
I have some doubts about the periodic table. I just don't see how all of the different stuff we see around us can be made of only about a hundred so-called "elements". There must be more to it than that. Anyway, that's my opinion and because I'm entitled to one, then it must be as valid as anyone else's. I just hate it when people who've studied chemistry in detail assume they know more about it than us regular folks.
Click to expand...

Remeber that it isnt just a hundred, but also the many combinations of those hundred elements :smug:
 
#120
I know Bruce has bumped an old thread here, but I thought this might be a worthwhile addition to it for those who would like to explore a bit further.

An understanding of evolution in modern scientific terms depends on a synthesis of Darwin's ideas with more recent developments in molecular biology. This is a 14 point summary of how it works.

VARIATION

1. Variation exists within all populations.

2. Some of that variation is heritable.

3. Base pair sequences are encoded into a set of self-replicating molecules that form templates for making proteins.

4. Combinations of genes that did not previously exist may arise via "crossing over" during meiosis, which alters the sequence of base pairs on a chromosome.

5. Copying errors (mutations) can also arise, because the self-replication process is of imperfect (although high) fidelity; These mutations also increase the range of combinations of alleles in a gene pool.

6. These recombinations and errors produce a tendency for successively increasing genetic diversion radiating outward from the initial state of the population.

SELECTION

7. Some of that heritable variation has an influence on the number of offspring able to reproduce in turn, including traits that affect mating opportunities, or survival prospects for either individuals or close relatives.

8. Characteristics which tend to increase the number of an organism's offspring that are able to reproduce in turn, tend to become more common after generations and diffuse throughout population; those that tend to decrease such prospects tend to become rarer.

10. Migrations of individuals from one population to another can lead to changes in the relative frequencies of alleles in the "recipient" population

SPECIATION

11. Populations of a single species that live in different environments are exposed to different conditions that can "favor" different traits. These environmental differences can cause two populations to accumulate divergent suites of characteristics.

12. A new species develops (often initiated by temporary environmental factors such as a period of geographical isolation) when a sub-population acquires characteristics to promote or guarantee reproductive isolation from the alternate population, limiting the diffusion of variations thereafter.

SUFFICIENCY

13. The combination of these effects tends to increase diversity of initially similar life-forms over time.

14. Over the time frame of the late Hadean to the present, this becomes sufficient to explain both the diversity within and similarities between the forms of life observed on earth, including both living forms directly observed in the present, and extinct forms indirectly observed from the fossil record.

People like the OP who lack a knowledge of basic ideas about biology are effectively saying they think that one or more of the above points might be untrue. So, this list could be helpful to focus thinking on the particular aspects of biology that they find hard to understand. :)
 

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