Freethought & Rationalism Archive

Doubting Didymus · 04-23-2003, 04:26 PM

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OK, so we're agreed that a "scientific" answer to a question is not necessarily a true one.

No answer is ever incontestibly true. Science makes something of a point of this: theories are always open to revision. Only theology claims absolute truths, which just goes to show.

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You and I go to court on a civil matter. I have 5000 pages of evidence; you have 1. Do I win? Not necessarily, because all that evidence may not support my contention.

You really need a better dictionary. The word 'evidence' used in the context: 'backed by evidence', means 'evidence in support of...'. You gain no ground by pedantic semantics.

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And so it is, I suggest, with evolution. Until you can show how something which is not alive can come alive, you have nothing.

Again you demonstrate that you do not even know what evolution is. It is generally considered wize to know at least something about your topic before you claim it is bunk. I strongly suggest you read something that deals with the topic of evolution before you make more pronouncements on its validity, as you have obviously never even tried to understand it.

On whether students should be allowed to place "I dont know" as an acceptable answer on test condition questions about such topics as the validity of the theory of gravity:

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In many cases, I would say yes - especially in those areas of natural law which are deemed to be ruled by probability.

This statement speaks for itself. You know nothing about evolution, or about the scientific methods, or about education.

Craig · 04-23-2003, 04:30 PM

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Originally posted by yguy
Yes. That's not to say those disciplines are worthless, but the idea that anything is ruled by probability as absurd at its root; and to the extent that this idea pervades any theory, that theory should be suspect.

Are you joking? Do you know how much of our economy, how many BILLIONS of dollars worth of products are built using these "suspect" theories? Like I said in my post above, the computer you are typing on right now is a direct result of quantum theory.

Caligula · 04-23-2003, 04:34 PM

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Originally posted by yguy
I stand corrected. Until you show that one kind of creature can evolve into another, you have nothing. Attempts to get fruit flies to evolve under the influences of various environmental stresses and mutagens, I've read somewhere, have been disappointing. Sorry, don't have a source.

It's already been done. And if you look here on that page, you get this:

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Speciation of numerous plants, both angiosperms and ferns (such as hemp nettle, primrose, radish and cabbage, and various fern species) has been seen via hybridization and polyploidization since the early 20th century. Several speciation events in plants have been observed that did not involve hybridization or polyploidization (such as maize and S. malheurensis).

Some of the most studied organisms in all of genetics are the Drosophila species, which are commonly known as fruitflies. Many Drosophila speciation events have been extensively documented since the seventies. Speciation in Drosophila has occurred by spatial separation, by habitat specialization in the same location, by change in courtship behavior, by disruptive natural selection, and by bottlenecking populations (founder-flush experiments), among other mechanisms.

Several speciation events have also been seen in laboratory populations of houseflies, gall former flies, apple maggot flies, flour beetles, Nereis acuminata (a worm), mosquitoes, and various other insects. Green algae and bacteria have been classified as speciated due to change from unicellularity to multicellularity and due to morphological changes from short rods to long rods, all the result of selection pressures.

Speciation has also been observed in mammals. Six instances of speciation in house mice on Madeira within the past 500 years have been the consequence of only geographic isolation, genetic drift, and chromosomal fusions. A single chromosomal fusion is the sole major genomic difference between humans and chimps, and some of these Madeiran mice have survived nine fusions in the past 500 years (Britton-Davidian

Doubting Didymus · 04-23-2003, 04:35 PM

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Originally posted by yguy
I stand corrected. Until you show that one kind of creature can evolve into another, you have nothing. Attempts to get fruit flies to evolve under the influences of various environmental stresses and mutagens, I've read somewhere, have been disappointing. Sorry, don't have a source.

Really, no source? You wouldn't be aware, then, that fruit flies have indeed been divided into two distinct and incompatible species, where once there was one?

I do have a source:
Dobzhansky, Th., and O. Pavlovsky, 1971. "An experimentally created incipient species of Drosophila", Nature 23:289-292.

This is one of the famous ones.

Before we go any further, please elaborate on exactly what kind of change we would need to demonstrate in a population before you would accept it as a new kind?

yguy · 04-23-2003, 04:40 PM

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Originally posted by Doubting Didymus
You really need a better dictionary. The word 'evidence' used in the context: 'backed by evidence', means 'evidence in support of...'. You gain no ground by pedantic semantics.

But you assume that all that data supports your conclusion. How can you determine that beforehand? If the DA presents evidence against a criminal, he THINKS it supports his case, but the judge/jury make the final decision. Who is the judicial authority here? The consensus of scientific opinion? That would put us right back where we were before Copernicus.

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This statement speaks for itself. You know nothing about evolution, or about the scientific methods, or about education. [/B]

Educate comes from the Latin educare, to bring forth from within. Modern "education" stuffs people with data and formulas from without, and has them regurgitate it on command.

Jayjay · 04-23-2003, 04:40 PM

Let me guess...

"They're still fruit flies!"

yguy · 04-23-2003, 04:42 PM

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Originally posted by Craig
Are you joking? Do you know how much of our economy, how many BILLIONS of dollars worth of products are built using these "suspect" theories? Like I said in my post above, the computer you are typing on right now is a direct result of quantum theory.

This contradicts what I said how, exactly? Because we understand particle physics well enough to build computers, our understanding is somehow without flaws?

yguy · 04-23-2003, 04:51 PM

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Originally posted by Doubting Didymus
Really, no source? You wouldn't be aware, then, that fruit flies have indeed been divided into two distinct and incompatible species, where once there was one?

I do have a source:
Dobzhansky, Th., and O. Pavlovsky, 1971. "An experimentally created incipient species of Drosophila", Nature 23:289-292.

This is one of the famous ones.

Before we go any further, please elaborate on exactly what kind of change we would need to demonstrate in a population before you would accept it as a new kind?

I've said earlier that the offspring from the two would have to be sterile often enough that such offspring couldn't sustain themselves.

Doubting Didymus · 04-23-2003, 05:06 PM

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Originally posted by yguy
I've said earlier that the offspring from the two would have to be sterile often enough that such offspring couldn't sustain themselves.

You mean offspring between the two populations, which were once one single species?

Well, then. If you're going to make it THAT easy, and seeing as you like fruit flies:

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From this talkorigins faq:
5.3 The Fruit Fly Literature

5.3.1 Drosophila paulistorum Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).

...

5.3.4 Sexual Isolation as a Byproduct of Adaptation to Environmental Conditions in Drosophila melanogaster Kilias, et al. (1980) exposed D. melanogaster populations to different temperature and humidity regimes for several years. They performed mating tests to check for reproductive isolation. They found some sterility in crosses among populations raised under different conditions. They also showed some positive assortative mating. These things were not observed in populations which were separated but raised under the same conditions. They concluded that sexual isolation was produced as a byproduct of selection.

From the same FAQ: my favourite exapmle, from the plant kingdom:

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Speciation as a Result of Selection for Tolerance to a Toxin: Yellow Monkey Flower (Mimulus guttatus) At reasonably low concentrations, copper is toxic to many plant species. Several plants have been seen to develop a tolerance to this metal (Macnair 1981). Macnair and Christie (1983) used this to examine the genetic basis of a postmating isolating mechanism in yellow monkey flower. When they crossed plants from the copper tolerant "Copperopolis" population with plants from the nontolerant "Cerig" population, they found that many of the hybrids were inviable. During early growth, just after the four leaf stage, the leaves of many of the hybrids turned yellow and became necrotic. Death followed this. This was seen only in hybrids between the two populations. Through mapping studies, the authors were able to show that the copper tolerance gene and the gene responsible for hybrid inviability were either the same gene or were very tightly linked. These results suggest that reproductive isolation may require changes in only a small number of genes.

yguy · 04-23-2003, 05:24 PM

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Originally posted by Doubting Didymus
You mean offspring between the two populations, which were once one single species?

Well, then. If you're going to make it THAT easy, and seeing as you like fruit flies:<snip>

Waal, hush mah mouf.

I asked for something like this about a week ago, and no one responded. For the time being, I'll have to drop the objection to that point.

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04-23-2003, 04:40 PM	#26
Jayjay Veteran Member Join Date: Apr 2002 Location: Finland Posts: 6,261	Let me guess... "They're still fruit flies!"

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