Freethought & Rationalism Archive

CardinalMan · 01-04-2002, 06:16 PM

The original Peanut Gallery thread is now quite long, and hasn't had a post in a couple of days, so I thought I would start a new one.

I would like to challenge the following comments by Douglas:

Quote:

I understand inference, implication, and logical deduction very well, in my opinion. As long as a "scientific concept" is not presented in a too-technical-for-the-educated-layman form, then I feel quite capable of determining if a "scientific inference or conclusion" is valid or not.

Quote:

Yes, I know. And which is why I believe that I, biological layman that I am, can discern valid and invalid science better than many or most trained and professional scientists.

In my experience, many people who study math have great difficulty understanding arguments and inferences in fields outside of mathematics, such as in science (or politics, religion, etc.). Many of the inferences in science, including evolutionary biology, are not absolute air-tight deductive logical inferences. Scientists draw their conclusions based on independent converging lines of evidence that are always fuzzy. No experiment or observation can be reproduced exactly, especially in sciences like evolution, geology, or astronomy, so of course one can always find inferences that are less than perfect in the sciences. What makes scientific inferences reliable is that scientists do not base grand conclusions on only a handful of observations and experiments, but rather on many experiments performed by many investigators. Demanding completely logical deductions and 100% proof in science is simply silly since it is impossible. We need to draw reliable (note not absolutely correct) conclusions based on imperfect evidence, and the scientific method works better than any other.

Douglas, how would you react in the following situation. A biologist questions a well-established mathematical result that you know extremely well. You realize that this biologist has only a limited knowledge of mathematics, but the result is rather deep. You could not possibly go through every step of a rigorous proof with him because this would entail going back to the axioms of set theory, and would take months. Hence, you skip some of the ugly details, and you help the biologist by giving some illustrative example of the theorem in action that suggest why the result might be true. However, the biologist is unsatisfied because of these shortcuts. You explain that in order to understand the result fully, one would have to spend years studying the subject. Instead of doing this, the biologist claims that the entire result is seriously flawed, that he understand mathematical inferences better than most mathematicians, and he prefers to get mathematical insight from the Bhagavad-Gita. I'm sure you would find this encounter frustrating.

CardinalMan

scigirl · 01-06-2002, 10:44 AM

Cardinalman,

Thanks for that analogy. I might just steal it!

I am working on a rebuttal. It will be pretty long, so maybe I'll split it into two rebuttals.

scigirl

Christopher Lord · 01-06-2002, 10:45 AM

Dont forget the end of the previous "scigirl/Douglas Debate Peanut Gallery" thread. A couple points where shreded before it faded away.

scigirl · 01-06-2002, 10:47 AM

Quote:

Originally posted by Christopher Lord:
<strong>Dont forget the end of the previous "scigirl/Douglas Debate Peanut Gallery" thread. A couple points where shreded before it faded away.</strong>

ok!

DB_Hunter · 01-07-2002, 07:34 AM

I've had debates like this, too. In one, a layperson had no clue about geology, and she thought that gave her the ability to understand it better than somone who actually studied the rocks, has picked them up, and even tasted them (err... mineral content, yeah, that it).

Then she had the chutzpa to complain that I was interjecting too many "facts" into the debate that she didn't understand. Hey, if you can't stand the heat...

Do they not realize the sheer pride inherent in that idea? It takes the rest of us YEARS to learn this stuff, and even those with doctorates in their fields STILL don't know it all... But we don't pretend to - we know that there is always new stuff to learn, new discoveries to make, no matter the field. New mathematical theorems, new rock formations (even exogeology), new genes...

For us, it's a never-ending journey of discovery.
For them, it's just something else thye refuse to understand...

DB

can't spell...

[ January 07, 2002: Message edited by: DB_Hunter ]</p>

Quetzal · 01-08-2002, 12:38 AM

scigirl:

There's a new article in the 7 Jan issue of The Scientist that might be helpful in your debate. <a href="http://www.the-scientist.com/yr2002/jan/lewis_p16_020107.html" target="_blank">"SNPs as Windows on Evolution"</a>. It discusses exciting new evidence from comparisons of single nucleotide polymorphism (SNP) in determining speciation events. Although the article overall is very interesting, I think the most significant part for your debate is the additional evidence provided for a hominid "out of Africa" scenario.

Quote:

SNPs reveal that Homo sapiens is a young species, with so little time having elapsed since origin that humans are what Venter calls "virtual identical twins." "The amount of variation in the human population is way less than expected for a population of 6 billion," concurred Andrew Clark, a professor of biology at Pennsylvania State University, indicating a rapid expansion.

"The poverty of variation tells us about the structure of the early human population. The rate of heterozygosity per nucleotide position is closely related to the size of a population and the mutation rate. Humans are a small population that grew large fast, from 10,000 founders in Africa 3,000 generations ago. Most of today's variation is the very same variation we walked out of Africa with. We are an extremely closely related species," says Lander [Eric Lander, director of the Whitehead Institute Center for Genome Research in Cambridge, Mass].

SNPs also provide outstanding support for evolution and natural selection in general.

Quote:

[They] then identified genes with the telltale nonsynonymous SNPs to generate "a raw list of potentially adaptively evolving genes." The researchers used a ratio of nonsynonymous DNA base changes to synonymous changes. A gene that has a high ratio indicates positive natural selection. The next step was to see which protein-encoding genes have high ratios in species that lie at the nodes of evolutionary trees, where an important change fueled branching of the tree. The coexistence of a SNP ratio indicating positive selection with a branchpoint signals evolution caught in the act, when a new protein variant that offered an advantage became fixed in the gene pool.

With a dose of imagination, considering the nature of the protein against the backdrop of an evolutionary tree, SNP ratios can reveal possible evolutionary scenarios. "The ratios are ... useful starting points for generating stories about the interactions between protein sequences and the Darwinian processes that shape these sequences. These stories help us understand how these sequences contribute to the fitness of the host," said Liberles. For example, nonsynonymous SNPs in the gene that encodes a plasminogen activator protein in the saliva of vampire bats may signal evolution of the ability to thin the blood of prey. The divergence of vertebrates on the animal family tree correlates to a high ratio for several genes that encode proteins involved in immunity. The genes that encode the satiety factor leptin, the double-muscle protein myostatin, and cellular adhesion molecules also undergo change at evolutionary crossroads. "At a biological level, the dataset generated here can be mined to provide global pictures of how evolution has occurred," Liberles summed up. [David Liberles, bioinformatics center at Stockholm University].

I love "The Scientist". Another nail in the creationist coffin.

scigirl · 01-15-2002, 08:58 AM

Woo hoo, I'm back! I've been off at med school interviews. . . fell in love with Creighton University (not because it's in Omaha Nebraska, but because the school kicks butt, and you get excellent training). Except, well, it's really really expensive, being a private school and all.

Oh, and I got to see the Olympic Torch. It was awesome--now I'm all excited about the Olympics. I've missed you guys though!

I have a rebuttal almost finished, and I plan to post it tonight. It will be rather long. I will be discussing two main topics. 1) mechanisms of evolution (such as gene duplications--stuff most creationists have never even heard of!), and 2) ways that evolution could have produced the "perfect eye" and other examples (i.e.--I ripped off Dawkins big time!). I'll try to relate these topics to the time issue as well.

I'll also be borrowing stuff from you guys. I doubt I'll use all your suggestions, but they are all bookmarked for the future. So thanks!

scigirl

RufusAtticus · 01-15-2002, 10:52 PM

scigirl,

Me likey.

I wonder if Douglas will respond.

I think Douglas has left II, although he still seems active on ARN.

-RvFvS

lpetrich · 01-16-2002, 08:16 AM

One interesting question is what is the absolute lower limit to humanity's ancestral population. It might be possible to answer that by comparing Human Leukocyte Antigens to their chimpanzee counterparts. If the common ancestor shared several LA's, then the absolute minimum number of individuals is half that, and the likely minimum much greater, to make genetic-drift drop-outs unlikely.

LA's are selected for variety because they are a cell's way of signaling that they are not to be attacked by immune-system cells. And one adaptation of parasites is to resemble their host's LA molecules. However, if there are several distinct LA's in a population, then that makes it difficult for the parasite to adapt. So the mechanism that makes organ transplants difficult is the one that protects us from parasites by giving them too many targets.

The Lone Ranger · 01-16-2002, 04:52 PM

Regarding Ipetrich's question on the absolute lower limit to humanity's ancestral population:

Some months ago, I glanced through a paper regarding the variation in certain MHC proteins. The particular gene complex in question that is responsible for this variation appears to have arisen at least 10 million years ago, given that it is shared by humans, chimpanzees, and gorillas, but is not present in other apes.

If I recall correctly, there are 32 known variants of the gene in question that are shared between gorillas, chimps, and humans. This means that at no point since the divergence of the human/chimpanzee/gorilla line from the rest of the apes could there have been fewer than 16 individuals alive who were direct ancestors of currently-living humans (and chimps and gorillas).

If anyone really wants, I could try hunting down the reference later.

Cheers,

Michael

[ January 16, 2002: Message edited by: The Lone Ranger ]</p>

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01-06-2002, 10:44 AM	#2
scigirl Veteran Member Join Date: Jul 2001 Location: Seattle Posts: 4,261	Cardinalman, Thanks for that analogy. I might just steal it! I am working on a rebuttal. It will be pretty long, so maybe I'll split it into two rebuttals. scigirl

01-06-2002, 10:45 AM	#3
Christopher Lord Senior Member Join Date: Feb 2001 Location: Toronto Posts: 808	Dont forget the end of the previous "scigirl/Douglas Debate Peanut Gallery" thread. A couple points where shreded before it faded away.

01-07-2002, 07:34 AM	#5
DB_Hunter Senior Member Join Date: Feb 2001 Location: Fort Worth, TX Posts: 755	I've had debates like this, too. In one, a layperson had no clue about geology, and she thought that gave her the ability to understand it better than somone who actually studied the rocks, has picked them up, and even tasted them (err... mineral content, yeah, that it). Then she had the chutzpa to complain that I was interjecting too many "facts" into the debate that she didn't understand. Hey, if you can't stand the heat... Do they not realize the sheer pride inherent in that idea? It takes the rest of us YEARS to learn this stuff, and even those with doctorates in their fields STILL don't know it all... But we don't pretend to - we know that there is always new stuff to learn, new discoveries to make, no matter the field. New mathematical theorems, new rock formations (even exogeology), new genes... For us, it's a never-ending journey of discovery. For them, it's just something else thye refuse to understand... DB can't spell... [ January 07, 2002: Message edited by: DB_Hunter ]</p>

01-15-2002, 08:58 AM	#7
scigirl Veteran Member Join Date: Jul 2001 Location: Seattle Posts: 4,261	Woo hoo, I'm back! I've been off at med school interviews. . . fell in love with Creighton University (not because it's in Omaha Nebraska, but because the school kicks butt, and you get excellent training). Except, well, it's really really expensive, being a private school and all. Oh, and I got to see the Olympic Torch. It was awesome--now I'm all excited about the Olympics. I've missed you guys though! I have a rebuttal almost finished, and I plan to post it tonight. It will be rather long. I will be discussing two main topics. 1) mechanisms of evolution (such as gene duplications--stuff most creationists have never even heard of!), and 2) ways that evolution could have produced the "perfect eye" and other examples (i.e.--I ripped off Dawkins big time!). I'll try to relate these topics to the time issue as well. I'll also be borrowing stuff from you guys. I doubt I'll use all your suggestions, but they are all bookmarked for the future. So thanks! scigirl

01-15-2002, 10:52 PM	#8
RufusAtticus Veteran Member Join Date: Nov 2001 Location: NCSU Posts: 5,853	scigirl, Me likey. I wonder if Douglas will respond. I think Douglas has left II, although he still seems active on ARN. -RvFvS

01-16-2002, 08:16 AM	#9
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	One interesting question is what is the absolute lower limit to humanity's ancestral population. It might be possible to answer that by comparing Human Leukocyte Antigens to their chimpanzee counterparts. If the common ancestor shared several LA's, then the absolute minimum number of individuals is half that, and the likely minimum much greater, to make genetic-drift drop-outs unlikely. LA's are selected for variety because they are a cell's way of signaling that they are not to be attacked by immune-system cells. And one adaptation of parasites is to resemble their host's LA molecules. However, if there are several distinct LA's in a population, then that makes it difficult for the parasite to adapt. So the mechanism that makes organ transplants difficult is the one that protects us from parasites by giving them too many targets.

01-16-2002, 04:52 PM	#10
The Lone Ranger Veteran Member Join Date: Oct 2001 Location: Eastern U.S. Posts: 1,230	Regarding Ipetrich's question on the absolute lower limit to humanity's ancestral population: Some months ago, I glanced through a paper regarding the variation in certain MHC proteins. The particular gene complex in question that is responsible for this variation appears to have arisen at least 10 million years ago, given that it is shared by humans, chimpanzees, and gorillas, but is not present in other apes. If I recall correctly, there are 32 known variants of the gene in question that are shared between gorillas, chimps, and humans. This means that at no point since the divergence of the human/chimpanzee/gorilla line from the rest of the apes could there have been fewer than 16 individuals alive who were direct ancestors of currently-living humans (and chimps and gorillas). If anyone really wants, I could try hunting down the reference later. Cheers, Michael [ January 16, 2002: Message edited by: The Lone Ranger ]</p>

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