pangloss

Still waiitng for those ref that you said you would supply.


I guess you can't and were just lying about it.

Typical for a TRUE christian creationist...

picklepuss

Hi;
That's nothing to do with what I said, via my analogy, etc. What I said was, that describing a cause (mutation} as "beneficial", strictly on the basis of an unplanned, accidental, unforeseen, entirely fortuitous outcome, is inappropriate.

It would seem to me that no cause should be described as beneficial unless it necessarily, inevitably, and directly, confers benefit upon something.

But laying that aside for the moment, and referring to them as 'fortuitous' mutations, I would not deny their occurence. I am sure that accidents can turn out happily, but I very much doubt that they often do. In fact, I should think that 'lucky accidents' in organismic evolution would be so anomalous as to be insignificant.

I know all about the appeals to 'time' and 'large numbers'. I'm just not impressed by them, that's all. Because when an organism needs to adapt to to a change in its environment, (its climate, for example), it seldom has the luxury of aeons and their large numbers at its disposal.

But that's just how I see it. I'm not trying to change anybody's mind.

[ October 29, 2002: Message edited by: picklepuss ]</p>

Camaban

the main thing is this:

a mutation is, on its own, neither good nor bad.

whether it's good or bad relies purely on context.

IE, Say a madman came into power (purely hypothetic case. this in no way reflects my future plans for world domination) that killed all people that don't have blonde hair and blue eyes.

Being Blonde and Blue would be beneficial.

But say someone came along who killed all Blonde and Blue's that would make being blonde and blue very bad indeed.

ALL mutations are simply mutations with no good or bad until bought into context.

Godless Dave

I was just minding my own business, watching PBS, and I heard about a mutation that confers a significant survival advantage:
quote from:<a href="http://www.science-frontiers.com/sf119/sf119p05.htm" target="_blank">Science Frontiers</a>

See also:
<a href="http://www.pbs.org/wnet/secrets/case_plague/index.html" target="_blank">Secrets of the Dead on PBS</a>
<a href="http://memorias.ioc.fiocruz.br/952/3919.html" target="_blank">More detail, also more technical</a>

And just so you can't say I suppressed some information, here's a story about how this mutation is beneficial in some circumstances but disadvantageous in others.
<a href="http://www.hivandhepatitis.com/2001conf/8thretro/2g.html" target="_blank">CCR5-Delta 32 Mutation Linked with More Severe Hepatitis C Virus Infection</a>

Non-praying Mantis

Dammit, Dave, you beat me to it!

NPM

pz

The delta-CCR5 mutation has been known for quite a while -- long enough that it has made it into most of the genetics textbooks.

You left out one of the interesting bits of the story. Libert et al. (1998) calculated from the molecular evidence and frequency of the allele that it arose in northeastern Europe, in about the 14th century, and spiked rapidly in frequency, most likely due to some selective advantage at that time...which coincided with the Black Death. They've hypothesized that the allele conferred some protection from the bubonic plague, perhaps by making white blood cells resistant to toxins from Yersinia pestis.

--
Libert F, Cochaux P, et al. (1998) The delta-CCR5 mutation conferring protection against HIV-1 in Caucasian populations has a single and recent origin in northeastern Europe. Hum. Molec. Genet. 7:399-406.

(oh, wait...I just checked one of your links, and saw that it does discuss the Black Death story. Never mind.)

[ October 31, 2002: Message edited by: pz ]</p>

RufusAtticus

Actually, pz, I've heard that further studies showed that the timing of the CCR5 mutant allele does not coincide with the Black Death.

Doubting Didymus

You biologists can never agree on anything.
You're as bad as dieticians.

pz

Where do they place it? Before or after the 14th century?

RufusAtticus

pz,

I'll ask Wyatt Anderson since he is the one who told me. If I get time, I'll see if I can find on my own where he might have got his info.