Understanding through Discussion

Welcome! You are not logged in. [ Login ]
EvC Forum active members: 64 (9038 total)
243 online now:
DrJones*, dwise1 (2 members, 241 visitors)
Newest Member: Barry Deaborough
Post Volume: Total: 885,693 Year: 3,339/14,102 Month: 280/724 Week: 38/91 Day: 3/3 Hour: 0/0

Thread  Details

Email This Thread
Newer Topic | Older Topic
Author Topic:   Genetic 'Bottlenecks' and the Flood
Member (Idle past 369 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003

Message 21 of 59 (41326)
05-25-2003 10:57 PM
Reply to: Message 20 by Alec
05-25-2003 10:30 PM

For example, species of amphibians, fish, and insects would not necessarily have genetic evidence of a bottleneck in them because they wouldn't have all died during the Flood of Noah.

Actually, for reasons that have been covered a few times, they would have died if they weren't on the ark.

Fish would have been killed by the change in salinity and temperature caused by flooding. Most species of insects are so adapted to their environments that drastic flooding would have elminiated them. For that matter, aquatic mammals would have died from starvation - baleen whales wouldn't be able to strain the thick mud of the flood and the destruction of fish species would have left the other cetaceans with nothing to eat either.

At any rate, a lack of bottleneck in any animal that should have been on the ark would be sufficient evidence against the flood model.

This message is a reply to:
 Message 20 by Alec, posted 05-25-2003 10:30 PM Alec has not yet responded

Member (Idle past 369 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003

Message 27 of 59 (41421)
05-26-2003 7:33 PM
Reply to: Message 25 by Alec
05-26-2003 6:50 PM

Woodmorappe [1996, pp. 143-144] discusses some evidence he believes contradicts this assertion. I quote (a long quote):

Yeah, some fish might have survived. That's a long, long way from all species of fish. Or even most. So far you've got mullusks, goldfish, and salmon. It's pretty apparent that the ability to survive multiple levels of salinity is a specific adaptation in most species, not the rule.

Coral reefs die if the temperature or salinity change by more than a fraction of a percent. And they grow so slowly that it's ludicrous to suggest that modern coral reefs are younger than 4000 years.

but will survive indefinitely in that medium if gradually acclimated to it.

Is that consistent with a sudden, global deluge? It doesn't seem so to me.

Also you didn't address insect populations. Many insects have lifespanse shorter than a year, and need specific, dry places to lay their eggs. A year's global flood would have wiped out the vast majority of insect species.

There's so many inconsitencies with the flood/ark model I don't know where to begin. The ark's too small to result in speciation on the scale we see it today unless you're willing to grant rates of mutation and speciation totally at odds with what we see today. There's no room for all the food that those animals would have consumed. There's no way that such small populations could survive in the post-flood world - a virtual waterlooged wasteland. There's no way an ark constructed with "antidiluvian" technology could have survived - and there's certainly no reason one big ark would have been the sole survivor, especially among fishing communities.

There's the fossil sorting problem - fossils are sorted in ways that have nothing to do with flood survivability (complexity of shell suture, for instance.) There's the total lack of flood sediment in certain areas of the world (the Canadia shield, for instance). There's the apparent lack of genetic bottlenecks in most species, as far as I'm aware.

The flood is a myth. It's thematic similarity to the flood myths of other cultures suggests that it's simply another version of the same fairy tale. Belief in the flood narrative as a historical account is only possible if you throw out basic information from a wide variety of fields such as engineering, biology, geology, literary criticism, and even theology.

This message is a reply to:
 Message 25 by Alec, posted 05-26-2003 6:50 PM Alec has not yet responded

Member (Idle past 369 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003

Message 29 of 59 (41431)
05-27-2003 1:55 AM
Reply to: Message 28 by Alec
05-26-2003 11:54 PM

As is, in the creationist model, the adjustment to one level of salinity.

That doesn't make sense. It takes far, far longer for a species to lose functionality (the adaptation to multiple salinity environments) than it does to gain it because there's no selection pressure for losing things unless their presence is somehow detrimental. For instance, that's why the metabolic pathways of your cells contain the machinery to do primitive anaerobic metabolism as well as the superior aerobic pathways.

Why would fishes have lost their adaptation to multiple salinities? What's the disadvantage in having it? Fish may have lost the ability to adapt to different salinities but it would have taken a lot longer than 4000 years. There's just no selection pressure for it.

The salt would not have all been immediately stirred up in the Flood, to my knowledge. It would have been more gradual, and it's possible that different depths would have different salinities.

In a vast, churning miasma? I don't find that reasonable.

There's a thread here that discusses how the flood would have had to have been simultaneously incredibly violent to deposit sedimentary layers in the way we see them, yet also pretty calm to allow a 600-year-old man and his boat full of animals to survive. The flood explanation just isn't self-consistent.

founder populations have a great range of variation.

Are you sure about this? I don't see how a founder population of two (or even seven) could have any significant amount of genetic diversity - certainly not enough to explain the diversity we see today.

Inbreeding depression would have selected for animals that would have been more fit early, also.

In a population of two, any selection at all ends the species.

I do know, for instance, that we find marine fossils near the top of Everest, for example.

Plate tectonics - ever heard of it? Mount Everest used to be a lot shorter. Used to be under a sea, in fact. (Plates colliding, and all.) I'll wager that you certainly don't find any contemporary sea life on the top of Everest. No whales, for instance.

We haven't mapped a great deal of genomes, and making accurate conclusions without doing so is questionable.

We don't have to map the genomes of every animal. We just have to map the genome of one animal that would have had to have been on the ark to disprove the ark story. I haven't looked, and I'm no geneticist, but I'd be very surprised indeed if there wasn't a mammal (for instance) with no recent genetic bottleneck.

I would think that Flood myths all over the world lend support to the historical fact of a literal, global Flood. It must have its roots in history, don't you think?

I find that the fact that only cultures that live near/on floodplains (or are decended from cultures that did) have flood myths suggests that they're all stories about local floods. Even if they're all stories about the same flood (a proposition that can neither be denied nor accpeted without a time machine), is that any reason to believe in a magically violent-yet-calm global flood? Isn't it much more reasonable to assume that the story is about a local flood that nearly wiped out a burgeoning human population and lives on in the decendants of that population as a legend? It wouldn't have had to be a global flood for the people involved to refer to it as "global". Sometimes your little corner of the world is all the world you have.

The flood model raises way more questions than it addresses, is self-contradictory, and simply fails to be reasonable. I don't really see how it can be taken as anything but a myth. Unless one is motivated by a desire for the Bible to be literally true, and then I would ask you - why do you think it must be so?

This message is a reply to:
 Message 28 by Alec, posted 05-26-2003 11:54 PM Alec has not yet responded

Member (Idle past 369 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003

Message 33 of 59 (41755)
05-29-2003 10:58 PM
Reply to: Message 32 by Alec
05-29-2003 10:04 PM

Therefore, because fish, etc., have become adapted to certain, specialized environments does not mean they didn't have this capability in the past and, as some evidence shows, does not mean that such variation is non-existent today.

I don't think you understand my objection. My point is that, since there's no pressure to lose temperance to changing salinity, there's no way most fish would have lost it in only 4000 years or so. That kind of genetic change takes far, far longer.

The mechanisms of mutation and natural selection are very well understood, and unless you can posit a potential survival advantage for an inability to tolerate different salinities, those mechanisms preclude such a change from happening in anything close to 4000 years.

Mutations are almost always known for their detrimental effects, and even though it would be advantageous for the organism to keep its function, a mutation can change that.

Actually they're almost always known for their neutral effects, for instance the four to fifty mutations you have, somewhere in your genetic code.

You're proposing that all species of fish have salinity-temperance pseudogenes? That appears to be your argument. I don't know how salmon (for instance) deal with changing salinity. I don't know what kind of genes that it takes.

If you do, please fill me in. I'm really not a biologist, just a reasonable person.

As for the selection pressure--if a species of fish has taken up freshwater lakes as its habitat, adaptation to multiple salinities would be irrelevant.

Exactly my point. If the trait is neutral with respect to the environment, we should see a lot more fish with it. If there's no reason to select for or against it, it should tend to continue in the population until random mutation disables it. That takes a lot longer than 4000 years.

Are you seeing my point with this? 4000 years isn't enough time for most species of fish to lose that trait. Since they don't have it now, either they lost it far, far longer than 4000 years ago, or else they never had it. My bet is the second choice. Most fish never were adapted to multiple salinities, therefore they wouldn't have survived a global flood. Since we have fish today we can assume, then, that the global flood never happened.

The dimensions of the ark, I have read, are such so that it could still righten itself if it was tipped 60 degrees.

As well as broken in half had it sailed into the trough of a large wave.

The dimensions are the optimum for ships--used today, if fact.

Boats built today are made from steel. Also they have keels. There's a hundred reasons why Noah's ark would have floundered in a violent sea.

However, marine fossils on top of Everest are a direct prediction of the creation model, too.

Sure. On the other hand, plate tectonics is supported by a host of other data, including GPS which comfirms the rising of mountains and the sliding of plates. Your flood story is supported by no evidence at all.

This message is a reply to:
 Message 32 by Alec, posted 05-29-2003 10:04 PM Alec has not yet responded

Member (Idle past 369 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003

Message 36 of 59 (46776)
07-21-2003 8:21 PM
Reply to: Message 35 by Alec
07-21-2003 8:13 PM

Since when do mutations need a selective advantage to occur and proliferate?

Well, they don't of course. The point that I was making (that you appear to have missed again) is that mutations don't proliferate at the rate that they would have to in order to eliminate salinity tolerance in most fish in under 4000 years without some kind of selective advantage.

As far as the whole salinity issue, I must admit I was taken off-guard and hardly know anything about it; I'm trying to be a reasonable person also

I realize that. As far as I'm concerned, I haven't heard anything to counter it. Fish simply wouldn't lose a tolerance for changing salinity in only 4000 years unless there was a major selective advantage in doing so. Otherwise it would have taken millions of years to lose through genetic drift.

[This message has been edited by crashfrog, 07-21-2003]

This message is a reply to:
 Message 35 by Alec, posted 07-21-2003 8:13 PM Alec has not yet responded

Newer Topic | Older Topic
Jump to:

Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2021