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Author Topic:   How did the stomach evolve?
CoolBeans
Member (Idle past 1111 days)
Posts: 196
From: Honduras
Joined: 02-11-2013


Message 1 of 18 (721970)
03-13-2014 10:28 PM


Dont gastric acids disolve the food but without the protection it would burn the stomach and for them to exist we would need something to be protected from. Im just curious.
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Admin
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Message 2 of 18 (721971)
03-14-2014 7:45 AM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


I think you're asking how gastric acids evolved before the protective stomach lining existed. I'll promote this now, if I got that wrong you can clarify.

--Percy
EvC Forum Director

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Admin
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Message 3 of 18 (721973)
03-14-2014 7:46 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the How did the stomach evolve? thread in the Proposed New Topics forum.
    
Stile
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From: Ontario, Canada
Joined: 12-02-2004
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(2)
Message 4 of 18 (721978)
03-14-2014 10:49 AM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


Basic Evolution of the Stomach
CoolBeans writes:

Don't gastric acids dissolve the food but without the protection it would burn the stomach and for them to exist we would need something to be protected from.

Yes, this is correct.

How did the stomach evolve?

The stomach evolved a long time before humans were around. By the time humans came around, the stomach had already evolved to the point where it had gastric acids and mucous protection.

The mucous would be present first... although not like the mucous we have. A much more basic version.
The mucous would work with a simple in/out system just helping things move around (before there's even a "stomach!").
Eventually, a "digesting pouch" evolves that we can sort of call a stomach.
Once this basic stomach exists, small amounts of gastric acids would help with digestion.

At this point, the acids and protection would evolve together.
As one gets a bit stronger... so does the other. Not necessarily either one over the other at any specific time.

And then... one day... a stomach!

And then... after a lot more days... humans with a stomach!


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Taq
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(1)
Message 5 of 18 (721979)
03-14-2014 10:51 AM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


Dont gastric acids disolve the food but without the protection it would burn the stomach and for them to exist we would need something to be protected from. Im just curious.

The first thing to keep in mind is that the esophagus, stomach, and intestines are considered the "outside" of your body. One of the things that the outside of our bodies needs to protect us from is pathogens, and that is exactly what our mucosal membranes do. The lining of the stomach is a mucous membrane.

I would strongly suspect that the first function of acid in the digestive tract was to kill off unwanted pathogens, and our stomachs still serve this purpose. The fauna in our intestine differs from our oral fauna partly due to our stomach separating the two.


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NoNukes
Inactive Member


Message 6 of 18 (721997)
03-14-2014 12:26 PM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


I don't see the conundrum
This question seems of a type with the question of how could an electric eel evolve, and I don't think it is too terribly difficult to come up with a starting point and a path that could work. As a class they require thinking of acids or electricity only at their most potent levels.

First, acids do attack the digestive track, but really weak acids need not do so at a rate that endangers the organisms survival. So a starting point might be a digestive system only able to digest the easiest foods. Natural selection might then favor variation providing greater resistance to stronger digestive fluid allowing more choice of foodstuff.

Organisms do have some control over eating stuff that upsets their tummies and also in the strength of the acid they secrete. But evolution could favor animals that can eat stuff that makes their competition sick.

Next up how did cheetahs evolve their great speed? Shouldn't they have all died out when they were too slow to catch gazelles or escape lions?

Edited by NoNukes, : No reason given.


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ringo
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From: frozen wasteland
Joined: 03-23-2005
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(1)
Message 7 of 18 (722132)
03-16-2014 3:02 PM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


CoolBeans writes:

How did the stomach evolve?


Very carefully.
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ProtoTypical
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Posts: 1744
From: Ontario Canada
Joined: 08-04-2010


Message 8 of 18 (722133)
03-16-2014 3:19 PM
Reply to: Message 7 by ringo
03-16-2014 3:02 PM


It wasn't careful at all. It just kept on evolving until it worked. In fact it could still use a little fine tuning.

Like for example, it should regurgitate anything that is not good and wholesome. Processed food should make you puke on the spot and illogical arguments should make us bilious.

If there was any care involved at all then McDonald's would have gone out of business long ago.


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ringo
Member
Posts: 13435
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 2.8


Message 9 of 18 (722134)
03-16-2014 3:27 PM
Reply to: Message 8 by ProtoTypical
03-16-2014 3:19 PM


ProtoTypical writes:

It just kept on evolving until it worked.


Well, no. It had to be working all along. Each step had to be "careful" in the sense that it couldn't be fatal.

ProtoTypical writes:

Like for example, it should regurgitate anything that is not good and wholesome.


If you talk about what it "should" do, you're arguing for design.

(If I had added, "like porcupines mating," would you have recognized the joke?)


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Cedre
Member (Idle past 1126 days)
Posts: 350
From: Russia
Joined: 01-30-2009


Message 10 of 18 (723902)
04-10-2014 7:25 PM
Reply to: Message 4 by Stile
03-14-2014 10:49 AM


Another just so story!
Stile said:
"And then... one day... a stomach!

And then... after a lot more days... humans with a stomach!"

Voila! Magic!

Edited by Cedre, : No reason given.


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AZPaul3
Member
Posts: 3428
From: Phoenix
Joined: 11-06-2006


Message 11 of 18 (723908)
04-10-2014 7:56 PM
Reply to: Message 10 by Cedre
04-10-2014 7:25 PM


Re: Another just so story!
Voila! Magic!

Since you believe in majik I would have thought this would make you happy.

I guess the slow time consuming incremental magic of evolution is just not majikie enough for you . You prefer the ...

... kind, like when your god blows his nose at you, I suppose.


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RAZD
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Posts: 18855
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.6


Message 12 of 18 (723944)
04-11-2014 3:25 AM
Reply to: Message 1 by CoolBeans
03-13-2014 10:28 PM


sponge ...
Dont gastric acids disolve the food but without the protection it would burn the stomach and for them to exist we would need something to be protected from. Im just curious

Consider a sponge.


we are limited in our ability to understand
by our ability to understand
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Stile
Member
Posts: 2941
From: Ontario, Canada
Joined: 12-02-2004
Member Rating: 3.9


Message 13 of 18 (723955)
04-11-2014 8:21 AM
Reply to: Message 10 by Cedre
04-10-2014 7:25 PM


Thanks! But please try again.
Your comment seems a little lacking in substance. Perhaps you could try again with a bit more information on your particular issues.
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Saviourmachine
Member (Idle past 1050 days)
Posts: 113
From: Holland
Joined: 01-16-2004


Message 14 of 18 (732242)
07-05-2014 7:14 AM


Dragons
I've been always amazed that fire has not invented by one branch of animals. It would have been great, you'll need a very tough stomach and a mother who breathes into you her fire when you are born. And of course, some sophisticated cooling mechanism would be required as well. However, after this, you can eat things, very few other animals can eat. Perhaps, if oil was closer to the surface, this would have been a valuable path for evolution.

To be able to handle an acidic solution seems less of a feat.


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Larni
Member
Posts: 3943
From: UK
Joined: 09-16-2005


(2)
Message 15 of 18 (732304)
07-06-2014 4:16 AM
Reply to: Message 14 by Saviourmachine
07-05-2014 7:14 AM


Re: Dragons
Bombardier Beatle says 'hi'.

The above ontological example models the zero premise to BB theory. It does so by applying the relative uniformity assumption that the alleged zero event eventually ontologically progressed from the compressed alleged sub-microscopic chaos to bloom/expand into all of the present observable order, more than it models the Biblical record evidence for the existence of Jehovah, the maximal Biblical god designer.
-Attributed to Buzsaw Message 53

The explain to them any scientific investigation that explains the existence of things qualifies as science and as an explanation
-Attributed to Dawn Bertot Message 286

Does a query (thats a question Stile) that uses this physical reality, to look for an answer to its existence and properties become theoretical, considering its deductive conclusions are based against objective verifiable realities.
-Attributed to Dawn Bertot Message 134


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