Evolution of the stomach - creationists' favorite argument
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04-05-2012, 12:52 PM
RE: Evolution of the stomach - creationists' favorite argument
(04-05-2012 11:34 AM)Stark Raving Wrote:  Bwahahahaha!!! The human body and the word perfect do not even belong in the same paragraph together.

Unless it's Gwynnies. And that's only cause I'm so, not. Heart



If you don't wanna kill the creationist, then question his authority on god. You're expected to know every nuance of evolutionary biology, and he gets to go, goddidit? I don't think so.

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04-05-2012, 01:22 PM
RE: Evolution of the stomach - creationists' favorite argument
ok, then you eat through your nose? one thing is that we, humans, make a poor use of our bodies, and other thing is that our bodies are poorly designed.
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04-05-2012, 01:53 PM (This post was last modified: 04-05-2012 01:56 PM by kim.)
RE: Evolution of the stomach - creationists' favorite argument
Hmm... digestion has most certainly evolved and quite differently in many different species.


Cows chew, swallow, and puke... chew it... chew, chew... it's a never ending process which works in conjunction with their stomach which has 4 compartments. The process of chewing "cud" and continuous digestive processes are what allow cattle and other ruminants (sheep, goats, deer, giraffe, etc.,.) the ability to consume grasses, plants, and vegetation that contain cellulose and other difficult to digest chemical compounds.

Rabbits, guniea pigs and similar animals, eat grass and veggies, poop, then eat the poop. A rabbit's digestive tract can not fully process their food to gather nutrients so they then eat their poop. They extract more nutrition from grass by giving their food a second pass through the gut. Soft pellets of partially digested food are excreted and eaten. It's a little bit different than their regular poop... which they don't eat.


Raccoons do not have salivation glands and must make their food wet before they can chew it... they aren't cleaning it, they just need it slippery and mushy so they can swallow... and they need the water.

Oh - don't get me started on birds and their craw... I think we all know about those dinosaurs. Dodgy

My point is... these animals' digestion and digestive tracts evolved along with their respective species' adaptations to circumstance... and so did ours.

As humans, our ability to adapt to changing needs is reflected in our omnivorous digestive system... of which the stomach is just one small part. It starts with our species' continually changing teeth configuration, ends with our colon, and everything in between changes right along with the circumstances we're delt.
And to get our proper nutrition, we don't even have to eat our own poop! One only does that to get lots of hits on YouTube. Shy

The perfect things will be killed off in the perfect storm... that's why humans aren't perfect. Wink

A new type of thinking is essential if mankind is to survive and move to higher levels. ~ Albert Einstein
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04-05-2012, 03:25 PM
RE: Evolution of the stomach - creationists' favorite argument
Gwynnies is the obvious exception. I thought that went without saying. Wink

So many cats, so few good recipes.
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04-05-2012, 03:55 PM
RE: Evolution of the stomach - creationists' favorite argument
Hey, Mike.

Of all the creationist anti-evolution arguments, this is one of the weaker ones. Normally they take a flying dump on eyes, but this one is a no-brainer.

Tell him this: Because we're heterotrophs.

Autotrophs can create organic carbon from inorganic carbon; like plants.

Heterotrophs are incapable of this and so they must consume autotrophs in order to get organic carbon. That's why we eat plants and animals (cause those animals have eaten plants too). It's also why we die if we don't eat food.

All life is pretty much divided into either camp: autotroph or heterotroph.

So all heterotrophic life, which includes all of the animals, fungi and some bacteria have to have the capacity to ingest and digest autotrophs (or other heterotrophs).

What I'm talking about, of course, is predation.

All predators need to be able to eat.

This includes single celled organisms.

So the mechanisms for consuming food date back literally billions of years to when the first heterotrophic singel-celled organisms let stuff in through the cell wall, into the cytoplasm and let their organelles have at it. As heterotrophic organisms evolved into multi-celled organisms over the last couple billion years or so, the complexity of their digestive systems increased accordingly. The stomach is just one heterotrophic solution to digesting food that has been selected for; one that has some interesting variation just among mammals!

Hey, Stark.

The human throat is an absolute train wreck. Choking to death is really primarilly a human concern. I mean sure, if another animal swallows a sharp bone sideways they're fucked, but choking a la blocking the airway is pretty much restricted to humans. Why? Because of the voice box. The human larynx in a terrible position but it's the only place it can be to work. So the question then is, why the fuck did it get selected for if it kills us? The answer. Meme-gene co-evolution. Our genes didn't want the voice box, our memes did. The voice box allows humans to be astronomically better at transmitting memes than primates who grunt. Just look at the complexity of our spoken languages. The voice box allowed for syntax, which is pretty much the reason we are who we are; thumbs be damned (although we probably wouldn't have started being so concerned with communicating if we didn't have to teach each other how to make stone axes). So the voice box was selected because it was more important to our memes than it was detrimental to our genes, even though a bunch of us choke to death because of it.

Ain't Darwinism cool!

Peace and Love and Empathy,

Matt
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04-05-2012, 04:17 PM
RE: Evolution of the stomach - creationists' favorite argument
Human body is definitely far from perfect. The fact that bacteria can reproduce every 20 minutes, mutate, and thus successfully develop resistance to our antibiotics shows that their "archaic" ways of life can successfully compete with our intelligence that took billions of years to evolve, by the way. At the end of the day we have only been around for 200,000 years or so as opposed to bacteria who have been around for 4 billion years. So that's irrelevant. We all know that an omnipotent creature could have done a lot better than this, since he chose to afford humans special privileges and status of "higher" forms of life.
Nevertheless, lets get back to the facts and evidence. I cannot think of a way how gastric acid could have evolved. At least, gastric mucosa must have evolved in tandem with it, because had it not, then our stomachs would have digested themselves, since HCl is a destructive compound. That leaves us the only possible outcome, in my view:
1). Gastric acid and gastric mucosa could not have evolved in tandem, because it is inconsistent with the notion that evolution is a slow and gradual process. Those two groundbreaking changes could not have evolved together all of a sudden. Therefore, it is likely that one preceded the other, in which case there must be some traces of intermediary species that had one, but not the other and were able to live with it. I am keen to find some evidence to support this. It is indisputable that evolution acted on our digestive system and changed it in dramatic ways. The question is, how did it do so in respect of these two components?
Another likely outcome, is that I profoundly misunderstand something, in which case I would gratefully take any rebukes.

“Science flies you to the moon. Religion flies you into buildings.”
- Richard Dawkins
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04-05-2012, 04:27 PM
RE: Evolution of the stomach - creationists' favorite argument
(04-05-2012 04:17 PM)mikeschneider Wrote:  Human body is definitely far from perfect. The fact that bacteria can reproduce every 20 minutes, mutate, and thus successfully develop resistance to our antibiotics shows that their "archaic" ways of life can successfully compete with our intelligence that took billions of years to evolve, by the way. At the end of the day we have only been around for 200,000 years or so as opposed to bacteria who have been around for 4 billion years. So that's irrelevant. We all know that an omnipotent creature could have done a lot better than this, since he chose to afford humans special privileges and status of "higher" forms of life.
Nevertheless, lets get back to the facts and evidence. I cannot think of a way how gastric acid could have evolved. At least, gastric mucosa must have evolved in tandem with it, because had it not, then our stomachs would have digested themselves, since HCl is a destructive compound. That leaves us the only possible outcome, in my view:
1). Gastric acid and gastric mucosa could not have evolved in tandem, because it is inconsistent with the notion that evolution is a slow and gradual process. Those two groundbreaking changes could not have evolved together all of a sudden. Therefore, it is likely that one preceded the other, in which case there must be some traces of intermediary species that had one, but not the other and were able to live with it. I am keen to find some evidence to support this. It is indisputable that evolution acted on our digestive system and changed it in dramatic ways. The question is, how did it do so in respect of these two components?
Another likely outcome, is that I profoundly misunderstand something, in which case I would gratefully take any rebukes.
I say mucus came first and then the body needed something to counter it.

Hey... maybe humans evolved from squid - they seem to be almost entirely mucus! Tongue

A new type of thinking is essential if mankind is to survive and move to higher levels. ~ Albert Einstein
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04-05-2012, 06:23 PM (This post was last modified: 04-05-2012 06:26 PM by houseofcantor.)
RE: Evolution of the stomach - creationists' favorite argument
(04-05-2012 04:17 PM)mikeschneider Wrote:  I cannot think of a way how gastric acid could have evolved.

Then stay out of biology. I cannot think of a way to be a telemarketer. Yeah, I wanna kill them too. Heart
(04-05-2012 03:55 PM)Ghost Wrote:  The human larynx in a terrible position but it's the only place it can be to work. So the question then is, why the fuck did it get selected for if it kills us? The answer. Meme-gene co-evolution. Our genes didn't want the voice box, our memes did. The voice box allows humans to be astronomically better at transmitting memes than primates who grunt.

That's a good answer. Fits in with my love/entropy thinking. Wink

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05-05-2012, 09:30 AM (This post was last modified: 05-05-2012 09:41 AM by Hafnof.)
RE: Evolution of the stomach - creationists' favorite argument
I just want to quickly clarify one thing, which is that fossil records are not good for discerning digestive anatomy of some past species. This makes it difficult to pin down for sure some changes. Fossils are good at preserving bone structures, but poor at preserving soft tissue structures.

In some cases our best guesses can come from knowing which living species descended along which evolutionary branches. We can examine the differences between our systems and those of gradually more distant relatives to look for common properties that were likely established early in our common ancestry and dissimilar features that we can be confident developed later.

The creationist argument here is that there is no possible way that such and such an irreducibly complex organ or structure could have evolved. To reject this claim all that is required is one possible way that the evolution could have occurred. Science will generally try to take this further and try to determine exactly which of the possible ways it actually occurred, but in some cases with limited evidence it can be difficult to reach a final conclusion.

So far all identified cases of irreducible complexity have been discounted due to a possible evolutionary pathway being identified to the resultant irreducibly complex system. Sometimes existing genes or structures are performing some other function before they become specialised to perform the new function. Sometimes they are able to perform the function at a basic level in a single evolutionary step, but their ability to perform the function improves over subsequent iterations.

I'll say this next section purely as layman speculation. I'm not referring to actual science, but: We know that any animal with a gut will have a certain quantity of gastric juices being produced to help the food along. If we are talking specifically about the subsequent evolution of the stomach, then we can imagine different types of juices beginning to be produced at different points in the digestive tracts. For example, saliva vs stomach acids vs bile. If we are worried about the stomach acids themselves then these may well have started out weak but improved in potency over time as the stomach part of the tract became more resilient to the acids involved through additional mucus production, etc. HCl in any potency would need to be preceded by the development of other gastric juices/mucus to avoid damaging the digestive tract. However, once the mechanism was in place it could become a stronger acid over subsequent iterations.

Bear in mind also that acid here is not really what does the digestion within the tract. What we are trying to do with this tract is to pass food directly into the bloodstream through the walls of the small intestine. The liver and other organs do some of the work to make different foods useful to us once they are in the bloodstream. The intestines house bacteria that do a lot more of the digestion work. By the time we are back to the stomach, it is not necessarily a digestive process that is required but more of a cleaning process. The stomach's main job is not so much to digest food but to kill microbes that could harm our essential bacterial colonies Smile Digestive actions at this level are almost a secondary concern. The acids therefore don't need to have a strong digestive effect in order to be a useful part of the digestive system. They just need to kill a few bad microbes to be evolutionarily advantageous and thus to be selected for.

Give me your argument in the form of a published paper, and then we can start to talk.
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05-05-2012, 10:07 AM
RE: Evolution of the stomach - creationists' favorite argument
Hey, Hafnof.

Quote:Fossils are good at preserving bone structures, but poor at preserving soft tissue structures.

True dat.

Peace and Love and Empathy,

Matt
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