Why did this happen?

[Don Burke]

The question was, what is the evolutionary benefit of a tendency toward sea-sickness? Since it's still in the genome, it must at one time have been a plus.

Perhaps the people who did not get seasick were more likely to venture out on the ocean and get killed, leaving seasickness prone people on the beach to reproduce.

 

[SmokingMirror]

Hmm. And why exactly should nausea arise? Why should the stomach get involved? You aren't convincing, Mirror. Not convincing at all.

Nobody else seems to have had difficulty with this, but perhaps I should have clarified further. Essentially, as I'm sure you're aware, motion sickness results in nauseous feelings (a queasy sensation in the stomach, etc.), but your assertion that all nausea stems from the stomach isn't quite accurate. Nausea that results from the stimuli we are discussing in this thread (viz. motion-sickness) is actually the direct result of the behaviour of a section of the brain known - appropriately enough - as the vomiting centre.

We've already explained in this thread how the brain has this, and other, sections stimulated by the signals being sent by the eyes and inner ear, and it is this vomiting centre which, through muscle control, causes the queasiness in the stomach which can result in vomiting. Of course, nausea and vomiting aren't quite the same thing, Bryan, and I'm more than happy to point you in the direction of some medical texts outlining the differences if you like, but the above explanation should cover it pretty basically.

In simpler terms, and as it happens the definition used in modern medicine, nausea is defined as the sensation of having an urge to vomit, such as when you are experiencing the motion sickness Zoe83 is talking about. Even the etymology of the word nausea refers to sea-sickness, coming from the Greek naus, which means ship, referring, obviously, to the queasy feelings and doubtless endless vomiting felt by early mariners!

Hopefully this makes it clear to you how nausea can arise as a result of motion(sea) sickness.

In the beginning of your post I fear you've confused morphologies with no impact on reproductive success (male nipples), therefore not selected against, with morphologies that once served a real purpose (the appendix, among other structures.) and which have not yet been selected out.

The two examples, rather obviously I personally feel, we not put into contrast with each other, but were being employed to try and explain to you that, as Xanthro very eloquently puts it, "it's a common misunderstanding that a trait has to have an evolutionary benefit to survive". Your attempt to take the two examples and complain about their lack of contrast to each other, rather than to your statement, just rather seems like lame obfuscation to me. I'm still interested to hear you address the point made (viz. that your statement "Since it's still in the genome, it must at one time have been a plus" is simply flawed). Perhaps you might also like to let us all know exactly what the appendix was/is for whilst you're at it, because I'm damned if I know, and your statement that the appendix "once served a real purpose" seems to suggest you have access to knowledge hitherto untapped by medical science!

I don't claim that the theory I presented is factual, or even that it could be tested. I do think your sarcasm betrays a lack of reasoning.

I don't believe that I actually attacked you personally, Bryan, rather that I said the statement you made was - IMHO - deeply flawed. I'm sorry you took it as a personal attack, but respectfully point out that if you react to contrary information with personal attacks ("I do think your sarcasm betrays a lack of reasoning.") you might do well to stop and think about what you're saying.

 

[Kriterian]

I just thought I'd interject here and try to stem off the insuing word-war.

state that disorientation causes nausea is to fail to explain why it does so. Why should we toss our cookies? There's no systemic connection, other than the fact that the stomach is wired into the CNS.

You're thinking of vomiting as a response to sea sickness on the part of the stomach, which it is not. It's a mixing of messages to the brain coming from vision and inner ear fluid balance. These "mixed signals" can cause anything from headaches to watery eyes, AND nausea or vomiting.

(On a sidenote, this is theoretically why wrist bands work. The wrists are one of the areas where nerve transmissions are sent through. Restricting that particular area is like shutting down a railway station, letting only certain cars through.)

In some cases, the brain says "I've got something in my eye, please increase tear production. This is not one of those cases, it's more like a captain saying, "We're getting conflicting damage reports from 3 different areas of the ship. Start pumping out water, throw everything overboard and we'll swim for it." Meanwhile, it's just a toilet overflowing...

 

[Zoe83]

Very interesting reading different causes and explanations you have answered my question in regards to motion sickness/sea sickness, but what about when i feel nauseus and may/may not have vomited already, from drinking the night before, or a stomach upset (eg food poisoning) and i feel fine in the water? is it because of things you have previously stated? that my body senses are familiar with the surroundings and therefore respond normally? if that is so, why, then, am i sick out of the water? as that is familar also and has not changed. is water known to have a calming effect on people? or am i just weird

 

[czjack]

You're not weird! You're a diver.

I believe water does have a calming effect and the biggest thing for me is that there is more rock in the boat than there is motion when you are in the ocean.

 

[SmokingMirror]

but what about when i feel nauseus and may/may not have vomited already, from drinking the night before, or a stomach upset (eg food poisoning) and i feel fine in the water? is it because of things you have previously stated? that my body senses are familiar with the surroundings and therefore respond normally? if that is so, why, then, am i sick out of the water? as that is familar also and has not changed. is water known to have a calming effect on people? or am i just weird

The honest answer is I don't know. Nausea as a result of motion-sickness aside, I can't see any medical reason why the effects of feeling sick from, say, drinking or food poisoning should lessen or vanish when diving, but, as I'm sure we've all experienced at some point, it does seem to work to some extent.

Certainly water does seem have a calming effect on human beings, especially on babies and the very young, but nobody seems to be absolutely sure as to why. Perhaps it has something to do with water slowing the heart beat.

 

[DandyDon]

The honest answer is I don't know. Nausea as a result of motion-sickness aside, I can't see any medical reason why the effects of feeling sick from, say, drinking or food poisoning should lessen or vanish when diving, but, as I'm sure we've all experienced at some point, it does seem to work to some extent.

Certainly water does seem have a calming effect on human beings, especially on babies and the very young, but nobody seems to be absolutely sure as to why. Perhaps it has something to do with water slowing the heart beat.

From my understanding:
(1) When you are in the boat's ready area or galley, watching or at least noticing things move unnaturally, your mind canot accept what's happening, and some get sick. The nausiating effect of the original "Blair Witch Project" movie came from this exact effect, as the movie was shot with a shaky camera, rather than a "steady cam," so subtle motion sickness happened to many.
(2) Yet, in the water, the mind expects motion, so it doesn't upset the body.

Doesn't always work. I know a group trip leader with hundreds of North Carolina rock-n-roll trips in her experiences, but she still gets sick on the boat and in the water. WE were diving in the St.Lawrence together a couple of weeks ago, the sponges were spawning, and all the moving particulate (baby sponges) in the water made her ill.

Motion sickness seems to strike women more than men? Could this be tied to why women get morning sick when pregnant - to tend to reject foods that would have been dangerous to the early women and their unborns? Perhaps. Why men? As hinted earlier: Why do men have nipples? So women can - as we start from the same, basic embryo.

One cowboy's opinion, anyway...

 

[SmokingMirror]

From my understanding:
(1) When you are in the boat's ready area or galley, watching or at least noticing things move unnaturally, your mind canot accept what's happening, and some get sick. The nausiating effect of the original "Blair Witch Project" movie came from this exact effect, as the movie was shot with a shaky camera, rather than a "steady cam," so subtle motion sickness happened to many.
(2) Yet, in the water, the mind expects motion, so it doesn't upset the body.

um....that's already been said. What Zoe83 is now asking is why - when you've left the boat/shore - water should have a calming effect on those who are physically sick (again, such as those with a hangover or food poisoning), rather than why it lessens motion-sickness induced nausea.

Motion sickness seems to strike women more than men? Could this be tied to why women get morning sick when pregnant - to tend to reject foods that would have been dangerous to the early women and their unborns?

Interesting point. I know there was a test done at the department of psychology in the Pennsylvania State University in which a control group were tested, the results showing that the women consistently proved to be more susceptible than the men. A similar experiment was repeated at the Royal College of Medicine here in my native England a year or two ago, with pretty much the same result, so it does seem that women are slightly more predisposed towards suffering from motion sickness than men are.

 

[DandyDon]

um....that's already been said. What Zoe83 is now asking is why - when you've left the boat/shore - water should have a calming effect on those who are physically sick (again, such as those with a hangover or food poisoning), rather than why it lessens motion-sickness induced nausea.

Uh, yes - I think even I have said it before. I put it there in comparions to: "(2) Yet, in the water, the mind expects motion, so it doesn't upset the body."

Interesting point. I know there was a test done at the department of psychology in the Pennsylvania State University in which a control group were tested, the results showing that the women consistently proved to be more susceptible than the men. A similar experiment was repeated at the Royal College of Medicine here in my native England a year or two ago, with pretty much the same result, so it does seem that women are slightly more predisposed towards suffering from motion sickness than men are.

I used to think that men were just tougher, but that's the unfortunate side of me. Women tend to be more adaptable, I think. My guess here is still a strech.

 

[Zoe83]

its ok guys, no-one has to argue, its all interesting to me hearing different theories/opinions of this topic. so basically what ur saying is theres no real scientific explanation of why I feel better/calmer in the water when i am sick, as opposed to sitting on my couch at home. that some people just do. maybe its just me who is sensitive, if i have a flu or am lethargic i like to ride my horse cuz its relaxing and remote, and she knows im sick so pays me extra attention and if im nauseus i like to swim, the fish & water relax me. when im at my worst i get back to nature for energy. I dont know why but im glad it works for me