# Evolutionary Moments- How??? **URL:** \ **Category:** Great Debates\ **Created:** [November 9, 2003, 6:48pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269 "2003-11-09T18:48:06Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Badtz\_Maru](https://avatars.discourse-cdn.com/v4/letter/b/e36b37/32.png) [@Badtz\_Maru](https://boards.straightdope.com/u/Badtz_Maru)\ **Post date:** [November 10, 2003, 7:23am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/21 "2003-11-10T07:23:11Z")
There are no humans who can breathe water, but there are humans who can hold their breath much longer than your average human. If a human population was put in a situation where we had to spend a lot of time swimming underwater, those who could hold their breath longer would be more likely to pass their mutation on. ---
**Author:** ![dakravel](https://avatars.discourse-cdn.com/v4/letter/d/85e7bf/32.png) [@dakravel](https://boards.straightdope.com/u/dakravel)\ **Post date:** [November 10, 2003, 7:45am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/22 "2003-11-10T07:45:00Z")
On a slight hijack, I’ve always liked [this](http://www.bash.org/?95326) quote about evolution. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 10, 2003, 8:26am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/23 "2003-11-10T08:26:22Z")
> [@](#): > > \*Originally posted by Bytegeist \* > **before land animals arose from marine life, insects and plants had already populated the land. This didn’t help fish leave the water, of course, since insects breathe atmospheric oxygen by a very different mechanism.** Actually, it might have helped, as it would mean that there was something to eat on land - specifically it might have been worth momentarily beaching yourself to take a snap at the arthropods at the water’s edge. ---
**Author:** ![Rashak\_Mani](https://avatars.discourse-cdn.com/v4/letter/r/ea666f/32.png) [@Rashak\_Mani](https://boards.straightdope.com/u/Rashak_Mani)\ **Post date:** [November 10, 2003, 12:59pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/24 "2003-11-10T12:59:48Z")
Well some quakers actually leave their communities and survive the contact with technology. So anything can be adaptable. 🙂 ---
**Author:** ![dropzone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dropzone/32/7515_2.png) [@dropzone](https://boards.straightdope.com/u/dropzone)\ **Post date:** [November 10, 2003, 3:06pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/25 "2003-11-10T15:06:00Z")
> [@](#): > > \*Originally posted by John Mace \* > \*\*That’s about the best, short description of evolution I’ve every seen. Nice job!! If I use it sometime in the future, I’ll try to remember to attribute it to you. \*\* You’re nicer than me. I was going to just steal it. Wow, that truly is a brilliantly simple description. As is **dakravel** ’s! ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [November 10, 2003, 6:15pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/26 "2003-11-10T18:15:11Z")
I think you may have meant , " Some Amish "… Quakers do not live particularly cloistered existences, whereas Amish or Mennonites do by comparison. ---
**Author:** ![KidCharlemagne](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@KidCharlemagne](https://boards.straightdope.com/u/KidCharlemagne)\ **Post date:** [November 10, 2003, 7:16pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/27 "2003-11-10T19:16:59Z")
> [@](#): > > \*Originally posted by dakravel \* > \*\*On a slight hijack, I’ve always liked [this](http://www.bash.org/?95326) quote about evolution. \*\* What made it twice as funny is that it seemed to be from a chat log or something. Is that the case? Props to **Squink** too. ---
**Author:** ![dakravel](https://avatars.discourse-cdn.com/v4/letter/d/85e7bf/32.png) [@dakravel](https://boards.straightdope.com/u/dakravel)\ **Post date:** [November 10, 2003, 10:39pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/28 "2003-11-10T22:39:37Z")
[bash.org](http://bash.org) is a repository of user-submitted IRC quotes, although as of recently people have been sneaking in AIM and ICQ stuff in there too. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [November 11, 2003, 4:03am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/29 "2003-11-11T04:03:59Z")
> [@](#): > > \*Originally posted by Cartooniverse \* > \*\*I think you may have meant , " Some Amish "… Quakers do not live particularly cloistered existences, whereas Amish or Mennonites do by comparison. \*\* Shows what you know about Mennonites. 😃 ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [November 11, 2003, 4:49am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/30 "2003-11-11T04:49:34Z")
Aww Shucks 😛 -Thanks for the kind words. ---
**Author:** ![KidCharlemagne](https://avatars.discourse-cdn.com/v4/letter/k/ed8c4c/32.png) [@KidCharlemagne](https://boards.straightdope.com/u/KidCharlemagne)\ **Post date:** [November 11, 2003, 5:33am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/31 "2003-11-11T05:33:38Z")
> [@](#): > > \*Originally posted by dakravel \* > \*\*[bash.org](http://bash.org) is a repository of user-submitted IRC quotes, although as of recently people have been sneaking in AIM and ICQ stuff in there too. \*\* That site had me in tears for an hour. ---
**Author:** ![Apos](https://avatars.discourse-cdn.com/v4/letter/a/838e76/32.png) [@Apos](https://boards.straightdope.com/u/Apos)\ **Post date:** [November 11, 2003, 5:36am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/32 "2003-11-11T05:36:19Z")
> [@](#): > > There are perhaps 7 billion people on the planet- not one of them can naturally process water inside of their bodies in a way that allows the absorption of oxygen, right? As far as anyone knows, sure. > [@](#): > > Lotsa humans…why are there not accidental mutations? Er, there are. > [@](#): > > Why is there no need, since living in water might be an interesting adaptation? Interesting, but not immediately useful for survival in the immediate environment. As individuals, we can think “oh, it might be nice if I could breathe water!” But evolution doesn’t happen to individuals. It happens to entire populations. > [@](#): > > I’m not trying to play stupid, I’m curious- of amphibians evolved through accident AND causality, why aren’t humans doing the same? For all we know, some could be. But it would require humans living for a long long periods in aquatic or near aquatic lifestyles. And by that, yes, we mean tens of thousands of years before any appreciable pressure for better adaptability would being to detecably shift the population traits towards those best suited to operate in aquatic environments. But even then that might not involve breathing water. There are many many ways to survive in aquatic environments, and no PARTICULAR solution would have to happen. > [@](#): > > In a hundred thousand years, what will we have adapted to? Maybe back into the water? This appears to be what happened with whales: land mammals that moved back into an aquatic lifestyle. There is even a much maligned but not incredibly stupid supposition that at one point the branch of the tree life we would eventually be the fruit of involved mammalian apes who did move to somewhat aquatic lifestyles. This is generally considered to be without much evidence, but it’s an example of the sort of suprises one might well find in any lineage of creatures. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [November 11, 2003, 7:47pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/33 "2003-11-11T19:47:17Z")
> [@](#): > > \*Originally posted by John Mace \* > \*\*IIRC, lungs didn’t evolve from gills, but from another organ that had evolved for some other purpose. Can’t remember where I learned that, so I don’t have a cite. I’d bet that our friend, **Colibiri** could clarify that. He usually shows up in these types of threads eventually, although more often in GQ than QD. \*\* And if I ain’t quick enough, **Tamerlane** gets to it first. 🙂 **Tamerlane** gives the general consensus of the process by which lungs (and swim bladders) evolved. From [here](http://www.madsci.org/posts/archives/feb2002/1014304962.Ev.r.html): > [@](#): > > Fish with jaws and fish capable of living in fresh water first arose in the Silurian period. The current consensus (as far as I can make out) is that earliest lungs were sacks used to hold air gulped in response to low levels of oxygen in stagnant pools. > > It is thought that drought (and hence fish stranded in stagnant pools) was common in the early Devonian period. The development of a "back-up’ breathing system would therefore have been quite advantageous, even if it worked rather poorly. > > Once developed, the protolung/gas sack could be easily modified to improve its efficiency as a gas exchanger. This would also make it possible to use regulator of density, i.e. to function as an swim bladder. > > As Romer and Parsons (1977) state, "The swim bladders is found only in one subdivision of the bony fishes, the actinopterygians, whereas the most primitive member of that group, and members of the Sarcopterygii as well, have a lung. It may be worth mentioning too the concept of **exaption** : Traits that are evolved for one purpose may later be adapted for some entirely different purpose. For examples, fossils suggest that feathers first evolved as insulation for homeothermic theropod dinosaurs, only later being adapted for flight in the bird lineage. Likewise, lungs were exaptions that allowed for the later evolution of swim bladders. ---
**Author:** ![\_possum\_stalker](https://avatars.discourse-cdn.com/v4/letter/_/b77776/32.png) [@\_possum\_stalker](https://boards.straightdope.com/u/_possum_stalker)\ **Post date:** [November 11, 2003, 8:16pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/34 "2003-11-11T20:16:39Z")
Colibri: I was taught that that was called “preadaptation.” Speaking of preadaptation/exaption, legs evolved BEFORE the colonization of dry land (by the 4-legged). _[Acanthostega](http://www.mdgekko.com/devonian/Order/new-order.html)_ was believed to be the first fish to walk on land, until further study showed its “legs” would have been worse than useless out of water. _Acanthostega_ used its leg-like fins to crawl along river bottoms, much as the _[Coelacanth](http://www.nrf.ac.za/publications/news@nrf/feb2001/coelacanth.stm#pagetop)_ pictured at the bottom of the page uses its fins to walk along the ocean floor. BTW, IC and ID are held in slightly lower esteem in the biological sciences community than phrenology, largely because it isn’t a falsifiable hypothesis to say that anything unexplained is a clear case of “Goddidit!” ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [November 11, 2003, 10:40pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/35 "2003-11-11T22:40:20Z")
> [@](#): > > \*Originally posted by 'possum stalker \* > **Colibri: I was taught that that was called "preadaptation."** Same thing, really, but “exaption” tends to be favored by many evolutionists nowadays to avoid the implication that a trait evolved “before it was needed,” as might be construed from “preadaptation.” See [here](http://www.talkorigins.org/indexcc/CB/CB926.html) ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [November 11, 2003, 11:04pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/36 "2003-11-11T23:04:26Z")
> [@](#): > > \*Originally posted by Colibri \* > Same thing, really, but “exaption” tends to be favored by many evolutionists nowadays to avoid the implication that a trait evolved “before it was needed,” as might be construed from “preadaptation.” And a good idea that is, too! There is so much misinformation floating around, even among folks who accept evolution, that the last thing we need is to **give** people a reason to misunderstand it. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [November 11, 2003, 11:24pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/37 "2003-11-11T23:24:27Z")
[aside - and a minor correction 😉] The term **exaptation** was coined by none other than S. J. Gould, along with Elizabeth Vrba. See: Gould, S.J./Vrba, E.S. 1982. Exaptation: A missing term in the science of form. _Paleobiology_ 8(1): 4—15. [/aside] ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [November 11, 2003, 11:44pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/38 "2003-11-11T23:44:16Z")
> [@](#): > > \*Originally posted by Darwin’s Finch \* > \*\*[aside - and a minor correction 😉] > The term **exaptation** was coined by none other than S. J. Gould, along with Elizabeth Vrba. \*\* :smack: ---
**Author:** ![Cartooniverse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cartooniverse/32/3084_2.png) [@Cartooniverse](https://boards.straightdope.com/u/Cartooniverse)\ **Post date:** [November 13, 2003, 7:55pm UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/39 "2003-11-13T19:55:28Z")
I feel like a fish outa water, but am following the thoughtful answers to my simplistic query with great interest, thank you for all of these posts. Keep ‘em comin’ . ( Get it? Fish outa water? Make no bones about it, when your writer works for scale, it shows. 😛 ) ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [November 14, 2003, 1:46am UTC](https://boards.straightdope.com/t/evolutionary-moments-how/212269/40 "2003-11-14T01:46:38Z")
> [@](#): > > \*Originally posted by Cartooniverse \* > \*\*I feel like a fish outa water, but am following the thoughtful answers to my simplistic query with great interest, thank you for all of these posts. Keep ‘em comin’ . > > ( Get it? Fish outa water? Make no bones about it, when your writer works for scale, it shows. 😛 ) \*\* What other questions do you have? Basically, the problem with the scenario in the OP is that fish did not evolve lungs so they could “venture out on the land” (as it is sometimes phrased). Instead: 1. Fish evolved lungs originally so they could better live _in the water_; specifically in stagnant water with a low oxygen content. Air has a much higher concentration of oxygen than water, so it’s easier to extract oxygen from it, if you can figure out a way to keep the absorptive surfaces moist. Fish are able to absorb some oxygen through the skin anyway; it was easy enough to develop a sac branching off the mouth that contained highly vascularized skin where air could be held and gases exchanged. The fish continued to live in the water, but would periodically gulp air from the surface, as is often seen in fish living in stagnant water today. 2. Fish didn’t go to the land, the land came to them. That is, the pools where they lived periodically dried out. Those that could breathe air and resist drying out long enough, and had strong enough muscles in there fins (or primitive legs) to push themselves along to the nearest pool that still had water, would survive to produce the next generation. (Today this kind of ability is shown by species like the [“walking catfish”](http://www.nrm.se/ve/pisces/clarias.shtml.en) that can cover considerable distances on land). These adaptations originally were so the fish could continue _living in the water_, not gallivant on land. But eventually, some became so good at it they could pursue insects on land at the edge of the pools, and gain a food source not available to other fish. Many of the steps in this process have parallels in living fish, so it’s really not a difficult scenario to visualize. [Previous page](https://boards.straightdope.com/t/evolutionary-moments-how/212269.md?page=1) [Next page](https://boards.straightdope.com/t/evolutionary-moments-how/212269.md?page=3)