How Organs Developed In Evolution?

[WarDude]

I can understand the basic concept of evolution, however I fail to see how random mutation can give a fish lungs and arms to even be able to be on the land (Frogs). I also can't see how stomach and/or liver can develop without an offspring borning with the entire organ so it work properly.
-Same goes for eyes and ears.
Also about the brain, how come some cells took command when the organism is only a handful of cells (I guess thats how it began).
What about chemicals which a natural body can produce (Poison, Stomach Acid), how come an organism started creating chemicals just because of a small mutation.
The list can go on, the main question is: How can complex organs and/or functions such as these created when most of them need more than a few random mutations to work.
For example - If a stomach does appear, and it lacks the slime to protect it, the acid will destroy it.

[Gaidin]

You so dropped this in the wrong forum, yo. How this works has nothing to do with ethics or morality. Look up Adaptation and Speciation though for a basic idea. They're the more high-level vehicles behind evolution and most of the low level concepts won't answer your question as they're mostly genetic in nature.

[Astaroth]

Moved to the science forum.

[CtrlAltDe1337]

A great question, and we've never seen anything like this form on its own in the real world AFAIK.

[Visna]

A great question, and we've never seen anything like this form on its own in the real world AFAIK.

Of course not. It takes longer than our lifespans. Thousands of generations. Say you were walking past a construction site at 5 am every morning. "Woah, that building is building itself. This is a miracle! God did it!" But if you sat there all day you could see the workers, the machinery, hell if you were nice and lucky, you may even get to look at the blueprints. We know how the workers and machinery work, and we know more and more about the blueprints as we delve deeper into evolutionary biology. It's like fiddling, improving. Sometimes things go wrong, but those individuals (or even whole species) die out, because their changes don't improve their survival. And that's the (temporary) end of that idea. But if it does work, then those species survive and the fiddling continues. It's an incredibly powerful technique, but, just like the construction of a building, it's a marvel, not a miracle.
Parts change gradually, change functions etc. The idea that complex parts or organisms just appear out of nowhere is a relic of creationism. And, since it's a part of creationism or "intelligent design" (yuck!), it's by definition complete nonsense.

[Tyler_the_Great]

^ah but the building WAS created and had a design. It didn't magically decided to build it's self one day.

[Gaidin]

^ah but the building WAS created and had a design. It didn't magically decided to build it's self one day.

Think of the 'design' as something you notice in hindsight and retrospect, looking back on the genetic line. Not something you sit down at a table with to form a new creature.

[Sphere]

This is a very good walk through of the evolution of the eye if you truly are interested.



Really though, if this is going to be a creation vs. evolution debate I don't think this should be in athenaeum. Scientifically the matter has been decided for 100 years now, at this point its no more than a social argument.

[WarDude]

Just to make things clear, I am an atheist. And what I ment is what is: How are few cells of stomach better than none? These few cells take more energy than what they can produce ( A stomach had to start from something)
Thanks for the videos by the way.

[Phier]

Just to make things clear, I am an atheist. And what I ment is what is: How are few cells of stomach better than none? These few cells take more energy than what they can produce ( A stomach had to start from something)
Thanks for the videos by the way.

Look at the simplest multicelled organisms.

Their cells are often close to identical, but there is an 'inside' and an outside. Cells on the inside touch the food, cells on the outside touch the world. A mutation on the outside which helps digest food better won't help the organism, but if it happens on the inside cell it would. Now take a time where food becomes scarce, which is easy to think of when you think of millions of years, and in such a time the ones who had cells better at dissolving food would survive better, and increase in the population. Likewise the same would work on the outiside cells, those better at sensing food or enemies would do better. Give it several generations (and evolution is actually very quick after a mutation) and you have a 'proto' stomach. Now multiply that for a few billion years and you have the true organs you see today.

[Plant]

I can understand the basic concept of evolution, however I fail to see how random mutation can give a fish lungs and arms to even be able to be on the land (Frogs). I also can't see how stomach and/or liver can develop without an offspring borning with the entire organ so it work properly.
-Same goes for eyes and ears.
Also about the brain, how come some cells took command when the organism is only a handful of cells (I guess thats how it began).
What about chemicals which a natural body can produce (Poison, Stomach Acid), how come an organism started creating chemicals just because of a small mutation.
The list can go on, the main question is: How can complex organs and/or functions such as these created when most of them need more than a few random mutations to work.
For example - If a stomach does appear, and it lacks the slime to protect it, the acid will destroy it.

Well eyes and ears are explained for you. As for fish being given "arms", I think it is that fish have fins to begin with, and it's honestly not hard to see how a fin can be used as a limb, and so a fin evolving into a limb, and that even a slight fold is useful as a control surface as a pre fin. You need to stop thinking about random mutations, as if it is the only mechanism of evolution. As for the stomach, the stomach doesn't exist by itself; it is a part of the digestive system. From what I can remember, unicellular organisms injest food, by surrounding the foodstuff and forming into bubbles Edit:Lysosomes, which are secreted with enzymes and acid. I suppose that would be a good basis to search from if you really are interested. It's not hard to imagine cellular specialisation in multicellular organisms forming the rudiments of a digestive sytem from this.

Just to make things clear, I am an atheist. And what I ment is what is: How are few cells of stomach better than none? These few cells take more energy than what they can produce ( A stomach had to start from something)
Thanks for the videos by the way.

No one has questioned your faith. Remember that a stomach is part of the digestive system, and all organisms have a method of digestion including bacterium. From there a stomach can start, and not neccessarily with the same cells as a stomach, as you can see that the original cells of the eye and ears not neccessarily have the cells of the eye and ear.

[MathiasOfAthens]

http://news.nationalgeographic.com/n...evolution.html

Heres a real world example.
Short synopsis... New invader species of lizards transplanted to a new home on an island rapidly evolve within 30 years.

In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say.
The transplanted lizards adapted to their new environment in ways that expedited their evolution physically, Irschick explained.

Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. Physically, however, the lizards were not built to digest a vegetarian diet.

Researchers found that the lizards developed cecal valves—muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.

"They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."

Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider.

It would be akin to humans evolving and growing a new appendix in several hundred years, he said.

[LSJ]

One thing to remember in evolution is that we only see the end product.

An example in this video is the eye. It starts as a patch of light sensitive cells. If the cells are on a concave surface, the organism can detect the direction the light is coming from. If the surface is formed into a deep bowl, we have a structure resembling the eye that detects direction and intensity of light, enough to create a blurry image. Mucus in the structure helps focus the light, and eventually develops into a lens. Muscles around the structure can allow the organism to move the eye.

The other good example is the Venus flytrap. It describes an intermediate stage (stickiness) that likely allowed the plant to capture prey without the speed that it relies on today. Once the plant developed suffiicient speed, it lost the stickiness.

The stomach could be just like the eye; it started with something simple, and became increasingly complex. It could also have developed in the way of the venus flytrap. Maybe the stomach worked very differently originally, and the strong acid is a recent feature. The stomach may have lost components that became obsolete once the newer, more effective system became established.

Our appendix may be like the venus flytrap's stickiness. Perhaps it used to play an important role that facilitated the development of our current digestive systems. It could be lost in the future. Creationists of the future post-apocalyptic world would then say, 'how could our digestive system have evolved without an appendix?' They just wouldn't know we had one because it was lost once it became obsolete.

[Elfdude]

The organs arise because they must. They only seem well defined because we categorize them that way. It's plausible for organs to solve the problems of maintaining life in a variety of ways. The fact of the matter however is that there's very simple universal requirements for the functioning of life.

In single celled organisms the requirements are simple, they need an energy source, they need a protective environment for that energy source, they need a way to replicate and a way to repair themselves. Bacteria take care of these requirements quite effectively but eukaryotes go about this completely differently. Eukaryotes are much larger than bacteria and actually seem to resemble entire modular colonies of bacteria each organelle resembling a specialized bacterium. Eukaryotes have much steeper requirements however they can account for this because they have much more efficient or specialized organelles than their prokaryotic ancestors.

Why? Well quite simply because they must. Eukaryotes are much larger and without a better support system their volume to surface area ratio (which limits their ability to utilize things such as natural diffusion) so they utilize heavier machinery so to speak. See the very basic blueprints for organs are something every individual cell has, organs are simply rather inflated versions of cells specialized at a singular task to account for the increasing requirements for live. Prokaryotes have it in enzymes and basic structures that are somewhat like organelles. Eukaryotes have what appear to be multiple prokaryotes working together to survive where no single one could compete without support. Multicellular organisms are no different. Instead of multiple prokaryotes however we have entire tissues (defined as a group of like cells) which are specialized to handle what previous designs on organs couldn't.

Think of the body of a living organism like a city. The organs are like the support structures surrounding that city. As the city grows more and more complex highways arise to cope with increasing gridlock/traffic and need for freight. A city with a million people couldn't cope with everyone burning their trash like a city of a hundred people. The million people would easily choke themselves out, thus it is necessary to include a garbage company to remove waste. At the same time there's an enormous requirement for food and it's not efficient enough for everyone to grow their own food when mass production can do so much more with so much less, further tractors are expensive. Thus farms arise to support the increasing demand.

Further the city itself falls into disrepair from time to time thus repair men and contractors are recruited to handle the building at a speed and effectiveness that ordinary people (cells) can't handle. As the city grows unrest moves in and invaders as well as criminals threaten their safety. A law enforcement organization arises, and city walls act as check points limiting entry. In order to properly orchestrate all of these activities a central governing office arises.

None of these items were necessarily planned for and in most old cities they weren't at all, the city's structures themselves evolving with society. Organs share a very similar gradual rise in complexity from the initial days as single celled organisms.

For an example I'll describe our ancestral evolution, many other creatures took different paths.

We started out in our history as eukaryotes. The common ancestor of probably all or at least most multicellular life. Some of these common ancestors found working together was more efficient to survive than any one of them working apart. As they grew more advanced everything around them grew more advanced triggering a technological (or evolutionary) build up. These early multicellular organisms required that every cell be in contact with water. Further the sensory organs that once gave the individual cells advantages were harnessed to produce cooperation. Cells communicated with each other with a very basic chemical transmission relying upon diffusion and osmosis to deliver the instructions. Cells sensitive to light at one end of the organism told the cells at the other end to activate their cilia to orient the organism towards the light. These sensitive spots on individual cells are the precursors to rods and cones in eyes.

Still before that could happen animals had to grow more complex. Cells at this point could communicate slowly with one another but for a truly large animal to grow the cells needed a faster method of communication. This was provided through long thin specialized cells that stretched from a central location delivering messages from one side of the body to the other at the speed of electrochemical propagation. These ancestors of ours were sea sponges. They used a complex cocktail of chemicals and electrical impulses to trigger their body's movement in order to avoid predators or position themselves better for feeding. In all animals today those chemical receptors are still present albeit not actively used by our bodies. Cannabis from which canabinoid receptors draw their name is a fluke of nature in which a plant chemical necessary for plant functions fits (albeit differently it still fits enough) enough to activate the otherwise unused neural pathways used to strengthen or weaken neural impulses. Modern animals use multiple pulses instead although the canabinoids still stimulate the moderating effect.

Even with the most complex folds the most complex creature you can produce without a circulatory system is a jelly fish. Jelly fish have a rudimentary nervous system eyespots (which later evolve into eyes) a digestive area and use the jets created by muscular contraction to circulate that digested food throughout their bodies. This digestive pouch which was tied directly into the circulatory system evolved into the isolated digestive tract we know and love today. The circulatory system was then isolated from the outside environment which allowed it to both work better and protected it to a greater extent from infection. Closely tied with the circulatory system the immune system probably also came into play around this time. In fact our blood resembles what early earth sea water probably did albeit more complex since then. Even plants have rudimentary circulatory systems.

At some point an ancestor evolved much like a jelly fish but different evolved with these advantages producing animals that were fast and ferocious. Thicker muscles allowed for greater power. New molecules were utilized in the construction of these creatures. Early animals evolved their eyespots into a variety of different ideas on eyes. Some animals had odd numbers some had even, some had single pinhole eyes, others had compound eyes, still others used little more than stalks and of course the eye spots alone persisted. Our ancestor at this time was something of a cross between a slug and an eel. It had one eye on either side of its head a central brain and a long central nerve that would later evolve into a backbone. It moved by undulating its body side to side as modern fish later would. It had a closed circulatory system and a long isolated digestive tract. Its eyes would eventually evolve to see more than just light or dark, they evolved blue cones multiplying their color perception by 100 times which in turn required a larger brain to make sense out of it. Eventually a green cone was created through the accidental duplication of the blue cone which resulted in mutated blue cones being incorporated on the retina. These ancestors evolved into fish who in turn varied into many different paths.

Still fish oxygenated their blood through gills directly by the sea water and though they could inhale and exhale to increase their buoyancy they couldn't be out of the oxygenated water for long. One fish very much like a modern amphibian, four fins and a tail evolved with lungs, little more than adapted buoyancy organs the rudimentary lungs allowed it to stay on land and colonize new territory. Although insect-like creatures and plants had already colonized the land with their own novel solutions. Still the fish had since ruled the ocean and they were about to make a dash for land. Over the next millions of years that lonely fish diversified into amphibians who evolved into reptiles and lizards who evolved into mammals and birds.

We owe our particular set of organs to more recent developments. Mammals evolved a more efficient heart that allowed them to more effectively regulate their activity, they began to take care of their young by adapting the egg chamber into an internal pouch hijacking the egg support structures to support a baby. They converted their scales into fur. They had five toes and five fingers. Two eyes and two external ears. They had large brains and best of all the ability to survive and adapt where others couldn't. Eventually what was essentially a tree shrew made the step towards becoming a monkey. That monkey made the steps towards becoming an ape and that ape made the steps towards becoming a man.

Much like cities may all end up looking different but still ending up essentially the same evolution could've gone a lot different ways. However we're the result of evolution that went like that. What caused the appearance of these traits? Well death of course. Death drives evolution and competition between organisms merely accelerates it. As new mutations arise they are tested, many mutations don't even work and because of the simple instability of dna (which has a natural predictable mutation rate) many 'potential' pathways never see life. Other pathways are lost to history as environments and competition drive them to perhaps a premature extinction. But one thing they all have in common is that they have to produce a combination that works. The natural progress of all of this random mutation (well not random, it's guided by predictable chemical law but I won't get into that) combined with the static and dynamic elements of the environment creates a constant source of new potential combinations.

If you're curious about the more technical principles of this increase in complexity a good source to visual it is a program called evolves 4.0. It's a program in which hypothetical block monsters who have mutating dna that emulates how real dna mutates (although you can alter these values if you're curious) gradually grow into diverse and complex creations. It only takes a few minutes for the simulation ran at its highest setting to produce creatures who are multicellular and evolve peculiar behaviors. While its not going to produce a dinosaur it will help visualize how chaos under a governing principle like death eventually produces complex creations who will continue to grow more complex in order to either claim novel resources or to utilize normal resources better.

http://www.stauffercom.com/evolve4/

[Sphere]

The rabbit has an interesting digestive system that uses an ad hoc way of processing cellulose. t

The main difference between our digestive system and the rabbit's is therefore that the majority of the breakdown of food in a rabbit's digestive system takes place in the cecum rather than the stomach. Because breakdown is occurring so far along the digestive tract the body does not have time to absorb all of the nutrients and much is lost in the feces. Because of this rabbits make two types of fecal pellets, one that consists primarily of waste and one that is rich in unabsorbed nutrients. The second kind is softer in consistency and is usually re-ingested by the rabbit in order to utilize the unabsorbed nutrients. The eating of fecal pellets usually takes place at night and for this reason often goes unnoticed by rabbit owners. It is however vital for the animals health and normal functioning.

Mammals in general have a poor digestive system for processing cellulose, and so a variety of work arounds have evolved. Rabbits eat their own droppings while bovines regurgitate their food to be re-chewed.

[MathiasOfAthens]

Disgusting sphere... too bad they cant read otherwise they wouldnt eat cellulose.

[Solid Snake]

It was God´s will!.....Seriously though, elfdude has nailed it, they formed because they must, altough for some reason that still does not cut the cookie for me. Like others said we only get to see the end product.....

[Elfdude]

Well perhaps that's not the best way to put it. It's not necessarily they formed because they must but rather if we imagine all of the legitimate possibilities (hypothetically) of reality as a tree, from the moment marked now as the trunk, no branch is going to produce what is essentially impossible because impossible branches (hell even technically possible branches are occasionally eliminated by luck or competition) are weeded out through death. Essentially you have a mechanism which is continuously adding both good and bad mutations which increase complexity (although some mutations simply rearrange the complexity that is there) and a mechanism acting upon that product (death) which is eliminating bad products.

However it's important to note that one good product may prevent one bad product from being eliminated. For example the great advantage of a circulatory system is all cells must have it, unfortunately the disadvantage of it is that if you lose your blood you essentially suffocate and die. As humans the advantages of this circulatory system outweigh the great risk however if you've lost someone to a bleed-out from say nicking their jugular you may be wondering how evolution could be so stupid. That's the thing, evolution can't be stupid it just is. It produces just as many flaws as it does advantages the important part is if those flaws are severe enough or aren't partnered with sufficient advantages they will be weeded out by death. So the poor knees, backs and pelvises we have which are only barely adapted to walking upright is the legacy of our evolution in the same way our organs are the legacy of our evolution.

Basically that is the halmark of nature. Even with our basic intelligence we could design species that are both far more terrible and awesome in every regard. The flaws produced by evolution are so obvious that were we to assign their responsibility to god such a god must be ignorant or malicious indeed.

Also he seemed to note earlier that he wasn't a creationist but rather a curious atheist.

Also Wardude, you seem to be underestimating the advantages gained through cooperation. Cooperation is more evolutionary advantageous than selfishness thus cells working together and shifting loads into what is an efficient organization are able to capitalize on more resources than cells not working together. The organs we see today are because of paths taken early on in our evolutionary history. Not through choice but through pressure. Like my city analogy every cell can't do every action on it's own there's simply not enough space in each cell and the machinery required to do so isn't something every cell can afford. Further the structures of many organs are just as important as the cellular composition. I.E. While 1,000 liver cells can form a structure which filters enough for 99,000 other cells 2,000 might be enough to filter for 250,000 and as more liver cells are incorporated the efficiency will increase. While those numbers are purely arbitrary it describes a lot of things in biology.

Why don't our bodies continue to grow more complex in order to solve the problems we currently face? Well mutation at a genetic level occurs very fast for single cells the process is slowed to a crawl for creatures the more complex they grow because fewer pressures are acting upon them as they become dominant. This is why we see the underdog in evolution in a few short years become the top dog. They evolve and thus adapt faster than the bigger ones. However cooperation again allows us to overcome these individual limitations with society. Just like cells had to advance to a certain point where cooperation become both possible and plausible animals had to advance to a certain point where cooperation became both possible and plausible. While many other animals have stumbled upon it millions of times humans are likely the first animal to evolve who (as a species) learn faster than their individual knowledge is lost to death allowing our kin to develop an ever growing toolbox at an ever growing rate.

[MathiasOfAthens]

Anyone who breeds animals knows this personally. When you breed you choose the strongest specimen, the strongest male. Nazi Germany prob would have instituted a national breeding program (actually they did ) if they didnt lose. Then we would have more blond and blue eyed germans than swedes.

[WarDude]

Anyone who breeds animals knows this personally. When you breed you choose the strongest specimen, the strongest male. Nazi Germany prob would have instituted a national breeding program (actually they did ) if they didnt lose. Then we would have more blond and blue eyed germans than swedes.

Wouldn't that cause some severe genetic diseases? (Being too homogenus*)
*I hope thats how to write it