Evolution question- how do complex organs form from random mutations?

Question

Hi- just wondering what science's answer is to this question. It is hard for me to imagine that simple random mutations are responsible for the formation of animal's organs.

Take for example the first animal that could see. I would think it would be highly improbable for random mutations to create the necessary faculties for sight. This animal obviously did not just suddenly have eyes, it would have been a more gradual change. How would random mutations alone slowly create the organs for sight? It would seem about as probable (or even less probable) than the sudden formation of single celled organisms from amino acids.

I'm not a creationist I'm just wondering about this issue. I know there are billions of years and many generations to create these things but statistically speaking it doesn't seem like it adds up.

Answer 1

When I was studying biology in college I had the same question - my analogy was that the random events required to form even a simple cell are so incredible that it would be like landing on the moon and finding a 'Toyota Corolla' that had assembled purely by 'chance'.

Over time, though, I came to understand it better - in part, by getting a grip on the abstract meaning of Millions and in fact Billions of years. This is the time scale in which the major evolution of life on Earth transpires.

When we consider that successful mutations are 'conserved' and built upon further in nature, and we consider the time scales above, it's not so impossible to believe.

For example, we believe life on Earth is about 4 Billion years old or so, and the simplest earliest life were the single celled bacteria - the prokaryotes. These organisms reigned on Earth for billions of years before the more complex Eukaryotes came into existence. The prokaryotes are very simple lacking membrane bound internal structures or organelles (they do not have a membrane bound nucleus, nor do they have mitochondria as examples) - so when Eukaryotes evolved with their complex cytoskeletons, membrane bound organelles and highly complex chromosomes it was a quantum leap - much like you describe with your question relating to the evolution of organs (in fact, these were the "first" organs if you think about it).

While random mutations did contribute to this, so did other processes in evolution - for example, endosymbiosis. This is the idea that some other organisms 'invaded' these early eukaryotes and then symbiotically specialized within the cells to become organelles. Literally - A bacteria entered a cell, became very specialized within that cell and 'evolved' into a symbiotic relationship to become 'mitochondria'. Indeed, this is why we believe there is distinct mitochondrial DNA in this specialized organelle to this day.

So the point - based on all of the above - is that conservation of random mutations over an unfathomably long period of time and other processes such as mutualism and endosymbiosis can combine to make complex leaps in evolution.

Thinking more about organs, it's probably good to look at early animals - like simple sponges and simple worms - more or less, the level of organ complexity in these early animals was mostly the evolution of a simple gut. From these early fairly undifferentiated forms more complexity is added over time and as the evolutionary tree branches.

A last thought, while I wholly accept evolution as a scientific process and do not subscribe to creationism - this does not preclude that there are 'patterns' in nature. In Chaos theory we see recurring 'fractal' patterns repeated throughout nature and natural processes. There is no reason that natural patterns, somehow embedded in 'reality' do not manifest as evolution unfolds - this may explain why things may seem structured to some extent in evolution, and also helps to rationalize examples of convergent evolution (why patterns such as 'dorsal' fins occur in both fish and dolphins - because the 'pattern' works).

I'm hoping this helps - though I know it's not an easy answer.

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Answer 2

everything you just said is flat out false. 1. mutations can be transcriptive or deleterious however there can also be base pair duplications and insertions, you just ignored the other common forms of mutation 2. the vast majority of mutations do absolutely dick all. there are around 150 mutations in your body, and 150 in mine and everyone else on the planet. everyone is a mutant. if your assertion was true and one mutation is harmful, then 150 should leave us in a hell of a mess but we're not. 3. now this is pure nonsense. first of all mutations do not always decrease the complexity (is your definition of that even quantifiable?) as i have already stated mutations can lead to the introduction of novelty. for example the enzyme nylonase employed by some strains of flavobacteria, this was the result of a single base pair duplication. since base pairs code in 3's, every subsequent triplet codon is thrown one base pair out of whack. this caused the creation of a completely new enzyme which allowed them to digest nylon, a material that didn't exist before the 1930's. in any case "information" (which is ill defined to begin with) and complexity are 2 different things. would you consider yourself more "complex" than a grain of rice? because a single grain of rice has about double the genetic material of a human. there is even a species of fungus that has over 2000 chromosome pairs, humans have 23.

Answer 3

Evolution Of Organs

Answer 4

A quick answer about the eye: it didn't just pop into existance in one generation or one mutation.

First, there were light sensitive skin spots that provided some advantage to organisms living in the sea. The progress toward eyes from that point would have been very slow indeed, but you have to remember, as others have said, that this occured over millions of years and 100s of thousands of generations. One tiny improvement can make survival much more likely and the ability to produce more viable offspring can increase dramatically.

Just for your information, the creationists used to use the eye as "proof" that evolution was/is impossible, but even they have given up on that one with the new information they have now had to accept.

Answer 5

Your assumption that statistically it does not add up is wrong. Given enough time, the proper conditions and the right events, these things evolve.

Evolution does not say how life began. It tells you how life evolved. The probabilities are different. We are still not certain just how life began on Earth. However, we are absolutely sure what state it was in when it began and how it evolved to be as it is today.

Remember, every challenge that evolution has faced has failed. Even the non-scientist when presented with the information in a proper manner by the proper people, will see the validity of evolution. They will also see that evolution is not attempting bring down Christianity.

Evolution
http://www.pbs.org/wgbh/evolution/

Understanding Evolution
http://evolution.berkeley.edu/

Answer 6

sorry,very pressed for time.....i'll leave you with this link on the eye that's pretty good.http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.html be sure to watch the video. I also leave everyone who asks evolution questions this :These are good resources,and i'll give you some of my reccomended books that ive read and are some of the best written so far:First,go to a websight like http://evolution.berkeley.edu/ It's going to take some work but will be rewarding if you stick with it.If you want to have a little more fun,check out http://www.talkorigins.org/ or http://www.pandasthumb.org/ If you want to look into more questions answers and debate check here http://www.iidb.org/vbb/forumdisplay.php... A good book to start off with is The Selfish Gene :http://www.amazon.com/Selfish-Gene-Anniv... Also you can read ,in no particular order.The Making Of the Fittest,Climbing Mount Improbable,Genome An Autobiography Of A Species in 23 chapters,The Blind Watchmaker,The Ancestors Tale,The Mating Mind,The Red Queen http://www.amazon.com/Ancestors-Tale-Pil... A few more i thought of Deep Time : Paleobiology's Perspective ,Genetics in the Wild , Frogs, Flies, and Dandelions: Speciation--The Evolution of New Species

Answer 7

One more thought about the "statistically speaking" part. It is not as if someone made a prediction at the dawn of time that animals would evolve eyes. An analogy I have heard used is a golf ball landing on a blade of grass in a golf course. One blade of grass out of a million. If I had predicted which blade of grass it would land on, the statistics would be: one chance in a million. Very improbable. But just looking at it after the fact, it is not surprising that the golf ball landed on the blade of grass. The fact that it was one chance in a million is irrelevant.

Answer 8

You are right, it would require trillions of combinations of animals not able to survive, allow all the genetic make-ups present by chance, which all of them are conveniently adapted to their environment and able to survive, right? The thing is, those trillions of combinations which are not able to survive, are dead. see? its called natural selection. If a tiger has a retard offspring, it dies and the population stays healthy. If a tiger has a genius offspring, it will be more able to survive, and reproduce, so eventually its "genius gene" woud override the "normal" gene, and all tigers would be geniuses, aka they EVOLVED. That's a crude example, of course, mutations are more subtle than "being a genius"