Evolution

[Chemeyes]

I'm get the survival of the fittest and adapting to changes in environmental conditions etc but I really can't get my head around the development of internal organs and blood vessels etc. What would have driven the development of the liver for example, at one point it wouldn't have been there and then whoosh there it is, it's like there is some kind of consciousness that necessitated the need for those functions? And sexual reproduction, what drove the need to mix up genes and establish variation and then for such a complex system of eggs and sperm and the process of combining them? It all seems too intelligent for the intelligent design corner and far too complex and logical for the evolutionists. is there any evidence showing development of these complex functions?

[Old_Geezer]

There is not whoosh it is in it's present form. There is a little something that helps, and then a future generation has an individual who has a better little something and that helps them and their offspring, and so on until something sophisticated has developed over the generations. It's not like it needs any conscious nudging to a predefined aim at all. It is simply inevitable.

It's not so much a need, it's a case of when something managed to exchange DNA there was a lot more variation in following generations. They were not all clones (more or less) so there was a lot more chance at any time some of the population would survive any particular disaster. So they flourished as a species (not as individuals) and became dominant.

Again gradual improvement generation after generation arrives at the system where one half stays with one gender (egg) and the other half is transferred from the other gender (sperm).

Complexity emerges out of simply change and activity. This process can be demonstrated on a computer where following very simple mathematical rules comes up with all sorts of fractal patterns. Same principle.

[bhg481]

Following on from OG's explanation - some of the species would evolve cells which produced bile. This helps with the digestion of fats, so these species would derive more energy from eating other animals, have a better chance of catching more food and hence have a better survival rate. These cells would eventually stay together to form the liver. So, as OG says, the liver wouldn't suddenly appear but the animals which were producing these cells would survive better and the liver would become a feature.

[Chemeyes]

Thanks both for your answers, I get the logic behind how it happened, but evolving cells to create bile? Such a complex molecule that breaks down lipids, shouldn't these materials exist freely in nature? If an animal with a liver can get more energy and have better chance of catching other animals, wouldn't there still be an array of surviving animals from the non-liver evolving camp? Doesn't everything just seem to work a bit too well? Transport of blood to the lungs before going round the body with the presence of valves to stop it going the wrong way? Development of blood cells that transport both the oxygen and carbon dioxide and replenish themselves as needed, never too much, never too little. Isn't it all a bit too exact?

[Old_Geezer]

No because the non-liver camp will be outbred by the liver camp and so will go extinct as they fail to compete.

It has to work too well as otherwise at some point something will randomly mutate beneficially and see the rest off gradually as the generations come and go.

It is to do with best fit to the environment. If your blood manages one task then you will do better than a creature who doesn't have blood. Then when one of your species mutates and develops a second function for the same fluid, it's offspring will outcompete yours.

Given enough time things just get better and better as they have to. Those that don't fall by the wayside.

There is no choice but inevitably species advance to the best fit. But the fit is a moving target as the environment changes which speeds up the change somewhat.

[bhg481]

Interesting that OG should state that the best fit is a moving target (true). "Everyone" knows that hedgehogs curl into a ball when danger is detected, with the spikes on the outside they are protected from most predators - this instinct has grown up over thousands of years. Then they invented cars and a colleague of mine claims that hedgehogs are now evolving such that it is the ones that run that survive, as curling into a ball does nothing to protect them. I have no eveince for this, only his say-so, but he does read more of the scientific magazines than I do.

[ck1]

Interesting regarding the hedgehogs, wouldn't we expect to see some hedgehogs with less spikes? I guess at one time they would have had none and then a mutation caused a spike. But doesn't that have an element of design behind it, it's like there is some knowledge that ea spike would be a good defense mechanism. I go with that kind of 'macro evolution' and get how it develops but I am becoming less convinced about the development of complex organs, nervous systems, endocrine systems etc.

[bhg481]

ck1 - It's not knowledge, it's trial and error on the part of nature and evolution. There are so many creatures and so many micro-variations each generation and the ones which work best are kept and the others eventually fail.

[woofgang]

explained here in a way that even i can understand
http://www.amazon.co.uk/Science-Discworld-III-Darwins-Watch/dp/0091951720

[Old_Geezer]

Yeah but how did the turtles evolve ?

[woofgang]

Tis all in the book OG

[wildwood]

The turtle evolved because the hare kept being run over by a car. :-)

[Peter Pedant]

I am not sure that a thread such as this can do justice to the ideas involved.

I got really interested in Zoology ( 1969 ) which I was doing to change course at uni. because of the comparative anatomy bit

Kidneys - start at a one cell animal - and it is organelles ( reverse pinocytosis ) - as you get more cells in the animals, flame cells I think and then they have to aggregate as diffusion wont do ...and then jump to pronephros, mesonephros and metanephros...

similarly with eyes/vision - is it jellyfish have a sensitiv light spot ? insect eye and mammalian eye.
Even Darwin said - once the (evolutionary) development of the mammalian eye has been worked out, it will prove evolution
Religionists say: the eye is so complex it musthave been designed by ... God !

Big shock a few years ago - a gene or protein they thought developed lately and was characteristic of mammalian eye was found in insects. When I was doing Zoo the standard view was that their development was completely separate

Evolution itself has undergone change - sorry evolutionary theory has undergone change. Punctate evolution seems to be the case - evolution doesnt creep around but has sudden bursts - which was invented by Niles ( yup that crazy guy ) and Steven Jay Gould - and they thought it was so different to Darwin that it should be given its own name (!) yeah well...

Niles and Gould are now dead and Darwin marches on.

Gould wrote the Structure of Evolutionary Theory which is now a set book at uni. ( " evo-devo" ) [ evolutionary development ] and if you wanna read a thousand pages of " me me me I'm right ! I'm right ! " then go ahead. I reapply myself to my copy every few years but neva got pass page 400

sexual reproduction - see here
http://www.britannica.com/EBchecked/topic/498588/reproductive-behaviour

[Peter Pedant]

// it's like there is some kind of consciousness that necessitated the need for those functions?//

what? the animal - without kidneys - said to itself O I will function much better if I have something called kidneys? Hey I will spend wednesday afternoon inventing them ?

No, real life isnt like that at all - that is something called anthropomorphism - making animals think like humans

Or do you mean that the consciousness is outside the animal in well, lets call him a really intelligent designer ? No I dont think that either

[Old_Geezer]

I thought Niles was quite good in Frasier. Only a little bit crazy.

[Peter Pedant]

amazing that Niles was able to combine acting with a cerebral subject like evolutionary zoology

I mean Glenda Jackson after Women in Love jsut managed a few speeches in the House of commons

[jno]

the more variation you have, the more your chances of resisting disease. Where you get species like, say, cheetah - which some people think were down to one breeding couple in the ice age - they're all very similar in terms of DNA and one epidemic couild wipe out the lot. So variety is a big evolutionary advantage.

[venator]

Do you think that developed countries are in danger of de-evolution, due to the survival of the unfittest?

[Old_Geezer]

A species can not de-evolve. No filtering process will select the least capable individuals to survive long enough to breed whilst killing off the most likely to survive, early. What may happen is the hardiness of the species as a whole may reduce, and the population start to depend on its ability to compensate via medicines, health related tech, etc.. A bit like garden plants need care whilst weeds thrive.

[Old_Geezer]

Yes, well, being in love can do that to you, Peter.

[Chemeyes]

Peter Pedant - thanks for your answer with regards to ://Kidneys - start at a one cell animal - and it is organelles ( reverse pinocytosis ) - as you get more cells in the animals, flame cells I think and then they have to aggregate as diffusion wont do ...and then jump to pronephros, mesonephros and metanephros...:// that kind of highlights my point (which I don't think I have made very well here!), what won't diffusion do exactly, and what is it that needs to be done that requires any kind of change to take place at all? I know how kidneys work etc but before they had evolved what was going on in a single cell that was not suitably efficient that it needed to combine with another. Why don't single celled organisms now join forces to create multi cellular organisms, with bacteria especially shouldn't we see some 2 cell / 3 cell / 1000 cell organisms where we can see that a load of amoeba have formed a collective to work better than they would alone?