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@the_great_she_elephant wrote:

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@rabbitearbandicoot wrote:

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@the_great_she_elephant wrote:

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@rabbitearbandicoot wrote:

what about a discussion on why did evolution cheat us humans out of a proper spine? {ala she ele}. I did ask but she hasn't answered so far.

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I did explain. It's because evolution, being a process, not  a creator, cannot go back to the drawing board to make "improvements" Evolutionary changes occur in miniscule steps to whatever is already there and there always has to be a compromise. For example. cheetahs developed a light and agile frame to make them more efficient at running down their prey - if their legs were a bit longer and a bit lighter they would be able to run even faster but it would increase the danger of them breaking those legs and dying of starvation. So there came a point where the optimum compromise was reached. they are also unable to brether while running flat out, and that is another evolutionary compromise.

Humans evolved from quadrupeds - the changes to their pelvic structure which enabled them to walk upright were obviously beneficial, and I imagine there may also have been a certain amount of change in the structure of the spine, but it may well be that any further changes - while they might have  have made the spine more suited to a  bipedal stance, might have been detrimental in other ways.

It is possible of course that if homosapiens is still around in another million years other changes may have occurred - though with modern medicine natural selection no longer applies. 

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so, can you explain to me, just what is bad about the human spine? and WHAT dictated that any further changes would be detrimental? ie that an optimum compromise had been reached?

 

It originated as a "suspension bridge" - ideal for quadrupeds. it is long and not very robust and the pressure put on the veribrae from walking upright is what causes them to crumble as we get older  and gives so many of us slipped discs. 

 

HOW did it originate? Where did the quadropeds get that first 'suspension bridge' ?

 

The reason we get so many back problems / slipped discs etc is because of our lifestyle. If we lived and exercised as we should, I would think that the muscular support around our backs, necks etc would be sufficient to stop all of those problems.

 

 

and ... with the cheetah - 'developed a light and agile frame ....'  so WHAT dictated to the cheetah that any further developments would have been detrimental?

Nothing 'dictated' it to them, as they evolved animals with longer legs were marginally better at catching their prey and therefore marginally more likely to survive and pass on their longer leg genes to their offspring. Once the optimum balance between speed and fragility had been reached those who whose legs went on getting marginally longer , became marginally more prone to injury and therefore marginally less likely to survive and pass on their genes.

 

also, you say "Evolutionary changes occur in miniscule steps to whatever is already there" - I can handle that. In other words organs can be slightly modified - BUT NEW ORGANS CANNOT BE ADDED, so where did the organs come from in the first place - let's take the first kidney, where did the first kidney come from - how did it evolve?

 

They evolved,in the same way that the wings of birds evolved from legs and legs evolved from fins. I am not a biologist so I can't explain the scientific details but there are books that can - Richard Dawkins would be an author to read.

 

That's just it - I could ALMOST swallow that legs evolved from fins BUT what did the fins evolve from? There had to be a point in between single cell lifeforms > multicell lifeforms > ????? > the first finned fish > the first legged animal. And please don't just say 'billions of years of selection'.

 

Because evolution or some animal decided that it would be better off with a kidneyt?

Nothing 'decides' anything in evolution, Some tiny random mutations become beneficial so those creatures which have those tiny mutations are marginally likely to do better than those who don't. Other tiny mutations are detrimental so those creatures who have them are marginally less likely to survive and pass on their genes. 

 

 

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You suggested Origin of the Species to me - I read it. ABSOLUTELY NO PROOF of anything except that his pigeons changed minutely over several generations but they didn't grow anything new or change into a new type of bird. All the rest was assumption UPON ASSUMPTION.

I am sorry, I cannot see how random mutation can produce anything NEW like new organs. Mutation is a downward spiral NOT an upward one.