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Originally posted by tauristercus
Oh, my apologies as I misunderstood that reference of 3 billion letters thinking that these might have been 3 billion "individual" letters ... actually they meant 3 billion instances of just those 4 A, G, C and T letters.
The symmetry gradient only tells each growth system to alter is construction to be left or right handed.
I understand that if you visualise the human body as being trillions of many differnet cells organised in the correct position then it seems impossible.
Everything being in the right place is because each separate system branches or differenciates. For example the main arteries will grow first and part of these arteries will turn into the heart. These will then branch into the rest of the vascular system. Many other systems also start as a simple tube, such as the brain and the rest of the nervous system.
Did you look up any Genetic Algorithm stuff?
Originally posted by tauristercus
I agree that there must be certain chemical control processes that instruct a cell how many times to divide ... but surely without some form of input instructing the cell as to which direction the resulting divisions should go, you'd end up with nothing more than a mass or blob of cells with the original cell stuck in the centre of the mass.
Take the femoral artery as an example:
it's approximately 4 cm in length and divides into superficial femoral & profunda femoris arteries.
What instructs the femoral artery at each branch point which direction to take with further cell divisions so that it successfully locates and joins with it's intended destination ?
This femoral artery branching (and destination joining) occurs identically in billions of humans ... and in each instance, the branch arteries always end up in the right spot.
That has to involve some kind of template and/or distance-angle information decision.
PS I've just noticed we are nearly at the end of page 2 and there has been no bashing, arguing or mentions of the Lord. Excellent!
Originally posted by LightFantastic
...Good post by the way! Did you look up any Genetic Algorithm stuff? It is a good starting point to see how complexity can arise from very simple rules.
Originally posted by tauristercus
So where is the information stored that determines the "physical" 3 dimensional shape (internal and external) of the organism ? Presumably also somewhere within the DNA
Otherwise if cells were allowed to simply divide and position themselves randomly, the foetus would most likely end up with a blob or some other weird shape for an arm.
Again, where does all the required physical length, distance, quantity, time information come from ? how is it stored and retrieved ? how does the bone or blood vessel know that its grown long enough in a certain direction and distance ? how does the vessel or bone know that it needs to continue growing but in a different direction and distance ?