Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: lyner on 14/09/2008 22:16:02
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Many years ago I found the Mandlebrot set of fractals and spent many happy hours looking at the intricate, 'beautiful' and detailed patterns produced by a very simple computer program.
I recently rediscovered them and spent some more time 'wandering around' inside the pattern.
Some people claim that nothing as complicated or as beautiful as a butterfly's wing or the eye of a fly could have arisen from a simple / random process like evolution. It would haver to have come from some 'intelligence' or purpose.
I suggest they look inside the Mandlebrot patterns
http://www.users.globalnet.co.uk/~dsalt/chaos.htm (http://www.users.globalnet.co.uk/~dsalt/chaos.htm)
and reflect that all that fascinating and beautiful stuff originates from a simple quadratic formula. Monkeys and typewriters could easily produce something as simple as that.
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Excellent example Sophie!
Though I would add that evolution by natural selection is non-random, which makes it easier for any thinking person to accept in my opinion.
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Excellent example Sophie!
Though I would add that evolution by natural selection is non-random, which makes it easier for any thinking person to accept in my opinion.
Could you elaborate on the non-randomness please?
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You have the random variation produced by mutation and recombination, which is then selected upon by whatever criteria the environment imposes on the survival and reproduction of those variations. Selection pressures include predation, competition for resources, climate, disease, the physical structures of the environment (trees, rock, land, water, air), that organisms can become adapted to thriving against. Just as a farmer selects the best of their stock, so too does nature.
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Non-random is a bit too 'strong' a term; there are many random events affecting survival. But the general trend is always explicable in terms of statistics which, impose more or less deterministic behaviour / development in a polulation.
My point was mainly that our perception of the state of things at the moment and our assessment of how they 'must have' arisen can be overly influenced by culture. Any attempt at reverse engineering a complex outcome tends to assume a complex cause. This is often very wrong where fractals are concerned.
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I agree, Sophie, but the point I was trying to make was that natural selection is not random; when it acts on variation in a population, you can predict the result: the genes that build organisms that are able to survive and reproduce successfully against the selective pressure, make it into future generations. The components may be random, but the process is non-random.
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I challenge your actual wording there. The outcome (trend), being the result of a lot of random processes has to be looked upon as random in the end- it's just that the spread of outcomes is relatively small but still random.
There will be occasions when there are, say, two, mutually exclusive, characteristics which arrive at the same time and they happen to be pretty evenly matched. The one which actually survives may well be selected on a very random basis and, once the species has committed itself in that direction, the other just has no chance. An example could be where there is a possible advantage in going aquatic or not. That could be clinched as the result of a 'random' rise or fall in water level.
And, of course, the actual selection of genes during sexual reproduction (during meisosis) really is random.
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I think we can agree on that.
I would like to know to what extent something is considered random, though. Climate change in my thinking is not really random, since it is the result of a range of processes and events that can be observed and whose effects can be predicted. So to take your example, a rise in sea level is "random" only if you imagine that the sea level appeared out of nowhere, with no climatic "history". Can we clarify this?
Further, where is the randomness in the act of a farmer selecting the best animals in his flock to breed?
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There is 'intention' in farming and a certain amount of predictability about natural events. But I read what you are saying as if you believe in determinism and I doubt that you can.
We all 'know' that nothing is certain in the end and that we can only predict outcomes within some spread. That's where I say that randomness has to come into it.
Where evolution is concerned there are a lot of random processes but the only outcomes which 'were obviously predictable' are the ones which we can see and which we can rationalise post hoc.
Certainly you can't predict what genes you're going to get from a parent. That's a real random element in the equation.
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Thanks for clarifying, Sophie :)
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Good - we are in accord, I think.
But, about the fractal thing; the perceived beauty of an orchid or the complexity of a peacock's tail patter, could , and is, often taken as proof that someone is designing things - whereas there are plenty of intricate patterns which arise from very simple rule-based processes.
It's just not an attractive explanation for someone who wants there to be a 'creator'.
There's a sort of null argument against creation and that is that a 'proper' designer could never be as kack handed as to invent a system like our body, which 'only just' keeps going and is full of systems which are only there to correct the effects of other systems. It's a bit like our social system, in fact; a real bodge which only works because it has to.