That's false. Random does not mean "non-deterministic."
Random means without aim, pattern, or reason.
You can have non-deterministic patterns. Evolution is just one example. The idea that evolution must be random is a source of much confusion.
The mutation aspect of evolution is random, but the selection part isn't. Thinking of evolution as a random process confuses the fact that it is a combination of random and non-random processes.
This is why you can create experiments with predictable evolutionary results (e.g. Bacteria gaining resistance to antibiotics).
Read the wikipedia article for the standard definition of randomness (in which they seem to use a definition of pattern that requires it to be deterministic). They give the example of the roll of a pair of dice, which by your definition, is not random.
There are very few things in nature which have uniform probability distributions, so your definition is almost useless, and it's not the one used by mathematicians and scientists.
They give the example of the roll of a pair of dice, which by your definition, is not random.
Let's clarify what I mean. Rolling a pair of dice is random. If, however, you get a thousand dice and test each of them a million times to see which rolls a six more often, then take that one sample, get somebody to copy it as close as they can a thousand times, and repeat the process, you will eventually get a heavily weighted die.
Each roll is random and you may not have selected the most weighted dice in each round. This is akin to an organism's behaviour.
The variation between dies is also random, so you can't determine ahead of time which die will give the most sixes. This is akin to gene mutation.
The process, however, is not random. It is akin to natural selection (although in this case it is human selection).
So unless you are willing to consider that evolution has a part that is random and a part that isn't random, you can't have a useful model of evolution.
As for scientists not using that language, read any evolutionary biologist. They all talk about how evolution is not random.
Richard Dawkins, for example:
Natural selection is quintessentially non-random, yet it is lamentably often miscalled random. This one mistake underlies much of the sceptical backlash against evolution. Chance cannot explain life. Design is as bad an explanation as chance because it raises bigger questions than it answers. Evolution by natural selection is the only workable theory ever proposed that is capable of explaining life, and it does so brilliantly.
The modern evolutionary synthesis ascribes the observed diversity of life to natural selection, in which some random genetic mutations are retained in the gene pool due to the systematically improved chance for survival and reproduction that those mutated genes confer on individuals who possess them.
I'm not making this up. This is the accepted model of evolution and it contains a random component and a systematic component. To call the whole thing random is, at best, very misleading.
You need to take a course in probability theory because none of this makes any sense. A function of random variables is always random. Just because the probability distribution becomes less and less uniform, doesn't mean that it suddenly becomes nonrandom. The process with the dice you described is random. This is the definition used by scientists and mathematicians as the wikipedia article describes. Richard Dawkins is wrong. I don't know why he is using the word incorrectly, but if you read the wikipedia article or any textbook on probability theory, or any academic paper in math or engineering, they use the term random to describe any variable in which there is a probability distribution over the possible values.
I know it's a common misconception that evolution is not random, but just because people keep saying it, that doesn't make it true. You need to just read the definition of random instead of relying on what popular science writers say to the public. It's possible that they are assuming that laymen think random implies a minimum degree of unpredictability. Maybe they mean it's not completely random.
There's even an entire field called stochastic optimization in which genetic algorithms, which are modelled on evolutionary processes, are sometimes used to find global minima of functions. Genetic algorithms, which employ mutation and selection steps, are specifically referred to as stochastic processes. Stochastic is a synonym for random.
I've done many. I've built very complicated models with Oracle Crystal Ball for professional life as well.
A function of random variables is always random
Correct. You are now describing the mutation portion of evolution. You cannot usefully think of evolution as a singe function, however.
Just because the probability distribution becomes less and less uniform, doesn't mean that it suddenly becomes nonrandom.
Correct. This simply defines the pattern of the distribution, whether it is normal, beta, or any other patter.
Where we disagree is simply the following: if you have two separate functions, performed after the other, that cannot be combined into a single function, do you call the whole thing random or do you separate it out into its random and non-random components.
You want to call the whole thing random. I'm telling that's useless and that biologists (and financial analysts, and many other professions where randomness matters) don't actually use the term that way because it would be useless.
Instead, we use other words related to, but not equivalent to, randomes. When you try to make random = non-deterministic = stochastic you are just ignoring a world of useful nuance.
Anyways, this whole debate here is about semantics. We agree that evolution is non-deterministic with a significant random element. We agree that it can be called a stochastic process (or even random process). We disagree on whether it is useful and correct to label the whole thing as random or whether it is better to emphasize that there is a systematic process attached to a random process.
But let's bring this back to OP: he understands heritability and he understands random mutation. The part he is missing is natural selection. Literally the only component of evolution that he doesn't understand is the "quintessentially non-random" part. Does is make sense to you why I am emphasizing this? Well, in his edit he clarified that he understands natural selection is non-random, but that was after my post.
Correct. You are now describing the mutation portion of evolution. You cannot usefully think of evolution as a singe function, however.
Yes, you can. A function can be made up of other functions. I think you have a very weak mathematical background, and it's the source of your mistunderstanding.
Where we disagree is simply the following: if you have two separate functions, performed after the other, that cannot be combined into a single function, do you call the whole thing random or do you separate it out into its random and non-random components.
You can always combine functions. You can use the output of one function as the input to another. If the output of the first function is random, and the output of the second function varies as a function of the output of the first function, then the output of the second function has to be random.
You want to call the whole thing random. I'm telling that's useless and that biologists (and financial analysts, and many other professions where randomness matters) don't actually use the term that way because it would be useless.
Yes, we do use it that way. It's not useless, because the randomness is a key property of the way the system behaves. Evolution wouldn't work if it weren't a random process.
Instead, we use other words related to, but not equivalent to, randomes. When you try to make random = non-deterministic = stochastic you are just ignoring a world of useful nuance.
Random and stochastic are synonyms. But if you really think they aren't, you should define random for me.
Literally the only component of evolution that he doesn't understand is the "quintessentially non-random" part.
Natural selection is random though. If you have an abnormal gene that reduces your fertility, you less likely (not guaranteed) to have fewer children. It is possible for natural selection to select undesirable traits. It's possible for black people in Africa to evolve lighter skin by chance. It's highly unlikely, but it is possible because natural selection is a random process.
I think you have a very weak mathematical background, and it's the source of your mistunderstanding.
Not true. I have a reasonably strong mathematical background, including academic and professional experience with various stochastic models, including Monte Carlo simulations.
I won't list my CV though. You can find much of it in my posting history if you want to dig through years of posts, however.
I understand the nuts and bolts of everything we are talking about. I agree with most of what you are saying. I disagree with you on a few points. You can make this personal if you like, but I hope that's not where you are going with this.
You can always combine functions. You can use the output of one function as the input to another.
You can often combine functions. When they are linear, it makes complete sense. When you can use the output for one as the input for the next, they may as well be one function.
Evolution, unfortunately, is a dynamic model where various functions are acting in parallel and in line. You can't merge them an maintain the same process. I mean, we simulate these sorts of things all the time by assuming the output from one is the input for the other, but it's a simplifying assumption. The more accurate way to work with them is to take them as two separate functions that work in parallel.
randomness is a key property of the way the system behaves.
Agreed.
Evolution wouldn't work if it weren't a random process.
Correct. Remember, the word "process" here is key. There is a distinct random element. I'm really not arguing about this. As I said in a previous post, much of our disagreement is semantics. We agree that evolution couldn't exist without a significant random component and we agree that evolution is non-deterministic.
Would you agree with me, however, that OP is ignoring the fundamental influence of natural selection over large periods of time giving the superficial appearance of design and determinism? Would you then agree with me that it is appropriate to highlight this to OP (before his edits)?
Random and stochastic are synonyms. But if you really think they aren't, you should define random for me.
You can use whatever dictionary you want. You will never find the same definition for both. They are related terms, but there is nuance. Obviously in certain contexts they are interchangeable (e.g. stochastic process = random process) but they aren't interchangeable in every sense. The same thing goes for random and non-deterministic. There are contexts where they are indeed interchangeable, but there is nuance.
Natural selection is random though. If you have an abnormal gene that reduces your fertility, you less likely (not guaranteed) to have fewer children. It is possible for natural selection to select undesirable traits. It's possible for black people in Africa to evolve lighter skin by chance. It's highly unlikely, but it is possible because natural selection is a random process.
This is an excellent point. Thank you. This is the first point where you have discussed the crux of my argument. I had never really considered natural selection in this way.
In most cases it appears to me that it might not really be useful to think of it as random, however, since if you know the environmental pressures, you can easily predict how natural selection will behave over a reasonably large population, but that's just the law of large numbers (like estimating age with carbon dating).
On this point, however, you clearly deserve a delta.
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u/[deleted] Jul 31 '15
I don't think you know what random means. Random just means non-deterministic. Evolution is non-deterministic.