I do truly wonder. I mean do you guys give absolutely zero consideration to the massive psychological difference in message ?
What does evolution say ?
Well, if one were to be really blunt, here's the message : First of all, the natural laws generally referred to as "conservation laws", mean that there is a finite carrying capacity of our planet. And even if we find more ... well this explains it far more eloquently than I ever could : http://www.youtube.com/watch?v=umFnrvcS6AQ . Second, evolution can only work with a high growth rate and a high rate of natural selection. Natural selection means you and your family/friends/... die.
Translation : whatever level of comfort, safety and survivability you currently have, evolution means that outside of very short exceptional periods (like the one we're in now : the oil/fossil fuel age, as it will be called when historians finally see the need for sane naming) it will go down. A large portion of humans will die without offspring, and if you allow for a few generations, most people (>90%) will not have any great grandchildren at all. The chances of you dieing without offspring, and without energy to keep you warm and without food to eat, are in reality over 30%. This is masked by currently being in an oil age, in a rich country. Evolution means that it will run out though.
The scientific view on this (which almost no-one accepts as true, especially the fact that evolution MUST stretch resources to the breaking point and the inevitable consequences of doing that) is accepted by almost nobody. I'm willing to bet you'll see plenty of evidence of that in replies to this post. But, for example, if evolution is true, global warming is unstoppable until oil/coal run out or get replaced. That's a trivial consequence of evolution, but nobody accepts it.
Oh and the correct reaction to global warming is to make it worse, as fast as possible. Any economics textbook about nash equilibria will tell you why, as will running computer simulations of actors surviving on limited resources.
Other things are that are beyond obvious make much more sense if viewed in the frame of evolution. Rationality, for example. Aside from the fact that it cannot exist (see your nearest philosophy of logic course, or read a course about the "failure of the AI project"), humans are not rational, they think along evolutionary lines. What does our mind do ? It looks for ideas, ways of doing things, what to do, how to behave. It changes the ones it finds a little bit, then executes them. If you look at the architecture of the human brain, I find it rather obvious that you do not have original thoughts. Some ideas' origins are really hard to trace, because they are a combination of what someone did in a tv show plus something you saw a squirrel do, and slightly modified, making it incredibly hard to see the connection between the "new" idea and the originals, but the same goes for genes. And yes, there are "new" ideas that you saw in a random pattern, but keeping in mind how fast human generations work, there would be no more than 1 of those per year for the entire human population, if that.
This of course means that no matter how convinced you are of the opposite, you are NOT thinking rationally.
There is plenty of proof that this is how it works. For example, kids that get raised by animals (it happens sometimes) do not walk on 2 legs (well except those raised by chimps and even then, I wouldn't call their gaits 2 legged), despite obviously still having a body that's built for walking on 2 legs.
There are fun experiments. Even the very signals we use to control our bodily functions are not actually generated by our brain. Our brain simply finds ways to process it's inputs to generate the correct signal to send, e.g. to your legs to walk. So if you give your brain an overwhelming signal that's explicitly designed to make processing it really hard then you can make the human brain sabotage it's own body because it can't reconfigure the external signal fast enough to make it useful. Result : human incapacitated (heart attack happens after ~2 minutes as was discovered by accident. Note that that figure is based on 2 accidental experiments and is probably not very accurate, but nobody's about to do more testing) [3]
And then you have the other side :
Christianity : good news ! Jesus will save you (and we will help you make the best of it in the meantime). You live in misery anyway ? That's God testing you. Invite more misery and help others and it will help you too[1].
Islam : that's may or may not be true, but you can fight and take richess (and -slaves-) from dar-al-harb (everyone else), in fact that's what those other guys' "God", henceforth called allah, wants you to do to earn your salvation. Oh you live in misery despite fighting ? Well either you're a traitor, or it's the enemy's fault.
Judaism : we have a contract with God, and as long as you follow these 613 rules to the letter, that will not happen. And don't worry, they sound insane, sure, but you can read them a million different ways. It happened anyway ? Look, you violated interpretation 5 of rule 328, you deserve it !
Buddhism : you will live in misery, true, salvation lies in accepting it and making the worst of it.
Socialism : that is true, but if we all pull together and follow the little red book/this charter/hitler/... we can make life comfortable for everyone through research, working together, building everything up, ... [2]. Didn't solve your misery problem ? Must be the bourgoisie/spies/traitors/... screwing it up ! Let's kill them.
I don't mean to be rude, but is anyone truly in doubt why atheism can never win ? Hell, I don't want it to win. If I ever am in real trouble, then I'd like to find a group of Christians in my path if you don't mind. Despite knowing more than 99.9% of hacker news about evolution and how the human mind works.
[1] I would argue that that last part is the essence of our modern states.
[2] I don't mean to make it sound so ridiculous, but it worked for large parts of the world for quite a while in the sense that it improved their situation considerably for up to half a century, so please don't think it can never work. This way of thinking got the first human to space, and collected pretty much the only information we have about the inner solar system.
Kudos! It drive me nuts how people who are supposedly devoted to rationality accept the premise that rationality will win simply because it is rational, despite the fact that you can show rationally (via Darwinian evolution!) that this premise is false.
I agree. And you know what sucks? Illogical people, office politics, and having to play them. We shouldn't have to... But a logical and analytical person understands they exist whether we like it or not and plays them (if they care about getting to a desired result quickest).
> Second, evolution can only work with a high growth rate and a high rate of natural selection.
This is false, quite false. Even a flat growth rate, a population that doesn't change in size at all, supports the mechanisms of natural selection. Examples abound in which one or more species that are pushing against the carrying capacity of their environments continue to evolve, both within and between species.
Can you give me an example of such a species ? Because I don't know any. The type of growth you're referring to would be like rabbits versus cats, and their numbers are anything but stable.
And frankly, even if you can actually do that, give a stable species, the fact is that humans follow a pattern of massive expansion followed by large die-offs, rinse and repeat.
Note the logarithmic scale. Realize what it means if, on that graph, there is a very slight but visible drop. Note that "details" like the holocaust + all worldwide WWII victims simply don't register on that graph at all (events like that have been a near constant throughout history, just read what happened during islamic expansion in Europe over 700-800 years, with constant extermination campaigns usually, but not exclusively, by the invaders. And that's something that barely registers if you compare it to the islamic massacres in India). Then realize that this is a smoothed graph, where you wouldn't even see the majority of die-offs at all.
The minimum you'd need to see it on that graph at all is a 10% die off, and that would be a flat horizontal line. Can you imagine a 10% die-off ? The minimum we'd need to detect it >200 years back, is a plague-sized event. There were lots of those, as you can see.
That's the species we are. That's how our numbers have evolved. That's the reason evolution works.
You need examples of species whose numbers aren't changing, but that are subject to the process of natural selection? Where shall I start? Well, there's one obvious starting point -- the fact that the theory of evolution models stable populations mathematically:
> ... even if you can actually do that, give a stable species, the fact is that humans follow a pattern of massive expansion followed by large die-offs, rinse and repeat.
You just answered your own question. From the standpoint of natural selection there's no difference between a species whose numbers don't change, and one whose numbers fluctuate up and down around a maximum defined by its environment.
In any case, apart from humans there are thousands of species whose numbers are limited by their environments, and natural selection continues to choose which members of that species survive, based on the changing nature of the environment. This is evolution 101.
> Still a fan ?
What are you going on about? Do you or do you not want to understand evolution? You have already accepted, and given examples of, the idea that natural selection applies to growing populations and declining populations -- all you need to do now is fill in the blank space lying between the two.
I note you failed to actually illustrate species with stable numbers. What the logistic function has to do with anything, I don't know. When reading through the reason they choose this function to model population growth it is exactly to construct a stable population growth, not because this was observed in practice.
And most certainly the human population curve looks nothing like the logistic function. It was going up much faster than the logistic function predicts. And the current slowdown of human population growth is so much faster than the ramp-up it's ridiculous to compare them. In the logistic function the slowdown mirrors the ramp-up. That's obviously not happening to humans.
I can give plenty of popular examples of wildly fluctuating population numbers. Cats versus kangaroos/wallabies versus rabbits versus birds in Australia. Buffalo's versus beavers versus cats versus ... in Yellowstone park. Those are well studied examples of major flips in population density. I also grew up in an area with lots of farms, and I know that for example the number of wolves living in nature follows this pattern. Some years it is so bad they actually attempt to eat adult humans (and sometimes succeed), sometimes there are none. We had a rabbit problem while I was at university, and the biology department investigated. There was an exchange between the number of cats (ex-housecats) and the number of rabbits. First the cats would eat nearly all the rabbits, then they'd starve to the point that few cats remained (and human interference like milk bowls does indeed make things worse), after that the rabbit population multiplied in two years by a factor of more than 1000, after which the cat numbers started growing again.
In all these cases you will observe massive swings in the population numbers. The swings were so large that just the swings themselves were at risk of making the species die off entirely (if a swing hits the number 1 or 0, the species never recovers, and has to be reintroduced. In practice that number is 9-10 according to the biology department. For rabbits or cats it never takes long for the species to be reintroduced of course). The biology department paper also claimed that while the timeframes vary wildly from species to species, these swings are the status-quo (within one habitat, the global population is more stable), not the exception.
I do know this more from an algorithmic point of view, and I learn biology only as I need it, or if I'm bored or stuck. Which is why I asked you for a few examples of these stable population numbers, as I wouldn't really know. In genetic algorithms stable population numbers don't occur.
Normally, because from time t -> t+1 you either let every current try duplicate n -> kn (higher k is better, but requires more resources), which is of course exponential growth. Then you kill all the ones that underperform (which is always basically all of them), or you select the k best performers. Or you can try to be smarter and model sexual reproduction, at which point you grow like n -> k n * (n - 1), which is even faster.
There are plenty of variations, but almost all the ones I've ever seen work have exponential growth + 90%+ die offs. Even then genetic algorithms are disappointingly slow in most cases. On the plus side, genetic algorithms will find answers no other algorithm is able to find (much better coverage of the search space). However this comes at a truly massive cost in resources (as you would expect, but it'd be nice if it didn't).
So you have an exponential growth, followed by a 99% dieoff (the number that die off has to increase the greater the population size becomes due to memory/cpu constraints).
> I note you failed to actually illustrate species with stable numbers.
In that case, you have no idea what stable numbers means -- it means a species whose long-term average remains the same. Or do you think species are like dormant bank accounts, with constant balances to the penny?
> What the logistic function has to do with anything, I don't know.
If you don't understand the evolutionary role of the Logistic Function, and since you didn't bother to read the article on that topic I linked, there's no point in this conversation.
> And most certainly the human population curve looks nothing like the logistic function.
Absolutely false. Do you really want to advertise your ignorance this way?
Here are some articles that demonstrate the relation between the human population and the logistic function:
> In that case, you have no idea what stable numbers means -- it means a species whose long-term average remains the same. Or do you think species are like dormant bank accounts, with constant balances to the penny?
Given the examples I've seen so far, I'd consider any species that stays within 50% of it's previous numbers over 2 generations stable.
But intuitively I'd have a stricter standard, something like no more than 10% per generation.
> Absolutely false. Do you really want to advertise your ignorance this way?
Essentially makes the case for malthusianism, and proposes to re-introduce population control measures (laws, forced abortions, ...). It's at least 50% a political paper. Need I go on ? I'd really rather not read it in detail. It's also hosted on a site by the social sciences department of the university of Hamburg. Even so, the paper merely intends to "fuel the debate" on this issue, not actually carry out analysis.
Allow me to copy a sentence from the paper's conclusion : "Although they [regulatory suggestions to overcome the "normal population cycle"] might seem strangely scandalous and even marginal today, the suggestions and effected regulatory measures to control population growth in the late 1960s and early 1970s merely followed a rigid and conservative accountancy logic still in effect" (I do know a bit of German, the last part is a way-to-literal translation from German.
It means to say that while population control laws were repealed, the reasons for having them have become stronger.
Now to put things bluntly, but when it comes to scientific credibility, the social sciences rank significantly below my local bookstore's "Fiction" section. I would note that the social sciences see it as their mission not to advance scientific knowledge, but rather to influence public debate and regulation. This obviously means that any social sciences related paper explicitly is NOT the facts, but an attempt to convince you, and should be read like a commercial advertisement.
A set of exercises constructed to match the logistic function by the math department ... The one example of human population it has actually contradicts your thesis : human population growth starting in 1927, and ending in 2071 (because at that point there would be no more growth) somewhat matches the logistic function. Needless to say this is a prediction. Further analysis reveals that human population growth was calculated at the UN using the logistic function, with the same parameters.
As to what this means, I'd have to say it's a very bad example of statistical fitting, nothing more. For example, they just assume they have the answer, and don't even bother to measure the error in their fitting.
Please note that this is not criticism of the authors of the paper, who undoubtedly are achieving exactly what they set out to achieve : train students to correctly evaluate a non-trivial calculus function. This is criticism of your interpretation of this paper.
Is a paper that I would say defends my side of the argument (I'd say it's a critique against the logistic model). Note the prominent line : "Why does the logistic model fail so spectacularly in this case (and many others)?", and look at the graph right above it, and the explanation below.
A quote : "Specifically, the logistic model fails to consider mechanisms of population regulation. When density increases, what is affected? Birth rates? Death rates? The r parameter in the logistic model is simply the difference in the gross birth and death rates when there are no conspecifics present."
"Given the examples I've seen so far, I'd consider any species that stays within 50% of it's previous numbers over 2 generations stable"
Most plants are vary stable as in within 5% over time as they tend to be vary resource limited, so they kill off competitors. Infact most species's say within 5% outside of environmental changes dispite boom and bust times simply because the planet is large enough that area A may go though a boom, while area B, C, and D is in bust period. EX: Deer.
You said you had no idea what the logistic equation had to do with natural selection, but you believed that human populations didn't show a correlation with the function. I provided the links only so you would have a way to find out how wrong that was, nothing else. But you're one of those posters who can't seem to stick to a single topic.
As to that topic, I can't believe that you're still unable to see that a stable population supports classic natural selection. In such a population, who survives is determined by their fitness, just when the population's size is changing. The fact that a population's size is stable or changing is irrelevant to natural selection -- it is unaffected. On that basis, population rate of change, and natural selection, are orthogonal factors.
The only way a stable population would interfere with natural selection is if there was no reproduction taking place, no births or deaths, and that is certainly not what a stable population means.
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