The Ant and the Blade of Grass

[NotReady]

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So, I think Dawkins has always been pretty careful about this


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Why is it logical and rational to look at nature, see apparent purpose and design, and conclude non-design, and irrational to look at nature, see apparent purpose and design, and conclude design. That's the big gap of logic in people like Dawkins.

[qwnu]

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I get how a wing, or spots, or tails evolve (even bi-pedal mammals). It is a gradual yet, beneficial change that gets passed on. But I cannot see how evolution could've hard wired this freezing behavior into an insect's brain. Insects that didn't freeze were eaten. Those that did, survived, but... How did those that survived pass this trait onto their offspring? Maybe I don't understand it, because I'm under estimating an insects intelligence?

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I'm unclear on what's not to get. How could those that survived NOT pass on the trait to their offspring?

One point of confusion might be "nature vs. nurture", i.e., which part of an animal's behavior is driven by genes and instinct, and which is driven by learning and culture. I think the behavior you're describing, especially in insects, is completely driven by instinct, and therefore completely heritable and subject to natural selection. Perhaps more complicated with the deer freezing when the lion comes along, but I'd be surprised if there was any evidence to suggest that this behavior was learned through observing other deer, rather than completely instinctive.

Another possible point of confusion might be your perception that this trait is somehow black and white, i.e., all or nothing, i.e., "freeze" or "don't freeze". It's probably more helpful (and accurate) to think of it as a continuum, in conjunction with lots of other factors, that results in small differences in the tendencies of different spiders to do slightly different things when confronted with the perception of movement.

In other words, the evolution of behavioral traits like these can be just as gradual as the physical structures you are more familiar with. All that's needed is a small variation (derived from some genetic difference) that confers the slightest benefit (relative to competitors) and we're off and running.

[Lestat]

Thanks. Your explanation helps. I'm not sure I even understand what I'm asking, so it's hard for me to pose the question correctly. I think you helped with this too....

<font color="blue"> I'm unclear on what's not to get. How could those that survived NOT pass on the trait to their offspring? </font>

Passing on a Trait. That's seems to be it. A physical trait gets passed on, because offspring fair better with the change. So it's retained, right? So I can see how you inherit a physical trait. I can also see how beneficial behavioral traits can be inherited. But...

Freezing, is a behavioral trait that occurs in mid-life. Unlike beneficial mid-life physical traits (like waiting to a certain age to become reproductive), this behavioral trait is presumably "learned" in adulthood. After the fact, so to speak.

I can see how a salmon "learns" to swim upstream at the end of its life, because it completes a purpose. A purpose that generations of salmon have completed before him. Freezing, on the other hand, doesn't necessarily complete any meaningful purpose. In fact, if a spider were never put into a position to have to freeze, it wouldn't. It only freezes under certain conditions. How does it learn what those conditions are is what I want to know. Remember, we are talking about an almost zero level of intelligence. Insects are pretty much automatons from what I understand. I could understand a gazelle learning something later in life from its herd. I can't understand how this ocurrs with spiders.

I know I'm very ignorant here, so I request people have patience with me.

[luckyme]

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In fact, if a spider were never put into a position to have to freeze, it wouldn't. It only freezes under certain conditions. How does it learn what those conditions are is what I want to know.

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It doesn't. Avoiding detection is a major'trick' used to avoid danger. There is no evolutionary difference between being speckled and being still. Ancestors that didn't freeze under those conditions didn't leave many offspring, just as the ones without camoflage.

Sometimes it hard to appreciate how far back in the chain some of the behaviors or traits can trace their origins. I have no idea if it's true but it wouldn't surprise me to discover that single cells in a pond may have evolved to stop cillating when pressure waves of a certain mix are sensed.

Millions of generations passing through the selection filters can pull of some neat stuff.

luckyme

[Duke]

You can look at any sufficiently complex behavior/situation/process and befuddle yourself trying to figure it out. This is pretty much the antecedent of every religion ever.

[Lestat]

<font color="blue">There is no evolutionary difference between being speckled and being still. Ancestors that didn't freeze under those conditions didn't leave many offspring, just as the ones without camoflage. </font>

Thanks luckyme. I understand that, I just don't think I'm explaining my question properly. One of the things I'm trying to understand is what direction evolution works from. For instance:

Through a random mutation a species of beetle devolops some spots, which it passes to it's offspring. These spots make it harder for a predator to detect, so they become more likely to survive as those without spots start disappearing, because they are now more likely to be the ones eaten. If that's close, then good enough. I have some understanding of how a physical trait is born. We can replace spots with webbed feet, wings, etc. Now let's move on to "freezing".

When the first spider froze at the sight of a predator, it presumably survied because of this. Since this is NOT a random mutation, I don't get how it is first got passed down and evolves. Unlike the the physical characteristic of spots, I don't see how a behavioral characteristic such as freezing is passed down for the firs time. Freezing seems to be a "learned" behavior. I understand how a wildebeast teaches its offspring to freeze at the sight of a lion, and I can even see how this might eventually become hard wired into future generations of wildebeasts. But insects don't possess the intellect to learn from watched behavior of parents (at least I didn't think so).

So exactly how does behavior in insects evolve?

I'm STILL not asking the question the way I want, but hopefully this is close enough.

[bunny]

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When the first spider froze at the sight of a predator, it presumably survied because of this. Since this is NOT a random mutation, I don't get how it is first got passed down and evolves. Unlike the the physical characteristic of spots, I don't see how a behavioral characteristic such as freezing is passed down for the firs time. Freezing seems to be a "learned" behavior. I understand how a wildebeast teaches its offspring to freeze at the sight of a lion, and I can even see how this might eventually become hard wired into future generations of wildebeasts. But insects don't possess the intellect to learn from watched behavior of parents (at least I didn't think so).

So exactly how does behavior in insects evolve?

I'm STILL not asking the question the way I want, but hopefully this is close enough.

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I think the bolded part is your error - presumably the "freezing" is the manifestation of some hormonal (or equivalent if spiders dont have hormones) event in the spider's brain (or equivalent, again). Why should this be any less likely to occur than a random change to a beetle's coloration?

I dont see that you're justified to conclude it is a learned behaviour rather than an instinct.

EDIT: Similar to luckyme's motionless amoeba - very primitive animals could accidentally develop a whole host of instincts like that. The later generations who have a developed enough brain to learn would more be adding to their inherited instincts, rather than supplanting them. Most animals are born able to walk - we have to learn. If there can be an instinct for walking, why not for staying still when you sense movement?

[luckyme]

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When the first spider froze at the sight of a predator, it presumably survied because of this. Since this is NOT a random mutation, I don't get how it is first got passed down and evolves. Unlike the the physical characteristic of spots, I don't see how a behavioral characteristic such as freezing is passed down for the firs time. Freezing seems to be a "learned" behavior.

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thanks for clarifying.

One problem point seems to be your affinity for brain. By similar reasoning, sunflowers can't turn to the sun. 'we can understand them being yellow, but how do they KNOW to turn at the right time? After all, it occurs in midlife and the seed didn't so it must be a learned behavior.'

Even if there were a 'first spider to freeze', ( which I very much doubt, danger avoidance is ubiquitous) surely there would be something in it's system that caused it and therefore the survival improvement would be the result of a random mutation.

The learning you mention occurs at the evolutionary level not at individual spider level. It's the spiders genetic code that 'learns' but yet it doesn't 'know' it in the sense you're using it, it learns it and knows it the same way it knows to be speckled.

luckyme

[carlo]

From what I can tell, your refering to instinctual behavior and how this could come about. Of course the genetic code is brought up along with environment to a lesser extent. If these were true I'd like to know the source of this "intelligence" in nature which knows how to change the gene then change the behavior. I will not accept the "G" word as an answer but would certainly like to hear the explanation. Also I would like to not accept the "R" word for it just puts the question into another sphere.

Perhaps a consideration of the mineral realm might shed light on instinctual behavior. The basic equation of an acid-base reaction is:

Acid + Base= Salt + Water + Warmth

Example: HCl + NaOH= NaCl + HOH + Warmth

This is the basic understanding of the reaction as found in nature/laboratory. Measurements are made,etc. and the above has common agreement.

The question again is: What is it that causes the parts and pieces of the reactants to form an entirely new resultant plus the water plus the warmth? Is there a genetic code here? Is there some intrinsic part of the elements which say: do this! when such and such happens? Please no "G" word or "R" word allowed.

Thanx in advance.

[qwnu]

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Freezing, is a behavioral trait that occurs in mid-life. Unlike beneficial mid-life physical traits (like waiting to a certain age to become reproductive), this behavioral trait is presumably "learned" in adulthood. After the fact, so to speak.

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I think you're making an artificial distinction between physical traits, which you understand to be genetic, and behavioral traits, which you presume to be learned.

But you've answered your own question by stating that insects are, to the first approximation, purely dumb automatons, incapable of learning. Therefore the behavior must be driven by genetic factors.

The expression of genes as physical structures is no less complex than the expression of genes as behaviors.

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Freezing, on the other hand, doesn't necessarily complete any meaningful purpose.

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In this context, I'd say staying alive is the most meaningful purpose there is.