Instinct and evolution?

Great Debates
1

How does evolution account for instincts? I read an explanation (rather weak, I thought) called the “Baldwin effect,” which essentially means first a creature learns a behavior, then the mutation to automatically know this behavior arises (what luck!), and naturally the ones that don’t have to spend time learning it are the fittest and survive.

I could stretch my imagination on that one for some creatures, like hunting behavior in dogs for instance, but it does nothing to explain intelligent behavior in totally unintelligent creatures. (I exclude humans from this because our behavior is too complex to easily say what we do by instinct and what by learning.) For instance, leaf cutter ants cut leaf pieces, bring them back to the nest, use them to grow mold, and feed on the mold. They’re practicing AGRICULTURE for crying out loud, and likely long before mankind did. For another example, in my college linguistics class, we discussed a type of honeybee that figures the location of honey using the geometry of the sun’s position and communicates it to other bees in an elaborate dance.

Obviously these insects could never learn such behavior, and obviously the behavior could not arise in steps or even in just one insect because it would be useless unless it was a complete system. Any ideas? I’m assuming that insticts must be encoded in genes anyway.

2

First off, I’m not sure that A follows from B. There could be other reasons that pieces of a behavior existed in the past other than as the means to a complete behavior we see now. Pieces of a behavior which may offer a particular advantage may be “repurposed” later to provide a new behavior (in combination with other pieces) that then provides an even stronger advantage. All by chance. Why not?

For example, leaf cutter ants may have cut leaves for some reason that in an of itself offered an advantage. Other leaf cutters may have brought things back to the nest. Still others could have scavenged for mold. Each of these might independently been behaviors that offered an advantage. None of them is farming. Obviously once combined, the effect is huge.

Second, I disagree with B. A behavior may exist that does not offer an advantage, but it is a mutation that propagates merely because it is dominant or colocated with a mutation that causes a behavior that does offer an advantage (or heck, maybe just by chance. Evolution does not say that neutral behaviors are selected out, does it?). Over time that behavior may vary, becoming more elaborate as it gets added to. At some point it can become an advantage. As long as the starting behavior is “lucky” enough not to be selected out for some reason, you can get from simple to complex.

Maybe leaf cutter ants originally cut leaves for no reason, random behavior. Who knows?

3

Behavior that works, persists. Bahavior that doesn’t work, does not persist. Successful creatures produce more offspring. Successful offspring become successful populations with programmed instincts that serve them well. Several minute/subtle behaviors add up to a more complex instinct system. Humans, sitting here at the end of 4 billion years of natural selection, are amazed to see how complex instinct is, but often fail to realize all the countless steps that were required to reach this complexity.

4

You are assuming that the complex instinct appeared all at once. This is not the case. It developed. The eye is often cited as an example of something that is irreducably complex (i.e., useless if missing one piece). But a complete complex eye did not evolve in one step. It started from something like simple photosensitive cells.

5

and the thing to remember about eyes is that our own are not perfect eyes. hell, they’re better than anything we can design right now, but they are not the ultimate incarnation of the Platonic Concept of Eyeness. A frog’s eye is a lot less complex; even moreso for the planarian’s eye. so (anthropocentrically speaking) a frog’s eye is better than a planarian’s eyespot, and a human’s eye is better than a frogs. but the frog’s eye is more useful to him than no eye, or an eyespot from a planarian.

given time, complexity will emerge, and environment will select among everything for the most fitting.

6

I wish to pick a nit:

Complexity will only emerge if there is an evolutionary pressure that favors the advantage it gives more than the maintenance costs it adds.

In fact there are numerous examples (in the current understanding of the evolutionary tree) of complex organisms which became simpler over time as a result of survival pressures.

If you look at the overall picture (all organisms over the course of history - at least those we can examine in fossil records etc.) it becomes clear that evolution in the direction of increased complexity is the exception and not the rule. Homo sapiens sapiens just doesn’t like to think of itself as an exception.

Ahhhh. I feel better now.

7

ren - I agree (except that I think H. sapiens DOES like to consider itself an exception). I just meant to point out that it takes time for complexity to occur and that the “irreducably complex” argument is lacking. As you pointed out, evolution certainly does not necessitate “improvement”, rather, only “change”.

8

I’m not looking anything up because I don’t feel like it.

But, out of about a gazillion species of social insects how many are the architypical “leaf-cutter ants”? One? Six?

Anyway, how many related ant species exhibit partial “leaf-cutter” behaviour? If there is some type of Designer who gave the “leaf-cutters” that behavioural complex why would he not give other ants this very useful group of instincts?

It is very difficult to make a statement about general processes based upon an extreme situation.

9

That really should have a :stuck_out_tongue: after it…

I agree with the last statement, irrespective of the first.

But.

  1. That first one really confused me. Why would our hypothetical Designer not feel inclined to give every ant the same set of behaviors? Maybe He just wanted variety! What’s that got to do with sentence #2?

  2. Also, why is the example of leaf-cutter behavior inappropriate? I thought it was a good example of a complex behavior that might produce and incredulous response at first sight. There are many of these (maybe not all in ants, though). The point of the OP was, how can we account for such exotic behavior with such a (seemingly) simple theory? If you used an example of a simple or common behavior, that wouldn’t really illustrate the question, now would it?

10

Okay, let’s try the other example I gave. Bee does neat dance based on the angle of the sun and communicates the position of honey to the other watching bees, who go and get it. How could such a complex system of reckoning and communication arise among creatures with basically zero intelligence? Don’t give me general statements; propose some steps.

11

Is this a contest to see how creative we can be, or do you have a point? We could spend a week positing various scenarios for bees and then you could say, OK, but how about this other behavior in antelope? Or this strange fish that does this?

Your OP said:

I think we’ve demonstrated how evolutionary processes can account for complex behavior.

If, on the other hand, you want the uneasiness you feel when you witness complex behavior to be rationalized away, I’m not sure anyone can achieve that.

Heck, every time I go to an aquarium and see the mind-blowing variety and detail in the colors of fish I think, there must be a God with a plan, because there’s just NO WAY this can be random. That’s a visceral emotional reaction that no amount of discussion will ever reduce. But it doesn’t mean that the mechanism described in the theory doesn’t work.

12

I guess the point I’m trying to make by asking for steps is this: if there seems to be no CONCIEVABLE way for something to happen, much less a plausible one with evidence, then in what way can we say it is accounted for by a scientific theory? It won’t do just to say “well evolution explains life, and this is part of life, so there you go, it must be true.” That’s the equivilent of “well God created it all, and this is part of creation, so there you go.”

So you may not be able to prove exactly how the bees got their dance. That’s okay. But if it seems impossible that it could ever happen, it’s not logical to assume you know the process that made it happen.

I can’t conceive of any way that the bees could start telling each other something they can’t understand in a method they’re too simple to formulate and have everything go smoothly. I’m asking if anyone else can.

13

Hmmm. Well, OK, I’d be willin’ to give this a go (less’n someone else beats me to it). I don’t really know what it will prove other than whether I have an imagination, though.

It occurs to me that I do not know in detail how the whole bee-dance thing works. Kinda hard to extrapolate without the details.

Care to fill me in?

14

I’m taking the bait…

(We could almost make a game of it…each person must create one evolutionary step…anyone who can’t do it on their turn must empty their glass…whatever…)

So, first off, the bee comes back home from the pollen. The BEE COMES BACK with the pollen. Like most creatures coming back, it’s ass now points toward where it has been. Any bee about to leave in search of pollen that travels in the direction a pollen covered bee’s ass is pointing is way ahead of the game. So that is the first step evolved.

Next step is that the bee returning with the pollen stops upon entering the hive. This gives more time for other bees to notice him (her?) and see which way his ass is pointing. Or maybe he doesn’t stop. Maybe he walks slowly. Maybe he goes back and forth. Maybe he…

Ah, who cares. I did the first step, Tripoverbiff has to do the next step, or he chugs his glass, first person to puke loses the game.

Second game will be leaf cutter ants. Alot of ants go out and collect food and bring it back. Alot of ants cut up big food into little food. Leaf-cutter ant ancestors (pre-agriculture) bring back too much food (leaves). Way too much food. Constantly. Bad programming, evolutionary mistep, ant energy wasted bringing in excess food. Bad evolution, bad,bad. Food lays around. Food molds. Mold is better food for ants than leaves were to begin with. Good evolution, good, good.

Anybody need a refill before we go on?

15

I don’t have the time to look up the references, but I’ve heard scientists proposing that simple organisms group together to create complex organisms - the parallel is given between brain cells, which in themselves would not be able to achieve anything, but combined create neural networks that ultimately lead to consciousness, and something like a nest of ants, where the individuals have very little consciousness, but get organised into a ‘larger organism’ (ie the ant ‘community’) that gets the job done. I think the bee example was actually given in the thing I heard. If someone has the time to look this up and post maybe a link, if it’s on the net, I’d be interested in looking it up.

The interesting thing, of course, is that if this was true, it can be used to support both evolution and creation, or any combination thereof.

Iguana.

ps - I may even have read this on Straight Dope somewhere - at least that should mean it won’t take long to track down.

16

But evolutionary biologists, DO study the subject scientifically. Theories ARE based on evidence (i.e., theories are not assumptions). Science is not a bunch of hand-waving like you may see in a message board. Peer review ensures that a particular person’s bias does not cloud theories.

17

A couple preliminary notes:

[ul]
[li]Note the first:[/li][/ul]

I get a strong feeling that as I move forward with this you’re going to object to the fictions I come up with to explain the dance. Of course what I say will be fiction because we don’t yet know for sure how the dance evolved (and may never know for sure for that matter). So before I begin I feel the need to revisit this point:

Pardon my bluntness, but what you seem to be implying here is that just because you may not have the imagination to come up with a story that explains how, using evolutionary principles, such behavior can evolve, that means it is not logical to assume that someone else can, or that the process they have defined is adequate.

Since when does the failure of your imagination constitute a flaw in scientific theory?

OK, that’s bound to push some buttons, so: The reason I’m going forward anyway is that I’m hoping what you really mean to say is that you want some education on how the evolutionary model works in practice, because you have a hard time going from theory to application. That seems reasonable to me.

The point of this long-winded rant is: If your goal is to understand how the model works, then it shouldn’t bother you that I’m making stuff up about the reasons bee behavior evolved, you’re only looking to have the model illustrated. On the other hand, if you start to object on the grounds that what I’m saying is made up, well, re-read this rant.

[ul]
[li]Note the second:[/li][/ul]

  1. Here is a description of the bee dance. To save some time I will also quote the relevant section below:

OK, so we’ve sighted our target behavior. I’ll be extrapolating using various other facts of biology and be behavior as necessary as well…

18

This topic definitely falls within the realm of Evolutionary Psychology.

19

These are some basic assumptions I’m starting with. I’m numbering these for reference later.

I’m trying not to go into too much detail about how the behavior evolved because that would make this explanation much longer, and I’m already going on at great length. If you think I’m making too many assumptions here, I suggest you take a few biology courses and maybe read up on bees.

A. Bees can locate food source and remember where food source is.

Obviously a crucial prerequisite to telling others. I posit that the behavior that allows bees to remember where a food source is located probably was present in the organism at whatever point in evolution it became what we now call a bee. It would have evolved from simple reflex behaviors like chemotaxis (attraction/repulsion to chemical signals) and phototaxis (ditto for light), and basic memory processes. The taxis behaviors exist even in simple organisms like planaria. As for memory, we see simple imprinting in other insects (like ants) and the like.

A bee needs to remember locations just to get back to the hive. Hive location can’t be hard-wired because bee populations move frequently. It therefore must be learned and remembered. Remembering where the food source is, is a variation of same. Putting two and two together, we conclude that

[list=1]
[li]a bee’s memory of where food is located is expressed internally as a memory of light source and chemical trace locations in three-dimensional space. This memory can be both stored and referenced. In other words the bee can access a memory of light and chemical locations and then knows how to fly around to try and follow same, bingo we’ve relocated the food.[/li][/list=1]

B. Bees can communicate via feelers, etc.

This probably started off as something like chemotaxis as well. I.E., when a primitive organism carrying a chemical marker touches another organism, the second one picks up the marker. From being able to figure out via touch that you are in contact with an organism like yourself (friend-or-foe recognition within species is so common as to be almost universal, I’d imagine), it’s a short hop to exchanging signals with a friend. Perhaps at first this would be involuntary, i.e., chemical traces exuded as a fear response. This may cause fear in others that pick up the trace, because:

[list=1]
[li]It works both ways (that is, chemical is exuded when organism is threatened, plus contact with chemical induces threatened reaction in organism). This is commonly observed in nature in a variety of circumstances and an important principle which I will leverage later. Note how it exists commonly as a primitive mechanism. Note that it is already leveraged in the remembering-where-food-is-and-getting-back-to-it behavior.[/li]
[li]I’m therefore assuming for purposes of this discussion that bee communication has already evolved to include the use of types of buzzing or movement as signals. Like the chemical fear response, bee buzzing constitutes an external expression of the internal state of the bee. This may be instinctive and not voluntary, but in any case, another bee in contact with that buzzing or movement would be able to sense the state of that bee.[/li][/list=1]

OK now let’s put a story together…

20

Let’s start by guessing how a bee dance, in and of itself, might evolve.

Say you’re an epileptic (stay with me here). You go to see the weird movie I saw in the experimental short films reel of the Seattle Film Festival which really made my eyes hurt (oops, sorry, different thread) and because of the visual input you are receiving you are thrown into a grand mal seizure (man they should have warned us before we got in there) (no I’m not epileptic and thank god no one else was).

So what’s happening here is that a stimulus to one of your senses is causing your body to spazz out, even after the stimulus is removed. This has to do with nerve “wires” being crossed in such a way as to cause stimulus to unintended parts of the brain. Through a mutation (or damage of some kind) maybe. (Please let’s not start arguing over epilepsy, I may be mischaracterizing it I know, I’m just using it as a lame example).

Now let’s say a bee happens to be the victim of a random mutation that causes it to twitch or buzz in a certain way (it’s not a dance yet) when certain receptors fire. Those receptors happen to be associated with the process of remembering and recalling locations of food sources.

So. Bee gets back to the hive, starts actin’ funny.

First question: Why is this behavior not selected out? Well, let’s say you have a mild form of epilepsy that makes your pinky twitch once in a while. Is there any evolutionary pressure on you that selects that out? No.

Second question: why is this behavior passed on? If it happened to be a hereditary condition you might pass it on to your children. If it happens to colocated on a gene which expresses a dominant biological characteristic (am I using them words right?) you might pass it on quite easily.

Third question: OH, come ON! You’re trying to tell me that this bee just HAPPENS to get this extremely specific behavior, and it just HAPPENS to be non-detrimental, so it isn’t necessarily selected out right away, and it just HAPPENS to be colocated where it will propagate with relative ease?? Isn’t that a lot to swallow? Answer: Yes, but no. People will say, OH, come ON! Life just HAPPENED to form randomly out of the primordial ooze billions of years ago! Uhhhh. Yup. That’s the theory. If you’re not gonna buy that random things like this can happen, I am wastin’ my time. Note: This stuff probably evolved over millions and millions of years. How many generations of bees (or proto-bees) do you think that is? There’s plenty of chance in my mind that something like this can happen. And it only has to work once in order to work at all.

So. Couple generations later, some bees go back to the hive, act a little funny.

Now we have the possibility of bees that react with external behavior that expresses some detail of the location of the food. Again, it may not be much, it may not even be enough that another bee could figure out anything useful. But we’ve arrived at a point where there is a link between the bee’s behavior in the hive and the food’s location.

Again, the disclaimer: I am MAKING THIS STUFF UP to illustrate a point. If we happend to have any better ideas what really did happen, please share, but don’t go off on me, man…