for instance a crab covering up its tracks on the beach so birds wont see, a complex type of instinct. Im sure there are more out there. How are these actions evolved, compressed into the DNA, and expressed by the crab
How DNA encodes information (ie. the amino acid blueprint for making proteins) and how that information is expressed (ie. how the cell uses that blueprint to make proteins) is known to a high degree of precision. See http://www.dnaftb.org/ for a tutorial. How this process translates into complex behaviours is, for the most part, a complete mystery.
Generally instincts are simply urges to do something. It is this urge that is coded in the genes. If it is truely an instinct and not a learned behaviour (which I highly doubt crabs have the intelligence for), the crab does not even know why it is covering up its tracks - it just feels r!ight. Instincts can be thought of as complicated reflexes. If you think of them this way you can see how easy they can be coded. For example think of the knee-jerk reflex and right down to how single-celled organisms move towards light etc.
While I agree with this, I think much of the mystery is our assumption that "we" (some conscious agent) do or make the "complex behaviors" occur. If you adopt the POV, which has a lot of experimental support, that "we" are the last to know what we will do or decide, then the mystery is not so deep. Our bodies do lots of very complex behaviors (but we tend not to call them that) of which "we" are totally unaware. For example move matter along in our intestines, regulate our temperature, breath without any awareness of doing so, control balance and mussels so we can stand, etc. I would venture to guess most of our complex behavior is "body created," without even the body informing the "we" - a conscious agent of these actions.
I suppose, but the key difference is that instinct-based behavior requires cognition and arises in the brain. Reflexes are processed in reflex centers, which I suppose could be thought of as very tiny single-purpose brains scattered about the body. The whole evolutionary advantage of a reflexive response to a stimulus is that it happens much faster than a conscious or even unconscious mental response. The signals don't have to travel all the way to the brain and then undergo the complicated processing that awaits them there. The key is whether the motion will occur when the person (or other higher animal) is unconscious (not just dreaming). If so, it's a reflex. The first three are autonomic activities (some are even muscle reflexes or glandular functions that bypass the brain), but balance is not. We have to learn to balance ourselves in an infinite variety of body positions, and this learning is conscious and accomplished in brain cells. Birds and giraffes can maintain their balance unconsciously, as they demonstrate every time they sleep, but humans cannot. If we are asleep or unconscious we lose all balancing ability, which is why we have to sleep in a more-or-less horizontal position. So our conscious brains are always involved. They just get so good at it that it's relegated to the background and we don't notice it. So far I have posed several challenges to this hypothesis. I think it remains restricted to autonomic reflex actions and the much slower glandular functions, all of which are pre-programmed and require no conscious thought in the first place.
I noted in my post that the "complex behaviors" I mentioned were not normally called "complex behaviors" and agree that they (and hundreds of others) are called by other names, but they still are "complex behaviors" even so, just as a rose is a rose by any other name. I also agree the brain plays a significant role in most of them, although some are just reflex arcs that close at the spinal cord -i.e. connect the stimulus to response produced "complex behaviors" (such as the leg jerk with knee tapped) Most of the brain’s activity has nothing to do with conscious thought yet often produces "complex behaviors." For example, by the brain’s processing of the slight temporal difference* between sudden onset sound waves arriving at the two ears your head will turn towards the sound source without any conscious thought to do so. We can call this a reflex, but it still is a "complex behavior." One can argue the boundary between “reflex” and instinctual behaviors and this example is problematic as present in new borns (but could have been learned in the womb as the mother did turn towards these sounds). None the less, these are all "complex behaviors." My point is that in many cases, if not all, brain processes determine our conscious behavior WITH NO CONSCIOUS ACTIVITY. For example, it is known that simple decisions are made by the brain up to several seconds and in all cases studied, at least a significant fraction of a second, before we are informed consciously of what has been decided in a binary choice decision. The early studies demonstrating this used electrodes contacting the exposed brain and the subject watched a faster than normal sweep second hand of a clock. And when he decided (not his brain, but his “conscious choice”) he noted where the sweep second hand was and seconds later reported the position. The doctor, monitoring the brain’s EEG signal knew what the choice would be up to a second earlier than the subject consciously did. With modern non-invasive technology the recorded signals have shown that the brain made the choice even a few seconds (in some cases) before the subject was aware of "making it." (I.e. had the illusion that he did consciously make the choice.) Thus much of our “conscious behavior” appears to be determined unconsciously by the brain and the conscious "we" is the last to know, but we have the illusion that we “decided.” Thus with these facts, there is very little difference between "complex behaviors" we have mentioned and given different names, in our ignorant belief that they were fundamentally different. The main difference between them is that “conscious behaviors” are the “complex behaviors” which the brain has made one conscious of. I will however agree that some “conscious behaviors” such a solving an algebraic equation may have essentially no “complex behaviors” of which we are not conscious; however much of routine, natural behavior that appears to be a “conscious behaviors” may just be an illusion of a separate conscious process or decision. This obviously gets deeply in to the question of the existence or not of “free will.” For many years I thought that too must be an illusion as every behavior is just the end result of discharges in the body’s neural network, especially the brain part of it. The laws of physics, especially diffusion of neuro-transmitters across synaptic clefs and the diffusion of Na ions into the nerve axons to propagate the nerve’s impulse down the axon, determine the firing of each nerve. How could there be “free will" with all this neural activity controlled by the laws of physics? I have discussed how free will might be consistent with the laws of physics in other posts but continuing here is too far off thread. SUMMARY of my view on the thread’s question: “complicated instincts” are not coded anywhere in the DNA. The DNA codes for molecular structures, like proteins. These 3D structures form complexes which further interact to perform functions and a viable body. What it does is a result of these structures and the experiences that body structure (brain included of course) has had. Crudely put: Because of their DNA specified structures, birds fly and snakes crawl, etc. ----------------- * Actually it is much more complex than this as even with only one ear one can crudely locate a sound source. - The sound waves bounce off the external ear also and how these weaker reflected signals combine depends on the locations of the sound source. You cannot even become consciously aware of the information the brain is using o locate the source. Like many other brain process, it is not something you consciously learned, like how to ride a bike, that later became automated. The brain is very pragmatic - it only tells your consciousness a very tiny fraction of what it is doing.
This is a very interesting question, one I've asked myself a number of times when reading books about animals. "How is that possible?" The sheer level of detail the DNA codes for is remarkable, from the beaver's instinct to dam, the bee's instinct to communicate high-detail location information from a dance. Babies are instinctively afraid of snakes and spiders. It does seem that genes make etch marks in our brains, which give us, and other animals pre-programmed instincts. I've read that babies have about twice as many neurons as adults and their brains are overly connected. As the babies grow and learn new things, neurons die off and cause pruned synapses. Over time, the "holes," if you will, represent things the organism learned. The holes make the connections meaningful, whereas when they were babies, it was just a jumbled mess of wires. What seems to be happening is that for some behaviors and preferences, that pruning has already been done and there is no need for experience to occur for a behavior to occur. While the baby's brain is a chaotic cluster fuck, there're still some portions that have hard-etched pathways, hard cut, pre-made and useful. From there it's easy to see how natural selection could take its hold on that pre-pruning process. Any modification to the hard-pruning that creates adaptive behavior will stick. Steven Pinker in one of his books said that learning and instincts are importantly tied in humans. Adaptive behavior for something is learned. But if that learning period can be made smaller by pre-pruning, then that will happen.
As just stated in prior post, I think that the DNA codes for molecular structures, not "instincts." Perhaps it also codes to some extent how these structures will interact, but more probably the structures themselves determine that. There are certainly a lot of examples of that – everything from taste “buds” to highly specific “lock and key” receptor cites on cell surfaces. (At least 100 different ones are well known.) For an example of experiment demonstrating this structure encoding of how to interact with other structures, consider: The right eye of a salamander was removed and replaced the discarded left eye. To any superficial level they look identical. (I forget all the details and no longer have the reference.) Its neural output connections migrated to the normal part of V1, etc. for a right eye, even though it was in the left eye location. Almost all of embryonic development shows clear "seeking" of target locations. Even quite late stages. For example Male human’s testacies descend into the scrotum a few months before birth, in most case but some after birth. Surely you do not think that complex behavior is a direct result of DNA action do you? I think my “structures and experience” POV is much more likely to be the foundation of complex behaviors than DNA which only made these structures. This pre-destine seeking of species specific structural connections or locations is at least by cells, if not by even larger aggregates, such as testacies, not by DNA encoded edits. No doubt the information controlling this seeking is INDIRECTLY recorded in the DNA, but IMHO, it far too much a leap of faith to think that the complicated behaviors is in any direct way encoded in the DNA. DNA only makes specific molecules, but the set it makes can (and do) lead to species specific structures (like hair root cells or wings at a much larger scale) Then the organism "discovers," usually un-consciously, what these structures permit it to do (fly, burrow into the sand, bore into trees, crawl up vertical walls, flert with opposite sex, etc.) - many different "complex behaviors." I.e. to take one of your examples, the beaver makes a dam because it can. Its structure permit that - make it easy - not because the DNA is instructing it to.
I think in some cases, the impact of genes is very direct, but mostly indirect. Take the case of hygienic bees. "Hygienic" bees are a kind of bee that look around for possibly contaminated eggs. The workers seek out diseased brood, cut open the comb, carry them to the outside and boot them out. Clever experiments showed that there are several genes that cause this behavior. I think they did it by breeding, but they bred hygienic bees that had only a subset of these genes. Some of these bees would seek out diseased brood, cut open the comb and then go about their day without disposing of the diseased brood. Others would march up to the diseased brood, not cut open the comb, and then make the motions they would otherwise use the oust the larvae. There was a subset of genes that appeared to have programmed for distinct, indivisible behaviors. That's not to say those were the only genes involved in producing the behavior. I believe it's likely that those are trigger genes, which "point" to other genes, whose cumulative effect is, say, uncapping the comb. The behavior may have been created in a distributed, clunky, roundabout way, but there is no doubt, at least in my mind, that they are still hard-etched in those ganglia. http://www.beeculture.com/storycms/index.cfm?cat=Story&recordID=290
I think we are in basic agreement, but tend to have slightly different emphasis. You provide some examples of how specific genes (if knocked out etc) lead to very specific behavior modification, and nearly conclude from this that the gene is coding for that behavior. (“in some cases, the impact of genes is very direct”) I focus on the known fact that genes code for molecular structures, not behaviors, however they can appear to code for a behavior if that behavior is necessitated by the absence of some gene or the behavior is impossible without the molecules the gene would normally produce. Your POV is sort of like the electrical technician empirically trying to discover the functions of the components in an old transistor radio. He temporarily removed various components (analog of your genes) to see the change in the radio’s “behavior.” Often it simply ceased to function. But one component he removed caused it to loudly whistle a high pitched note. He concluded that component’s function was “whistle suppression.” In this case, the impact of that component / gene is very direct, but that does not mean it codes for that behavior (loud whistle or uncapping honey comb). These complex behaviors are the result of complex interactions of many components in the radio (or of the molecules the genes do code for in the bee). IMHO, it is wrong to conclude the radio component (or the bee’s gene) coded for the observed behavior (loud whistle or uncapping comb behavior). My point is that we know what genes code for (molecules). There is no reason to think they code for behaviors; however the absence of only one of these molecules can lead to a specific behavior. For example the absence of the enzyme molecule (lactize ?) can lead to the behavior in humans of avoiding drinking milk, etc. but lactize molecule making gene does not code for drinking milk behavior. GENES CODE FOR MOLECULES - PERIOD.
I understand what you are saying now and I agree. Genes produce structure and those structures are what create behavior and other phenotypic traits. I do think there was some confusion brought about, which you exemplified with your comparison of the hygienic bees and the transistor radio. The confusion lies in the fact that radios are designed and hygienic bees are not. So when it's said that a part is "for" a purpose, in the context of the radio, that's literally what it means. It means the engineer of the radio intended a component for this purpose. Whereas when scientists talk about a gene "for" some purpose, it means something different. It means in the presence of that gene, the talked about phenotypic trait is more commonly expressed. Strictly speaking, I wouldn't say it's entirely wrong to say that being born without the gene which codes for lactase codes the behavior of not drinking milk. So, like you said, I think we do agree. It was just a slight semantic hangup.
To François: Thanks for the information about genes and bees. That was new to me (probably unknown when 35 years ago for two summers and the winter between I had a hive of bees.) I bought them ~1 pound plus a queen in separate small box from Montgomery Ward which the post man delivered. Mine was on some wooded land I owned that I visited less than once a week. Often to cut fallen wood for my fire place - one pickup truck level full. Sometimes I dusted with fine flour one or two of the bees doing "ventilation duty" on the landing porch of the hive when I first arrived. They were still in the same spot working hard nearly an hour later. I also used a tiny bit of flour inside the hive to follow a particular bee's activity on frame I had removed. Once in mild winter, I closed down the entrance slot ~50% with a brick place on the landing ledge. When I returned after cutting my wood, there was a cloud of confused bees in front of the hive. Fortunately, I knew that bee’s vision is very different from creatures that form images and understood why, I so removed the brick. I had already tested what I had read about bee vision once in summer - I.e. moved the hive sideways only about two feet - that too made a cloud of bees form in front of the original hive location. Bees really do not see any objects. - They learn patterns of concurrent illumination intensity angles. Also bees "see" way out into the UV and the white flowers (for humans) have many different colors for the bee - how they find and go directly to the white to humans flower that currently is giving nectar. Do you keep bees? They are very educational. I read several books on them and studied their behavior more than I got honey as once the entire hive had been knocked over by some malicious boys. Fascinating creatures. Everyone should keep a hive if they can at least thru one winter and two summers.
