How much are we genetically pre-programmed

[Adrian07]

I am a complete layman in this but have been wondering about what makes us us.
While I think I am right in saying the brain works on electrical and chemical impulses there also appears to be what I would call rom and ram (from computing) or instinct and learned behaviour, how much is genetic pre-programming. I ask this from observations about birds which seem at least to me about halfway between higher and lower animals.
The thing with birds is that you can tell the species, generally, just from looking at the nest. Nestbuilding as far as I can see is not taught yet is extremely complicated in some species. Birds of the same species will build the same nests using the same materials, you cannot tell the difference between a novice and one that has built previously, a ground nesting bird will build on the ground etc. This to me suggests that how to build, what materials to use and where to build are all genetically pre-programmed, whereas finding food is taught, I have seen this.
The higher up the scale you go the less seems to be pre-programmed and the more taught. I wonder though how much of our makeup is genetic and how much learnt. Children brought up much the same can be completely different to the extent that upbringing cannot explain, there are characteristics that seem to be inherited.

 

[Simon Bridge]

This is the "nature vs nurture" debate - the best answer is "nobody knows".

 

[Ygggdrasil]

In many animals, basic instincts and behaviors are encoded in the organism's DNA. The DNA provides instructions for the body to build specific genetic circuits to perform certain behaviors in response to certain stimuli. For example, flies have an escape response triggered by certain stimuli, such as a shadow passing over them. Researchers have identified a specific nerve cell in the fly that controls this response and this nerve cell is the same in all flies of the same species. Artificial stimulation of this nerve cell triggers the escape response.

In humans and other higher mammals, the situation is very different. Whereas most animals are born with innate behaviors and instincts, humans are born with very few innate behaviors and instincts. For example, many animals (insects, fish, reptiles, amphibians, etc.) are fully capable of walking, feeding themselves and even surviving independently after birth. In contrast, human babies can do practically nothing after birth. The difference is that the DNA of humans does not specify a wiring diagram for the brain. Rather this wiring diagram is formed on the fly on the basis of the experiences of the individual. For example, if you were to take a newly born baby and cover its eyes for its entire early childhood, the child's neural circuitry for interpreting visual stimuli would not develop and the child would be blind despite the fact that the child's eyes work perfectly well. Another consequence of this strategy is that everyone will develop different neural circuits to perform the same functions. For example, whereas the same nerve cell will trigger the same escape response in all flies, activating a specific nerve in humans would likely trigger very different responses in different individuals.

While this wiring-on-the-fly strategy has many disadvantages in the younger phases of life (babies and children are very much dependent on others for survival), this plasticity of the brain associated with the wiring strategy gives humans an unparalleled ability to learn. This is one reason why humans have learned how to do things like create a system of reading and writing while other organisms have not.

 

[Pythagorean]

Human babies are of course still born with several consistent muscular reflexes: the Moro reflex, the Palmar and Plantar grasps, sucking and rooting reflexes (for eating), and many more.

They also have a smile reflex when they pass gas and have several different cries with their own meaning.

From there, lots of behavior is learned through social feedback from the parents. Once they can crawl and explore, they star becoming little hypothesis generators (and testers!) and it's essentially up to the parent to safely guide their hypothesis testing and expose them to new observations and experiences.

 

[Adrian07]

I would like to express some further thoughts regarding instinct.
From post 3 these are encoded in the DNA. Going back to birds, a bird that builds a nest out of mud say must do so out of instinct, they have no-one to teach them what mud is to begin with so mud must be built into its preprogramming and so with different birds using different materials also the size and shape of the nest and where it is built.
Instinct also seems to use a lot less brain capacity, the smaller the brain the greater the level of instinctive behaviour.
While we take it for granted that we learn about and how to use our environment is it possible that environment and its use can substancially be encoded in DNA, am I right in thinking that in lower animals such as insects their existence is almost completely instinctive which would mean that almost everything they need to know about how to live and survive is in their DNA not just how the body is put together and how it works.

 

[Simon Bridge]

I would like to express some further thoughts regarding instinct.
From post 3 these are encoded in the DNA. Going back to birds, a bird that builds a nest out of mud say must do so out of instinct, they have no-one to teach them what mud is to begin with so mud must be built into its preprogramming and so with different birds using different materials also the size and shape of the nest and where it is built.
Instinct also seems to use a lot less brain capacity, the smaller the brain the greater the level of instinctive behaviour.
While we take it for granted that we learn about and how to use our environment is it possible that environment and its use can substancially be encoded in DNA, am I right in thinking that in lower animals such as insects their existence is almost completely instinctive which would mean that almost everything they need to know about how to live and survive is in their DNA not just how the body is put together and how it works.

No.

How their bodies are put together is a big part of their behavior.
eg. A fly can land upside-down on the ceiling.
It's actually a complicated process... the instructions to do it are not in the DNA - the DNA is too small: especially if you want to include all the other possible surfaces, other things the fly has to be able to do, and the "junk" parts. But the DNA includes a recipe for building a fly ... and part of the physiology is a switch that says when the leg-hairs are pressed, the wings stop beating - and the leg hairs stick to surfaces. To land on the ceiling, all the fly has to do is reach out with a leg and touch it - the wings stop beating, the leg sticks, the fly swings around and the other legs cushion what is otherwise a crash. (To take off again, the fly has to jump - unsticking all the feet, the wings start beating. This is all hardware.)

This is a much simpler that coding for a landing process, and comes from the behavior, environment, and physiology, feeding into each other. This feedback effect can be very subtle and is what leads to the complexities of living things.

Not all the instructions to build a fly are in the DNA itself - a fly is built by interaction of all the bits of a fly egg. That's why I described it as a recipe rather than a blueprint. A recipe does not contain every single instruction either... eg. the recipe says to bring water to boil ... it does not tell you what altitude to do this at (the boiling temperature varies with altitude) - the recipe will only work under some conditions. Similarly DNA to build a fly won't work if it is placed in a chicken egg. You don't even get a weird hybrid fly-chicken.

You also need to be careful thinking in terms of "higher" and "lower" creatures. Every creature alive today is at the same evolutionary "level". There are all kinds of hierarchies possible and they tend to be worked out to put humans on top... scientists can be pretty arrogant but there are humilities in science: one of the humilities comes with the realization that humans are just not important - and being OK with that.

(It took me quite a long time to appreciate how subtle all this is.)

 

[Adrian07]

Hi Simon.
When you say no are you saying that I an completely wrong. Does the fly actually know then that it is flying.
A fly is surely born to fly, this is more fundamental than what you have described.
Going back to birds and nests, how does a particular species of bird know what to build its nest out of, surely it must be born knowing the difference between mud and straw for example, otherwise nests would be built out of whatever was available.
I meant higher and lower intelligence our importance I think depends a lot on your religeous leanings.
A recipe of course requires you to know what the ingredients are. A cake recipe is useless if you don't know what eggs, flour and sugar are. How does DNA know its using the right ingredients, i.e iron for blood, calcium for bones etc without the ingredients being labeled somehow.

 

[Pythagorean]

Animals (including humans) don't have to know, they just have to behave appropriately. Of course as humans, we know that we know some things and can share and talk about it with each other. We can't ask a bird, though they share some brain homology with us. It's not likely that a fly "knows" in the same way a human does. Completely different architecture, not nearly the neural systems we have.

DNA doesn't "know" at all. DNA is a molecular configuration that survived, many configurations failed to persist. It's like throwing a die and keeping the 2's. The die doesn't know it needs to be a 2 to survive, it just survives because it wasn't destroyed by the selection criteria.

 

[Simon Bridge]

When you say no are you saying that I an completely wrong. Does the fly actually know then that it is flying.

Is a fly conscious? Anybodies guess.

When I said no I also told you what I was disagreeing with.
I said the relationship between behavior and DNA is more subtle and complex than your statements so far would suggest and provided an example. DNA does not work the way you seem to think it does.

 

[Adrian07]

If DNA doesn't know then what does. Everything needs instructions in order to function.
Why do bird species use different nesting materials rather than whatever is available.
We build out of local materials and design our houses this is obviously learned behaviour and completely different, we are not born with the knowledge unlike the birds.

Animals (including humans) don't have to know, they just have to behave appropriately.
How do they know what is appropriate behaviour.
Physically at least we are no more than biological machines, a machine cannot run without instructions.
I am willing to accept that DNA has nothing to do with those instructions but I fail to see where else they can come from.

 

[Pythagorean]

They don't have to know, it just has to feel good. DNA instructions are like "go left, go right" and they just happen to get you to Vegas. The instruction is nothing like "go to Vegas". That's just where the instructions happened to lead you.

 

[Simon Bridge]

They don't have to know, it just has to feel good. DNA instructions are like "go left, go right" and they just happen to get you to Vegas. The instruction is nothing like "go to Vegas". That's just where the instructions happened to lead you.

... and if you started out in the wrong place, the instructions will take you someplace else.

DNA just codes for other molecules ... these molecules just feel electromagnetic forces. The behavior of the organism is emergent behavior. At best you just feel attracted to certain motions... "move so the nice smell and the pretty lights are closer": you won't find anything in the DNA that says that.

One of the ways to get a feel for this sort of subtlety is to study cellular automata.
If you play http://en.wikipedia.org/wiki/Conway's_Game_of_Life]the[/PLAIN] game of life - for example - you see groups of cells behaving in regular ways ... yet there is nothing in the underlying rules which tell them to do that... not in so many words.

It is not surprising that people have a hard time with the idea that all this need not have a controller at least programming in the rules at the start.

 

[Drakkith]

DNA is a blueprint for how to physically build an organism, which reacts the way it does thanks to the way it is put together? Is that pretty much what you are saying?

 

[Ryan_m_b]

DNA is a blueprint for how to physically build an organism, which reacts the way it does thanks to the way it is put together? Is that pretty much what you are saying?

Blueprint is an often used but incorrect analogy. DNA sequences are nothing more than a template for RNA whose transcription is dependent on mechanical environmental factors. It's a really hard concept to get across but there are no genes for specific behaviours, those emerge out of a complex interplay between all the biochemical elements and that of the environment.

Let's use the example of the hypoxia response as it's quite simple. Hypoxia is a state where oxygen demand exceeds supply. The hypoxic response is a series of behaviours that cells enact when in a state of hypoxia such as increasing anaerobic respiration, releasing angiogenic factors to encourage blood vessel growth towards them, stimulating red blood cell production etc. But there is no gene for any of that, there's no set of instructions that say "if the oxygen levels drop by X then perform the following". Instead when a cell enters a state of hypoxia an oxygen dependant reaction that leads to the degradation of hypoxia-inducible-factor 1A halts. Because of this HIF-1A (a protein constantly synthesised before being degraded in normoxic conditions) accumulates, migrates into the nucleus, becomes HIF-1 and binds to a series of promoter sites on the DNA sequence that activate a bunch of other genes.

There's no higher order command, it's all unthinking and reactive.

 

[Drakkith]

I'm taking that to mean we act certain ways because we are built certain ways.

 

[gravenewworld]

Epigenetics anyone?

Also, there are more bacterial cells in your body than human cells, and DNA transfer is known to happen. What's the effect of that?

People hardly know anything about the bacteriome. Also, much is also not known about the function of the majority of DNA, which is labeled as "junk" DNA, that really isn't junk at all.

Why do identical twins have the same DNA, but act differently?

Read up on the mosaic model of brain development, which is quite fascinating. Mutations happen all of the time neural stem cell differentiation. Mutations can arise at any step in the series of >100 billion cell divisions required to generate the number of neurons found in the fully developed brain, resulting in variably sized populations of neurons that share a unique somatogenetic inheritance. Chances are high that an individual who inherits a recessive mutation in a critical gene will have some subset of neurons in which the same gene is also mutated. This may represent an entire brain structure (e.g., cerebellum), smaller regional structures, or even scattered populations of neurons that migrate throughout the brain after neurogenesis.There may be SOME genetic pre-programming in your DNA, but it's probably not as much as you think.

 

[Drakkith]

Epigenetics anyone?

Also, there are more bacterial cells in your body than human cells, and DNA transfer is known to happen. What's the effect of that?

I've not heard of this before. Do you have a reference by chance?

Why do identical twins have the same DNA, but act differently?

To my knowledge the cells in your brain reach out and make connections with other cells during development, but the connections themselves aren't pre-programmed or whatever. The dendrites shoot out in random directions, so the connections are different for every person even if their DNA is exactly the same. Since the connections are different, people don't act the same.

 

[gravenewworld]

f

I've not heard of this before. Do you have a reference by chance?
To my knowledge the cells in your brain reach out and make connections with other cells during development, but the connections themselves aren't pre-programmed or whatever. The dendrites shoot out in random directions, so the connections are different for every person even if their DNA is exactly the same. Since the connections are different, people don't act the same.

Sure:

http://www.wired.com/medtech/health/news/2004/10/65252[/URL]

We're essentially a bacteria hybrid, and our cells are outnumbered by alien cells.

Also check out this article that says were really 'super organisms':

[url]http://www.nature.com/nbt/journal/v22/n10/abs/nbt1015.html[/url]

Example of gene transfer between alien organisms and eukaryotes:[url]http://www.sciencemag.org/content/292/5523/1903.abstract[/url]

http://www.the-scientist.com/news/display/53552/#ixzz1YEkWvHov

Now people are studying the effect of gut bacteria health and its relation to brain diseases like Parkinson's and brain development. Really strange, but quite fascinating. [url]http://www.pnas.org/content/early/2011/01/26/1010529108.full.pdf[/url]Hardly anyone knows what the overall function of the bacteriome does, what the effect of gene transfer is, or how the bacterial-human symbiotic relationship can modulate development.

 

[Drakkith]

Interesting. I wonder how much of our body weight/biomass comes from these bacteria.

 

[Pythagorean]

Psychoneuroimmunology. They've actually started to find personalities typically associated with certain gut bacteria types. Three types this journal claims:

http://www.nature.com/nature/journal/v473/n7346/full/nature09944.html

Other relationships between personality and gut bacteria:

http://onlinelibrary.wiley.com/doi/...ionid=AC758E1CEF822CE1985F043BBD4FC018.d01t03

Maybe... the bugs are my co-pilots

 

[Ygggdrasil]

Interesting. I wonder how much of our body weight/biomass comes from these bacteria.

There are about 10 times as many bacterial cells in our body as human cells. However, because bacterial cells are about 10 times smaller than human cells (and because mass scales with length^3), the bacterial cells are ~1,000 times less massive than human cells. Thus, bacteria compose only about 1% of our total body mass.

 

[Simon Bridge]

I'm taking that to mean we act certain ways because we are built certain ways.

I'd take it to mean that organisms tend to act in certain ways because of their circumstances - among these circumstances are the ways the organism has been built (and lovely red uniforms ;) )

Ryan_m_b is saying that the analogy in which the DNA is a blueprint for the building process is flawed in that "blueprint" is too strong a word to describe what happens. The trouble when we try to be succinct (like above) is that the resulting statement ends up echoing Popeye.

This sort of topic has come up before...
https://www.physicsforums.com/showthread.php?p=4055510
... in this case restricted to appearances and twins.

 

[Drakkith]

Got it.

 

[Adrian07]

Interesting. Post 14 sounds like pure chemical reaction but is still talking about physical processes which is not what I talking about.
A computer without a programme is an ornament.
A zebra without a programme is dead, it would just sit on the ground after birth without attempting to walk until a hungry lion passed by.
I keep coming back to birds but it is the most obvious example, use of particular materials is not taught if its not taught then there must be a reason why a particular species builds a nest in a particular way to the extent where you do not have to see the bird to know what species built the nest. Every nest is the same this suggests pre-programming, all birds working to the same set of instructions and those instructions are about how to build a nest in a certain way, no variation whatsoever. How can this be due to environmental factors.

 

[Ryan_m_b]

Every nest is the same this suggests pre-programming, all birds working to the same set of instructions and those instructions are about how to build a nest in a certain way, no variation whatsoever. How can this be due to environmental factors.

It's not down to the genes really. The interplay of genes and the environment creates emergent constructs (tissues, organs, organisms etc) which, dependent on the enironmet, exhibit certain behaviours. It's not really a case of referring to some computer code.

This is an annoyingly hard concept to describe it seems; I'd love to see someone come up with a good way to describe this to laymen because this comes up very often.

 

[Simon Bridge]

Complex behavior does not imply a program, or even a computer.
People used to build very sophisticated mechanical automata before computers were invented... if we can do it, why not Nature?

In Conway's Game of Life there is any amount of complex behavior, including self-replicating Turing-complete computers. Nowhere in the glider will you find instructions to tell it to go diagonally across the board - or how to react when it encounters other "life". It is following it's construction and the rules of the game.

In that game, the bahavior of something like a glider is entirely and directly due to the laws of physics of the automata ... IRL we prefer to distinguish "environment" from "self" for organisms. Nobody is saying that bahvior and construction are entirely and solely environmental ... just that the role of DNA is more mindless and subtle than suggested by the idea that it is a blueprint of a program.

In the end, though, you just have to see it happen in Nature lots of times to get it.

 

[Ygggdrasil]

Interesting. Post 14 sounds like pure chemical reaction but is still talking about physical processes which is not what I talking about.
A computer without a programme is an ornament.
A zebra without a programme is dead, it would just sit on the ground after birth without attempting to walk until a hungry lion passed by.
I keep coming back to birds but it is the most obvious example, use of particular materials is not taught if its not taught then there must be a reason why a particular species builds a nest in a particular way to the extent where you do not have to see the bird to know what species built the nest. Every nest is the same this suggests pre-programming, all birds working to the same set of instructions and those instructions are about how to build a nest in a certain way, no variation whatsoever. How can this be due to environmental factors.

You keep asserting that nest building by birds is an instinctual skill, but this may not be true:

"Individual birds varied their technique from one nest to the next and there were instances of birds building nests from left to right as well as from right to left.

As birds gained more experience, they dropped blades of grass less often.

"If birds built their nests according to a genetic template, you would expect all birds to build their nests the same way each time. However, this was not the case," added Dr Walsh."​

http://www.bbc.co.uk/news/uk-scotland-15053754
cited study: http://dx.doi.org/10.1016/j.beproc.2011.06.011

Indeed, evidence that birds instinctually know how to build nests is not so strong and seems to suggest an important role for experience-dependent learning:

"The classic method of demonstrating that there is a learned component to a behaviour has been the ‘deprivation experiment’: does an animal deprived of an experience while growing up nevertheless perform the behaviour perfectly the first time it has the opportunity? Amazingly, such an experiment was apparently carried out by the English naturalist John Ray in the 17th century, since he writes of birds building their nests: “and this they do though they never saw nor could see any nest made, that is though taken from the nest and brought up by hand”. The next such study did not take place until the 1960s when deprivation experiments carried out on village weavers (Ploceus cucullatus) showed that effective weaving of the grass strands that make up the nest depended substantially upon building experience. In the subsequent years, virtually no further work has been done to establish the extent and nature of the learning processes involved in the nest building of this or any other species.

In spite of the number and ubiquity of birds' nests, we know little of the cognitive processes that might be involved in their construction (Figure 2). Although there is enough similarity in nest design for a nest collector to recognise which species built a nest, we do not know how a bird knows what nest shape/size to build."​

http://dx.doi.org/10.1016/j.cub.2008.01.020

As others in the thread have suggested, nest building might emerge from a simple set repetitive behaviors:

"The simplest possibility is that the bird has no concept of what it is aiming to produce but has a set of rules for its behaviour, which if followed in appropriate order lead to the emergence of a nest."​

http://dx.doi.org/10.1016/j.cub.2008.01.020

 

[nitsuj]

I am a complete layman in this but have been wondering about what makes us us.

I ask this from observations about birds which seem at least to me about halfway between higher and lower animals.

The thing with birds is that you can tell the species, generally, just from looking at the nest. Nestbuilding as far as I can see is not taught yet is extremely complicated in some species.

The higher up the scale you go the less seems to be pre-programmed and the more taught. I wonder though how much of our makeup is genetic and how much learnt.

"How much are we genetically pre-programmed?" Simply asked like that I'd say at least 100% "pre-programmed".

Don't forget what is involved with learned behavior.

A mocking bird is genetically "pre-programmed" to mimic bird calls. It's learning isn't? I guess "pre-programed" to learn (mimic, what's the diff) in other words.

Emotive responses are "pre-programed" and imo govern [STRIKE]external[/STRIKE] behaviors. Such as ants that are "born to" defend, build, scavenge ect.

Or a bird that favors a particular style of nest.

There is no genetic coding that implants the concept of a nest, raw materials ect.

So imo this scale you are vague about is related to social/communication abilities, and that's genetic as well. This is why I answered we are 100% pre-programed.

So I guess I am asking what do you mean by learned & genetically "pre-programmed"? I don't see a definitive dichotomy there.

 

[Adrian07]

"The simplest possibility is that the bird has no concept of what it is aiming to produce but has a set of rules for its behaviour, which if followed in appropriate order lead to the emergence of a nest."
It is where that set of rules comes from that I am talking about and I can see no source other than its DNA constructing a part of the brain with a built in set of instructions that cannot be changed, the same way we build pre-programmed micro-chips. Those rules must include instructions about the environment.

A bird does not favour a particular style of nest.
From what I have seen a bird has no choice in the size/style or materials used in building its nest. These things are not learned so where do the instructions come from. I suspect a bird will learn to hide the nest better, may learn to build it better and faster, learn that certain types of vegetation offer better protection but these are learned environmental factors and just improving pre-set behaviour.

 

[Simon Bridge]

"The simplest possibility is that the bird has no concept of what it is aiming to produce but has a set of rules for its behaviour, which if followed in appropriate order lead to the emergence of a nest."
It is where that set of rules comes from that I am talking about and I can see no source other than its DNA constructing a part of the brain with a built in set of instructions that cannot be changed, the same way we build pre-programmed micro-chips. Those rules must include instructions about the environment.

You cannot think of some other way to do it, therefore that must be how it is done?

If the rules came from the DNA as a computer program, then then the program has to be executed via a set of rules: where did those rules come from? The DNA must encode the program according to a set of rules. Where did the DNA get it's rules from? This path leads to an infinite regression.

I'm saying that the "rules for building a nest" are emergent from a much simpler set governing the entire behavior of the organism. Did you look at cellular automata yet?

Biology has to obey simpler rules than computers do.

 

[Ryan_m_b]

It is where that set of rules comes from that I am talking about and I can see no source other than its DNA constructing a part of the brain with a built in set of instructions that cannot be changed, the same way we build pre-programmed micro-chips. Those rules must include instructions about the environment.

You really need to get these computer analogies out of your head, they are very detrimental to your understanding. DNA does not contain rules for how to build a brain. You can go and look this up and you will not find a set of genes that say "put this neuron here [here's how to build it] then this one here and wire them like so". It's all emergent as Simon has been trying to say. A good example of this is the establishment of the posterior/anterior and dorsal/ventral axes

https://www.youtube.com/watch?v=GntFBUa6nvs

I suggest you look into purchasing an introductory book on developmental biology, perhaps Principles of Developmental Biology or just the latest issue of Developmental Biology (I have an older issue around here somewhere but can't find it atm). Alternatively this one is written by a very eminent scientist within the field and is meant to be concise and accessible to the layman.

 

[marty1]

Don't overlook the grandest pre-program of all. The program that can program.

 

[Drakkith]

Don't overlook the grandest pre-program of all. The program that can program.

What?

 

[Pythagorean]

marty1, "Program" as its used in cellular biology processes should really not be confused with human programming. It's really not comparable.

 

[Simon Bridge]

All analogies are flawed in some way - the computer-program analogy for how DNA works breaks somewhat faster than most and is not very helpful to start with. We are used to computers these days so everything tends to get compared to them. In Newton's day everybody was into clockwork so that was the most common analogy. It is important not to get carried away.

OP has displayed a marked unwillingness to learn, look at references etc, and a tendency to diverge substantially and fruitlessly from the topic of his own thread before. Just look where this one started out.

I think that the needed explanations have been presented - certainly for the original topic - if OP does not want to believe them there is no helping that. One of the advantages of science is that belief is not needed. Not being prepared to learn on the other hand...

Do we see signs of willingness to learn?