Is this how instinct is passed to offspring? Do we know enough about brain physiology to answer this?
As far as we know, no. This would be a form of Lamarkian evolution, or the inheritance of acquired characteristics, which generally does not occur.
How exactly instinctual behaviors are coded by DNA is not well known; but we don’t know of any mechanism that could transmit individual memories genetically.
I’m sure there’s no single mechanism for the encoding of instincts in DNA. Surely each individual instinct is the product of some separate ad hoc mishmash of genes which just happen to give the right effect.
But I’m just some guy, so why I am I even posting?
-FrL-
I understand what you mean but I am not sure you are answering the question OP is postulating. I think the OP might be basing the question on the ‘brain’ vs. ‘mind’ view of the human neural system and is asking whether DNA encodes the instincts and other ‘genetic memory’ type of information into a ‘blank’ brain. This question is fortunately faulty and has no answer since to the best of our knowledge the neural system cannot be logically separated into ‘structure that holds information’ and ‘information that the structure holds’.
The DNA provides a certain amount of coding that is sufficient for the development of a neural system that represents the information in question. Any alternative would involve instincts being learned from external sources or instincts not being confined to the neural system, both of which are extremely unlikely given what we know.
As far as it’s currently known, DNA will stimulate some neural connections in all developing brains. However, none of these connections will be ‘memories’ of anybody but the owner of the brain, and these are more stimulated by sensory experiences than by DNA - that’s why they’re memories.
The reason why, as others have hinted at, is that there is no mechanism known by which a parent’s experiences and memories will affect the DNA that he or she passes on to children. They have evolved with certain DNA that stimulates useful ‘instinctual’ neural connections, that help produce responses that are useful in the real world. However, IFAWK, those genes developed by random mutations and random recombinations, just happening to settle on something that ‘worked’. (And when you start to think of all the possible behaviours that could be randomly generated, you see what a slow, hit&miss process that could be.)
Yes, I agree that the question is somewhat unclear, since the question actually posed in the OP is at odds with the question in the subject line, because it seems to imply that instinct is a form of memory.
In this context, “memory” should be restricted to the knowledge acquired by an individual organism through learning, which is as far as we know encoded through new neural connections generated during the lifetime of that organism. We know of no mechanism by which that knowledge can be transmitted via DNA.
“Instinct” could perhaps be viewed as a kind of “species memory,” but this is really a figurative use of the term. Instinctual behaviors by definition are innate, not produced by learning or experience. While the mechanism is obscure, as far as we know instincts are genetically based.
IIRC, Monkeys are born with a fear of snakes. Is that the sort of thing you’re getting at?
But once something did work that conferred a small advantage then runaway sexual selection could progress quite rapidly, both in terms of instinct and morphological changes that go along with it. It’s almost easier to think of it like (and I’m stealing from Dawkins): a brain that learns to do X will make a new generation that will have brains more likely than an average member from a different parent to learn to do X; a couple thousand or million generations later and everyone will have brains that will learn how to do X so fast that it’s basically an instinct. Again, as long as learning X is genetic and as long as it confers a sexual advantage.
Then again, Dawkins was just WAGing while poking fun at beavers and their unending thirst to make dams, even in a lab setting where it’s impossible and all they can do is go through the motions. As others have stated, we don’t know enough about brains yet to really lay down the law.
Yeah, that sounds plausible enough. Just as long as you keep in mind that the genes don’t have to do with memories of ancestral beavers building dams… just the results of natural variation in genetic patterns, and the patterns that were better at dam-forming having a survival advantage.
Weren’t there studies involving teaching planaria (flat worms) mazes and then grinding them up and feeding them to untrained planaria who knew the mazes or perhaps learned the mazes faster? Or is this an urban legend? Or perhaps were the studies later debunked?
The research was debunked, insofar as nobody was able to replicate it. The charitable suggested that the researcher failed to wash the mazes between trials, so the later worms simply followed the slime trails of earlier worms. The less charitable suggested he made the whole thing up.
Thanks for the replies so far.
I’m not talking about individual memories. I guess it might be more accurate to call the ‘memories’ I’m asking about “knowledge built into a brain upon initial physical construction.”
I mean, the brain isn’t a blank slate at birth; how does a mammilian baby know to suckle, for example, and Shalmanese’s example about monkeys.
If it’s not DNA, what is it?
…Huh. I remember reading about that in my science textbooks in the mid-eighties.
Consider my ignorance successfully fought for today.
Here’s your mistake. That knowledge IS the brains initial physical construction. The baby knows how to suckle not because it is written into the brain to be able to do so, but rather because the brain is structure causes this behavior. To make it even more clear, your mention of “blank slate brain” would be no brain at all – the there is no logical separation between the information and the structure.
Don’t think of it as a canvas, but think of it as a sculpture. What’s a blank sculpture?
I think this could be answered a bit easier with the stimulus-response model. Basically at the core, a certain combination of DNA causes an organism to make certain decisions based on a specific stimulus from the environment. It just so happens that you, me, and all organisms living today have the proper “response” encoded in us by our DNA, i.e. when we see something in the environment, it is run through the computer in our brain which has been designed by a specific DNA sequence, and we respond in such a way based on our genes that we survive, and not perish. So at the core, the DNA passed on to each generation is just the result of natural selection in that it survived and did not perish when presented with specific stimuli. This DNA contains the blueprints for our brains, brains that make the right decisions when confronted with a specific problem.
A rock.
The same experimental error is thought to have been responsible for an even further out-there hypothesis called Morphic Resonance, the idea that if you train a rat to negotiate a maze, all other rats become better at negotiating the maze, because they’re part of some ‘morphic field’ that stores experiences related to a set of similar objects (well, something like that, anyway). Needless to say, there isn’t any reliable evidence in support of this idea, but I thought it worth mentioning for purposes of information and general interest related to this thread’s topic.
Which is why these days rats are trained to swim through mazes filled with water. No scent trail. It’s amazing how many early experiments failed to replicated once water was added to the maze.
Right, but then I can imagine that even though I’m a decent swimmer there are a lot of mazes I could walk out of that I couldn’t swim out of – simply because it’s hard to think and swim at the same time. :dubious: