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DNA would seem to be the only candidate for propagating instinctual behavior, yet I find that not credible. DNA mainly codes for the production of protein structures (like enzymes) and is mainly about cellular mechanisms like respiration. It is said that we have 99% of our DNA in common with another primate (Chimpanzee? Do we behave much like them?) and that we have about 50% in common with plants (Carl Sagan said an Oak Tree) which would indicate that only cellular-level information is contained in DNA.

It is a mystery how tissues and systems arise, so it should be an even greater mystery how behavior could be somehow passed along in a mechanism for folding proteins. Is there any model that definitely links instincts to DNA, such that if the DNA is altered, the instinctual behavior changes? If not, are there any candidates for the actual mechanism of instinct transmission?

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http://www.theguardian.com/world/2007/dec/12/japan.justinmccurry Here they talk about scientist who shut down fear of cat in mice behavior. After genetic engineering the mouse isn't afraid of the cat smell. The conclusion of this study is that fear (at least in this case) is not learned through experience, but a consequence of genetic evolution. In the end, they even explain that mice are still afraid by the sound of the cat. So it's seems to be possible to modify a really precise reaction and not just a large class of behaviors.

Also, all the complex chemicals activities in our brain are coded by dna, so it's not surprising that our instincts are inherited. For the 99% of dna in common with Chimpanzee, I have to say that 1% is still a big number of genes, and can make a huge difference. Also they might be some part of the dna that are not used anymore in the 99% (they are just relics of evolution).

Actually I found information (one from Carl Sagan) saying that big parts (sometimes 80% or 97%) of our dna are unused. I'm not sure about those numbers thought, and one has to be careful because the sources don't seems to be always reliable to me. (The best might be non-coding dna on wikipedia)

References

Kobayakawa, K., Kobayakawa, R., Matsumoto, H., Oka, Y., Imai, T., Ikawa, M., ... & Mori, K. (2007). Innate versus learned odour processing in the mouse olfactory bulb. Nature, 450(7169), 503.
DOI: 10.1038/nature06281 PMID: 17989651 PDF: http://www.academia.edu/download/45075404/Innate_versus_learned_odour_processing_i20160425-21574-dycs42.pdf

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  • $\begingroup$ Welcome to CogSci and thanks for your interesting and referenced answer. However, the question is specifically on the propagation of instinct and not so much on its location in the brain. Plus, the information on 'junk' DNA is quite out of place. As of now, this is more of a comment than an answer. $\endgroup$ – AliceD May 26 '16 at 7:45
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    $\begingroup$ I can't comment yet, but if you think it should be move, it's fine for me. The part about unused DNA makes it possible for an answer to exist, as it answer the objection about DNA shared between species, so I thought it was somehow important to mention it. $\endgroup$ – JSFDude May 26 '16 at 7:55
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    $\begingroup$ Yes, you'll nee a bit of rep to comment. Without a better alternative I think it's OK as is. Perhaps you could elaborate a bit more on that Japanese experiment and show users here what they achieved. Pretty cool stuff actually! If you could do that I'm happy to upvote this answer actually. $\endgroup$ – AliceD May 26 '16 at 7:59
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    $\begingroup$ @Christiaan actually, the idea that much of the DNA could be "unused" strengthens my argument. I read that there is the equivalent of 1.5 Gigabytes of information in DNA, which is not very much to encode all cellular processes, systems and general structure, let alone behavior! If some of that total is inactive, so much the less there is to encode behavior. It seems impossible to me. I think that instinct and behavior must arise from something else, although there seems to be no candidate for that. Still, eliminate the impossible to get to the truth, right? $\endgroup$ – user9634 May 26 '16 at 20:50
  • $\begingroup$ @nocomprende - wise words! $\endgroup$ – AliceD May 26 '16 at 20:57

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