Essentials: Genes & the Inheritance of Memories Across Generations | Dr. Oded Rechavi

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Welcome to Huberman Lab Essentials, [music] where we revisit past episodes for the most potent and actionable science-based tools for mental health, physical health, and performance. I’m Andrew Huberman, and I’m a professor of neurobiology and opthalmology at Stanford School of Medicine. And now for my discussion with Dr. Oded Rakavi. Oded, thank you so much for being here.

Totally my pleasure. Today, what I mainly want to talk about is the incredible questions that you probe in your lab, which are incredibly significant for each and all of our lives. I think most people have a general understanding of what genes are, what RNA is, and so on. But maybe you could explain to people in very basic terms. And I’ll just preface all this by saying that I think most people understand that if they have two blue-eyed parents that there’s a higher probability that they their offspring will have blue eyes than brown eyesh.

Mhm. >> But most people generally understand and accept that if they spend part of their life um let’s say studying architecture that if they have children that there’s no real genetic reason we assume that their children would somehow be better at architecture because they contain the knowledge through the DNA of their parents. They might be exposed to it in the home so-called nature nurture nurture in that case but that they wouldn’t inherit knowledge. Today I’m hoping you can explain to us why eye color but not knowledge is thought to be inherited and the huge landscape of interesting questions that this opens up including some evidence that contrary to what we might think uh certain types of knowledge at the level of cells and systems can be inherited. >> So DNA are the is the material the genetic instructions that is contained in every one of our cells.

We have the set of genes containing the entire set is called the genome and this is present in every cell of our body. The same set of instructions. Genes are made of DNA and chromosomes that are containing chromosomes. Chromosomes is the DNA and the proteins that condense the DNA because we have a huge amount of DNA in every cell that you need to condense it to. >> Sort of like um thread on a on a spool, >> right?

Huge amounts that you have to condense. And we have the same genome, the same DNA in every cell in our body. It’s good to have an analogy to to understand how it works. This is like the IKA book that you have in every cell in your body, the instructions to make everything that you need in your house, the chairs, the the kitchen, the pictures, but in every room, you want something else. So in the kitchen, you want things that fit the kitchen, and in the toilet, you want things that fit the toilet.

So you only remove one particular page of instructions, which is the instruction of how to build a chair. H and this you place in the living room. Okay. And the toilet you put in the toilet. So the genome the is the instruction to make everything.

This is the care book. And in every cell we we take just the instructions for make one particular furniture. And this is the RNA. And then the end you’ll build a chair. The chair is the protein.

This is true for one particular type of RNA which is messenger RNA. And in fact this is just a small percent of our of the RNA in the cell. So we have a very big genome and less than 2% of it encodes for this messenger RNA. However, a lot of the genome is transcribed to make RNA that does other things. Some of these RNAs we understand and many of them we don’t.

I think it’s a beautiful description and IKEA is not a sponsor of the podcast. So it’s totally fair game to to use the IKEA catalog [clears throat] as as the analogy for DNA. The specific instructions for specific pieces of furniture is the RNA and the furniture pieces being the proteins that are that are essentially made from RNA using messenger RNA. Right. >> Okay.

Despite the fact that the same genes are contained in all the cells of the body, is it fair to say that there is basically one very important exception which is sematic cells versus germ cells. And would you mind sharing with us what that distinction is? >> So yes, every cell every cell type is different. We have cells in the legs. We have cells in the brain.

We have in the in the brain we have cells that produce dopamine, cells that produce serotonin and so on. But we can make one very important distinction between the somatic cells and the germ cells. The germ cells are supposed to be the only cells that contribute to the next generation that out of which the next generation will be made. So each of us is made just from a a combination of a sperm and an egg. These are two types of germ cells.

And then they fuse and you make you you you get one fertilized egg and out of this one cell all the rest of the body will develop and what happens in the soma which is which are all the cells that are not the the germ cells should stay in the soma should not be able to contribute to the next generation. This is very important and is sought to be one of the main barriers for the inheritance of acquired traits, the inheritance of memory and so on because for example like the example that you gave in with learning architecture if I learn about architecture the information is encoded in my brain and since my brain cells can’t transfer information to the sperm and the egg because the information is supposed to reside in synaptic connections between different neurons. in particular circuits that developed. H so what’s what what happens in the brain shouldn’t be able to transfer to the next generation. Even simpler a simpler example if you go to the gym and you build up muscles you know that your kids will will will have to work out on their own.

It won’t this short out won’t won’t happen. This is something that we know intuitively even if we don’t have any background in biology. This is connected to the fact that as we said at the beginning, every cell in the body has its own genome and the next generation will only form from the combination of the genomes in the sperm and the egg. Even if you somehow h acquire the mutation or a change in your DNA in one of particular brain cells, it wouldn’t matter because this mutation, there’s no way to transfer it to the DNA of the of the germ cells that will contribute to the next generation. There is this idea and I’ll say it so that you don’t have to that dates back to Lamar and Lamarian evolution very controversial right um and maybe not even controversial I think it’s very like offensive even to certain people this idea of inheritance of acquired traits the idea that one could change themselves through some activity use the example of going to the gym we could also use the example of somebody who becomes an endurance runner then decides to have children with another endurance runner and has in mind the idea that because they did all running and not just because they were biased towards running in the first place but because they of the distance they actually ran that their offspring somehow would be fabulous runners.

This Lamarian concept is we believe wrong. So how do we talk about inheritance of acquired traits? What’s the proper language for us to frame this discussion? Lamak this is what he believed and and he thought this what is this is how evolution progress progressed and and later um Darvin showed that it’s really natural selection the selecting of the organisms that already contain the particular qualities are selected based on the whether they survive or not in particular environments and therefore their um evolution progresses they become more common and take over. This is very different two different explanations.

Most common way this is contrasted is the neck of the giraffes. This is the classic example. According to to