19 ms·
Memories of positive associations get written onto DNA
- samatman 13y agoMethylation can happen in gametes also, making some epigenetic changes heritable. The precise mechanisms of methylation are under intense study, but not well understood; it doesn't appear to be a random process in general. This points to an almost-paradox in biology, which I call Lamarck's Lemma: There may be evolutionary advantage to being able to pass on acquired traits to one's offspring, and no known physical law that prevents it. Why, therefore, would biology not develop at least some Lamarckian mechanisms, since they could offer fitness in the Darwinian sense? Answer: there appears to be exactly that. It's an exciting time for genetics.
- nollidge 13y agoI don't see why it's a paradox. Lots of things would offer fitness - why can't all animals talk? Why can't plants move? Surely these things would offer greater Darwinian fitness.
- samatman 13y agoIt's not a paradox, it's an almost paradox, which is kind of like being almost pregnant from a logic perspective. Lamarckian and Darwinian evolution were debated and Darwin won. Lamarck's Lemma, which is a term I made up, points out that, were a random walk to create a mechanism for Lamarckian evolution, Darwinian evolution might well keep it around, as it could offer fitness. That's why I phrase it as a lemma on Darwin's theory: even if it proves true, as epigenetics suggests, it doesn't make Lamarckian thinking correct. If anything, the opposite: it shows that Lamarckian effects can be explained through natural selection. Plants can of course move, the classic example being the sensitive plant. Whether or not non-human animals can "talk" depends, basically, on whether one means "signalling" or "language proper". The bee dance can give arbitrarily complex instructions in one particular domain: there is no 'one' bee dance, each performance is roughly as unique as a sentence or so of text.
- VladRussian2 13y ago> Whether or not non-human animals can "talk" depends, there is at least one animal that we know is able to talk, at least in our definition of "talk" - this animal is humans, so the Evolution did produce a talking animal.
- samatman 13y agoI did want to address one other total misconception here: Darwinian fitness is a result, not an effect. There is no adaptation, at all, which predictably increases fitness. Evolution is not a direction. "Surely these things would offer greater Darwinian fitness" is as basic a mistake as "Surely we can figure out whether this program will halt without running it". EDIT: In fact, as I think about it, there is a deep connection between the thought "Knowing the genes of this organism, we may predict its fitness" and "Knowing the instructions of this program, we may predict its halting". I'd love to see a paper on that.
- tel 13y agoIt's an effect on the side of survival, correct? It's not that some particular change was "selected" in order to increase fitness but instead that all minute changes were selected simultaneously and some were pruned. There needs to be a smooth path from the "current location in design space" to any improvement under which there is never anything damaging enough to prune off that path. And then, this "smooth path" idea relates neatly with topological notions of computability.
- rflrob 13y agoThat doesn't seem rit to me. There's lots of adaptations that could probably increase fitness of offspring as a function of the parent's environment. In the same way, you can look at some programs and predict whether they halt, just not all programs, and potentially not even all "interesting" programs, for some definition of interesting.
- XorNot 13y agoYou contradict your own point though: yes, we can predict - but we can't know that a program - an arbitrary program - will halt. Evolution is much the same, but most people are worse at it because they make the mistake of prioritizing human-values as evolutionary advantages for all species. For example, cows get slaughtered by the billion by humans. But they're an evolutionary success story from a Darwinian perspective: by being easy to domesticate by early tribes and delicious, they've proliferated far beyond anything which would've happened un-aided by humans.
- sadkingbilly 13y ago> Why can't plants move? Surely these things would offer greater Darwinian fitness. Not necessarily for plants. They do in fact move. They just do it differently. They have no problem spreading their DNA throughout the world via seeds and pollen. They use a lot less energy too, compared with sprouting legs and getting up to walk around. If they did this, they would likely require much greater quantities of food, including protein, which would put plants at a disadvantage. In any case, plants have also evolved on a completely different fitness track than that of animals. Plants have evolved incredible manipulation of chemistry, far beyond what humans can produce today, let alone even understand. I recently finished reading Botany of Desire (Michael Pollan) where he describes how plants have co-evolved with humans, appealing to our selection of flowers, fruits, and vegetables to further distribute their DNA. Who's actually farming who? Interesting stuff.
- nollidge 13y agoI was being a bit tongue-in-cheek. You're absolutely right that supposed "benefits" might have unforeseen tradeoffs. In this case, having some sort of pseudo-Lamarckian inheritance could possibly be a detriment due to energy requirements or something like that. Or indeed it could have a neutral effect on fitness, in which case it's unlikely to take hold in the population, barring genetic drift or other non-selection evolutionary mechanisms.
- VladRussian2 13y ago>I don't see why it's a paradox. Lots of things would offer fitness - why can't all animals talk? Why can't plants move? Surely these things would offer greater Darwinian fitness. this is why we have live organisms that able to move - it is called animals, and we have animals that can talk, and we'll possibly have [some milleniums later] animals that are able to efficiently transfer memory through DNA (possibly after these animals become able to calculate and select what memories they'd like to encode into their own DNAs and what of these memories they want to transfer to the offsprings)... Evolution isn't finished as of today, it is possibly only starting :)
- j2d3 13y agoAnimals can talk --- to each other.
- jonnathanson 13y agoDarwinian natural selection doesn't select for absolute/universal fitness, because there is no such thing. It selects for fitness into a specific, local niche. Humans may be more fit than chimpanzees in some areas, for example, but less fit in others. It is a fallacy to assume that evolution is linear, and that it progresses toward some sort of universal optimum. There is no universal optimum. There are only specific, local optima. A good example is the megalodon. From all we know, the megalodon was basically a massive, faster, more badass, more ferocious version of the great white shark. Why did the megalodon die out, and the lines that led to the great white survive? Surely big-badassedness is a desirable quality in an apex predator like a shark, right? Well, not really, because circumstances changed. Ocean temperatures changed, prey got scarcer and smaller, and eventually, size became a detriment. Megalodon was too big not to fail. What fit one day no longer fit the next. The same thing may happen to humans someday, and some other animal may step up to take our places. It seems unlikely, but nature is the one doing the "selecting" in natural selection -- not us. Environments and circumstances change, and as they change, so do the criteria that "fit" the new context. In the Darwinian sense, "fit" refers to suitability to a habitat; it does not refer to "fitness" in the modern sense of the word. Think "product/market fit," not "physically fit."
- jostmey 13y agoMethylation of the nerve cells has no effect on the germline. Changes in the brain are not heritable.
- samatman 13y agoRelevant to the article, and worth pointing out. It has no direct bearing on my comment, which was about (heritable) methylation of the gametes. I believe what you mean to say is "We have been able to observe no correlation between methylation of the nerve cells and methylation of the gametes". Unless you can cite detailed studies supporting this null hypothesis. My understanding is that we have no idea.
- swamp40 13y agoHow would you explain why birds raised in isolation can still build nests? And sing the songs of their species? I would propose that it is possible that some animal "instincts" are really inherited memories from their ancestors. And that if we look hard enough and deep enough, we may find similar human "instincts". Have you ever seen a baby with a fear of spiders? Whose parents swear the child has never even seen a spider before?
- chc 13y agoThe leap from "Instincts are inherited" to "This is because memories are inherited" is the furthest thing from science you could possibly get.
- foobarbazqux 13y agoAny falsifiable hypothesis is scientific.
- chc 13y agoAnd this hypothesis presents no testable predictions. It's more or less equivalent to "A wizard did it."
- gizmo686 13y agoEven without Methylation, we have another mechanism for passing on traits to offspring, raising them. Admittedly, there are many species where this is not relevant, but for species where the young live with their parents, or other members of the older generation, it seems reasonable that information and traits could be passed by cross generation interactions. The most obvious example of this is humans, who have minimal (if any) genetic advantage over cave-men. I suspect we can find simmilar instances in other species.
- bencollier49 13y agoDodgy newspaper pop-sci interpretation involving past lives in 3..2..1..
- pnathan 13y agoWhile snarky, you're right. Also see the 1910-1940 idea of "Racial Memory". One of the more popular and weird ideas to come out of Lamarkian concepts.
- awda 13y agoInteresting that they could also block memory formation in addiction centers. I wonder if there is a preventative treatment possible in that direction, by blocking addiction before it happens? It's a nice dream, anyway.
- contingencies 13y agoErr, err, centralized government bureaucracy imposing own will-of-committee between world and consciousness to inflict totalitarian conformance to pre-approved homogeneity ... not good, even if: drugs/childporn/terrorism/etc.
- awda 13y agoWhat makes you think this is pushed by the government? I'm envisioning opt-in.
- rflrob 13y agoI'd need to read the paper, but the write up seems to ignore the possibility that methylation is required to express the genes necessary to form memories, and not that the methylation itself is, in any meaningful sense, the memory itself (as in "memories [...] get written onto DNA).
- karpathy 13y agoThis was my first reaction as well. Blocking methylation is a drastically global operation for a cell as methylation is involved in so much of the epigenetic regulation. Turning it off probably disabled much of the normal functioning of those cells and could have had all kinds of downstream effects. It doesn't seem fair to jump to the conclusion that the memory is actually encoded in the methylation pattern somehow. Based on a skim of the paper, the researchers don't seem to claim this either.
- dekhn 13y agoAh, I only skimmed the article describing it, and originally jumped to the conclusion they had actually claimed that "memory state" (IE factual encoding) was being stored in methylation. Modification of gene expression of genes associated with memory (in the form of changes to neuronal toplogy and excitation thresholds) seems like a more mundane and reasonable explanation.
- dnautics 13y agothe title in the write up is unnecessarily sensational, your impression is exactly the model proposed in the paper. You could not read out the methylation pattern in a cell and retrieve the memory, the memory is the methylation + the cells.
- JunkDNA 13y agoThis is fascinating but unsurprising given all the things that have come out lately with regard to epigenetics. If your mental model of DNA involves some image of a pristine blueprint that is followed with clockwork-like precision in the exact same way by every cell in your body, your model needed updating quite some time ago. I feel that many researchers, even geneticists who should know better, still have not internalized the idea that epigenetics is pretty good evidence that somatic DNA is a read/write medium. This leads to sloppy thinking about genetic causes of disease as well as continued persistence of the idea that if we can just collect enough sequences, all genetic causes of disease might be found.
- hobbes78 13y agoThe DNA doesn't sport standard read/write access, what's happening is that the expression or not of some genes can occur on an individual and be inherited by its offspring. The DNA doesn't change (save for the chance of a tiny few random changes, as usual)...
- Blahah 13y ago(de)methylation is DNA read/write. The DNA does change, although the sequence of bases doesn't.
- foobarbazqux 13y agoMethylation is like setting a preference in a config file.
- total__C 13y agoIn the situation described by the article, the changes in gene expression are happening in the rat's brains. These changes aren't going to make it into the rat's gametes.
- mathattack 13y agoBy this argument, culture can be imprinted into DNA too, no? This also implies that it would be much tougher to do a Jurassic Park recreation, because the environment is different. You can't just start from scratch with the DNA. Or am I misinterpreting?
- XorNot 13y agoI'm hoping this turns out to be incorrect - a false lead. It would really suck if in order to download mindstates, we needed to get inside the chemistry of neuronal cells. We can conceivably find an imaging technique that would let us 3D snapshot a brain and all it's connections. But its a big step from that big step down to getting nanoscopic views of the chemistry in every cell.
- gizmo686 13y agoIf you want to download a mindstate, you will almost have to deal with details at a molecular level. I am not familiar with the details of how the brain works, but consider that their is likely a huge evolutionary advantage to storing data more densely.
- StandardFuture 13y agoI really like the potential implications of this to future A.I. research. ;)
- nateabele 13y agoThe takeaway: ASSASSIN'S CREED WAS RIGHT!!oen1 :-D
- xzrrwe 13y agoGenetic memory.
- nsxwolf 13y agoSo... the premise of Alien 4 might not be as ridiculous as it seemed at the time? :O
- ust 13y agoThere was an interesting article in the Discover magazine about epigenetic changes: http://discovermagazine.com/2013/may/13-grandmas-experiences-leave-epigenetic-mark-on-your-genes http://discovermagazine.com/2013/may/13-grandmas-experiences...