11 ms·

Inherited Learning? It Happens, but How Is Uncertain

73 points by cbkeller 7y ago

carlsborg 7y ago
How do wasps learn how to build those honeycomb structures that make up their nests. If a wasp is brought up in isolation and is able to do this, clearly its inherited.
- sacrificedcapon 7y ago
  That's the inheritance of instinct rather than the inheritance of learning. If one generation of wasp colony "learned" that building their structures under blue canopy was good (researchers protected these structures) and red canopy was bad (researchers destroy these structures each time wasps make them ) and you take the offspring of this colony and raise them in isolation and they still build under blue canopy and avoid the red canopy, then you can perhaps say "learning" was inherited. It's like how infants inherit the instinct to cry and suckle. Inheritance of learning would be if the mother (since childhood ) was taught to wink and she'd get more attention and food/milk and her infant winked at her instead of crying when the infant wanted attention.
  - klmr 7y ago
    Furthermore, it has nothing to do with epigenetics. It’s good old genetics.
  - abathur 7y ago
    This is a good response. Building a little (but speculatively... I don't know much about wasps and their nest-building instincts): I often wonder what (if any) fractions of behavior that gets chalked up to "instinct" are actually the result of some biological/mechanical affordance, normal learning, and reasoning. (I don't mean to deny instinct as such, but I guess I feel like the razor should exclude it until it's the only option left?) To use the hexagonal example, the term "instinct" implies that the creature could do this thing in a variety of ways, but doesn't. But it wouldn't quite be "instinct" in the sense we mean it if the hexagonal structure is just a coincidental emergent byproduct of some detail of the species' visual system, physiology, etc.
    - jerf 7y ago
      Even in humans, which are relatively short on instincts as animals go, you can see cases where the "instinct" and the "behavior" are not the same thing. Humans have a suckling instinct, which allows us to drink at birth. But it's not an instinct that says "ok, here's how human reproduction works, and here's how milk is produced, and you need to drink from things that look like this and then when you do these things, your hunger will be slaked"; it's an instinct that says when you are tickled here in this manner, turn a bit and start some muscle contractions which result in sucking. They don't cry to say "hey, I need to suckle"... they cry because they feel bad. They don't know "understand" the bad feelings or know how to make them go away. But a combination of a few basic instincts and the environment combine over time to teach them how to eat for the first time. Many other animals have much more complicated instincts, but even then you can often see the instinct starts as something very simple. A fawn "knows how to walk" at birth, but, look at video of a fawn at birth. I say it's a lot more like "a fawn knows to recognize it is falling and trigger an only-modestly complicated reaction to stab the closest leg out in that direction", a neural circuit so simple with a bit of effort you could almost assemble it by hand in some sense. A little bit of control circuitry on top gives it a small amount of mobility. I think one of the reasons "nervous systems" are so evolutionarily successful is that they do give that mechanism to go from simple instinct to a much richer learned behavior, and it's obviously a combination of many things to get to that point. It's amazing how some of these things work on not necessarily all that many "instincts".
SuoDuanDao 7y ago
No mention of Dr. Sheldrake's work on the matter, pity. I wonder whether his work will be considered mainstream in my lifetime.
- klmr 7y ago
  Rupert Sheldrake is an esoteric quack and pseudoscientist. He has not done any relevant work in this field, and his theoretical claims are fundamentally unsound.
  - SuoDuanDao 7y ago
    His early work on rates of learning in birds is definitely relevant if one is agnostic about its legitimacy. What do you consider unsound about his theory?
- s_kilk 7y ago
  Will the work of a crank be considered mainstream? Probably not.
klmr 7y ago
Nick is a former colleague, and I’ve co-authored one of the relevant papers with Isabelle, and with the greatest respect to the two of them I need to caution anybody against taking away the wrong message from this misleading article: these findings are fundamentally not translatable to humans — and even in most cases to mammals, research in mice notwithstanding. Furthermore, most, if not all, transgenerational effects of epigenetic inheritance even in C. elegans is transient. Meaning, the effect attenuates over just a few generations and then vanishes completely. To be absolutely clear: Learning is not inherited in humans. There are good reasons to make this a categorical statement. What’s called “learning” in C. elegans is completely different from “learning” in humans, and adaptive changes in mouse behaviour are, so far, still not clearly demonstrated to be caused by epigenetics, and there are good reasons to be sceptical, as summarised by Kevin Mitchell: http://www.wiringthebrain.com/2013/01/the-trouble-with-epigenetics-part-2.html http://www.wiringthebrain.com/2013/01/the-trouble-with-epige..., and by Bernhard Horsthemke: https://www.nature.com/articles/s41467-018-05445-5 https://www.nature.com/articles/s41467-018-05445-5
- SCHiM 7y ago
  Isn't there a similar mechanism in humans though? Like this: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127768/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127768/ """ One the most provocative observations regarding Holocaust offspring was the report that Yom Kippur war veterans were more likely to develop post‐traumatic stress disorder (PTSD) in response to combat if they had a Holocaust survivor parent25. A higher prevalence of PTSD, mood and anxiety disorders was also observed in Holocaust offspring, largely selected from a convenience sample of people seeking treatment for Holocaust‐related problems, compared with controls26. These findings were replicated in a study assessing the relationship between PTSD in offspring and their own parents, assessed directly by clinical interview of the parent (s)27. """
  - klmr 7y ago
    > Isn't there a similar mechanism in humans though? No. That review paper doesn’t discuss an actual mechanism, with good reason: the authors don’t have a mechanism. At the risk of sounding harsh, the underlying research has been throughly rubbished by the community [1, 2]. It uses a tiny sample size, tenuous correlation and, as mentioned, utterly fails at highlighting a plausible mechanism. It’s bunk: there’s absolutely no need to invoke the spectre of epigenetics to explain why children of traumatised parents may likewise be jumpy, just as there’s no need to invoke epigenetics to explain why children of English parents speak English. In fact, even the review you link to acknowledges as much: > studies in humans have not yet demonstrated that the effects of trauma are heritable through non‐genomic (i.e., epigenetic) mechanisms [1] http://sciblogs.co.nz/code-for-life/2015/08/28/epigenetics-and-the-holocaust/ http://sciblogs.co.nz/code-for-life/2015/08/28/epigenetics-a... [2] https://www.theguardian.com/science/blog/2015/sep/11/why-im-sceptical-about-the-idea-of-genetically-inherited-trauma-epigenetics https://www.theguardian.com/science/blog/2015/sep/11/why-im-...
juskrey 7y ago
Learning, usually depicted as some tedious process, may in reality result to just some one simple bifurcation triggered by some environmental properties, which of course can be encoded in DNA, why not.
- klmr 7y ago
  Sure, and that happens all the time in unicellular organisms. But it’s fundamentally different in multicellular organisms because they have distinct cells forming the germ line. So any (random) changes to DNA in other cells won’t be transmitted. And while mutations in the germ line do happen, they are also random. So far there’s no known mechanism for systematic, guided DNA changes, and no good reason to assume that such mechanisms exist (on the contrary). Furthermore, the article is discussing epigenetic changes which, by definition, are not encoded in DNA and are instead transient (and thus not inherited trans-generationally).
  - blotter_paper 7y ago
    > So far there’s no known mechanism for systematic, guided DNA changes, and no good reason to assume that such mechanisms exist (on the contrary). Why are we significantly less likely to have mutations on our mitochondria than in our fingers? It seems obvious to me that our DNA has error correction mechanisms, and some subsystems are more stringently error corrected than others. This amounts to a control on how much different aspects are allowed to deviate from the last generation. I would be incredibly surprised if a crocodile, who has been in a state of relative homeostasis for millions of years, has the same rate of mutation as a human. Note that I haven't suggested that a directional bias exists, just a set of mechanisms for changing variability of different traits. I wouldn't be particularly surprised by a mechanism for directional bias in some cases, but I don't assume there is one and I certainly don't feel comfortable making the case for it.
    - klmr 7y ago
      > Why are we significantly less likely to have mutations on our mitochondria than in our fingers? I’m afraid this is simply not a biologically meaningful statement to begin with. Mitochondria are subcellular organelles. Fingers are complex organs that are formed from spatial arrangements of multiple cell types. Furthermore, mutations happen on the level of DNA, not on the level of either organelles or organs. Apart from that, mutation rate is (not quite, but more or less) uniform across the whole genome (the exceptions, due to e.g. GC bias, are not relevant here). Viable mutations are not uniformly distributed because of selection; that’s precisely the striking insight that Darwin had (though he was unaware of DNA and genes). Importantly, this does not require a guided error correction mechanism. Simply put, even slight variations in the oxidative phosphorylation pathway of the mitochondrion are likely to kill you during gestation; whereas similarly extreme variations in finger morphogenesis, at worst, make you unable to hold a tool. > some subsystems are more stringently error corrected than others This is virtually certainly not the case, because of what I’ve just described. Selection is sufficient to describe the outcome, and there is no evidence whatsoever to point to the mechanism you postulate. > I would be incredibly surprised if a crocodile, who has been in a state of relative homeostasis for millions of years, has the same rate of mutation as a human. Evolutionary mutation rate is governed by effective population size and generation time. That’s why fruit flies evolve fast and crocodiles evolve slowly. This, too, doesn’t require variable mutability of different traits, and no biologist has yet seriously suggested such a mechanism.
Guthur 7y ago
Totally random. I was thinking of this exact scenario on the way to work today. Not my field, just thought that there seemed to be a growing body of evidence that parental environment was having significant effects on offspring and this further scenario seemed some what logic.
thewhitetulip 7y ago
I've seen domestic cats getting repelled by any object looking like a snake if you bring it sufficiently close to it and that too suddenly.
hi41 7y ago
East Asian men are known to add belly fat. This is a cause for concern because it raises risk for cardiovascular diseases. It is said that this is happening because of famines causing cells to store more fat so that the human can survive no-food scenarios. Is this epi generics? Is it really true?
karmakaze 7y ago
I'm sure there's lots of research being done in these areas but I was always bothered by how behaviors are learned or just instinct. What the hell is instinct? A priori knowledge or just selected, random hard-wiring? I hope we make some progress during my lifetime and start scratching surfaces of these mechanisms. I just hope it doesn't turn out to be via gut microbes--I want it to be digitally encoded.

73 points by cbkeller 7y ago

How do wasps learn how to build those honeycomb structures that make up their nests. If a wasp is brought up in isolation and is able to do this, clearly its inherited.

sacrificedcapon 7y ago
That's the inheritance of instinct rather than the inheritance of learning. If one generation of wasp colony "learned" that building their structures under blue canopy was good (researchers protected these structures) and red canopy was bad (researchers destroy these structures each time wasps make them ) and you take the offspring of this colony and raise them in isolation and they still build under blue canopy and avoid the red canopy, then you can perhaps say "learning" was inherited. It's like how infants inherit the instinct to cry and suckle. Inheritance of learning would be if the mother (since childhood ) was taught to wink and she'd get more attention and food/milk and her infant winked at her instead of crying when the infant wanted attention.
- klmr 7y ago
  Furthermore, it has nothing to do with epigenetics. It’s good old genetics.
- abathur 7y ago
  This is a good response. Building a little (but speculatively... I don't know much about wasps and their nest-building instincts): I often wonder what (if any) fractions of behavior that gets chalked up to "instinct" are actually the result of some biological/mechanical affordance, normal learning, and reasoning. (I don't mean to deny instinct as such, but I guess I feel like the razor should exclude it until it's the only option left?) To use the hexagonal example, the term "instinct" implies that the creature could do this thing in a variety of ways, but doesn't. But it wouldn't quite be "instinct" in the sense we mean it if the hexagonal structure is just a coincidental emergent byproduct of some detail of the species' visual system, physiology, etc.
  - jerf 7y ago
    Even in humans, which are relatively short on instincts as animals go, you can see cases where the "instinct" and the "behavior" are not the same thing. Humans have a suckling instinct, which allows us to drink at birth. But it's not an instinct that says "ok, here's how human reproduction works, and here's how milk is produced, and you need to drink from things that look like this and then when you do these things, your hunger will be slaked"; it's an instinct that says when you are tickled here in this manner, turn a bit and start some muscle contractions which result in sucking. They don't cry to say "hey, I need to suckle"... they cry because they feel bad. They don't know "understand" the bad feelings or know how to make them go away. But a combination of a few basic instincts and the environment combine over time to teach them how to eat for the first time. Many other animals have much more complicated instincts, but even then you can often see the instinct starts as something very simple. A fawn "knows how to walk" at birth, but, look at video of a fawn at birth. I say it's a lot more like "a fawn knows to recognize it is falling and trigger an only-modestly complicated reaction to stab the closest leg out in that direction", a neural circuit so simple with a bit of effort you could almost assemble it by hand in some sense. A little bit of control circuitry on top gives it a small amount of mobility. I think one of the reasons "nervous systems" are so evolutionarily successful is that they do give that mechanism to go from simple instinct to a much richer learned behavior, and it's obviously a combination of many things to get to that point. It's amazing how some of these things work on not necessarily all that many "instincts".

SuoDuanDao 7y ago

No mention of Dr. Sheldrake's work on the matter, pity. I wonder whether his work will be considered mainstream in my lifetime.

klmr 7y ago
Rupert Sheldrake is an esoteric quack and pseudoscientist. He has not done any relevant work in this field, and his theoretical claims are fundamentally unsound.
- SuoDuanDao 7y ago
  His early work on rates of learning in birds is definitely relevant if one is agnostic about its legitimacy. What do you consider unsound about his theory?
s_kilk 7y ago
Will the work of a crank be considered mainstream? Probably not.

klmr 7y ago

Nick is a former colleague, and I’ve co-authored one of the relevant papers with Isabelle, and with the greatest respect to the two of them I need to caution anybody against taking away the wrong message from this misleading article: these findings are fundamentally not translatable to humans — and even in most cases to mammals, research in mice notwithstanding. Furthermore, most, if not all, transgenerational effects of epigenetic inheritance even in C. elegans is transient. Meaning, the effect attenuates over just a few generations and then vanishes completely. To be absolutely clear: Learning is not inherited in humans. There are good reasons to make this a categorical statement. What’s called “learning” in C. elegans is completely different from “learning” in humans, and adaptive changes in mouse behaviour are, so far, still not clearly demonstrated to be caused by epigenetics, and there are good reasons to be sceptical, as summarised by Kevin Mitchell: http://www.wiringthebrain.com/2013/01/the-trouble-with-epigenetics-part-2.html http://www.wiringthebrain.com/2013/01/the-trouble-with-epige..., and by Bernhard Horsthemke: https://www.nature.com/articles/s41467-018-05445-5 https://www.nature.com/articles/s41467-018-05445-5

SCHiM 7y ago
Isn't there a similar mechanism in humans though? Like this: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127768/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127768/ """ One the most provocative observations regarding Holocaust offspring was the report that Yom Kippur war veterans were more likely to develop post‐traumatic stress disorder (PTSD) in response to combat if they had a Holocaust survivor parent25. A higher prevalence of PTSD, mood and anxiety disorders was also observed in Holocaust offspring, largely selected from a convenience sample of people seeking treatment for Holocaust‐related problems, compared with controls26. These findings were replicated in a study assessing the relationship between PTSD in offspring and their own parents, assessed directly by clinical interview of the parent (s)27. """
- klmr 7y ago
  > Isn't there a similar mechanism in humans though? No. That review paper doesn’t discuss an actual mechanism, with good reason: the authors don’t have a mechanism. At the risk of sounding harsh, the underlying research has been throughly rubbished by the community [1, 2]. It uses a tiny sample size, tenuous correlation and, as mentioned, utterly fails at highlighting a plausible mechanism. It’s bunk: there’s absolutely no need to invoke the spectre of epigenetics to explain why children of traumatised parents may likewise be jumpy, just as there’s no need to invoke epigenetics to explain why children of English parents speak English. In fact, even the review you link to acknowledges as much: > studies in humans have not yet demonstrated that the effects of trauma are heritable through non‐genomic (i.e., epigenetic) mechanisms [1] http://sciblogs.co.nz/code-for-life/2015/08/28/epigenetics-and-the-holocaust/ http://sciblogs.co.nz/code-for-life/2015/08/28/epigenetics-a... [2] https://www.theguardian.com/science/blog/2015/sep/11/why-im-sceptical-about-the-idea-of-genetically-inherited-trauma-epigenetics https://www.theguardian.com/science/blog/2015/sep/11/why-im-...

juskrey 7y ago

Learning, usually depicted as some tedious process, may in reality result to just some one simple bifurcation triggered by some environmental properties, which of course can be encoded in DNA, why not.

klmr 7y ago
Sure, and that happens all the time in unicellular organisms. But it’s fundamentally different in multicellular organisms because they have distinct cells forming the germ line. So any (random) changes to DNA in other cells won’t be transmitted. And while mutations in the germ line do happen, they are also random. So far there’s no known mechanism for systematic, guided DNA changes, and no good reason to assume that such mechanisms exist (on the contrary). Furthermore, the article is discussing epigenetic changes which, by definition, are not encoded in DNA and are instead transient (and thus not inherited trans-generationally).
- blotter_paper 7y ago
  > So far there’s no known mechanism for systematic, guided DNA changes, and no good reason to assume that such mechanisms exist (on the contrary). Why are we significantly less likely to have mutations on our mitochondria than in our fingers? It seems obvious to me that our DNA has error correction mechanisms, and some subsystems are more stringently error corrected than others. This amounts to a control on how much different aspects are allowed to deviate from the last generation. I would be incredibly surprised if a crocodile, who has been in a state of relative homeostasis for millions of years, has the same rate of mutation as a human. Note that I haven't suggested that a directional bias exists, just a set of mechanisms for changing variability of different traits. I wouldn't be particularly surprised by a mechanism for directional bias in some cases, but I don't assume there is one and I certainly don't feel comfortable making the case for it.
  - klmr 7y ago
    > Why are we significantly less likely to have mutations on our mitochondria than in our fingers? I’m afraid this is simply not a biologically meaningful statement to begin with. Mitochondria are subcellular organelles. Fingers are complex organs that are formed from spatial arrangements of multiple cell types. Furthermore, mutations happen on the level of DNA, not on the level of either organelles or organs. Apart from that, mutation rate is (not quite, but more or less) uniform across the whole genome (the exceptions, due to e.g. GC bias, are not relevant here). Viable mutations are not uniformly distributed because of selection; that’s precisely the striking insight that Darwin had (though he was unaware of DNA and genes). Importantly, this does not require a guided error correction mechanism. Simply put, even slight variations in the oxidative phosphorylation pathway of the mitochondrion are likely to kill you during gestation; whereas similarly extreme variations in finger morphogenesis, at worst, make you unable to hold a tool. > some subsystems are more stringently error corrected than others This is virtually certainly not the case, because of what I’ve just described. Selection is sufficient to describe the outcome, and there is no evidence whatsoever to point to the mechanism you postulate. > I would be incredibly surprised if a crocodile, who has been in a state of relative homeostasis for millions of years, has the same rate of mutation as a human. Evolutionary mutation rate is governed by effective population size and generation time. That’s why fruit flies evolve fast and crocodiles evolve slowly. This, too, doesn’t require variable mutability of different traits, and no biologist has yet seriously suggested such a mechanism.

Guthur 7y ago

Totally random. I was thinking of this exact scenario on the way to work today. Not my field, just thought that there seemed to be a growing body of evidence that parental environment was having significant effects on offspring and this further scenario seemed some what logic.

thewhitetulip 7y ago

I've seen domestic cats getting repelled by any object looking like a snake if you bring it sufficiently close to it and that too suddenly.

hi41 7y ago

East Asian men are known to add belly fat. This is a cause for concern because it raises risk for cardiovascular diseases. It is said that this is happening because of famines causing cells to store more fat so that the human can survive no-food scenarios. Is this epi generics? Is it really true?

karmakaze 7y ago

I'm sure there's lots of research being done in these areas but I was always bothered by how behaviors are learned or just instinct. What the hell is instinct? A priori knowledge or just selected, random hard-wiring? I hope we make some progress during my lifetime and start scratching surfaces of these mechanisms. I just hope it doesn't turn out to be via gut microbes--I want it to be digitally encoded.