Hacker News Reader

Comment by molticrystal | Hacker News Reader

Along similar lines of interesting memory studies of simpler lifeforms, there is an article titled "These Decapitated Worms Regrow Old Memories Along with New Heads"[0] and study [1] which can alter your assumptions on how and where memories are stored and retrieved.

Also there were claims starting in the 50s where planarians were taught a maze or to respond to certain stimuli and then fed to other planarians and that the trait would sometimes transfer as well. I don't know if any of those studies were reproduced, thus the claims might be dubious, but it would be interesting if they were true.

[0] https://www.smithsonianmag.com/science-nature/these-decapita...

[1] https://pubmed.ncbi.nlm.nih.gov/13881412/

View on HN

Not only simpler lifeforms. Cases with humans that may indicate a memory transfer after organ transplants are also documented:

https://pubmed.ncbi.nlm.nih.gov/31739081/

> The acquisition of donor personality characteristics by recipients following heart transplantation is hypothesized to occur via the transfer of cellular memory

http://www.namahjournal.com/doc/Actual/Memory-transference-i...

> There have been perplexing reports of organ transplant receivers claiming that they seem to have inherited the memory, experiences and emotions of their deceased donors, and which are causing quirky changes in their personality.

Yeah, find these highly dubious. A heart transplant is quite a traumatic event, both physically and emotionally, who knows what side effects the patients were experiencing after the procedure.

Yes but the heart contains a lot of neurons so it's an interesting theory.

Over half of all neurotransmitters, including 80-95% of seratonin, originates in the gut. I wouldn't be surprised to hear a microbiome-based theory of personality but cellular memory is a new one to me

Possibly related: it turns out horizontal gene transfer is way more common in humans than we could expect and we really don't have a good explanation for how it's happening

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5379729/

Over half of all neurotransmitters originates in the gut, but the barrier preventing the entry of neurotransmitters into the brain is very effective in healthy individuals.

Signals from the gut to the brain arrive via the vagus nerve and probably also the other cranial nerves.

Interesting! The way I've often heard it is that "over half of neurotransmitters originate in the gut" — making it sound like it's talking about the neurotransmitters already at the brain. Do you have any citations that could clarify this?

I probably learned that fact from an episode of neuroscientist Andrew Huberman's podcast--more likely than not episode one:

https://youtu.be/H-XfCl-HpRM

Neurotransmitters are used all over the body. A lot is centralized in the brain, but the periphery also uses neurons and neurotransmitters.

Neurotransmitters in general don't particularly imply they're being used in the brain. Some neurotransmitters travel through the body, but a larger fraction are produced locally by a cell and intended only for close neighbors.

that concept is part of the premise of Parasite Eve, a great novel, turned into a shitty movie, turned into an alright game.

Same as "The Marked heart" / "Palpito" / "Herzschlag" on Netflix.

(For those about to watch it: the soul-vibing Neighbours-esque intro song is all part of the charm of this show. The shittier the intro, the more dramatic the needless melodrama is in contrast)

>Also there were claims starting in the 50s where planarians were taught a maze or to respond to certain stimuli and then fed to other planarians and that the trait would sometimes transfer as well

So superpowers were transferred when ate? Kirby devs were on to something.

Plants too seem to be able to pass down epigenetic memories

https://www.cell.com/trends/plant-science/fulltext/S1360-138...

Given this and the recent discovery that plants can pass down RNA through mycorrhizal networks and can recognize their own offspring, it seems plausible that memories can also be passed through mycorrhizal networks.

What stories does the soil hold?

I've long had this crackpot theory that mycorrhizal networks are to plants what skin and digestive microbiome are to humans

Not that crackpot imo. The essential difference between animals and fungi is that at some point one group decided to digest things internally with a stomach (animals) and another group decided to digest things externally with enzymes (fungi). This external relationship to nutrients might make fungi as an organism simply more modular and able to make more interesting symbiotic relationships. Acting not just as partners but organs of a larger body

The planarian result was probably insufficiently sterilizing the maze, and following previous scent-trails.

Feynman quoted a Mr. Young for admirable rigorousness in maze-running experiments.

“Finding Mr Young”[1] identifies him as: “Mr Young was probably Quin Fischer Curtis, in his theses published in 1931/1936, as part of John F. Shepard’s multi-decade research programme at the University of Michigan into ‘floor cues’, going well beyond just putting sand on the floor.”

1: https://gwern.net/maze

Genes can transfer between species, so I don't see why this wouldn't be possible.

https://en.m.wikipedia.org/wiki/Horizontal_gene_transfer

That's typically through parasitic/grafting/symbiotic relationships, and even that takes a few half millienia of repeated symbiosis and selective pressures to take. What's being described here is much faster and much more immediate.

In micro-organisms, HGT happens in a very short timeframe. In fact, some soil fungi have been observed to somehow purposely increase their rates of HGT when put in a new and stressful environment. Borrowing genes from entire other domains of life like bacteria or archaea. Also study after study keeps showing that rates of HGT in complex multicellular species like fish[0][1] and even humans.[2] I'm not trying to be sensational (and generally agree it's likely not that relevant to the current discussion) but one thing that's clear from our consistent underestimation of the prevalence of HGT is that there's still a lot more to it than we currently understand

[0] https://www.quantamagazine.org/dna-jumps-between-animal-spec...

[1] https://www.nature.com/articles/srep18676

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5379729/

thanks for the extra material!

It's all very abstract, and hard to narrow objectively, considering considering that we don't really know what a "memory" or skill is. The mechanism.

> alter your assumptions on how and where memories are stored and retrieved

I remember reading an anecdote about a baby who didn’t like being held by their father, who happened to beat the baby’s mother during pregnancy. No idea of the veracity of the story but something about it had me thinking similarly about “instincts” and where they come from. The meaning of the word does seem to be a lot like memories that are “passed on for generations”.

In late stage pregnancy babies in the womb can hear voices, and can often identify their father after birth by their voice immediately after birth. Violence often includes a lot of shouting, and physiological stress on the victim which would affect the baby. I’m guessing the baby learned to associate these.

n=1, but I sang to both my daughters in the womb (different songs) and after they were born singing "their" song would calm them down a lot faster. I don't think this is as much "instincts" as it is "very early experiences".

Make it n=2.

Babies develop a preference for their primary caregiver, who is usually the mother.

Young children generally are more cautious around men than women, which is probably good risk management. Instinctive? Possibly.

> probably good risk management

Is it, though? This data [0] says otherwise.

[0]: http://www.breakingthescience.org/SimplifiedDataFromDHHS.php

Did they start collecting data 100k years ago? Cause that is the timescale for this stuff no?

This is an extraordinarily important point to make, especially in light of the GP comment and the perception that it reflects.

That’s one very specific type of risk, and a thankfully rare one. (That also appears to be a men’s rights activist site with an axe to grind on this subject).

A more neutral source:

https://bjs.ojp.gov/content/pub/pdf/htus8008.pdf

… which suggests the opposite (but there’s not much in it).

In terms of broader risks, males commit a clear majority of violent offences and a vast majority of sexual offences.

This isn’t even just a human thing. Male primates (and mammals generally) exhibit more aggressive behavior than females. It’s probably a deep consequence of anisogamous sexual differentiation:

https://www.cell.com/trends/ecology-evolution/fulltext/S0169...

hehe, that's the first thought that came to mind.

I don't know about people in biology in general, but it seems a whole new space of considerations.. topological communication, spread of information..

and if people are curious about other aspects of this, google peter reddien, he had a lab who focused on planaria regeneration too, and by playing with location and numbers of cuts they triggered some cascading patterns of regeneration (think https://www.explainxkcd.com/wiki/index.php/File:iso_paper_si... but with biological tissue and organs)

Reply on news.ycombinator.com