Brainless Embryos Suggest Bioelectricity Guides Growth
quantamagazine.org
quantamagazine.org
I don't get it. Where does that electrical guidance came from? The brain. Where did the brain came from? The DNA.
If DNA is the ony information that makes it from a parent to offspring (and we can grow organisms in a petri dish from fertilized eggs) is the DNA, then whatever electrical guidance or other abstraction must have been encoded in the DNA first. (Plus some constants encoded in the enviroment.)
I don't think this assumption is warranted. Human embryos develop in utero, not in eggs like amphibians. They are connected to the mother through an umbilical and immersed in amniotic fluid. Both the umbilical and the amniotic fluid are full of chemical signals in many forms, not just hormones. Human embryos (and all mammals, really) develop in symbiosis with their mother.
What you are saying is another one of these CS-centric views of the world that only focus on where the information for development comes from; that the development of the brain is somehow encoded in DNA, and that the entire development of a human is therefore also encoded in the DNA.
I've come to doubt this view, not only because of mammal development, but the fact that immune systems and digestion (the microbiome of the GI) develops in response to the available biodiversity of food and encountered pathogens.
So the view that we just put the little DNA program in a dish and feed it raw materials and energy and out pops a fully-formed human is just false.
Humans develop in cooperation with, and in response to, the environment.
It's a bit like staring at the code of a machine learning model and expecting to figure out how it works. The system (a human) contains a lot of code (DNA) but also responds to data (training set)--much more so than we ever realized.
Or like a Smalltalk programming environment, which consists of an image with live, editable objects, not just a static text program.
A neighbor comment mentions the shape of the uterus, but AFAIK this only matters in later stages of development (extrauterine pregnancies happen, and are quite deadly unless aborted since most tissues are not meant to be invaded by the placenta).
Some of the non-electric signals are given by gradients of expression of the Homeobox genes.
There is also a process of mutual differentiation where neighbouring tissues cause each other to differentiate. For example, holoprosencephaly happens when the brain fails to (fully) develop into two hemispheres.
The most severe cases results in the formation of a single eye that in turn induces gross face deformity (Cyclopia, with a nose stub above the single eye).
The mildest cases result mostly in normal people with a lack of smell and a single top central incisor.
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From the article:
> The rationale [...] was that “since DNA is what is inherited, information stored in the genes must specify all that is needed to develop.”
> The extreme form of this view is “to explain everything by saying ‘it is in the genes,’ or DNA, and this trend has been reinforced by the increasingly powerful and affordable DNA sequencing technologies,” Huang said. “But we need to zoom out: Before molecular biology imposed our myopic tunnel vision, biologists were much more open to organism-level principles.”
> The tide now seems to be turning, according to Herrera-Rincon and others. “It’s too simplistic to consider the genome as the only source of biological information,” she said.
(emphasis added)
If genes are all-powerful, there is no hope for those who begin to deteriorate. But if our bio-electric fields are more important than our genes, there is much greater possibility for improving our health than the geneticists have led us to believe.
While genetic screening is desirable, it is going to take a long while before we can have it on a species level. But if we can develop chemo-electric interventions that can alter the progression of genetic conditions, that would be a fresh change in the field, impacting many lives.
As we hit the physical limitations of interventions based on central dogma(which is still years away), we will have to look elsewhere, with an emphasis on the temporal progression of gene expression with respect to different variables. This is going to be difficult, but I can hopeful that some controlled processes might turn out in the future - given our data processing abilities.
This would be one hypothesis. The article is about how the competing field of inquiry ("bioelectricity") has been mistakenly ignored for the past 60+ years.
What if the field is more important than the genes?
Meanwhile, in terms of the parent article, yes- it turns out that "bioelectricity" is an important part of the embryonic development. But this is not at all serving the same role as DNA; DNA stores durable information, whereas these fields are being used for, essentially, intercellular communication. I would think that the fact that the researchers successfully replace a frog's entire brain, for developmental purposes, with a simple tweak to an ion channel, pretty clearly demonstrates that the amount of vital information being carried this way is minimal.
It's been a while since I was in a devo lab, but I've watched a few presentations regarding wound healing and denervation such as seen in paraplegics with sacral ulcers. The hypothesis was that the nerves were gone and therefore NGF and other trophic factors were gone leading to impaired healing. I'm assuming healing and development are nearly synonymous in some tissues. Like you said, it's not the electrical signals that necessarily matter that much, it's the chemicals produced by the nerves.
The discussion of what layer we should concentrate our research on has been going on for a long time actually. I remember reading some passionate arguments a decade or so ago about how we should concentrate on cells as the basic unit of biology.
What about HOX genes?
[1] https://www.amazon.com/Life-Unfolding-human-creates-itself-e...
You see, the Matrix itself is the proof-of-work puzzle, formatted for compatibility with the neocortex. The simulation of a circa-1999 metropolis is not just something to keep the humans' brains occupied while they power the machines; its very substance is a cryptographic hashing process in the form of a simulated world, which also explains why everyone has to be in the same Matrix rather than instanced versions. Agent Smith's real job was just to prevent 51% attacks!