Modern physics is all about conserved quantities. Every physical law can be described through an associated conserved quantity. Noether’s theorem establishes a connection between the two.
It makes sense to try to copy that approach to biology, or at least it’s worth a try. The conserved quantity in a living being is the genetics, i think. Because while the body has cell turnover rate, the information that says how the body is built, is constant. That’s why it can be used as a marker and to identify an individual, i.e. when we try to establish whether a person is still the same as they were last year (ship of theseus), we look at whether they have the same blueprint; Similar to how we don’t identify a river by the water molecules in it, but by its trajectory on the landscape. And if that shape is still the same, then we call it the same river, independent of whether the water molecules changed. So the abstract shape or blueprint of something is the conserved quantity that we use to define identity, and therefore it’s the conserved quantity that is relevant in the system. And that’s why it should be considered an important concept, i think.
Share your comments.
the information that says how the body is built, is constant
Shamelessly stolen from Reddit
“Every cell division can result in random mutations. Also DNA of single cells can mutate due to radiation and other events. So you would not get a 100% match in a DNA test, wenn you sequence a single cell. Certain cell types also change their DNA permanently (B and T lymphocytes to be able to produce the same antibodies permanently). However, when you sequence a sample of a lot of cells these mutations won’t be visible in the results because it would be just noise. So overall, the result should be close to 100% but there will always be sequencing errors as well… And there are telomers sequences, which get shorter every cell division. So these will be different as well. On the other hand when you look at tumor/cancer the DNA can be very different. But this is a topic for itself. I hope this helped!”
Noether’s theorem specifically establishes a connection between conserved quantities and continuous symmetries. What’s the continuous symmetry associated with the genome—something analogous to changing time or location that can be varied continuously while leaving biology unchanged?
yeah noether’s theorem isn’t perfect because it only discusses continuous symmetries. nevertheless, it still applies here.
the symmetries that are associated with the genome are rather broad, actually. for example, if a living organism moves both in time and in space, the genome stays the same, while the proteins in the body might change due to different gene expression (Regulation of gene expression). and therefore the metabolites produced change as well.
if a living organism moves both in time and in space, the genome stays the same, while the proteins in the body might change due to different gene expression
That sounds like a reaction norm—all the various phenotypes a single genome might potentially develop into under different environmental conditions. Which doesn’t seem quite analogous to Noetherian properties like momentum and energy, which are conserved in the sense that they can change inside a system as long as there are balancing actions that preserve the property for the system as a whole.
