>I was surprised to find out that I could not find a single neurotransmitter that is not shared between humans and mice (let me know if you can find one, though).
As far as I can tell, this is true. The closest I could find is a single subtype of receptor that a frameshift mutation in a primate ancestor made nonfunctional.
I suspect you’d have to go even further back in terms of divergent ancestry to find actual differences in the neurotransmitter substances themselves. There are definitely differences in receptors and affinities, but the actual chemicals? From a quick search, you’d have to go all the way to ctenophores, which are so different that some have posited they evolved nervous systems independently.
>I was surprised to find out that I could not find a single neurotransmitter that is not shared between humans and mice (let me know if you can find one, though).
As far as I can tell, this is true. The closest I could find is a single subtype of receptor that a frameshift mutation in a primate ancestor made nonfunctional.
https://www.sciencedirect.com/science/article/pii/S0021925818352189
I suspect you’d have to go even further back in terms of divergent ancestry to find actual differences in the neurotransmitter substances themselves. There are definitely differences in receptors and affinities, but the actual chemicals? From a quick search, you’d have to go all the way to ctenophores, which are so different that some have posited they evolved nervous systems independently.