How do neurons communicate?

With domesticated viruses, yes, no kidding. Let me explain: between 5% and 8% our genome is not ours but comes from viruses that have been petrified inside our DNA.

But, how did they get in our DNA?

Well, this can only be done by a type of special virus called retrovirus. The best known of all is the HIV or AIDS virus, normal viruses enter the cell and release its genetic material, deceiving the cell to read, process and work for it.

Retroviruses are a bit more sophisticated and what they do is enter the cell by releasing their genetic material and inserting it into our own DNA. In this way when our cells read their DNA they believe it's theirs but in reality they're reading that of the retrovirus.

We have this percentage of viral DNA for the infections that our ancestors overcame, this is something that has been known for some time but scientists thought that this DNA was inactive and that we never used it because in the end we are not viruses. Why are we going to want to use it?. The scientific community has focused on a specific gene called ARC that was long known to be important for communication between neurons for the consolidation of memories but it was not known exactly how it worked.

When looking at it in depth they have realized that the neurons what they do is make a capsid, which is like a box, inside that box they put RNA, they leave the neuron and they get into the one next and they cause changes in their way to work. We could say that the neurons have taken something that a long time ago was an enemy and have turned it into a tool that's now at the service of the neuron.

How long have they been inside the DNA?

They have realized that this ARC gene is present in mammals, birds, reptiles, amphibians but practically no fish. This indicates that the original infection, the one that put this DNA in our genome, took place just after we separated from the fish when we started walking on the mainland, more than 400 million years ago.