Thousands of years?
We've only had the tech to be able to research this in some technical depth for a few decades (both scale of computation and genetics / imaging techniques).
We've only had the tech to be able to research this in some technical depth for a few decades (both scale of computation and genetics / imaging techniques).
Even skin cells exchange information in neuron-like manner, including using light, albeit thousands times slower.
This switches complexity of human brain to "86 billions quantum computers operating thousands of small neural networks, exchanging information by lasers-based optical channels."