Evolution of the human brain: when bigger is better

[Rynn]

Well, here's an idea for you. Consider that the subcortical areas of the brain (hippocampus, amygdala, cerebellum, etc) decrease in size as a percentage of the brain as it increases in mass. So, for example, a brain sized at 9 kilograms, assuming it retained the same proportions, would have a subcortical area of zero percent!

This is a trend that has been true for human evolution, it is not a universal trend even in mammals. Sperm whales have 9kg brains with one of the largest cerebella of all animals.

This is obviously not desirable, you can't have a brain composed of 100% white and grey matter. Or can you?

It's pretty clear that cranking up a natural human brain in size isn't going to lead to continuous gains in capacity. That hasn't been a disputed idea in biology for a long time. Nor in science fiction (including OA) where different cognitive architectures are a frequent strategy.

Supposing we were to make the spinal cord itself the cerebellum, hippocampus, amygdala and so on. That would allow for a truely massive brain, around 8750 cubic centimetres in mass, devoted to nothing but cerebral cortex tissue for thinking with. Meanwhile, the 'non-thinking' areas of the brain could be located along the spine in the torso. They still play important functions, but the latency issue is less critical since they're not directly involved in human cognition.

Whilst coordination overhead cannot be completely solved with increased speeds faster action potential propagation can (and has in evolutionary history) significantly reduced latency in nervous systems.

This would allow these peripheral areas to be located further away from the rest of the brain, without compromising the main thinking process. A compubone skull could store short-term memories that the main brain might require in a hurry, while long-term storage could take place in the spine.

Meanwhile, the left and right hemispheres of the main brain are shrouded in the extra neocortex layer, which monitors their thought processes and allows for new types of cognition and thinking that wouldn't normally be possible for a biont. As a side effect, limited Transavant thinking processes become available. Unlike a normal Transavant, these aren't limited to one specific area, but cover a broad range of basic Transapient thought.

I was thinking that rather than being the result of a prank, the design of this brain would be carried out by First Federation Transapients in order to research spikes in toposophy. We know from the Encyclopedia Galactica that in 1116 AT (click here), a Transapient managed to achieve a spike in intelligence to the S2 level. Perhaps they created the Highbrows to investigate the nature of Transavants, and to understand how to move past these isolated places on the toposophic landscape to the next true singularity level.

I don't really see the need to rewrite the highbrows along these lines. They already have superior level augmentations to the coordinating parts of their brains. It's up to ai_vin if he'd like to go into more detail with them. As it stands there's nothing wrong with the article. Any questions of "how is the coordination handled in such a brain" is explained by "they have much better neural circuitry for coordination".