I kind of skipped through this article, but one thing occurs to me about big brains is - cooling. In Alastair Reynolds Conjoiner novels, the Conjoiners have to have heat-sinks built into their heads, and are on the verge of not really being human at all. Which I guess may be OK, if that's what you want.
I believe it's the Revelation Space series of Alastair Reynolds novels that mention the Conjoiners.
Yes, and other ones, such as "The Great Wall of Mars" - it's the same shared universe, all of which feature the Conjoiners and their brains and starship drives.
Likely would be larger skulls and bodies, not more dense, https://en.wikipedia.org/wiki/List_of_animals_by_number_of_n...
Desert hares (jackrabbits) have heatsinks built into their heads too.
https://en.wikipedia.org/wiki/Hare
Couldn't you just watercool brains? Isn't that how they're cooled already?
Well, our entire body works as a swamp cooler via sweat evaporation, yes. The issue with us is wet bulb temps and dehydration. It can already brain damage us pretty quickly and makes some parts of the world already dangerous to exist in outside.
Adding to this cooling load would require further changes such as large ears or skin flaps to provide more surface area unless you're going with the straight technological integration path.
Reminds me of how Aristotle thought that the brain’s purpose was to cool the blood.
You know this, but it just shows that geniuses like Aristotle can be completely wrong - most of our body is trying to cool the brain!
Even coming up with a plausible wild guess takes some skill.
trivia: brain heatsinks also feature in Julian May's Pliocene Saga (in The Adversary IIRC) and A.A. Attanasio's Radix
Rocky from Project Hail Mary is also heatsinked.