What are the conditions in which a creature would evolve more than one brain?

Would any creature ever need to evolve a second (or multiple) brain(s)? If so, under what conditions, why, and what implications would it have on the creature's intelligence?

Note that while an octopus' arms are independent from its brain, the animal itself doesn't have more than one brain.

Also note that it was discovered that the stegosaurus didn't actually have nervous tissue in its tail section, and as such fails the 2 brain minimum requirement.

In order to qualify as having multiple brains, the brains must be able to work as individual unit(s), while at the same time being able to cooperate to focus on more intensive tasks. If the creature were to lose one brain, the other brain(s) must be able to assume full control of the creatures body, such that it would be able to function (almost) as efficiently as before. In other words, you can't have a brain that deals with just movement while another one deals with just regulating bodily functions. The brains must be able to "swap jobs" as necessary.

I'm not looking for the design of a creature that has 2 brains; however, if the answer so requires the design in order to make sense, feel free. I'm more for looking specifically at the "how this evolution would make sense".

The environment: doesn't matter; it can be in a jungle, the sea, the land, the skies, whatever you see fit, but assume an earth like planet and its current environmental conditions (without the humans).

Predators and prey of said creature: Whatever makes sense. Perhaps the creature needs a second brain to rotate sleeping functions in order to avoid predators (not unlike the dolphin, with Unihemispheric slow-wave sleep that rotate sleep - however, still one brain, so it fails the requirements)

Note: Not a duplicate of Creature with a non-centralized brain because even though the requirements are similar, I'm asking for more than one centralized brain while the other is asking for no centralized brain.

Note: while it's very true what most answers have pointed out regarding the inefficiency and improbability of this occurring, the question does in fact ask for the conditions of said mutation occurring, and not the plausibility of of the mutation. My reality-check is not about how likely it is, but how it could happen. Please do consider coming up with an environment in which said mutation would occur instead of telling me why it won't occur (at this point, I already know it's highly unlikely).

posted over 9 years ago

Aify‭

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