How do living things without brains function?
In: Biology
Same as things with a brain function; endlessly cascading chemical reactions that result in the eventual reproduction of said being.
Sure, our brain is a lot more sophisticated than pretty much every other biological machine out there, but that doesn’t mean they can’t function.
You can think of a cell’s nucleus as that cell’s brain, for all intents and purposes it has the same function as being the central hub that is controlling how things react around it.
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Brains are pretty much irrelevent for most of the things that living things do. Biochemistry _within_ a cell, from photosynthesis to respiration (breaking down sugars), doesn’t require any input from nerves at all. Cell division and growth doesn’t require nerves. Local responses to chemicals don’t require nerves. Immune responses don’t require nerves. Anything a plant does, basically doesn’t even need nerves to happen, much less brains.
But nerves are useful, they allow animals to sense things and transmit that stimulus to cells that can then contract. They also form the building blocks of memory and processing information. For something like a jellyfish or anemone, a simple network of nerves is enough to handle the extremely simple information processing that happens. Something touches the end of a tentacle, the nerves transmit the signal and get muscle cells to contract the rest of the tentacle. For slightly more complex animals like some worms and starfish, it can be enough to have clumps of neurons here and there in the body to handle slightly more complicated tasks, even thought there isn’t a real brain.
A proper brain is really only necessary for animals that need to process a lot of information, remember things, and control complex muscle movements (granted, these animals can be as simple as worms or flies or other things we think of as not very bright).
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