Is there a specific size range for intelligent life under biological constraints, or could smart aliens be as much smaller than bugs or much larger than whales?

Question

I read a long time ago an essay by Asimov that described what elements could support life as a building block and why most elements cannot. I didn’t fully understand that at the time but it was interesting to see why carbon based makes sense and some other random element does not work.

Similarly, I wonder if under different planetary conditions, smart alien life (so not single cell life) can be very tiny or very large, or if there are biological constraints that would restrict that size range regardless of basic setup.

In: 324

Answer 1

There are restrictions in the small direction. Cells could be smaller than ours but not arbitrarily small. Brains smaller than ours can be very smart, but there need to be billions of neurons or otherwise it will be limited in ability.

Those together mean there is some lower limit, but I can’t tell you where it is. Squids and birds on earth prove that with their comparably small brain and short lifespan that intelligence can work with very few ressources.

In the other direction there is no real limit. There are gigantic organisms even in earth, with tree colonies or gigantic mushroom networks that are basically just one organism that is connected. There is nothing that would rule out such a being evolving a form of intelligence