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

Some of it depends on local gravity. Gravity lower than Earth’s would support larger creatures more easily. Living in water also helps offset gravity. Higher gravity would mean smaller animals, because larger/heavier would have a hard time moving around. “Square-Cube” law applies.