how do scientists come to the conclusion that certain animals have the intelligence of a ____ year old?

Question

I hear an octopus has the intelligence of a 7 year old or a monkey is as smart as a 5 year old….. how they figure that out.

In: Other

Answer 1

They give the animals and small children tests and see how they solve them.

If they don’t have object permanence (knowing something is still there even if they can’t see it) thats about equivalent to a less than 7 month old human child.

If they know how to use tools, then that’s about equivalent to a 2 year old child.

We have studied lots of children so we know when their brains develop these skills.