[AstralTraveller (David)]

Interesting question, to which I certainly don't know the answer. But that won't stop me commenting .

Intelligence is obviously a fraught concept. What is it? Can it be measured? Is there any truly intelligent life on Earth? Nailing down exactly what intelligence is probably akin to nailing jelly.

It is true that there are social creatures that we would consider intelligent (primates, dolphins) but what about ants and termites, perhaps they have a communal intelligence but the individuals are automations. Then there are communal creatures that don't work together, wildebeest for instance hang out together for mutual protection but individually all they do is eat grass - they have no group project like building nests.

Don't underestimate the role of labour and tool making in developing intelligence. It's true that other animals make tools but none of them are equipped with the human hand. A beak or tentacle is not able to perform all the actions of a hand. Even other primate's hands are less useful than the human hand. Could it be that the development of intelligence has gone hand-in-hand with the development of the hand (sorry, couldn't resist).

The better communication skills of humans is certainly a product of our intelligence but it is also a driver. Other animals have to learn by watching but we can also impart knowledge, including abstract concepts like morality and algebra, verbally. Also, all of human knowledge doesn't have to fit into one head. It can be spread around society or written down.