[PeterisP]

The octopus is a counterpoint to this, being very intelligent but absolutely solitary.

[mcv]

But it has excellent hands.

Humans may be unique in having both complex social structure as well has hands.

[nicoburns]

Arguably elephants fall somewhat into this category...

[mcv]

I've often wondered whether elephant-like aliens would make sense, exactly because of this.

I guess Niven and Pournelle had the same idea for Footfall.