I suspect the desire to climb things at 8 months may well indicate a GT kind of curiosity, but the ability to do so seems more related to speed of myelination, and that seems unrelated to IQ -- at least IMO.
Is that a professional opinion, or an intuitive one? The relationship between myelination (not sure about "speed of" it) and IQ seems to be complex, but not non-existent, see e.g.
http://dx.doi.org/10.1016/j.neuroimage.2008.07.038The relationship between physical and cognitive precocity is something I've wondered about a lot, because my DS was a very late talker, and in most other physical respects age-typical, but [oh golly, even here I find it really hard to type stuff about him, it feels like boasting - gulp here goes] he is obviously cognitively exceptional. He obviously understood everything very young, and was good at getting what he wanted by non-verbal means, but at his 22 month health check, I remember, I couldn't tick the box for "uses at least 5 words regularly". By 24 months, he had >100 words, and by 26 months, he was talking in 4-5 word sentences; since then, his language has always been advanced. Several of his first ten words were numbers, and he knew his letters before he could talk (he loved Starfall, and I found he could correctly "point to a letter [whatever]" in arbitrary context well before 2). Not typical!
My [common sense rather than professional] opinion is that most practical skills are complex. For speech you need both the cognitive intention to make the right sounds, and the physical control to be able to make them. It looks to me as though for most (even the vast majority of?) children the limiting factor is cognitive, in that the physical ability is usually in place well inside the first year but the cognitive ability is not. However, I surmise that there's the odd child, like my DS, with later physical development, so that that becomes the limiting factor. This is consistent with a tendency for GT children to speak early, but not a universal rule.
Climbing, I would guess, is a less clear case as the physical requirement probably dwarfs the cognitive requirement. Still, the latter will be there. One thing I wonder is how much it has to do with parenting style: I've known a few children climb before they can walk (in fact mine did, though not as dramatically) but I observe that most parents aren't comfortable with this, so most children don't get much opportunity!
