Is brainsize a physical determinant of intelligence?

[Sweet James]

It's a controverial topic that I've never breached in person.

[Bill Haywood]

No. There are plenty of brains that weigh less but are more intelligent than others.

Neanderthal, I have a vague memory, may have been on average heavier than ours.

Brain weight is I believe more related to body size.

[CORed]

Birds have very small brains, compared to mammals, yet some birds, particularly those in the parrot and crow families, are quite intelligent.

[Sweet James]

[ QUOTE ]
No. There are plenty of brains that weigh less but are more intelligent than others.

Neanderthal, I have a vague memory, may have been on average heavier than ours.

Brain weight is I believe more related to body size.

[/ QUOTE ]

We all know that it's an inherited trait though. So there must be some measurable physical characteristic.

[MadScientist]

Brain structure rather than weight or size is what has a marked effect on intelligence. A deformation in structure will result in retardation often and someone like Kim Peek (google it) has a phenomenal memory because of it.

[Matt R.]

Isn't surface area a much more reliable indicator of intelligence than volume? Or is surface area still too simplistic to draw any type of correlation? (I'm looking at you, Rduke)

[Silent A]

I think it's possible to find correlation with any number of simple size measures. The problem is that the correlation is too weak to be useful.

[Rduke55]

Surface area is also too simplistic. It's pretty much accepted that brain size (not gross brain size but the ratio of brain size to body size - encephalization quotient, or related measures that don't use body size but some other measure for "housekeeping" tissue in the brain) generally reflects intelligence between non closely related species but that it's useless (some would say worse than useless) for conspecifics or closely related species.
Brain size measures ignore the complexity and functional diversity of the brain. we may see a time when measures of more specific areas of the brain can correlate with certain aspects of intelligence (because "intelligence" is a pain to define, much less measure) but we're not there yet.

[Phil153]

[ QUOTE ]
but that it's useless (some would say worse than useless) for conspecifics or closely related species.

[/ QUOTE ]

So rduke...

If I was to take 1,000 males with a brain volume of 1450c
And 1000 males with a brain volume of 1250cc

their average IQs would be identical (within statistical limits)?

[Borodog]

[ QUOTE ]
It's a controverial topic that I've never breached in person.

[/ QUOTE ]

Yes. Everything else mentioned in the thread are higher order corrections, but to zeroth order, yes, of course.