Re: Brain size, IQ

Bryant (
17 Sep 1996 08:45:16 -0600

In article <>,
Ralph L Holloway <> wrote:
>When neuron packing density is high, the cells tend to be smaller and have
>fewer ddendritic branches. I sincerely doubt that that correlates
>"positively" with brain size, which tends to show quite the opposite (see

Thanks! I've asked for the ref I referred to, and will chase it down.
Maybe that will shed light on what's going on here (I have probably
somehow garbled the meaning of the paper I mentioned).

>What exactly is "developmental stability"?

"Good development." Developmental *in*stability is imprecise expression
of developmental pathways. The classic measure of DI is fluctuating
asymmetry in normally bilaterally symmetrical traits (like hands, eyes,
etc.). hence, at a population level, traits which are supposed to be
symmetrical will have a normal distribution of left minus right values
with a mean of zero, or symmetry. (Drawing this may make what I'm saying
more comprehensible.)

DI is a measure of developmental stress.

>R. Holloway