brain sexual dimorphism [cont'd]

Sun, 19 Feb 1995 02:01:00 PST

Foss writes:

"... quoted Dr Sally E. Shaywitz ... to the effect that
there was no evolutionary survival or sexual advantage for the dimorphism,
considering that males and females performed the decoding task equally well.
Are all the parts of the latter suggestion equally valid?"

Foss's questioning of this interpretation of the sexual dimorphism in brain
functioning is well taken. Following the same kind of reasoning, one might
say that sexual dimorphism in male and female body size is without advantage
on the grounds that both males and females eat and digest food equally well.
One argument (and there are other arguments) for sexual dimorphism in males
and females relates to the difference in total metabolic requirements of
males and females where for females the metabolic "cost" of reproduction
and fetal development needs to be included in the total metabolic requirement
(Larry Mai, personal communication). Lack of apparent dimorphism in behavior
in one area (decoding) does not exclude dimorpphism in behavior or abilities
in other areas as Foss goes on to suggest.

D. Read

As Foss goes on to ask rhetorically, there are many areas where there is an
apparent difference in male/female performance in language skills which
conceivably relate to