WOMEN - A MORE BALANCED BRAIN

On the basis of knowledge prior to 1988, Ashbrook pointed out that whe reas most men are primarily dependent on the left cerebral hemisphere (''dominant hemisphere'') for verbally related functions, women show a greater hemispheric balance in this respect. For men, he argues, thei r possession of a ''speaking'' and a non-speaking hemisphere'' results in a positive-negative, bipolar way of thinking that may be character ized as dualistic and dialectically hierarchical. In contrast, the gre ater balance of hemispheric function in women appears to promote great er generalization and synthesis in their thinking. In this article I c ite more recent neuroanatomical and brain imaging studies that provide further evidence of disparities in structure and function of the brai ns of men and women. As background for an attempt to explain these dif ferences, I give a brief review of the triune evolution of the mammali an brain leading up to the human cerebrum. It is of major significance that the female has played a central role in mammalian evolution for more than 180 million years and that the evolutionary transition from reptilian therapsids to mammals is characterized by the development of (1) nursing, conjoined with maternal care; (2) audiovocal communicati on for aiding mother-offspring contact: and (3) play. In human beings, the infant-carrying hypothesis suggests one means by which, over gene rations, certain parts of a woman's right hemisphere could undergo fun ctional and eventual anatomical expansion. The mother-infant communica tion of basic mammalian sounds with vowel and consonant components sug gests a basis for the origination of speech. Finally, in an expansion or Ashbrook's original thesis, we arrive at the provocative considerat ion that, unlike men, with their dialectical reasoning, women, with th eir more balanced brain, are provided with a trialectial ladder for cl imbing to achieve knowledge. In terms of quantum mechanics, the partic le and wave would correspond to the substance and strength of the side s of the ladder, and the derived psychic information (which is neither matter nor energy) would compare to the rungs in between.