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(1) Human beings are dimorphic.
(2) Dimorphism in humans is a method of continuing the species by role segregation so as to accommodate a long gestation period as well as serving to accommodate the extended maturation period that is necessary to effect the developement of a speaking brain.
(3) It is important for men to proceed quietly when hunting and fishing and argriculturing.
(4) It is important for women to exchange information pertaining to the safety of the collective nest.
(5) I will assume that you women can infer the rest.



I don't think this is as cut-and-dry as you would have us believe.

I read about sexual dimorphism and parental investment recently in The 21st-Century Brain (2006) by Steven Rose. Only he puts much less emphasis on sexual dimorphism in humans than you do.

If I understood Rose correctly, the level of parental investment by the male of any given species is inversely proportional to the degree of sexual dimorphism. (In plain English: The more similar the male and female of a species look, the more of a "mummy" the daddy is likely to be be). Homo sapiens has a VERY low level of sexual dimorphism compared with other species.

I don't have the book on hand but the same idea is found in the Wiki article on Sexual Dimorphism:

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Human male and female appearances are perceived as different, although Homo sapiens has a low level of sexual dimorphism compared with other species. For instance, the relative similarity in the sizes of many male and female human beings suggests that divisions for homo sapiens are less clear than other species as the overlap of sizes between the two sexes is slightly less than 1 standard deviation. The Centers for Disease Control and Prevention published new American curves in 2000. [1] See also intersex.
The body masses of both male and female humans are approximately normally distributed. In the United States, the mean mass of an adult male is 78.5 kg (173.1 lb), that of the adult female mean is 62.0 kg (136.7 lb). The standard deviation of male body mass is 12.6 kg (27.8 lb), so 10% of adult males are lighter than the average female.
Some biologists theorise that a species' degree of sexual dimorphism is inversely related to the degree of paternal investment in parenting. Species with the highest sexual dimorphism, such as the pheasant, tend to be those species in which the care and raising of offspring is done only by the mother, with no involvement of the father (low degree of paternal investment). Conversely, the low level of sexual dimorphism in humans is said to correlate to the human species' high degree of paternal investment (fathers make a high investment in childrearing).



It might therefore be concluded, argues Rose, that male gender roles are more the result of enculturation than evolution.

It is interesting to note that the male mammary glands are capable of producing milk under the right conditions, and that the Viking men are said to have sometimes breast fed.

In conclusion: The fact that women are more talkative than men cannot be explained by arguments that focus single-mindedly on the social habits of early, pre-civilized man. Case in point: You might also argue—(I am not)—that modern man, as the bread winner, went out into the world in a more social, language-taxing role than his poor wife who stayed at home looking after the kids and scrubbing the floors with little adult contact.