http://www.mega.nu:8080/gender.html

Sexuality is an indispensable mechanism whereby biological evolution bridged the immense gap between asexual/Lamarckian unicellular organisms, and the now plainly preeminent humans. For tens of millions of generations, the lineage leading to humanity has been formed and continued exclusively by sexual procreation. The precise microbiological mechanics of sexuality vary widely from species to species, while the functional consequences - strictly sexual procreation, in which each individual has precisely two parents, each contributing roughly half of the individual’s genome - is absolutely conserved. This evidences the overwhelming evolutionary pressure in favor of the sexual mechanism.

In this essay, I give an overview of the differences between the male and female human phenotypes, concentrating on mental distinctions. For a broad treatment of human brain structures and mental phenomena, see The Symphonic Architecture of Mind, also by this author.

The only universal genetic difference between a male human and a female human is that the male has an additional chromosome, ``Y’’, and it is by far the smallest of all. This tiny minority of genetic content is all that’s necessary to toggle between a male and female phenotype - and in fact most of the male-specific blueprint is not on the Y chromosome at all, but only toggled by it.

Phenotypically, males and females share every organ - every muscle, every bone, every viscus, and indeed every suborgan of the brain - each serving the same function, interrelated to other organs in precisely the same manner - with qualitative gender dimorphism in only the tiny minority with exclusively procreative functions, and a small fraction of the machinery of the brain, particularly certain portions subserving emotion. Overall size - and certain proportions (particularly hip dimensions, but also nuances of facial features, relative neck size, and various other details) - are dimorphic, and males obviously have more hair (particularly on the face), but males and females otherwise look the same.

The basic evolutionary pressures on males and females are identical. Without regard for gender, genes tend to flourish which encode phenotypes that are successful in obtaining for themselves and their relatives (those who share their genes - particularly children, of course) healthy and regular supplies of water and foodstuffs, in procreating, and in protecting themselves and their relatives from the diseases and injuries that are caused by environmental elements, microbial insults, from social or predator attack, or from accidents and errors of action. This success has ample social dimensions, and because humans are highly social, there is a definite - if modest - gender dimorphism in the mechanical and mental aptitudes of males and females. Nonetheless, these dimorphisms are quantitative differences. Neither gender has anything approaching a monopoly on any qualitative capability aside from the basic mechanics of procreation themselves (impregnation vs. pregnancy and infant nutritional provision).

In particular, cognition and emotion are characterized by very little dimorphism. It is far easier to enumerate the differences than the similarities, and I will do this forthwith.

Cognitive and emotional gender dimorphism correspond directly to dimorphism in somatic anatomy and metabolism.

Female procreative organs implement the mechanics of pregnancy. The activation of this system is expensive metabolically, and grossly impedes the envelope of physical performance. This activation is, however, prerequisite to survival of the species. Female procreative organs are internal and substantially protected from the elements and from injury. Male procreative organs, in contrast, are exceedingly exposed, so that male fertility has an elevated sensitivity to physical injuries that are symptomatic of non-competitiveness. Male procreation does not usually involve any metabolic or physical taxation beyond that incurred by the sex act.

Sexually mature females have mammary glands that are deleterious to performance in locomotion, combat, and many other physical activities, but permit the provision of nutrition (and immune system information) to children, which is prerequisite to survival of the species.

On average, within any congenetic and ethnically homogeneous sexually mature human sample space:

* Females have a higher proportion of body fat, which is mildly deleterious to locomotive and other types of physical performance, but is conducive to survival in lean times and to successful metabolic provision during pregnancy. At puberty, an average female adds approximately 30 pounds of fat in the hip region, amounting to 80,000 calories used to fuel fetal development in the third trimester of pregnancy.

* The dimensions of the female pelvis deviate from those of the male pelvis in a manner deleterious to locomotive performance, but permitting successful childbirth.

* Females have immensely less facial hair, reducing resistance to injury, but increasing expressiveness (and therefore depth and precision of psychological influence), and through visual resemblance to children, increasing the prospect that others will protect them.

* Females are smaller, and have less musculature, than males. This reduces metabolic load, in exchange for the reduction in locomotive and other physical performance made inevitable and permissible by the other dimorphic adaptations.

* The female reproductive system cycles with a period approximating that of the lunar cycle, purging itself in menstruation at the end of each cycle, and being capable of initiating pregnancy for only 5 of the 28 days (with the actual fertilization window lasting for only a single day).

* Females who reach menopause live longer than males who reach a chronologically equal age - that is, absent trauma, women live longer than men.

On average, males are distinctly superior at hurling rocks and spears at targets. In fact, on average they are discernibly superior at the pursuit of goals through direct action without a social intermediary. A female on average has a corresponding advantage in using social mechanisms (particularly, language) to lead another person to act in pursuit of her goals. Though the dimorphism in tendency and aptitude is definite, of course males nonetheless pursue goals through social mechanisms, and females do so through direct action without a social intermediary.

Famously, males tend to navigate spatially, while females tend to navigate using landmarks. This has been accounted for by reference to the stereotypical role of the male as journeying hunter and the female as homebody managing the inventory of household implements, but of course this tendency is far from a hard and fast rule, and so does not in fact evidence a strict compartmentation of roles along those lines.

....much more at the link.