The Book of Genesis says that when God let Adam rest, He took out a rib of Adam and made out of it a Woman, Eve. The word woman literally means, out of a man. Such is the close relationship between man and woman. Man has not been able to rest since woman was created. It is an emotional trip, a necessity, an outlet for man's inexhaustible needs. With woman, God created desire. Desire to like, to touch, to feel, to inhale, to be with and at times to be without. Ironies, dilemmas, clairvoyant attitudes all blame the existence of two genders as the cause of all perplexities.

Why should a man like a woman is an old question which has never been adequately answered. "Just because" is perhaps the best answer. How many ways a man can like a woman is quite different from the limited number of ways a woman can like a man. Men fall in love, women hardly do so quickly. Such is the dichotomy of the two "species" forced to live together.

Whether men and women are really different from each other or that they appear different because of the stereotypical roles society expects them to perform is an ancient question. Much has been pondered, a lot has been said and a great deal more has been meant between lines in debating this issue. Until recently, this was considered a dead issue--Women having won the issue of equality, at least in the developed world. Now brews the storm again. All those scientists that thought that it was the issue of Nurture and not Nature, now find it hard to swallow that they were wrong--dead wrong. Studies in the structure and development of brain, made possible by new molecular techniques, now prove that men and women are quite different.

Women and men differ not only in their physical attributes and reproductive function but also in the way in which they solve intellectual problems--making them literally species apart.

In this day and age of equality of sexes, the liberation movement and justification of every cause, it is considered impolite to suggest that these differences between the sexes are more than the result of their cultural and social experiences. Sociologists will point out that girls behave different from boys because that's how they are raised--they are captive to the stereotypical Mom to daughter relationship. Unfortunately, facts recently discovered point to a different reality.

The difference between the two sexes comes primarily from the differences in the amount and nature of hormones they are exposed to since conception. The effects continue throughout life. The effect of sex hormones on brain organization occurs early in life and thus environment is acting on differently wired brains in girls and boys. The very premise of studying environmental, social and cultural effects is flawed because of their differently expected effects on the two types of brains. It is like comparing apples with oranges. The paradigm of different types of brains fits nicely into nature's dictum of evolution and survival of species to give the two sexes greater flexibility in their cognitive abilities. Instead of duplicating, Nature has chosen to supplement the abilities of the two sexes.

The argument as to which ability is more important and necessary for survival is redundant because neither sex is perfect in its own right.

Major sex differences in intellectual function seem to lie in the patterns of ability rather than in overall level of intelligence. We know people with similar intelligence are differently adept at for example using words or performing a physical task. Men perform better than women on certain spatial tasks. For example, tasks that require rotating objects or manipulating them in some way are better performed by men. They also outperform women in mathematical reasoning tests and in navigating their way through a route. They are also more accurate in tests of target-directed motor skills--in guiding or intercepting projectiles.

[A female secretary used to communicate with her computer as Hey, You Big Fella. The boss asked, what makes you think the computer is a male. Came the answer because he needs to be told what to do.]

Women are better adept at rapidly identifying matching items, a skill called perceptual speed. They have greater verbal fluency, including the ability to find words that begin with a specific letter or fulfill some other constraints. They outperform men in arithmetic calculations, recalling landmarks from a route and performing certain precision manual tasks such as placing pegs in designated holes on a board. Though many of these differences appear mostly after puberty, some attribute begin to appear different even at age three such as targeting. It is now confirmed that sex differences in spatial rotation performance are present before puberty.

The differentiation of sexes begins at conception. The genetic material is identical between men and women, except the sex chromosomes. If Y chromosome is present, the fertilized ovum will create testes or male gonads. This is the first critical step towards becoming a male. If the gonads do not produce male hormones, the default form is female.

Women should take solace in the fact that the default form of fetus is female. It is only when a random Y chromosome appears that a male is formed; God begins with female forms.

Testosterone produced by gonads in males promotes development of male ducts and regression of pre-existing female ducts of the default model. If anything goes wrong at any stage of the process the individual may be incompletely masculinized. Besides differentiating genitals, gonadal hormones also shape behaviors.

Current studies also show that sexual behavior or preference reflects anatomic differences in brain. For example, a specific part of brain--an interstitial nucleus of the anterior hypothalamus--is small in homosexual men than in heterosexual men. Sexual preference, it now seems, has a biologic substrate. Homosexual and heterosexual men also perform differently on cognitive tests. The peculiar heterosexual acuity in spatial tests such as throwing a projectile is less developed in homosexual men, who do better at ideational fluency or listing things that were of a particular color.

The effects of hormones on brain appear consequential only at the early stages in life when they alter the brain function permanently. Giving the same hormone at later stages in life does little. The hormonal effects go well beyond sexual or reproductive behavior: they appear to extend to all known behaviors in which males and females differ. They seem to govern problem solving, aggression and tendency to engage in rough-and-tumble play. The last behavior is particularly related to dihydrotestosterone working through amygdala in brain.

The theories articulating these differences have been proven in animals where they were exposed to hormones during early development. Depriving newborn males of testosterone by castrating them or administering estrogen to newborn female rats results in a complete reversal of sex-typed behavior in the adult animals. Conclusive studies demonstrate that girls exposed to high levels of androgens because of a genetic disorder called congenital adrenal hyperplasia (CAH) or when pregnant women took synthetic steroids, in the prenatal or neonatal stage, they grow up to be more tomboyish and aggressive than their unaffected sisters. The affected females also selected more typically masculine toys--for examples cars over dolls and demonstrated better spatial abilities such as discovering a hidden figure within a complex one and rotation tests. There however does not seem to be a linear relationship with amount and extent of exposure of hormones. Longer exposures do not accentuate their effects.

Though no major changes occur later in life with exposure to hormones, cognitive patterns remain sensitive to hormone fluctuation throughout life. For example, performance of women in doing certain tasks changes throughout the menstrual cycle. With enhanced level of hormones their spatial abilities are depressed while articulation and motor capabilities are enhanced. Men show seasonal variation in their performance also. In spring when testosterone levels are low their performance improves.

How these differences are related to a broader picture of human evolution remains to be determined. To understand why the brains of the two sexes developed differently we must examine the history of evolution and then conjecture whether the current state of development is relevant to the modern life.

Our brain structure has barely changed over the last 50,000 years, yet significant changes in its working have appeared. We lived in small groups of hunter-gatherers, a few millennia ago. There was a division of labour: men hunted large game which required long-distance travel, defending the group against predators and enemies, shaping and using weapon. Thus developed in men route-finding ability and targeting skills. On the other hand women most probably gathered food near the camp, tended the home, prepared food and clothing and cared for children. This required short-range navigation, perhaps using landmarks, fine motor capabilities to carry out tasks in circumscribed space and perceptual discrimination sensitive to small changes in the environment or in children's appearance or behavior.

Men and women had, as a result of their experiences and different occupational interests and abilities, gotten hard-wired into their brain their abilities. Demands of the modern life carved these abilities and interests but the basic difference remained.

It is neither needed nor necessary to force equality upon men and women; instead, the differences can be exploited to make work force more efficient. There are things women can do better; others can be left better to men. Understanding that men and women are different is the first step in accepting duality of their roles. Nature does have its ways of expressing.

[02 June 1993 The Daily Dawn]