Since males of all sexually reproducing species are naturally drawn to signs of fertility in females (Zuk 2002), they naturally express more interest in females when they ovulate, or come into heat in the vernacular applied to non-human animals. In many other species that do not rely as much on a monogamous pair bond for the survival of the fetus (Barash & Lipton 2001), females exhibit very clear external signals corresponding to their ovulation. This system is very well suited to species where a single male (or several) mate with many females, such as among lions and many mammals; in fact, it probably reduces any potential for conflict among harem females for male attention.
Human females replaced the outward signals of ovulation and fertility by evolving a suppression of any outward manifestation, precisely, to ensure that males provided for, guarded, and protected them continually rather than only that portion of the time that females were most fertile (Margulis & Sagan 1999). Furthermore, male and female primates, (including human primates), even evolved gender-specific behaviors for increasing their statistical probability for long-term genetic propagation by supplementing the genetic contribution of their mate with genetic material from other partners (Margulis & Sagan 1999). Several species of female primates and non-primates have evolved a tendency to stray from their primary pair bond on occasion. The most interesting aspect of these dalliances, is that they tend to do so very specifically when they are fertile rather than at random times. As it turns out, (Margulis & Sagan 1999) human females exhibit the very same predisposition: studies of infidelity among married females indicate that the occurrence of illicit sexual affairs spiked in relation to their ovulation.
Even more interestingly, those studies also suggested that their specific choices of partners for sexual affairs tended to emphasize both raw physical attractiveness as well as some of the very characteristics associated with male dominance and strength that, fundamentally, may be inconsistent with male traits like fidelity for which they selected their husbands (Margulis & Sagan 1999). It seems that modern human females have evolved a preference in their illicit affairs for the very male candidates whose genetic material supplements the relative deficiencies in their primary partner's. Finally in this regard, the most fascinating aspect of theses studies is that the marked coordination between female sexual affairs in marriage (and the preference for superficial traits instead of those suggesting that a man is good long-term mate potential) exists even when the woman very specifically does not wish to become pregnant from the affair (Barash & Lipton 2001). Such is the unconscious effect of biologically-evolved sexual adaptations on modern human behavior.
Human males and females display characteristic differences in their relative degrees of natural ability in communication skills and in their natural responses to infants and children as well. Whereas males tend to communicate with children primarily in the context of teaching and disciplining, females are much more attentive to the subtle needs of children for focused attention, feeding, and nurturing. Men often exhibit better navigation skills, sense of direction, and analytical ability, whereas women exhibit better social skills, linguistic, and communication skills.
Distinguishing Biology From the Contributions of the Human Socialization Process:
One complication in interpreting modern manifestations of human behavior is that the social evolution of human societies has also had a profound effect on observable human behavior, including many aspects of differential male and female characteristics (Zimbardo 2005). Recent literature (Angier 2007) emphasizes the degree to which certain components of what we consider to be "typically" male or female behavior are the result of the socialization process that begins as early as the color selection of the blankets placed over newborns in the hospital, continuing into childhood and even into our expectations of adult choices.
Disparate treatment, rather than genetic differences can also account for many directional choices, but the vast majority of evidence strongly suggests that socialization, while significant, pales in its power to determine our behavior compared to biological influences (Macionis 2002). In this regard, some of the best anecdotal evidence comes from children born with externally ambiguous genitalia, as well children born with an obvious natural predisposition toward a reversed gender identity. It is relatively common practice, for example, that in the case of children born with both male and female genitalia, physicians generally make the choice of whether or not to remove the penile structure based on its apparent degree of departure from normal development: barely formed penile tissue is simply removed and the child raised as a female, and vice- versa, in the case of better developed male genitalia (Zimbardo 2005).
Some of these children raised as females experience opposite gender identification from their earliest memories, preferring toy trucks and climbing trees to the proverbial "sugar and spice and everything nice" despite being treated and raised as girls since birth. Likewise, some of these children whose male sexual identity was selected arbitrarily for them by physicians exhibit equally obvious male gender identification ever since birth. Notwithstanding the acknowledged effect and influence of socialization and expectation on male and female roles in society, evolved gender-specific biological differences make themselves apparent in too many ways to attribute their behavioral manifestations substantially to socialization.
Without a doubt, biologically-evolved tendencies are profoundly influential on modern human behavior, just as they are on other animal species and as they were on our early human ancestors. The concurrent evolution of human society has changed many of the external manifestations of those gender-based differences, but to the careful observer and to the scientific researcher, the roots to our distant past lie just below the surface of our more modern socially acceptable conduct.
Exceptions to many of those observations exist, just as exceptions to most basic rules and principles of biological evolution exist across the wide spectrum of animal life on Earth. However, rather than contradicting those basic rules and observations, those exceptions merely represent more novel evolutionary solutions to issues, just as tiny side streams running along a main current of water indicate minor differences in terrain and its relative resistance to the flow of water than an entirely different path from the main stream.
In fact, the testable evidence for the influence of biological evolution on the modern expressions of gender-based behaviors is so strong that it suggests conclusions that utterly transcend the issue of sexual evolution. The parallels between human sexual behavior and gender-specific differences are so striking and multidimensional that it is very difficult to maintain any belief that homo sapiens is fundamentally different from other biological life forms.
Ultimately, we are merely another, albeit the most intellectually evolved, form of animal life that evolved through the general process of biological evolution that characterizes life on this planet. The implications of that realization should impact on our belief in a god who values human life more than animal life, as well as on our moral obligation to treat animals (especially the ones we raise for profit or consumption) greater respect and compassion for their suffering than might be deserved by life forms significantly different from us in kind rather than merely in relative degree. REFERENCES
Ackerman, Diane. (1995) a Natural History of Love. New York: Vintage
Angier, Natalie. Birds Do it. Bees Do it. People Seek the Keys to it; the New York Times (Apr. 10/07)
Barash, David, P. And Lipton, Judith E. (2001) the Myth of Monogamy. New York: Henry Holt.
Branden, Nathaniel (1999) the Psychology of Romantic Love. New York: Bantam.
Macionis, J.J. (2002) Sociology. New Jersey: Prentice Hall