© 1981 rev. 2004


This Essay may help you understand the aspects of gender that both separate and unite the human male and female.


Especially how these things contribute to Long-term bonds and attachment between the sexes.

Human reproduction involves distinctly different biology in each gender, but obviously, there must be mutual willingness to engage in sexual behavior, if pregnancy is to occur.

Males might be best served to simply mate with any fertile female and let her fend for herself. Biologically, males have a nearly inexhaustible supply of sperm and this strategy would certainly provide for genetic diversity. without an doubt, many females and offspring would not survive the rigors of pregnancy, and early childhood, but many mammals breed in exactly this fashion.  The highly social Bonobo, one of our closest relatives, breeds indiscriminately and rarely demonstrates significant pair bonding.

For a female, Human, the impetus to engage in sexual behavior must be very strong, as pregnancy is a dangerous and vulnerable time for her. If she survives the pregnancy, nurturing her offspring requires an additional commitment for an extended period of time.  Her well being and survival depend upon her ability to find and create a strong bond with others that can help protect her and provide for the needs of their offspring.

Human females evolved a virtual arsenal of biological tools to help them foster and sustain the bonds they need to survive and promote the deep commitment required for successful reproduction. Humans are one of a very few animal species that disguise estrus, this allows her to enjoy and provide sexual pleasure nearly all the time. She also has exaggerated secondary sexual organs. Her highly visible breasts, rounded buttocks and prominent pudenda serve to reinforce awareness of her sexual nature.  However, her most powerful tool is an intense, joyful, emotional, attraction, that is typically associated with familial bonding. We call it LOVE...

Modern cultural ideals associate love with the heart, but love encompasses our entire body and brain. Research is unlocking many of its mysteries and what we describe as love in psychological terms, is largely based upon the primitive biology and chemistry of the oldest part of our brain, the limbic system.

Love occurs in three distinct stages we can describe as; lust, attraction and attachment. This sequence evolved out of our strong biological drive to reproduce, and our need to nurture children over their extended developmental period. Regardless of age or intention to have children and even in the case of Homo-sexual love, the same biological/psychological sequence occurs between mates.

MRI and PET imaging technology allows Scientists to pinpoint specific brain and chemical systems that drive behavior. Specifically, the hypothalamus, caudate nucleus, nucleus accumbens, septum, and frontal lobe areas, are especially active when love is on our mind. Polypeptides and Hormones flood the brain. Dopamine, norepinephrine, serotonin, endorphin, oxytocin, vasopressin, testosterone, and estrogen, excite and inhibit the body/brain systems that regulate the behavior of love.  It's PARTY TIME all over our body and brain when love is in the air!

The process begins with what we describe as lust. As adolescence and puberty arrive, testosterone and estrogen provide our children with a powerful urge to go looking for love in all the wrong or right places. Variations in the systems and molecules that regulate sexual behavior seem to predispose nearly 10% of all mammals to choose same sex partners. Pheromones and familiarity, help to narrow the field and eliminate close relatives, but regardless of who or how we choose, Humans need LOVE!

Sometimes things heat up slowly and sometimes we get that feeling of skyrockets going off, but at some point, generalized biological lust leads to an emotional feeling that cannot be ignored. This highly focused attention upon a specific BELOVED becomes the most important thing in life and absolutely everything else becomes background noise, to be ignored. If the attraction and the action remains mutually satisfying during this time, the relationship will grow stronger. Initial impressions will be fine-tuned as doubts and fears are resolved and the third stage of LOVE will arrive right on time.

Attachment is for the long haul, since it must maintain the relationship through inevitable distractions and stresses. Children typically arrive and enter into a loving relationship with their parents at this point. A variety of polypeptides, hormones, and endorphins form the glue that maintains the bond between mates as well as the attachment between parent and child. Oxytocin levels rise significantly in nursing mothers and cuddling behavior elevates oxytocin, vasopressin, and endorphin levels in both parents and child. Mother Nature provides this chemical stew for us, as our long term survival depends upon children falling in love with their parents and parents falling in love with them. We humans can hardly resist a new baby and these strong feelings for each other last until puberty. Then lust kicks in again and our adolescent children go looking elsewhere to pass on their genes and continue their biological destiny.

Obviously, love, attachment, bonding, and human social behavior is far more complex than this simple model. What we call love is a marvelously supportive and adaptable human quality. The complex biochemistry of attachment also fosters dominant and subordinate behavior patterns and these emotional drives allow humans to form stable communities, tribes, and clans. Humans are unique in our ability to communicate ideas and concepts and we are predisposed to cooperate. We will teach, nurse, and coach, the children of others.


We humans are the sexiest animals on Earth, People who may be infertile, still fall in love, attach to communities and cooperate with friends. Those who have lost a partner, usually fall in love again and the aged remain slaves to our biology long after reproduction is even a factor.


Biological and observational evidence points to a cyclical effect or tendency for human mates to separate and find new partners every few years. This makes sense in terms of biology and evolution, as genetic diversity of offspring is better for the species. Nevertheless, it seems our ancestors usually remained attached to their tribe or clan despite changing mates periodically. Sex and bonding weren't necessarily related to reproduction exclusively. Even today there are primitive societies that don't understand the connection between sex and children.

Some people might think that reducing human social/sexual behavior to neuro-chemistry and activated limbic systems, demeans the concept of love, but I disagree. I believe all these wonderful feelings have been implanted in us by Mother Nature and have evolved to bring us joy and pleasure.

AS human populations grow, culture becomes more important and complex. Religions and rules supplement or supplant our instincts. We learn to apply new ideas and technologies and we can survive with far less dependence upon each other. Despite those intellectual accomplishments, we cannot LEARN new emotions. We must remember that almost every human endeavor is driven by the powerful chemistry of desire, attachment, and LOVE.