Sex, Time, and Power
Page 1
Sex, Time, and Power
Also by Leonard Shlain
Art & Physics: Parallel Visions in Space, Time, and Light
The Alphabet Versus the Goddess: The Conflict Between Word and Image
Sex, Time, and Power
How Women's Sexuality
Shaped Human Evolution
LEONARD SHLAIN
Viking
VIKING
Published by the Penguin Group
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First published in 2003 by Viking Penguin,
a member of Penguin Group (USA) Inc.
Copyright © Leonard Shlain, 2003
All rights reserved
Illustration credits appear on this book.
LIBRARY OF CONGRESS CATALOGING IN PUBLICATION DATA
Shlain, Leonard.
Sex, time, and power : how women’s sexuality shaped human evolution / Leonard Shlain.
p. cm.
Includes index.
ISBN 978-1-1012-0039-1
1. Sexual attraction. 2. Mate selection. 3. Human evolution. 4. Social evolution.5. Sex (Biology) 6. Evolution (Biology) I. Title.
HQ23.S45 2003
306.7—dc21 2002041186
Without limiting the rights under copyright reserved above, no part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording or otherwise), without the prior written permission of both the copyright owner and the above publisher of this book.
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To my wife Ina, my daughter Kimberly, my son Jordan, and my daughter Tiffany—four very inspiring people who have inspired me.
Preface
There is a female human nature and a male human nature, and these natures are extraordinarily different…. Men and women differ in their sexual natures because throughout the immensely long hunting and gathering phase of human evolutionary history the sexual desires and dispositions that were adaptive for either sex were for the other tickets to reproductive oblivion.
—Donald Symons1
Error is the inevitable by-product of daring.
—Stephen Jay Gould2
Iron/Sex
Juxtaposing the words “iron” and “sex” creates an odd couple. The two rarely have occasion to appear together in the same sentence, much less find themselves standing side by side with so little editorial support. In the following pages, I will propose that the first word fundamentally influenced economic matters between men and women and, as a result, profoundly affected the politics of the second word. Along the way, I will present a scenario for how the kaleidoscopic, maddening, exciting, enchanting, and baffling man-woman dance, more commonly referred to as “a relationship,” evolved.
This book arose out of a question I posed to a professor when I was a second-year medical student, making rounds on patients in a large ward. Although the incident occurred over forty years ago, I had never really forgotten or accepted his answer.
The sophomore year of medical school represents a major transition for students. They leave the cadavers of the freshman year behind and begin having contact with respiring, perspiring patients. On this particular day, we were being taught how to interpret laboratory results.
Shifting from bedside to bedside, our knot of students listened intently to the professor. Every patient admitted to the ward, he explained, had three basic laboratory tests: a chemistry-26 panel, a urinalysis, and a complete blood count (CBC). The first measured the concentration of twenty-six constituents floating about within the patient’s bloodstream.
The amount of a patient’s circulating sodium or potassium, for example, provided a snapshot of the health of various internal organs, such as the heart and kidneys. The measurement of every one of the twenty-six constituents was like having a miniature finger figuratively take the pulse of some very important cellular function, which in turn reflected on the state of one or more of the body’s organs. The lab reported each value on a slip that was placed in the patient’s chart. Neatly aligned, parallel to the patient’s results, was a column stating the expected normal ranges for each particular variable. What caught my eye that morning was the list of normals. Of the twenty-six numbers on the chem panel, none distinguished between the values for a man and a woman. And why should there be any? After all, sex has nothing to do with the way a lung or a stomach goes about its business, so I would not have expected any variation between the sexes. The same held true for the normal values reported on the urinalysis.
The CBC, however, was distinctly different in this regard. A complete blood count measures several different parameters of the red and white cells circulating within the body’s miles of vascular tunnels. Although the white-cell numbers were the same for the two sexes, I noticed that the red-cell normals for men and women were surprisingly askew. I thought that was very strange.
A red cell’s chief function is to pick up oxygen in the lungs, transport it through the blood vessels, and deliver it to every organ in the body. For all complex creatures, oxygen is the staff of life. Deprive them of this most precious element and they will rapidly die of asphyxiation. Yet a man normally has a 15 percent higher concentration of circulating red cells than a healthy woman has. I puzzled over this discrepancy (even after taking into account that, generally, a woman is smaller in stature and has less muscle mass than a man), and it prompted the question that lies at the heart of this book. Why would a woman need less of blood’s critical essence than a man?
I raised my hand and asked the professor to explain the reason for this vital disparity. He replied, in a way that suggested he thought the answer was obvious and my question, had I given it more thought, was unnecessary:
“Women bleed and men don’t.”
Somewhat annoyed that I had interrupted his train of thought, he then returned to the subject on which he had been discoursing. I reddened.
I remember thinking at the time that his curt answer could not be the whole story. Later, as I turned over his reply in my head, I could not think of a plausible explanation for this difference. Why would a species evolve whose females—but not males—operated routinely on less than a full complement of tankers to ferry a fuel as crucial as oxygen? (One could argue that the female has a normal amount and the male has a 15 percent excess capacity. Either way, the inequality begs for an explanation.)
The magic behind a red cell’s seamless performance is the protein called “hemoglobin.” And, like a set of nested Russian babushka dolls, at the core of hemoglobin lies the element iron. Iron and oxygen, because of the salutary arrangement of their outer electron shells, eagerly seek out each other’s embrace. Once merged, the two form a mole
cule called iron oxide. Everyone is familiar with this substance. We call it “rust.”
Rust has a signature red color. Iron oxide in rock lends to the Grand Canyon its spectacular chromatic array. It colors the fields in Kenya and the plantations of Hawaii, and rust’s distinctive hue made the earth of Scarlett O’Hara’s beloved Georgian Tara red. The hemoglobin molecule, with its precious complement of iron atoms, makes blood red and white skin pink, and it tints medium-rare steaks with a distinctive ruby sheen.
Hemoglobin transforms iron’s strong affinity for oxygen into a delicate “grasp and release” maneuver, allowing oxygen to be easily acquired in the lungs and readily relinquished farther down the line to the cells. The felicitous combination of iron, oxygen, and hemoglobin is central to the process that facilitates the neurons in your brain to extract meaning from the sequentially aligned squiggles you are reading on this page.
A few weeks after I had posed my red-cell question on rounds, a second incident piqued my interest in the subject. During a rotation on the obstetrics-gynecology service, I was assigned to the prenatal clinic, where wise, experienced nurses instructed me how to care for pregnant women. Detroit’s Harper Hospital in 1958 served a large population of poor people who had emigrated from other states, hoping to improve their lives in the city’s then booming auto industry. Unfortunately, most women we served were unaware of the prenatal program and did not enter it, if at all, until late in their pregnancy. Playing catch-up, I counseled these soon-to-be moms about the importance of maintaining a healthy diet, for both themselves and their unborn children.
A key element of my care was to monitor each woman’s weight, blood pressure, CBC, and blood-sugar levels. My goal was to keep these four cornerstones of prenatal health within a normal range. Specifically, I tried to maintain their hemoglobin level in the 11–12 range, using iron pills to supplement their dietary intake if necessary.* A hemoglobin level below 10 heightened my concern, because it confirmed the diagnosis of anemia.
Consider my consternation and sense of helplessness when I discovered that it was exceptional to find one among the late-term women visiting my clinic in possession of a normal hemoglobin count. More often, they ranged from mild (8–10) to severe (5–7) anemia.* My mentors sadly shook their heads, explaining to me that fetal brains would most likely not develop properly if the mother was anemic; at worst the babies would suffer mental retardation, and at best they would fail to attain their full intellectual potential.
Outwardly, these very pregnant women seemed normal, but I soon learned to discern their anemia’s telltale signs of apathy and lethargy. Paradoxically, they appeared well fed, and, even more puzzling, many were actually overweight. A peculiar side effect of iron deficiency is the dulling of the taste buds that sense sweets. To compensate, an iron-deficient woman craves carbohydrates.
I was often disconcerted to observe a pregnant woman bringing a carton of cornstarch into my examining cubicle, eating the white powder right out of the box during my interview—so great was her drive to satisfy her carbohydrate hunger. Meanwhile, she was unaware that the real culprit was a lack of a vital mineral in her diet. Increased intake of calories contributed to her weight gain, giving her a deceptively healthy appearance; cornstarch, which in 1958 contained negligible amounts of iron, only contributed to masking the problem.
In the years that followed, I reflected many times on my frustrating experience in that metropolitan prenatal clinic. After I had immersed myself in evolutionary theory, I wondered why Mother Nature would favor the evolution of mothers whose internal circuit breakers did not protect them from endangering their babies and themselves. Humans, like all animals, have sensitive trip wires alerting us whenever salt, water, oxygen, or carbohydrate levels enter the red zone. Why were women in general and pregnant women in particular so blissfully unaware of their susceptibility to iron deficiency?
Human intelligence is measured, for want of a better standard, in IQ points. In the long march from anthropoid hominid toward Homo sapiens, the piling up of one IQ point upon another eventually propelled our species to the top of the IQ heap. Low maternal iron depots ultimately subtract IQ points from offspring, thus subverting the entire thrust of human evolution. Our species’ females, it would appear, had traded away sufficient maternal hemoglobin levels, but for what? Where, I wondered, was the beneficial offset that could possibly justify such a Faustian bargain?
Curious about this matter, I sought the answer in my authoritative physiology textbook. The explanation proffered was that males led a more strenuous life than females and therefore needed a more robust aerobic circulatory system. Although initially I accepted this answer, as I grew older I increasingly suspected that it could not be the complete story. I doubted that any man engages in a more metabolically taxing activity than trying to form a seven-pound infant over a nine-month period from scratch.* Also, the drain upon the energy stores of a breast-feeding mother are of the same order of magnitude as the demands made upon an Olympic shot-putter during his rigorous training.†
A similar disparity appears in the CBC in some other animal species, such as chimpanzees and gorillas. Hematologists suspect that this differential has something to do with the red-cell-enhancing effect of testosterone and the red-cell-depressive effect of estrogen. (Men treated with estrogen for prostate cancer are at risk to develop anemia.) Compared with these other animals, however, the differences between a man’s and a woman’s CBC are deeper and wider. This variation gains in significance because the other species that manifest an inequality in the number of red cells between the sexes do not have a brain as large as humans do, and as we shall see, the human brain is very sensitive to any factor that diminishes its ability to gain access to oxygen. Also, anemia is quite rare among pregnant primates, yet it commonly occurs in the human line. Many years later, after learning more, reading more, and experiencing more, I began to harbor a growing suspicion that an important missing piece of the human evolutionary puzzle was hiding somewhere behind the innocuous-looking numbers I had noticed that morning so long ago on a routine CBC slip.
I confess that I had difficulty staying focused on this subject during medical school. An overwhelming avalanche of other facts, lessons, and procedures cascaded down upon me, and distracted me from pursuing the question. Besides, the subject of blood was not my passion in those days. As a teenager, I had stumbled onto Sigmund Freud’s Civilization and Its Discontents, one of those seminal books that one discovers in youth that rock one’s beliefs. My curiosity whetted, I made subsequent explorations deep into Freud’s subterranean warren. I was so intrigued by what I was learning there, I became convinced very early on that my destiny was to become a psychoanalyst.
Looking back now, I think it would be difficult for someone who had not lived through the 1950s to appreciate just how profoundly Freud’s ideas permeated the intellectual climate then. A rough indicator of his influence was that over 30 percent of my 1957 medical-school freshman class had initially aspired to be psychiatrists. (Many medical students switch from their original choice of specialty, as did a lot of my classmates.) I envisioned that I would become a dauntless spelunker of the mysteries of the mind. Psychoanalysis seemed to be the “open sesame” to the entrance of that dark cave.
As a young boy, I had loved to build model airplanes and play sports. I enjoyed drawing and fancied myself a budding artist. When I rotated on the surgery service, I discovered, to my delight, that this field of medicine provided an outlet for the skills I was incubating. Surgery seemed a perfect fit for me. It was romantic, challenging, and intensely exciting. The drama I witnessed daily, combined with my sensing the enormous gratification surgeons seemed to enjoy, changed my mind about a career choice. I decided to specialize in general and vascular surgery. Though I remained faithful to my aspiration to be an explorer, now I decided I would navigate the interior passageways of the body.
Maintaining adequate circulating levels of red cells in my patients became a central concern
of mine. As a young surgical resident at Bellevue Hospital in New York, I experienced an exhilarating frenzy while running with a group of emergency-room nurses and doctors gripping a gurney carrying a gunshot victim. Our goal: Reach the operating room before the patient “bled out.”
Throughout my career, I have, on occasions too numerous to count, glanced up from a particularly vexing operative field to monitor anxiously a forest of IV poles, their precious transfusions hanging like ripe fruit. I have had many years during which to contemplate the nature, importance, and vitality of this substance we call blood.
These musings have convinced me that significant differences in iron levels between the sexes were the initial driving force behind many uniquely human cultural innovations. I shall trace the connections of art, calendars, marriage, mayhem, fatherhood, and homosexuality, to name but a few, back to this arcane feature of human physiology. Along the journey, I shall also explore the links between the moon and menses, sex and death, and funerals and paternity.
Throughout my life, I have maintained a lively interest in matters relating to life-forms and evolutionary theory. As a premed undergraduate learning the wondrous stages of embryology or comparing the anatomy of differing species, I recall having moments of pure rapture whenever I grasped the intricacies behind some aspect of the breathtaking beauty of life. The study of its sumptuous diversity is, for me, the quintessential melding of science and aesthetics. I still marvel over the improbability of a caterpillar’s metamorphosis, the texture of a calla lily’s singular petal, or the amazing grace of a formation of pelicans skimming waves. I will try to infuse this book with my sense of awe and enthusiasm for the processes of life while I elaborate my theories on the bonding glue that holds human relationships together.