Bobbi S. Low

Why Sex Matters

A darwinian look at human behavior

By Bobbi S. Low

PRINCETON UNIVERSITY PRESS

Copyright © 2015 Princeton University Press
All rights reserved.
ISBN: 978-0-691-16388-8

Contents

Preface, xi,
1 Introduction, 1,
2 Racing the Red Queen: Selfish Genes and Their Strategies, 14,
3 The Ecology of Sex Differences, 28,
4 Sex, Status, and Reproduction among the Apes, 47,
5 Sex, Resources, Appearance, and Mate Choice, 69,
6 Sex, Resources, and Human Lifetimes, 82,
7 Sex and Resource Ecology in Traditional Cultures, 104,
8 Sex, Resources, and Fertility in Transition, 116,
9 Nice Guys Can Win—In Social Species, Anyway, 135,
10 Conflicts, Culture, and Natural Selection, 152,
11 Sex and Complex Coalitions, 170,
12 Politics and Reproductive Competition, 185,
13 Sex, Resources, and Early Warfare, 198,
14 Societal Complexity and the Ecology of War, 212,
15 Wealth, Fertility, and the Environment in Future Tense, 225,
Notes, 253,
Glossary, 319,
References, 329,
Index, 399,

CHAPTER 1

Introduction

Probably a crab would be filled with a sense of personal outrage if it could hear us class it without ado or apology as a crustacean, and thus dispose of it. "I am no such thing,'' it would say: "I am MYSELF, MYSELF alone." —William James Varieties of Religious Experience (1902)

To the same natural effects we must, as far as possible, assign the same causes. —Newton

WHY CAN'T A WOMAN be more like a man?" wailed Professor Henry Higgins in My Fair Lady, the musical derived from George Bernard Shaw's Pygmalion. Certainly in many societies, across time, there have been women who were "more like a man." Think of Joan of Arc, who was burned at the stake (on the minor charge of wearing men's clothing); or of George Sand, of whom Elizabeth Browning said, "You are such a large-brained woman and a large-hearted man." Yet in part, we remember such women because they are singular, whether we envy their ability to break free or whether we imagine that they missed a lot. What really contributes to the patterns we see—and to their exceptions?

Here I want to explore sex differences from a relatively unusual perspective, one that is often misunderstood. Understanding and explaining human behavior is a central concern for all of us. But doing so—especially when sex differences are the issue—presents a real dilemma. We are complicated, highly social beings. We live in a staggering array of environments, both ecological and social. Our families, lovers, and friends are not exemplars or prototypes, but unique, particular individuals. None of us wants to be "reduced" to some formula.

For, like William James's crab, we know we are above crude analysis. Even the name we give ourselves, Homo sapiens, reflects both the value that we give to understanding and the fact that we feel ourselves to be special. Like that crab, many people may be appalled at the approach I will use here, that is, to assume that, once we understand environmental and social pressures, we humans are as predictable as other animals in our behavior and are governed by the same rules. And I want to begin with simple rules, no less.

Many of us assume that humans operate under rules that are different from these other species, that our rules are based entirely on culture rather than on biology, or some combination. I will ask: what can we learn if we begin without assuming that this were true? I want to begin by exploring what a biologist would predict if he or she knew only that here was a smart, upright-walking, highly social primate and nothing more. I will explore the ecology of being male and female, beginning with simple rules and with what I can discern about the environments with which the evolutionary rules interact.

The approach I use, behavioral ecology, is an evolutionary approach with roots in Charles Darwin's work. It focuses on the question, how do environmental conditions influence our behavior and our lifetimes? This approach has proved profitable in exploring other realms of human behaviors. Behavioral ecology and its intellectual relatives seek to understand how comparatively simple operating rules interact with historical accidents, and with temporal and spatial specifics, to yield a rich diversity of patterns. There is no doubt that genes influence not only our physical structure and physiology but also our behavior; there is no doubt that historical accident often plays a role, nor is there any doubt that cultural and social pressures can influence behavior. But where lies the balance? Perhaps by beginning with very simple rules and assumptions, and finding where they fail to predict well, we can gain some insight.

Vampire Stories and Beyond

Humans have always sought to explain the patterns they see. In fact, one of the strongest selective forces on human behavior has been to understand pattern—not only in order to deal with environmental variation but also to be the first in one's tribe who is able to predict events and when they will occur (imagine being the first human to predict a solar eclipse). But creating stories that more or less match our observations is not science but folklore.

Consider vampires. From Bram Stoker through Anne Rice, from Bela Lugosi to Tom Cruise and Leslie Nielson, vampires have always fascinated us: aristocratic, sexy, dangerous, and (almost) invincible. Vampire folklore provides a wonderful example of how our need to explain can drive us to spin stories that seem to explain something that we see, and that can be hard to refute, but that nonetheless do not reflect what actually happens.

The folklorist Paul Barber, in a delightful examination of vampire myths around the world, notes that the ways people in preindustrial societies interpreted phenomena associated with death and the decay of corpses are "from our perspective, quite wrong. What makes them interesting, however, is that they are also usually coherent, cover all the data, and provide the rationale for some common practices that seem, at first, to be inexplicable."

The variety of myths and legends about vampires all begin simply: death—especially unexpected or unusual death—brings more death. If someone died, "why" was usually unknown, and epidemics leading to death and more death were once far more common than today. Once people were buried (often without coffins), not all corpses had the decency to stay below ground. In a prebacteriology culture, people weren't likely to see a "flailing" corpse as the natural by-product of bacterial decay, but rather as the will of the dead person or as the rejection of the corpse by Mother Earth. Since death brings death, those first to die, as in an epidemic, were dangerous and somehow had to be disarmed so that they could not continue to bring death. Only when all "changing" ceased, and ashes or bones alone remained, was the corpse neutral, inactive, and no longer dangerous.

People thus began with a repeatable observation: that death brings death. This applies not only to vampires but also to the general idea that dead people call to their relatives and friends and must be propitiated to protect those still alive. Because they had no knowledge of disease transmission, people imbued the corpse with dangerous properties. Not a bad idea, particularly in times of plague, when unexpected deaths were frequent and vampire fears were...