Essay Series 1.3: Charles Darwin and his successors came to false conclusions about the sexes and their behaviors.

Western societies’ sexist myths have their roots in ancient Greece and Rome. These myths were thriving during the Victorian era when Charles Darwin was doing his work on the theory of evolution.

Darwin was one of the most influential scientists of the 1800s. His assertions about animal behaviors were that aggressive males dominated passive females. He and other evolutionary theorists assumed male dominance was the natural order for the human species.

As women entered the sciences in larger numbers, they and others have shown that sexist stereotypes are incorrect for many animal species, including humans.

Darwin’s Theory of Evolution

Darwin’s theory of evolution explains how animal species change over time. Those animals that have traits that improve their fertility and longevity pass their successful genes onto their offspring. These offspring are more likely to survive and reproduce. Over generations, this process changes a species’ characteristics. The theory relies on the concepts of natural selection and sexual selection. Natural selection is the struggle for survival, in other words, “the survival of the fittest.” Sexual selection is the struggle for mates.³⁹

Darwin developed his theory during the 1800s’ Victorian era based largely on his observations of male behavior in various animal species. Darwin and his followers assumed that male actions drove evolutionary change and females reacted to male behaviors.^{40, 41}

Charles Darwin’s On the Origin of Species (1859) and other publications said that women were inferior to men because they had smaller brains and women were more prone to emotion than men. Women were supposed to be passive and primitive. Darwin asserted these things with little analysis of women’s or female animals’ activities and social roles.⁴²

For about 100 years after Darwin, most scientists believed that males were active and spread their sperm to many females so that their family line survived. Another belief was that females were passive, stayed with one mate, and tended to their young.⁴³ The myth of the inferior and subordinate female has lasted well into the 21st century because many scientists followed Darwin’s lead without question, and others have dismissed women scientists' findings.

Science continued on this path until women gained greater access to the same scientific education and jobs as men in the 1960s and 1970s. As women entered the sciences, more studies documented behavior in the female half of the animal world. More recent studies of various species have upended traditional beliefs about there being only two sexes and about behavior by sex type. These women scientists' work often goes unrecognized, although their work has changed scientific understandings.⁴⁴

Recent studies of animal behavior show that an animal’s sex can change; females can have multiple sex partners, be aggressive, and dominate males; and the sexes often share parenting.

Sex Changes

Most scientists agree that biological sex is variable among animals.⁴⁵ Genes, hormones, environment, and life experience affect an animal’s sex and reproduction. Here are some examples:

1. At least 500 species of fish and some worm species have male and female sex tissues or organs.

1. Females in about 100 species of fish, amphibians, and lizards can clone themselves.

1. Some worm species reproduce asexually by splitting in two.

1. Sex reversal occurs in a range of reptiles, fish, and amphibians.

1. Scientists have documented intersex birds, butterflies, insects, crustaceans, and humans.⁴⁶

So, the myth that animals have only two sexes that never change is false because biological sex in many non-human animals can change. In addition, a small percentage of humans exist with female and male sex characteristics.

Multiple Sex Partners

Beginning in the 1970s, studies of animal behavior found that females in many species have sex with multiple male partners. Following are some examples:

1. Female lions can have multiple male sex partners.

1. Females in about 90 percent of bird species may have sex with more than one male.

1. DNA testing has found that female animals from most groups have multiple male partners.

1. A lifelong relationship with one partner occurs in less than seven percent of known species.

1. Females in many primate species have multiple male partners.⁴⁷

Scientists believe that females who have multiple male partners may do so because any male who thinks a female’s babies are his is less likely to kill her infants. These males are more likely to help raise the infants. Also, females may want more genetic diversity among their offspring.⁴⁸

Aggressive Females

In many species, females are aggressive and sometimes larger than males. Examples are:

1. Certain female hyenas are larger and more aggressive than males.

1. Many female spiders, other insects, and octopuses eat males during mating.

1. Females compete over resources related to fertility and parenting.

1. Females in some species compete or even fight with each other over access to the most attractive males.⁴⁹

Female Domination

Male animals don’t always dominate females. For example, certain hyenas, elephants, and orcas live in matriarchal clans. And most species of lemurs have females that manage the group socially and sexually.⁵⁰ One of the most important animal examples is the bonobos. Bonobos are apes who are largely matriarchal and peaceful. Female bonobos form relationships with unrelated females via sex play. Female bonobos are slightly smaller than the males. However, females’ tight social bonds give them a power advantage, especially when they join together to keep aggressive males in check.^{51, 52}

Shared Parenting

The females of the species aren’t always the ones responsible for caring for their young. Many exceptions occur:

1. Up to 10 percent of mammal species have fathers that take on some care of their offspring.

1. Ninety percent of bird couples share parenting responsibilities.

1. Most males in fish species that provide care to their young have some form of parenting responsibility for the eggs. It often takes the form of defending the offspring from predators.

1. Sea horse males give birth to their young.⁵³

Rigid assumptions about the sexes’ behaviors aren’t true. Evolution has led to a variety of adaptations to life on Earth that have resulted in the fluidity of sex type and variation in the sexes’ typical behaviors. There is little reason to assume that humans’ behavior always conforms to rigid expectations about men’s dominance and women’s passivity.

Reflections

Darwin’s theory of evolution was groundbreaking and explains much of the variation in nature. However, Darwin developed it based on incomplete data because he largely studied males. So, much of what I learned early in life about animal and human behavior was incomplete or inaccurate. The evidence in this essay shows that a variety of animal sexes and behaviors exist. Also, many animal species, like some human societies, are matriarchal, where the females lead.

My assumption, until I started reading about bonobos’ and elephants’ matriarchal clans a few years ago, was that males always dominated females and that males often sought out multiple sex partners. Learning that females could lead and also seek out multiple sex partners made me question what I grew up thinking about relationships between women and men.

Women’s and men’s behaviors don’t fall into rigid sex roles. Just as in the rest of the animal kingdom, women can dominate and women and men can share caregiver roles. Women no longer confine themselves to one sexual partner as was the ideal in the Victorian era. Women’s and men’s roles in families vary as other species’ roles do.

How does what you learned in this essay affect your thinking about women’s and men’s roles and behaviors?