Eve: How the Female Body Drove 200 Million Years of Human Evolution

Eve: How the Female Body Drove 200 Million Years of Human Evolution is an evolutionary science nonfiction book by scientist Cat Bohannon and was published by Knopf, Borzoi Books, a division of Penguin Random House, in 2023. The book explores the female contributions to human evolution and the female ancestors linked to the development of various human traits, including breasts and milk, uteri and pregnancy, perception, bipedalism, toolmaking, brain development, language and voice, menopause, and love and sexuality. It explores the themes of The Evolution and Historical Impact of the Female Body, The Intersection of Science and Gender, and Debunking Myths About Female Biology. Eve was listed on the New York Times Best Seller list in October 2023 and won the Foyles Non-Fiction Book of the Year award in December 2023. Bohannon is a researcher with a PhD in the evolution of narrative and cognition from Columbia University.

This study guide refers to the 2023 Knopf hardback edition.

Content Warning: The book contains references to and/or discussions about sexual violence, including coercion and rape in both animal species and human environments, infanticide in animal species, pregnancy loss, suicide and suicidal ideation, birth trauma, female genital mutilation, and child marriage. This guide touches on most of these topics.

Summary

Cat Bohannon argues that science and medicine, especially evolutionary science, treat the male sex as the default and ignore female human biology, to the detriment of female healthcare. To remedy this, she created her own evolutionary science manual tracing back the various “Eves” from whom humanity is descended. She first begins with Morganucodon, or “Morgie,” the Eve of milk, from whom mammals inherited the ability to lactate. Bohannon argues that breast milk developed to protect mammals’ babies from harmful bacteria, keep them fed until they could eat solid foods, and build their immune systems with good bacteria. The milk also helps babies learn how to fight pathogens from their mother and learn about their environment through their mothers’ hormones. Bohannon theorizes that it was the development of milk and the invention of wet nurses that eventually led to human urbanization.

She then discusses Protungulatum donnae, or “Donna,” the Eve of the womb. Donna developed a uterus and started giving birth to her offspring to protect them from her urinary and fecal bacteria, external predators, and the elements. The womb’s development better protected mammals’ offspring but had the adverse effect of gradually making pregnancy and childbirth far more dangerous for human mothers and babies. Menstruation later began in hominins and humans as a method of surviving the dangers of human pregnancy and childbirth. Soon after, to survive their changing environments following the ecological disaster Chicxulub 66 million years ago, Donna’s descendants needed to become primates. The first primate Eve and the Eve of perception, Purgatorius, or “Purgi,” developed stronger senses of hearing, smell, and sight to survive living in forest trees, care for her babies, and find nutritious foods. This perception remains with those with female bodies in the modern world, who also have stronger senses of hearing, smell, and sight than male individuals. These developments would later lead to bipedalism.

Around 4.4 million years ago, Ardipithecus ramidus, or “Ardi,” the Eve of bipedalism, learned to walk upright on two legs. However, walking upright put a strain on her leg and foot muscles, which has led to modern female bodies having more knee and foot problems. As Bohannon talks about Ardi, she shares the story of Captain Griest’s training to become an Army Ranger. She concludes that though male bodies are physically stronger than female bodies in general, female bodies have just as much, if not more, endurance; like with Ardi, female strength comes from their endurance and perseverance. Then, between 1.5 and 2.8 million years ago, Homo habilis, or “Habilis,” developed the first hominin tools. She and her descendants used these tools to cut and chop plants for food and to hunt. Still, the most important tool she developed was gynecology. With it and female cooperation, she and her descendants could manipulate their reproduction and use it to help them produce healthy babies when they were ready. Throughout this section, Bohannon compares Habilis’s toolmaking with the beginning montage in Kubrick’s 2001: A Space Odyssey. Some time after, her descendant Homo erectus, or “Erectus,” left Africa and colonized the Earth, mastering her toolmaking along the way. During this, her descendants’ brains grew larger, which helped them evolve but also made birth more dangerous and taxing.

Eventually, the hominins evolved into Homo sapiens, “Sapiens,” or humans. In discussing the growth of human brains, Bohannon addresses the common understandings and myths about the female human brain. She addresses the idea that male individuals are smarter than female individuals, challenging it by showing that stress, family income, and societal pressure often lower female test scores. She also states that young female individuals have higher proficiencies in verbal language and reading and writing, while young male individuals have higher proficiencies in math, spatial reasoning, and problem-solving. However, these scores do not tell the full story. She also challenges the idea that female individuals are inherently more fragile emotionally, stating that many mood problems come from fluctuating hormones but that female and male individuals still deal with many psychiatric problems equally. She states that food is essential for brain growth and that motherhood also changes female brains. She concludes by stating that girlhood in sexist environments creates many problems for women and that as societies become more egalitarian, these problems will decrease. She then talks about how humans’ large brains have allowed them to learn language and speech, which no other species can do. She then compares the strength, pitch, and lung power of male and female voices, stating that while people assigned male at birth have more lung power and stronger voices than those assigned female at birth, female voices are more evolved scientifically, having become more precise and built for close-range speaking. This is because this voice is important for mothers to communicate with their babies. Mothers’ voices and speech are important for babies and help them learn language. Bohannon theorizes that the first story and expression of language was a mother telling her baby a story and that the story of humanity as a whole is survival.

Bohannon then tells a story about an old grandmother helping deliver her granddaughter’s baby 8,500 years ago in Jericho. Seeing that her granddaughter’s baby is breeched, she puts her hand inside her granddaughter and turns the baby around, dislocating her granddaughter’s hip in the process. She safely delivers her great-grandson but waits to see if her granddaughter will recover. Bohannon explains that menopause occurs because egg cells are made of more material than sperm and thus more can go wrong with them and more must be disposed of. She theorizes that female individuals go through menopause because they are much more likely to grow very old than male individuals and can thus provide guidance and wisdom for the community on problems and events that younger people in the community do not remember. She then states that menopause is also female individuals outliving the male individuals in their lives and coming to terms with that loss. She then explores the origins of human love and sexuality. She looks at sexuality in various primate societies, including gorillas, chimpanzees, bonobos, baboons, and geladas, to find a model that fits humans’ physical markers. She concludes that hominins were initially matriarchal, but to protect their babies, female hominins agreed to become monogamous with male hominins. This later led to the rise of patriarchal and patrilineal institutions. Though sexism might have benefitted humanity in the past from an evolutionary standpoint, Bohannon states that it has become too harmful. It is endangering female humans’ and children’s health, preventing societies and communities from obtaining more prosperity, and depriving children, girls, and women of important brain growth and knowledge. To combat this, humans must work together and combat harmful institutions and demagogues and the threat of climate disaster. This will be difficult, but Bohannon concludes that female individuals originally gave patriarchies their power, and it is possible to take that power back.