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

Morganucodon, or “Morgie,” was one of the first Eves in human history and is the first known Eve that Bohannon traces. Morgie is the Eve of milk, being the first known mammal to develop lactation as a method to feed her young. Morgie lived about 205 million years ago and is described as a furry “cross between a weasel and a mouse” and used sweating fur patches in her lower torso to secrete milk (21). She and her descendants also lived in burrows and fed on insects. Unlike the Eves that followed her, Morgie was a monotreme who had a single cloaca and laid eggs, much like platypuses and echidnas.

Morgie’s development of milk was essential in helping create the animal class of Mammalia, and this development allowed mammals after her to protect their young from dangerous bacteria and feed the good bacteria in their immune systems. Her milk also contained hormones and cells that informed her young of their environment, any pathogens they might have been carrying, and what they needed to do to survive. This would later become even more important with the development of hominin and human babies, whose large brains require sustenance to grow well. Furthermore, Morgie’s trait of lactation would later lead to the formation of mammalian teats and then nipples and raised breasts.

Protungulatum donnae, or “Donna,” was another early Eve and is the second Eve that Bohannon covers in the book. Donna is the Eve of the placenta and uterus. She was the first Eve to develop a uterus and placenta and to give birth to live young rather than lay eggs. She lived 67 to 63 million years ago and is described as a small weasel or rat-like creature with hind legs that go below her pelvis, unlike Morgie. She, like Morgie, was an insectivore.

Donna was one of the few creatures to survive the ecological disaster Chicxulub and likely developed a uterus and the ability to gestate her young inside her body to help better protect her children. She also was the first Eve to have three holes: a urethra, a rectum, and a vagina. Her development of the uterus and placenta allowed mammals to protect their young from the mother’s urinary and fecal bacteria. In addition, giving birth allowed Donna and her descendants to keep their offspring warm and moist without having to limit when they could look for food. Moreover, Donna’s uterus and placenta allowed her to protect her babies from predators. However, to survive the changing environment, her descendants had to evolve into primates.

Purgatorius, or “Purgi,” was one of the earlier Eves and is the third Eve that Bohannon explores in the book. She is also the Eve of perception and the first primate Eve. Like Donna, she lived 67 to 63 million years ago and had to survive in forest trees in the aftermath of Chicxulub. She was a contemporary of Donna and is described as “monkey-weasel-squirrel” by Bohannon (22). Though she ate insects like Morgie and Donna, she also ate fruits.

Living in the trees, Purgi needed to develop stronger senses in order to survive. These main senses were hearing, smell, and sight. Her heightened hearing allowed her to be able to hear her babies and protect or feed them, as well as to hear any predators she needed to flee. Her keen sense of smell allowed her to smell males and predators, and her strong sight allowed her to detect which fruits were nutritious and safe for her to eat. These strong senses remained in her descendants and remain still in female humans. It is due to her that those with female anatomy are able to hear high-pitched sounds so well, are able to smell even faint smells, and can see colors much more vividly than those with male anatomy.

Ardipithecus ramidus, or “Ardi,” is one of the later pre-human Eves and the fourth Eve that Bohannon explores in the book. She is the Eve of bipedalism. Ardi lived 4.4 million years ago, and her skeleton was found in Ethiopia. She resembles a cross between a female human and a chimpanzee and, according to Bohannon, was “a big jump, both in time and in evolution, from the squirrely Eves that came before her” (22).

Ardi was the first Eve to walk upright on two legs, presenting an outstanding development in the history of natural science. However, because her bipedalism was such a new trait, her legs and feet had difficulty handling the weight of her body, especially when she and her descendants became pregnant, with the weight causing their spines to curve when they stood and walked. This caused her to likely have foot, knee, and lower back issues that still plague modern female humans. Despite the musculoskeletal troubles she and her descendants had, Ardi was a testament to the endurance and perseverance of female hominins, and it is from her that female humans inherit their endurance in survival, caring for their children, and accomplishing their goals.

Homo habilis, or “Habilis,” was one of the later Eves in pre-human evolutionary history and is the fifth Eve that Bohannon explores in the book. Habilis is the Eve of “simple tools and simple intelligent sociality” and the last Eve to stay and become extinct in Africa (22). She lived between 2.8 and 1.5 million years ago and coexisted with her evolutionary descendant Homo erectus before her extinction.

Habilis was a spectacular toolmaker who created stone tools to help cut and chop food and occasionally hunt—though she was more of an herbivore. These tools are highly impressive for animals to use, and her tool use indicates that human toolmaking and tool use started with her before male hominins started making and using tools. The most important tool Habilis developed, however, was gynecology. By using her knowledge of plants, especially bitter ones, to manipulate her reproduction and female cooperation to help with childbirth and the protection of babies, Habilis is a groundbreaking human ancestor in the development of reproductive choice and female collaboration. For this reason, Bohannon believes that human evolutionary studies and media focus too much on male hominin violence and the invention of weapons rather than recognizing the importance of gynecology in advancing the human race.

Homo erectus, or “Erectus,” is the last pre-human Eve and the sixth Eve that Bohannon explores in the book. Erectus is the Eve of “complex tools and more complex intelligent sociality” (22). She lived between 1.89 million and 110,000 years ago and, unlike Habilis, migrated across the Earth and colonized it. She also improved greatly upon Habilis’s toolmaking, making far more intricate tools that helped her and her descendants survive. She also had a much larger brain than all the other Eves before her.

Though Erectus’s large brain made her much more capable of abstract and complex cognition than her ancestors, she still did not reach the level of cognitive ability and language that her human descendants would. Her and her descendants’ larger brains also had the negative effect of making pregnancy and childbirth far more dangerous than it had been for the other Eves. Because her pelvis was much smaller and her babies’ heads were much larger, childbirth could be highly perilous, and if things went poorly, both she and her babies could die. These problems would only increase as her descendants evolved more and became humans. Eventually, her descendants would develop an even higher cognition and become Homo sapiens.