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

Bohannon details the beginning of Stanley Kubrick’s film 2001: A Space Odyssey, which shows the evolution of humanity from the perspective of men developing weapons. The tools that made humanity are depicted as weapons, which Bohannon wants to challenge. She explains that tool usage is something multiple animals do, including non-mammals such as crows. She also states that a female likely invented the first hominin weapon. Bohannon then describes a female chimpanzee in modern-day Senegal killing a bush baby with a spear. She uses this to explain that due to having more urgent food and safety needs and less body strength, female hominins needed tools they could use to work around their lower physical strength. She then introduces the Eve of tools: Homo habilis, or “Habilis,” who lived 1.5 to 2.8 million years ago and was found along with her tools in Tanzania. She likely used her tools to grind up tubers, grasses, and nuts and to cut meats. She was also likely a scavenger, taking scraps of meat rather than doing much hunting.

Bohannon then explains that because Habilis’s babies were so much needier, they needed tools to help them with their evolutionary deficits. She adds that humans are much worse at reproducing themselves than other animals; the fact that there are so many humans now should be miraculous. The tool that has helped humanity survive and overcome this deficit is gynecology. Because Habilis and her female peers had much smaller pelvises than their ancestors and their babies had much larger heads, pregnancy and childbirth had become far more taxing on the female body, and labor had gotten longer. Bohannon suggests that the invention of midwives was part of this rise in gynecology and that hominins developed a society of cooperating females. She first explores that possibility with chimpanzees but decides that the competitiveness of female chimps makes this unlikely. She then explores the possibility that early hominin species’ female cooperation resembled that of bonobos. Bohannon details an observation of bonobos watching a birth and then an observation of bonobos assisting a birth in 2018. She concludes that hominins were more like bonobos in this aspect.

She also says that reproductive choice was another important part of gynecology in female evolution. She describes the violent sex that dog and cat anatomy causes because of the males’ locking penises, as well as the way that sexual violence has shaped the evolution of anatomy in mallard ducks and dolphins. She also details how females of certain species, such as mice, geladas, and horses, will often miscarry if a new male who is not the father is brought into her environment. This is likely to avoid infanticide and to avoid mating with the new male. If the young are already too developed and are born, the new males will often kill the young to bring the females into heat sooner. Humans do not have these biological features, which suggests that hominins did not commit much sexual violence or infanticide. Hominins did appear, however, to still try to manipulate their reproduction by using plants and other tools. After Habilis went extinct, her descendant Homo erectus, or “Erectus,” left Africa and began colonizing other parts of the world. Erectus’s brain was even bigger than Habilis’s, and she improved the tools her ancestor made. Gynecology, including reproductive choice, made this possible, as did the growing brains of the evolving hominins. One such way these tools were used to help humans survive was by tackling diseases such as the Zika virus—which caused Microcephaly in the babies of infected pregnant people, dengue fever, and malaria—which kills large amounts of pregnant people. Bohannon finally concludes that it was not weapons made by male individuals, but rather gynecology that led the evolution of humanity. She then reimagines the introduction of 2001: A Space Odyssey, detailing female individuals caring for their babies and making decisions about their reproductive health in the future, including a flyer for a Planned Parenthood facility in space.