It doesn’t take much to understand that women have had it tough throughout history. While seemingly in our age there is near parity (with many women heads of state in Mexico, Italy, Moldova, Iceland, etc.), they only gained the right to vote in the U.S. 105 years ago (with the 19th Amendment to the Constitution), which was 50 years after Black men in 1870 (the 15th Amendment). There have always been contrary and conflictual views toward the female sex espoused by men. Women as the goddess, whore, muse, the anima, the maternal caretaker, the sensitive supportive one, the “fairer” sex (whatever that means), the weaker sex, the emotionally unstable sex, the passive sex, etc.

Of course, there can be no men or women without women bearing children. It took humans until the Axial Age (around 500 BC) before pregnancy was clearly associated with sex, likely due to the long period of pregnancy (nine months) separating causation and various magical theories of divination. Conception was interpreted in many non-scientific/non-physiologic ways for eons.

Ancient and classical theories of conception

Hippocrates (the father of medicine, 470-375 BC) proposed the two-seed concept contributed by each parent but claimed “weaker” seeds produced girls and “stronger” seeds boys. Aristotle (384-322 BC) put forth a more agrarian concept with men contributing the seed and women being the soil (matter) where the seed grew and developed into a human in the womb. He continued the idea that stronger seeds produce men. Galen (AD 128-216) was influenced by Hippocrates and promulgated the two-seed theory but added that “hotter” seeds produce boys even though there is a “natural” tendency to produce girls by women. This idea was extended with the thought that women with “hotter passions” produce more boys. These concepts held strong and were extended over the next millennia and a half.

Medieval medical manuals advised women who wished to have a boy to eat warm foods, engage in vigorous intercourse, or conceive during certain moon phases or positions. There was a growing belief that women could control the sex of the baby with various behaviors. In the major religions (Jewish, Christian, and Islamic traditions), it was assumed that a woman could shift the sex of their baby by controlling her passion and timing. It was commonly believed that if the man climaxed first that a boy was more likely and if the woman climaxed first it would lead to a female birth.

The burden of blame and continued mythology

Consequently, widespread belief blamed women for having daughters because of their “colder” bodies, weak seeds, and bodily imbalance “turning” a male fetus into female. Never was it thought men could be at blame. The height of this mythology might be with Henry VIII’s accusations of his many wives having inferior reproductive capacity, the cause for their lack of producing a male heir. It was always the woman’s fault.

In the 18th and 19th centuries, these concepts extended to believing that a mother’s emotions and thoughts could shape the sex of the child, specifically having daughters if she had minimal male qualities, were “cold,” emotional, and insufficiently passionate. Somatic typing also cast women with physical frailty and a nervous disposition more likely to have girls and that strong, tall, athletic women more likely to have boys. In France, physicians advised women to eat meat, exercise, and avoid sadness to produce boys.

Microscopes and preformation theories

In 1651, William Harvey working with bird egg fertilization put forth the idea that “all life comes from the egg,” which helped end the concept of spontaneous generation still quite prevalent then. However, nothing was known about mammalian or women’s ova (eggs). With the advent of the microscope in the 17th century, Antonie van Leeuwenhoek observed sperm for the first time. Finally, the male seed was able to be identified.

“Spermists” began believing and touting that a pre-formed human was in each sperm which then simply grew into a human in the woman’s womb. This concept brought back Aristotle’s ancient idea of women merely being a receptacle for growing a human without any other contribution. The other theory of preformation of humans was with the “ovists” who thought all beings came from eggs, although again not yet discovered in humans. With both of these theories, the concept of which sex developed was still assumed to be how strong the preformed human was with males being the stronger.

Scientific breakthroughs and modern reality

The scientific understanding of conception and embryology are recent developments. The 19th century brought with it the discovery of the mammalian ovum in 1827 by Karl Ernst von Baer. Then in 1877, Oscar Hertwig and Hermann Fol observed the fusion of sperm and egg nuclei in sea urchins.
The old concept of preformed humans was finally put to rest. The science of comparative embryology began, and the understanding of fertilization was finally elucidated.

However, old biases die hard. While it was known that sperm entered the ovum by penetration, many believed women’s eggs were still just passive receptacles for the strongest, most aggressive, invasive sperm that “won” their way into it. Modern science has shown the remarkable ability of the ovum to actually select the “best” sperm to fertilize (among the roughly 200 that make it to the edge of the ovum) based on physical fitness and genetic compatibility. A nice evolutionary benefit of having the best humans produced during conception. Oh, and importantly, the ovum only allows one sperm to enter and fertilize it.

Of course, now we know that each parent contributes exactly half the number of chromosomes (23 each) that make up the child. Sex in humans is determined by the combination of the sex chromosomes X and Y. XX are girls, and XY are boys. To bring this full circle, males do determine the sex of humans by contributing either an X or Y; women can only contribute an X. Also, we know that humans develop slowly by embryological differentiation that develops into the various components that make up a body and are not preformed little bodies.

However, there persists various modern myths about how the sex of babies is determined without any scientific foundation such as: deep penetration during sex producing boys, severity of morning sickness, food cravings by the mother, intercourse timing, lunar cycles, testicular temperature, and a host of others.

Let’s be hopeful that other misplaced misogynist myths will be eventually squelched for good.

George F. Smith is an internal medicine physician and author of Tales from the Trenches: A life in Primary Care.