Sex Before Sexes: The Evolutionary Case for the Female First

In the debate over human origins and the nature of sexual reproduction, religious and scientific perspectives often diverge. The Bible claims man came first, with women derived from man’s rib. Yet, from an evolutionary standpoint, it’s far more plausible that female-like organisms preceded males, especially considering that asexual reproduction—the earliest known mode of reproduction—requires no second gender. The evolutionary journey from single-gender replication to the introduction of males suggests that “female-first” may not be metaphorical but a biological reality.

Life on Earth began with simple asexual organisms, such as bacteria and single-celled eukaryotes, reproducing by binary fission or budding. These processes involved no mates and produced genetically identical offspring. This efficiency raises the question: Why evolve the more complex and costly mechanism of sexual reproduction? Research suggests that the key advantage of sexual reproduction lies in genetic diversity, which increases adaptability in changing environments (Crow and Kimura, 1965). However, in those earliest days, only one reproductive type existed—a precursor to what we might now identify as “female.”

As sexual reproduction evolved, particularly in fungi and protists, a crucial innovation occurred: the development of gametes (Heitman, 2015). Initially, these gametes were isogamous—morphologically identical. Over time, anisogamy developed, leading to distinct gametes: large, resource-rich eggs and small, motile sperm. The egg, which carries most of the cytoplasm and nutrients necessary for embryonic development, resembles what we associate with female reproductive cells today. The sperm evolved later as a means to enhance dispersal and fusion probability. From this model, the female role—egg provider—can be considered evolutionarily primary (Baker and Parker, 1973).

The Plasticity of Sex and the Evolutionary Add-On of Males

Supporting this, many ancient organisms reproduce solely through eggs, including certain reptiles, amphibians, and insects that can perform parthenogenesis—development from unfertilized eggs. Alligators provide a modern glimpse into how gender is environmentally influenced. Their sex is not genetically fixed at conception but is determined by the temperature during egg incubation. At around 30°C, more females emerge; at around 33°C, more males are born. This plasticity implies that sex differentiation is a flexible evolutionary trait (Geary, 1998).

Such biological evidence undermines the claim that males are biologically dominant or original. Instead, the male role evolved as an addition, possibly to increase gene mixing and enhance species survival in varied ecosystems. Males carry genetic traits from both lineages and serve as vectors of genetic novelty. Still, their existence represents a strategic adaptation rather than a foundational necessity (Engelstädter, 2008).

The evolutionary emergence of the male sex did not create new life from nothing—it was built upon the biological systems already perfected by asexual or female-dominant organisms. As the genetic mixing benefits of sex became apparent, organisms with differentiated sexes (male and female) came to dominate, especially among vertebrates. Yet, the female role retained its primacy in reproduction. Even in humans, the female reproductive system is more complex and central, capable of nurturing life independently for weeks before the male contribution becomes relevant.

Biology vs. Patriarchy: A Historical Inversion

A stark irony emerges when we contrast this biological narrative with human history, particularly its patriarchal structures. Despite the evident evolutionary precedence and reproductive centrality of females, most societies historically subjugated women under male-dominated rule. This inversion likely arises not from biological hierarchy but from the consolidation of social, technological, and military power, which men came to dominate due to differences in size, hormonal drives, and social structures.

In this light, patriarchy does not appear as an outcome of natural order but rather as a cultural construction that developed in contradiction to biological roots. If we accept that “woman came first,” then our social systems—law, religion, property rights—that favor men are not extensions of biology but deviations from it. Recognizing this allows for a re-imagination of gender roles in modern societies, aligning more closely with evolutionary truths than ancient mythologies.

This view does not aim to flip the hierarchy, but rather to dissolve it. Understanding sex as an evolutionary tool and the female role as foundational instead of supplementary offers a compelling narrative that challenges outdated ideologies. Biology doesn’t prescribe subjugation; it highlights diversity, adaptation, and cooperation. Evolution is a story of emergence, not dominance.