Michael Thacker

“Tracing the Deep Roots of Sex Differences and the Emergence of Human Consciousness”

Author’s Note

This series examines how sex differences, consciousness, and culture have evolved together from our earliest ancestors to the modern world. My aim is to provide a clear, balanced, and empirically grounded account of how men and women have shaped — and been shaped by — the forces of survival, cooperation, and societal transformation.

These essays are not ideological; they are an attempt to understand our shared history with nuance, humility, and depth. I invite readers to explore these ideas with an open mind and a willingness to see our past and present in a broader, more integrated light.

— Michael Thacker

Introduction

Women’s rights have progressed tremendously over the past several decades with the first milestone completed in the 1920s that granted rights for women to vote. At present, women work alongside men in the workforce and even either own or manage large corporations — positions that were absent from society a century ago. Women also own property, bank accounts, file for divorce, and do just about anything within the confines of lawful behavior. Comparatively, women also hold positions of power within the political sphere, including the first woman becoming a Vice President in America’s previous presidential term.

With this wealth of progress in such a short duration, it begs the question: how did all this progress transpire?

Feminism has contributed much to the transformation of laws that have provided the rights to women that now allows them to fully participate in society. The fundamental axiomatic idea within the ideological structure of early feminism was that women are as valuable as men and can thus contribute the same as men. This idea is fundamentally true; however, it is partial. How? Men and women can contribute the same value and impact, albeit, in different forms. A more elaborate answer will be articulated in later sections.

Present day feminism is fundamentally different than its predecessor as it has radicalized itself towards a new ideal — women not only can contribute the same as men, but they can do it better. Competition rooted in resentment is the fundamental axiom derived from Marxist’s ideals. Why did this shift occur? Feminism’s response to the tyranny of the modern patriarchal society was and is justified; however, it was a response nested in left hemispheric perception. It has articulated a narrowed interpretation of the overarching reality that is at play.

To understand precisely what has transpired over the past century regarding the progress of women’s rights, and the potential future they may unfold from this enlightening transformation, one must perceive this phenomenon in a holistic manner. With that said, men are fundamentally different than women both physiologically and neurologically — differences that have developed throughout humanity’s 7-million-year evolutionary past. These differences, however, do not promote inequity between the two sexes, but rather contributions of fundamentally different kinds that contribute to the conducive whole of humanity’s survival and success.

The key to understanding and promoting these diverse contributions is interpretational adaptation. As humanity progresses technologically, the collective’s perception is updated in accordance with these changes. Only then can a balanced value structure emerge that promotes diversity among the sexes in all its glory.

Evolutionary Foundations of Sex Differences

7-million-years have elapsed since humans last shared a common ancestor with chimpanzees, and from this time a variety of changes have occurred both physiologically and neurologically. From Australopithecus to Homo erectus, we grew significantly taller and slenderer, while also doubling in brain size. The transition from Homo erectus to Homo sapiens and those in-between revealed substantial changes, not the least being another increase in brain size and resulting cognitive complexity.

These developments in cognitive complexity are tangibly evident from the first rudimentary Oldowan stone tools dating from 3.4 million years ago to the more precise Acheulean tools that emerged around 1.6 million years ago and lasted until 200,000 years ago around the time that Homo sapiens first emerged. From there, tool variety and refinements accelerated that emphasized precision and utility (Tattersall, 2013).

Similarly, beginning in the Upper Paleolithic around 50,000 years ago in Europe, elaborate artwork began to emerge that further demonstrated the development of the psyche of evolving humans. Following this creative explosion was the construction of megalithic structures such as Gobekli Tepe, along with the innovative leap of agriculture and herding — characterizing the Neolithic period (Cauvin, 2000).

During the early Neolithic Period (PPNA: 12,000 to 9,600 years ago), religion was an ambiguous concept that manifested itself in the dichotic form of female and bull figurines and carvings. However, in the late Neolithic (PPNB: 9,600–8,000 years ago), refinement of these divine figures occurred with a more detailed female figure and the initiation of a male figure (Cauvin, 2000; Gimbutas, 1989). No longer were the conceptualization of the intrinsic nature of humanity portrayed in ambiguous, symbolic representations — rather, the ability for the psyche to properly differentiate the human species became apparent.

Though this ability of perceptual differentiation among the species may have become apparent in the late Neolithic, the actual physiological and neurological differences were evident millions of years prior to this revelation. The first evidence for sexual differentiation occurred approximately 200 million years ago with the first observance of anisogamy (Hamaji et al., 2018). As time elapsed, these differences, influenced by the interaction between organism and nature, emerged in a variety of ways — sometimes in significant, explicit characteristics while others in subtle form.

These differences between males and females are called “sexual dimorphism”, and in Australopithecus (4 million to 1.4 million years ago), sexual dimorphic differences were large. For instance, height and weight differences between males and females were substantial with males averaging height of 4’11” tall while weighing in at 92 lbs. compared to females of just over 3’ and weighing 64 lbs. Albeit, these differences have narrowed significantly since the induction of the Homo genus around 2.5 million years ago, and even further still since the emergence of Homo sapiens.

Sexual dimorphic differences are not restricted to anatomical features but rather include neuroanatomical differences as well. Recent evidence provided by Ryali et al. (2024) found a significant difference in the distribution of neural networks within the brain between males and females. For instance, one of the most significant differences were found in the Default Mode Network (DMN) — connections that significantly influence how males and females perceive and choose to interact with themselves and the world around them.

These physiological and neuroanatomical differences between males and females are predominantly influenced by hormones — specifically that of testosterone and estrogen. On average, men produce substantially more testosterone than women which not only influences physical strength and size differences but also impacts neurological features such as mentioned previously. Moreover, it is this hormone that helps initiate and substantiate intrinsic drive in men to move out into the world with the goal to explore and create. However, it can also promote status-seeking behaviors wherein individuals compete against one another (Losecaat Vermeer et al., 2020) — a common characteristic among our closest relatives the chimpanzees.

Due to this drive (testosterone) to explore and create, in conjunction with the evolving human psyche, and intergroup cooperation (oxytocin/estrogen-modulated), humanity advanced to an improved state of coherence and stability — that which was provided by the emergence of civilization nearly 6,000 years ago.

In Part 2, we will turn to how early civilizations, hierarchies, and ego development shaped what later became known as the patriarchy. 

References:

Cauvin, J. (2000). The birth of the gods and the origins of agriculture. Cambridge University Press.

Gimbutas, M. (1989). The language of the goddess. Harper San Francisco.

Hamaji, T., Kawai-Toyooka, H., Uchimura, H., Suzuki, M., Noguchi, H., Minakuchi, Y., Toyoda, A., Fujiyama, A., Miyagishima, S. Y., Umen, J. G., & Nozaki, H. (2018). Anisogamy evolved with a reduced sex-determining region in volvocine green algae. Communications biology, 1, 17. https://doi.org/10.1038/s42003-018-0019-5

Losecaat Vermeer, A. B., Krol, I., Gausterer, C., Wagner, B., Eisenegger, C., & Lamm, C. (2020). Exogenous testosterone increases status-seeking motivation in men with unstable low social status. Psychoneuroendocrinology, 113, 104552. https://doi.org/10.1016/j.psyneuen.2019.104552

Ryali, S., Zhang, Y., de Los Angeles, C., Supekar, K., & Menon, V. (2024). Deep learning models reveal replicable, generalizable, and behaviorally relevant sex differences in human functional brain organization. Proceedings of the National Academy of Sciences of the United States of America, 121(9), e2310012121. https://doi.org/10.1073/pnas.2310012121

Tattersall, I. (2013). Masters of the planet: The search for our human origins. St. Martin’s Griffin.