All people are born with either male or female sex characteristics, aside from a miniscule population of “intersex” individuals, who inherit both. Gender, however, is a social construct based on the norms, behaviors, and societal roles expected of individuals based upon their biological sex.

Like most mammals and some plants, humans are also dimorphic, meaning the sexes on average exhibit measurably different morphological attributes. In addition to sex organs and the secondary sex characteristics that bloom at puberty, these differences typically include height, weight, musculature and a variety of hormonal phenotypes.

My late mother-in-law, rest her soul, was fond of saying that the true purpose of sex is procreation, not recreation. But in truth, you don’t even need sex to reproduce.

Single-celled prokaryotes – archaea and bacteria - have procreated successfully for billions of years without using gametes to exchange chromosomes. A variety of asexual reproduction techniques also exist among larger organisms. They all provide offspring with a full set of genes from one parent, as opposed to the zygote produced by meiosis, which carries complete copies of the chromosomes from both parents.

Conflicts about sex, gender roles, and competing interpretations of our dimorphic nature are rife throughout recorded history. The persistence of sexual violence and friction over gender norms beg the question, is there virtue in distinct sexes?

Most eukaryotic (multi-cellular) organisms – and particularly animals - reproduce sexually, although some can switch on asexual reproduction in response to environmental conditions. It turns out, evolution is unkind to those that can only reproduce asexually. The fossil record is littered with extinct species that never invented sex or evolved away from the practice.

Asexual reproduction has advantages in stable environments or when rapid population growth is needed, while sexual reproduction introduces genetic diversity more rapidly, maximizing adaptation to changing environments. Thus, the evolutionary advantage of meiosis is that it marries the combinatorial variety of chromosomal fusion with an inherent propensity for transcription errors that produce unique mutations.

Edward O. Wilson, the eminence grise of biology, reminds us that evolution is a multivariate process driven not only by individual genetic mutations, but also by the epigenetic influences of the environment.

Evolution is defined as a change in the genetic constitution of a population over time. In the biological context a “population” consists of the freely interbreeding members of either an entire species, or a discreet subsegment of the species.

Given the obstacles to dating across political lines, it is possible our red and blue tribes could evolve into discrete subspecies, as H.G. Wells foretold in The Time Machine. The fair, childlike Eloi of that class-conscious satire bear at least a passing resemblance to the thin-skinned literati who animate the progressive left, while the savage, simian Morlocks share at least some characteristics with the nihilistic, populist right.

In many cultures gender role differences are vast and the social conventions that enforce them quite rigid. Witness the killing of 22-year-old Mahsa Amini by Iranian “morality police” for violating their hijab law. While this is less true in America, the landscape looked radically different a few generations back.

Fifty years ago, Marlo Thomas released a landmark album called Free to Be…You and Me. The sappy music and dramatic vignettes it contained were part of an emergent effort to bend traditional gender roles by casting off the stereotypes we transmit to our children.

This ethos of “liberation individualism” encouraged parents to help daughters dream about becoming doctors and police officers. Boys were urged to express feelings. Unisex clothing gained acceptance, and cinema began to move beyond the John Wayne archetype of emotionless masculinity.

Eliminating rigid gender boundaries to create options for women was a central preoccupation of second-wave feminism, but a funny thing happened on the path to gender equity. The same forces that created Title IX and criminalized workplace sex discrimination also expanded tolerance for variations in sexual behavior, ultimately paving the way for broader acceptance of premarital sex, divorce and gay rights.

In 1996, just 27% of Americans believed same-sex marriages should be recognized as equal to traditional marriages. By 2015, when the Supreme Court ruled in Obergefell v. Hodges that states had to recognize same-sex marriage, popular support had increased to 60%. Today it stands at 70%.

Instead of relaxing boundaries, a vociferous faction in the progressive left today seeks to abolish gender roles. They advocate a fundamental reimagining of human society based on “gender identity theory”, which postulates that a person’s selfperceived gender should be accepted as transcending their biological sex.

Supporters see transexuals and nonbinary people as the victims of religious persecution, bigotry and hatred - the same discriminatory impulses that the feminist and civil rights movements have combatted. Yet there are distinctions to be drawn.

Feminism seeks to establish political, economic and legal equality for a constituency that comprises half of humanity. The civil rights movement essentially seeks the same goals on behalf of the 42% of 2020 US census respondents who self-declared their race as something other than white. According to the Williams Institute, 1.4 million adults identify as transgender, or roughly ½% of the population.

Feminists have battled religious doctrines, laws and social conventions so powerful that even today a large portion of the global female population are essentially the property of their spouses or male relatives. Racial justice advocates have similarly contended with a multitude of blatant and camouflaged barriers to equality since chattel slavery, the greatest sin in US history, was abolished. Transgender and nonbinary people face ostracism, barriers in accessing public bathrooms and difficulty competing in sports as the gender of their choice.

In the halcyon days of Marlo Thomas, liberalism asked us to simply be more tolerant of otherness. Fifty years later, an overwhelming majority of Americans support the right to love and marry as you choose, regardless of gender. That we’re arguing about imposing new pronoun dogmas in order to ease the gender anxieties of ½% of the population signals just how successful the quest for individual identity has been, and also how absurd the last mile of the journey has become.