Teddy Wayne recently wrote a piece for the Sunday New York Times called “The Childless Life” (the digital version is titled “No Kids for Me, Thanks”) which at face value was a discussion of the individual choice to go vocally, self-righteously extinct. In it, he reviewed a recent collection of essays written by persons who will leave behind no descendants, on purpose. “Selfish, Shallow, and Self-Absorbed” is an anthology, the collected expressions of a group of 16 authors, all of whom have chosen both to remain childless and to write about that fact. The Venn diagram of scientists and writers should have some modest overlap, but apparently not in the case of these Lineage-Enders.

In fairness, it was @HollyDunsworth who first suggested the title “Lineage-Enders” in a tweet that anticipated someone might be reading the NYT article and wonder why it seemed so utterly uninformed by Darwinian thought. We complain a lot in America because numerous opinion surveys show a majority of us do not believe or understand the theory of evolution. Responsibility for that seems to extend to the literati, as it’s basically nonsense to write about the self-selected infertility of the educated elite without gazing through evolution’s eyepiece. So with your indulgence, I will discuss the evolutionary implications of Lineage-Enders (LE).

One need not read every word of the childless to come to an overarching theme: Children bother these people. They resent that children are loud with unstructured lives that interrupt what adults would be doing if left alone. Lineage-Enders as a group resent sharing of space, patience, silence, and resources with small and uncivilized toddlers. They complain loudly that, when burdened by childcare responsibility, they as adults are not as completely happy and fulfilled as they imagine they otherwise might be. They are basically bad parents, and many admit as much. There have always been “bad parents,” but it is important to separate the pejorative from the shrewd life strategy trajectory.

Just for argument’s sake, let’s propose that two distinct parenting behavioral strategies resting on separately heritable genetic foundations arose in early hominids. The first we will call Ultra-Nurtures (UN) and although the genetics of this condition are not certain, the phenotype is well understood. Everyone knows a UN human being, and it might be argued that this behavior is the more prevalent human pattern. Being UN allowed us to be farmers and to treat all manner of non-human things as we would treat our own children. Thus, helpless wolf cubs were coddled and fed, turning them into dogs instead of small bite-sized breakfasts. Tiny sprigs of green were watered, sheltered, and turned into wheat and corn. The same for small, orphaned foals, who most likely would have required the milk of a human female to survive long enough to begin to eat grass and start the long journey to domestic horses. Ultra-Nurture humans are both male and female, but the endlessly cheerful daycare lady sitting on the floor with kids piled around her lap is a good icon.

(There exist already long and contentious threads of discussion about behaviors and their heritability as well as their teachability. There isn’t any question that there are environmental inputs that act on underlying, genetic predispositions to act out behavioral programs of activity. Those include reproductive life strategy activities. For the rest of this essay, I will refer to the LE and the UN behaviors as being enabled by a small number of discrete and identifiable genetic elements, full stop. This is not a nature/nurture debate.)

The second group is the one we are now calling Lineage-Enders (LE), but for millions of years they were anything but—it is more accurate to call them parental resource hoarders and to recognize that they had a robust reproductive strategy that exploited the weaknesses of their UN relatives. As soon as early hominids were living in cohesive, complex social groups of cousins, grandparents, and other close relatives, abandonment of one’s own toddler at an early age into the arms of a more devoted aunt, sister, or other relative would have enabled the child-intolerant (LE) female to engage again in sex and speed her own re-entry into the reproductive cycle. On the other hand, the indulgent, patient, Ultra-Nurturing adoptive parents of these abandoned infants probably shared many genes in common with them and so continued to enhance their own Darwinian fitness through proxy reproduction of close kin. Aggressive, child-intolerant males could devote themselves to building alliances of dominance instead of building toys and teaching life skills to children. That works especially well if they are able to mate with a number of females, preferably from both LE and UN backgrounds. With the right fractional survival of each type of offspring, the coexistence of LE and UN fractions within human society is evolutionarily stable. It does give rise to the occasional pejorative, as earlier noted, and so we have “bad parent,” “loose woman,” “ladie’s man,” and a host of others, as each judgmentally examines the behaviors of the other and looks for exploitation.

Prior to the transition to eusociality, LE genes would have been catastrophically disadvantaged. But I would argue that cognitive patterns that typify LE parenting styles are also fundamental to our explosion of intellect. It’s not hard to conceptualize that the urge to study intently, to concentrate, and to think carefully and methodically might have some conflicts with the typical modern parenting experience. Still, the genes underlying LE behavior have probably been under positive selection for millions of years.

This equilibrium was demolished by the molecule norethynyl estradiol, invented in 1951 by Carl Djerassi and now universally known and understood as The Pill.

This earthshaking chemical advance enabled women for the first time to be absolutely in control of their fertility, while simultaneously opening the door of extinction to the Lineage-Enders. Prior to effective, cheap birth control, the LE fraction of humanity was reproducing fitfully, if distastefully. Their lack of interest in caring for children did not preclude an avid interest in the activity, sex, that produces them, and so were born countless under-parented, neglected, and sometimes abandoned small people who made their own selfish way in the world the best they could. Most of them who survived and even thrived did so because the other important group of humans, the Ultra-Nurtures, took pity on these children and made sure they were fed and well cared for. But for the last several generations of man, the desire not to reproduce could be acted upon in an executive manner by any woman with LE inclinations. Those unwanted children would no longer be born—but why?

The widespread human predilection to adopt and care for unrelated children is anticipated by sporadic cases of infant adoption in social, non-human primates. There is no such biological precedent for the Lineage-Enders, so their motivations must be taken at face value. An attenuated gag reflex can be helpful here. Much has been written, in addition to the above mentioned anthology. Sezin Koehler is a Lineage-Ender, and she writes about that here. So pleasant to know that all this hyperbole is just a few decades from dying out.

The poster child for LE humans is probably @Ericholthaus, the “sniveling beta-male” ridiculed by Fox News for his labored public weeping over the multiple challenges of humanity and the gratuitously self-indulgent idea that his own personal vasectomy might have such an impact as to represent a turning point for mankind. Even more hilariously, he then squelched, backed out of the sterilization, and got his partner pregnant—the rationalization being that this made him feel “hopeful.” Never has there been a person more in need of a gentle reminder of his own inconsequentiality. And although he has blurred the line demarcating his own extinction by a generation, he does bring to mind a salient point: If Mr. Holthaus had the intellectual capacity of a fig tree, he would recognize that he is currently living in a period of rich and plentiful food and resources. If the dreaded future that he envisions is really just a generation to come, then his most viable and Darwinian reproductive strategy would be to produce as many babies with as many women as physically possible and distribute them far and wide, the better to insure that some fraction of them actually pull through his imaginary, upcoming human population bottleneck. That is—he would be masting.

Neuroscience has discovered interesting discontinuities between what we actually do and how we describe why we took these actions once we become aware that they have happened. The rationalizations of LE humans ramble with hand wringing piousness over carbon footprints, disease, malnutrition, and the peculiarities of their personal psychoanalysis with repetition of terms like fulfillment, actualization, achievement, and etc. (gag). I would argue instead that they are LE because this is their genetically predisposed reproductive strategy, and their verbalizations are all just window dressing to try to spin up their self-induced extinction to a crowd of inquisitive onlookers.

I am not a Lineage-Ender. In typical UN fashion, I have raised to maturity 3 unrelated stepdaughters who share no immediate genetic relationship to me, although they now share 25% of their genes with four of my children. I have raised two millennial males to adulthood (well, not quite, but to that amorphous near-adult state that is specific to this generation), and I have three more kids not yet out of high school. As a semen donor when a younger man, I donated my genes and any inclusive parenting predisposition to many dozens of women who lacked only male gametes in their profound desire to reproduce and have a baby for themselves. My kind will go forth and multiply, exponentially.

In closing, I have only some final thoughts for the Lineage-Enders. The first is that no one will notice. The freeways will be just as jammed in 2040 despite the absence of your un-offspring and their un-purchased automobiles. Other campers will still beat me to the signup counter in Yellowstone Park, making me wait an additional day to go with my grandkids to my favorite campsite at Black Tail Deer Creek. Airlines will still manage to cram 300 people onto an airplane when tickets have been sold to 320 and the plane was designed for 288. Atmospheric carbon dioxide concentration will still march forward in its inexorable grandeur, and will not twitch in the slightest 0.0000000001 ppmv due to anything either of us has done.

But what will change is something called the allele frequency, ƒ, for any unique genes that you may be carrying on your chromosomes, versus the ones on my chromosomes. For your genes, you are placing an a=0 value in the equation ƒ=a/n*N. For myself, I am placing a large integer value in the place of a, probably about 400. There is no implication that those particular genes unique to me, or to you, are also advantageous. Sometimes I think some of mine may be detrimental, or in the case of my null mutant KCNQ3 ion channel, perhaps responsible for some really intractable insomnia. But this is not for me to judge—it is for the viability of future generations to establish by that most Darwinian process called survival of the fittest. For you, the process is done. You are completely unfit. Oral contraceptives have been the undoing of your reproductive strategy. And do you remember that annoying woman stuck in the elevator with Tom Hanks in “You’ve Got Mail,” so anxious to get out so she could have her eyes lasered?  Future humans may notice a few less of those.