We tend to talk about reproduction as if it simply means having kids. But really, for an organism to be reproductively successful, simply producing offspring is not enough, especially not for mammals like us who are born mostly helpless and mature slowly. It is trivial to get (someone) pregnant only to see one’s genetic line nonetheless end soon after. Making kids is the fun & easy part (the pain, stress, and other difficulties of pregnancy and childbirth notwithstanding); ensuring their success, in biological terms, is another matter.
So we talk about producing “viable” offspring instead. I’ve heard that in the early 20th century when daycares and public elementary schools were starting to become widespread, there was a catchphrase “five to thrive” used by employees of those institutions, reflecting the idea that if your kid made it to five years old then it was past most of the big hazards that tended to kill young children at the time.
But what does “thrive” mean in that context? A reasonable definition, one I suspect those childcare workers might have given, would be “grow into a healthy adult”. And part of that health, whether they thought of it or not, is certainly also reproductive health. Rearing children who make it to five years old but are always incapable of ultimately producing children of their own would suggest some sort of failure on the part of those doing the initial rearing.
In this sense, “reproduction” does not end when a child is born, or even when a child makes it to five years old. Instead, it ends when the child becomes capable of producing children, which can really only be proven out by actually doing it. Only if each generation thinks of and acts on reproduction in these terms, with this overlapping leapfrogging of reproductive ambition, is a genetic lineage assured to continue.
I wonder if this might be an evolutionary reason why so many people look forward to being grandparents, and pressure their own kids to make them grandparents. I try not to make this a burden my kids have to carry, for reasons related to their psychological health, but it is definitely something I hope they do, and when they talk about someday having their own kids I am always inwardly excited and outwardly supportive, hoping they don’t ultimately change their minds at some point.
I wonder also if this explains some of the disappointment parents might have at finding out their children are gay, even if the parents otherwise have no moral qualms or squeamishness with homosexuality. How many of these parents hope their gay children will at least seek biological reproduction by some other non-romantic means (sperm donor/surrogacy)? I would bet it’s a large majority.
The urge to see our genes carried forward is powerful and not entirely rational, baked into us over millions or billion years. It’s an odd sensation to feel as though you’re in control of most of your urges but realize you have no power over this one.