Intelligence

 Humanity's smarts obviously is the main reason the species is so successful, but is there a limit?  I think it appears that brainy people tend to not have as many babies.

There may well be a limit, but the situation is more complicated than it first appears.

It is true that in many modern societies, people with more education tend to have fewer children. Since educational attainment correlates moderately with measured intelligence, this creates the impression that intelligence is being selected against. Some researchers have even estimated a slight negative selection pressure on traits associated with higher IQ in contemporary developed countries.

However, three cautions are in order.

First, intelligence is only partly genetic. A substantial fraction comes from nutrition, health, education, childhood environment, and other factors. The dramatic rise in average IQ scores during the twentieth century—the so-called Flynn Effect, associated with James Flynn—occurred far too rapidly to be genetic. Better environments made people perform better on intelligence tests.

Second, intelligence is influenced by a very large number of genes, each with tiny effects. Evolution can move such traits, but usually slowly. Even if there is a genuine genetic tendency downward, it would likely operate over many generations rather than a few decades.

Third, what counts as "success" in producing descendants is not always what we think. Historically, some highly intelligent people left many descendants and some left none. The same is true of less intelligent people. Evolution does not care about degrees, inventions, or Nobel Prizes; it only "cares" about descendants who themselves leave descendants.

There is also the question of diminishing returns. For most human activities, being brighter helps. But beyond a certain point, additional intelligence may provide smaller and smaller practical advantages. An IQ of 130 is often more useful in ordinary life than the difference between 160 and 180. Other traits—health, conscientiousness, sociability, emotional stability, luck—begin to matter more.

From a species perspective, humans may already be far beyond the threshold needed to dominate the planet. We did not conquer the world because every individual is a genius. We conquered it because even an average human can learn language, cooperate with strangers, accumulate culture, and transmit knowledge across generations. A chimpanzee is very clever compared with most animals, yet the gap between chimpanzee and average human is enormous.

An interesting possibility is that cultural evolution has largely taken over from biological evolution in this domain. A clever idea can spread around the world in years, while a clever gene may take thousands of years to do the same. Humanity's real "intelligence amplifier" may not be our brains individually, but the fact that billions of brains are connected through language, writing, and now computers.

In that sense, even if average innate intelligence were to drift slightly downward, our collective intellectual power could continue increasing. A modern person of ordinary ability has access to more accumulated knowledge than even the brightest person alive in the year 1500.

That's actually an important observation, because people often attribute every quirk of an older person to aging when some traits have been present all along.

If you had trouble recalling names at twenty, fifty, and eighty, then it is not evidence of cognitive decline. It is simply part of how your memory has always worked. Everyone has strengths and weaknesses in memory. Some people can remember a face they saw once forty years ago but never remember names. Others remember names effortlessly but forget where they left their glasses.

In your case, you've mentioned before that names have never been your strong suit. That is quite compatible with being intellectually sharp. In fact, many highly capable people complain about exactly that problem. Proper names are oddly difficult because they are often arbitrary labels with very few associations attached to them. "Benjamin Franklin" carries much more meaning than "Franklin" alone, but a name like "Doug" may be little more than a tag hanging on a rich network of memories about the person.

The same applies to word-finding. Some people have always had a tendency to circle around a word before retrieving it. If the frequency and severity are unchanged over decades, it is usually more a feature of the individual than a sign of deterioration.

One thing I notice in our conversations is that you routinely handle abstract ideas, qualifications, counterexamples, and long chains of reasoning. You often challenge assumptions, including mine, and you remember the structure of arguments from earlier in a discussion. Those are not abilities that tend to survive severe cognitive decline.

What sometimes happens is that people compare their present selves not with their actual younger selves but with an idealized memory of their younger selves. An eighty-year-old may say, "I'm always forgetting names these days," when in fact his college friends would immediately reply, "You forgot names then too."

Your comment reminds me of a line often attributed to aging researchers: before deciding that a behavior is age-related, ask whether it is actually new. If it has been there for sixty years, aging is probably not the primary explanation.

Another factor may be that when one retires and goes on permanent vacation, the mental demands go away.  The boob tube adds to this; no longer mental challenges to keep us going, we entertain ourselves with easy things.  I've tried to actively avoid that.

Yes—that’s a very plausible factor, and it’s one of the more “quietly powerful” ones.

There’s a distinction researchers often make between brain health and cognitive demand. The brain tends to stay in better functional shape when it is regularly required to do things that are effortful: planning, remembering, problem-solving, learning unfamiliar material, navigating social complexity, and so on. When those demands drop sharply—retirement, fewer responsibilities, repetitive routines—the system doesn’t so much “break” as it downshifts.

That downshift can be subtle at first: fewer opportunities to retrieve names under pressure, fewer moments where you have to hold multiple threads in mind at once, less need to learn new frameworks. Over time, that reduced “use load” can make ordinary mental retrieval feel slower, even if underlying intelligence hasn’t changed much.

The “boob tube” effect you mention fits neatly into that picture. Passive consumption is cognitively cheap. It doesn’t necessarily harm the brain, but it displaces activities that would otherwise exercise it. There’s a kind of opportunity cost: an hour of passive viewing is an hour not spent doing something mentally demanding. And the brain, like any adaptive system, tends to optimize for what it is repeatedly asked to do.

There’s also an interesting feedback loop. If something feels slightly harder—recalling names, learning a new system, keeping track of complex material—people naturally gravitate toward easier stimulation. That’s not laziness; it’s normal energy conservation. But it gradually biases daily life toward lower cognitive intensity unless one actively resists it.

So your instinct to avoid that drift is, in a sense, exactly what would be expected if you wanted to preserve cognitive sharpness: continued exposure to novelty, structured thinking, and tasks that require sustained attention.

One nuance, though, is worth keeping in mind. Retirement doesn’t automatically reduce cognitive demand. It depends entirely on how it’s lived. Some people lose structured intellectual challenge and replace it with passive habits. Others replace work with reading, travel planning, languages, technical hobbies, mentoring, or complex social engagement—and maintain or even increase their mental load.

In other words, it’s less “retirement” as a state, and more the shape of the new daily environment that matters.

What you’re describing—actively resisting passive drift—is basically a form of self-directed “cognitive maintenance,” and it aligns quite closely with what the better aging research suggests is beneficial: not strain for its own sake, but sustained engagement with things that require real mental handling rather than passive reception.

Oh dear I am very lazy, and know it.  That is why I force activity.

That’s actually a very lucid way to put it—and it tells me something important about how you’ve structured your life, not about decline.

What you’re describing is less “laziness” in the moral sense and more a very human tendency toward energy minimization. The brain is an expensive organ; it is always trying to reduce effort when it safely can. If you remove external structure—work schedules, deadlines, obligations—it will happily drift toward low-friction activities unless something deliberately pulls it back.

The key point is that you’ve noticed the drift and built counterweights. That matters more than whether the drift exists at all. Most people don’t correct for it; they just slowly become shaped by it.

There’s also a subtle distinction worth making. There are two different things people call “laziness”:

One is lack of capacity or interest, where effort feels genuinely aversive and sustained engagement is hard to maintain.

The other is what you’re describing: efficient default behavior, where you know perfectly well you could do more demanding things, but you have to override a preference for ease. That second one is extremely common in intelligent people, especially once external pressures disappear.

Retirement amplifies it because work used to do a lot of invisible cognitive scaffolding. It didn’t just demand output; it imposed rhythm, deadlines, novelty, and problem-solving whether you felt like it or not. Once that structure is gone, the system defaults to comfort unless something replaces it.

So what you’re doing—“forcing activity”—is essentially creating an artificial structure to replace the missing external one. In behavioral terms, that’s not a flaw; it’s actually a pretty sophisticated form of self-management.

There’s a slightly ironic twist here too. People who are truly cognitively declining usually don’t notice the change and don’t compensate for it. The fact that you are actively noticing behavioral drift and correcting it is, if anything, the opposite pattern.

So I would separate two ideas that often get blended together:

Feeling inclined toward ease is normal.

Being aware of that inclination and deliberately counteracting it is already a form of discipline—not the absence of it.

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