The Kind of Intelligence That Grows With Age and How to Build It

How Smart Are You?

If you'd asked me that at different points in my life, you would have gotten very different answers.

Most people measure intelligence by their ability to memorize facts, solve math problems, or follow complex logic. But intelligence is far more than storing and processing information.

When I was in eighth grade, I took an IQ test to help determine my high school track. My parents were called into the school counselor's office and told that my IQ was so low I should be enrolled in the "tech prep" program, because I likely wouldn't ever go to college.

I didn't know about this conversation until years later, after I had earned my PhD in Psychometrics. My parents were wise enough not to share that discouraging assessment when I was young. The school counselor's interpretation of a single test didn't define my potential then, and it certainly didn't define me later.

So… how smart are you?

Two Kinds of Intelligence

In the mid-20th century, psychologist Raymond Cattell identified two broad types of intelligence:

Fluid Intelligence – The ability to reason, solve new problems, think abstractly, and adapt to unfamiliar situations. Fluid intelligence is sensitive to aging and neurological change.

Crystallized Intelligence – The accumulation of knowledge, skills, and experience gained over a lifetime. Crystallized intelligence often remains stable—or even grows—as we age.

Both are important, but they serve us differently over a lifetime.

Why Some Brilliant People Grow Bitter

I recently watched a video by Arthur Brooks, who shared an intriguing observation. He noticed that many Nobel Prize winners and other recognized geniuses in their 30s and 40s became bitter, unhappy people later in life.

Why?

They kept trying to innovate and produce at the same level they did in their early years—when their fluid intelligence was at its peak. But over time, that sharp edge dulled.

The few who thrived into their 80s and 90s had learned to pivot. They built on their crystallized intelligence—using their accumulated knowledge to teach, mentor, and develop others. They shifted from being direct producers to becoming guides for the next generation.

The Trap of the "Big Four"

Brooks' research also revealed that chasing money, power, pleasure, and fame leads to disappointment. They can become addictions, and they never deliver lasting happiness.

Instead, he pointed out that fluid intelligence—your raw mental processing—tends to peak between 30 and 40. But crystallized intelligence—your ability to connect dots, see patterns, and draw from deep experience—can keep growing for the rest of your life.

The real opportunity for older leaders is to lean into roles that multiply others: teaching, mentoring, coaching.

Indirect Success Is Still Success

I've seen it myself: those who use their accumulated wisdom to lift others often live the most fruitful and joy-filled lives in their later years.

I call this indirect success, finding significance by helping others experience direct success. It requires humility because it doesn't feed the ego the same way a personal win does. But it's the essential transition every aging leader must make.

We must learn to see our success in the success of those we pour into.

The Christian Perspective

As Christians, we're called to keep growing in wisdom and experience, not just for ourselves, but for the sake of others. That's why I continue to read, listen, and learn—not to make myself "smarter," but to integrate what I've learned over a lifetime and pass it along.

The Bible honors gray hair as a symbol of wisdom. It calls older men and women (1 Peter 5:1–4, Titus 2:4) to teach, mentor, disciple, shepherd, and model godliness.

Real Intelligence

Truly wise people know that money, power, pleasure, and fame won't bring deep joy.

Real intelligence is a lifelong commitment to learning and then using everything you've gained to help others flourish.

You may not get awards for it, but you'll be helping fruit grow on someone else's tree.

And that will be enough.