The Age of Intelligence? It May Be Later Than You Think

While there is little doubt when we hit our peak age in terms of physical strength and agility, a new groundbreaking study suggests the peak age for mental and intellectual prowess comes far later in life, perhaps peaking as late as 65 years old.

That would probably come as something of a surprise to British poet Lord Byron, who in November 1812 penned his immortal line that “the days of our youth are the days of our glory.”

A two-man team of Australian and Polish psych professors has published data in the November-December 2025 issue of Intelligence suggesting that our intellectual peak, tempered by life experiences, comes much later, in the years between 40 and 65.

There’s never been a shortage of older folks producing amazing results, of course. Ludwig von Beethoven wrote his most famous Ninth Symphony at age 50. On Sept. 24, 1847, at age 70, Noah Webster published the first edition of his American Dictionary of the English Language, a two-volume work whose pages were packed with 70,000 clear and concise definitions. Roy Kroc was a 52-year-old struggling blender salesman when he teamed up with two partners to take over a popular hamburger restaurant called McDonald’s in San Bernardino, Calif. By the next year he had opened a second store in Illinois that eventually propelled the international fast-food revolution around the globe.

Julia Child published Mastering the Art of French Cooking in 1963 when she was 52 and almost single-handedly introduced French cooking to mainstream America.

Author and home entertainment doyenne Martha Stewart is still going strong at 84 years old. And her stint in a federal prison in 2004-05 for insider trading was certainly a life experience that most people won’t ever have but which she built into her comeback story.

Gilles Gignac of the University of Western Australia and Marcin Zajenkowski of the University of Warsaw in their study focused on 16 age trends. It suggests the accomplishments by older folks are not outliers, but are really a natural mental and psychological outcome tempered by life experiences.

The list of things they proposed to measure begins with the obvious intellectual traits: their subjects’ ability to reason, the speed with which they processed information, the state of their memory, and how well they used words to communicate and learn. Next up were a number of personality traits with conscientiousness (defined as being careful, diligent, and responsible) and emotional stability leading the way. They also factored in qualities people are likely to learn by life experience: how to experience emotions, how to handle money, how to make moral decisions and accept the need to be sufficiently flexible to learn from others while being empathic to those others’ needs.

Mashing this all together, the two researchers concluded that “most adults between about 40 and 65 show the strongest blend of insight, stability, and decision-making prowess. That helps explain why career peaks and leadership roles often cluster in the late 50s to early 60s. It also suggests that high-stakes decision seats are rarely optimal for people younger than 40 or older than 65.”

Which is not to denigrate the abilities of an army of young tech moguls or some of the skills of emerging young politicians on the scene today. But it does say accomplishments by people in the older middle age to early senior bracket should be viewed as a natural outcome, not a surprising outlier.