Original article: "Topological turning points across the human lifespan" - https://www.nature.com/articles/s41467-025-65974-8

Abstract: "Structural topology develops non-linearly across the lifespan and is strongly related to cognitive trajectories. We gathered diffusion imaging from datasets with a collective age range of zero to 90 years old (N = 4,216). We analyzed how 12 graph theory metrics of organization change with age and projected these data into manifold spaces using Uniform Manifold Projection and Approximation. With these manifolds, we identified four major topological turning points across the lifespan – around nine, 32, 66, and 83 years old. These ages defined five major epochs of topological development, each with distinctive age-related changes in topology. These lifespan epochs each have a distinct direction of topological development and specific changes in the organizational properties driving the age-topology relationship. This study underscores the complex, non-linear nature of human development, with unique phases of topological maturation, which can only be illuminated with a multivariate, lifespan, population-level perspective."

Here we go again, with overzealous correction of "myths" that aren't myths.

>Like many myths, the “age 25” idea is rooted in real scientific findings, but it’s an oversimplification of a much longer and more complex process.

In order words, it's a legitimate observation if you engage in charitable interpretation instead of completely strawmanning it. During childhood/adolescence the brain engages in "synaptic proliferation" creating an excess of synapses, and follows that up with "synaptic pruning", paring back the excess based on frequency of activation, and at the same time myelination adds a fatty layer for better insulation.

The pruning and myelination really do, mostly, finish (emphasis on mostly), in your mid 20s, and criticizing that as a myth because it's not an absolute finish to the process, or not absolutely concluded when the clock strikes midnight the night before your 25th birthday is asinine.

What's worse, in this case, is the article is every bit as comfortable proposing a target date, at age 32 instead of 25, which, if you want to be similarly uncharitable, you could decry as a myth for spurious reasons relating to the non-absolute nature of biological averages that year 32 is attempting to represent.

But what's worst of all, I think, is that it's not even disputing pruning and myelination timelines, it's talking past the point about structural maturation of the frontal lobe, a real thing, to simply emphasize a different thing, the efficiency gains revealed from studying white matter topology, a kind of long distance structural reinforcement, as if it's a correction or refutation of the age 25 thing. But in truth it's a real but complementary finding that shifts the window for long distance efficiency to 32, which isn't even a different form of structural buildout or pruning but about the reinforcement of existing highways.

I want to make a ruling here that science reporters are no longer allowed to use the word "myth" to characterize known and true processes being complemented by new research. There has to be a hook to celebrating the complexity of the brain that isn't constantly recycling the myth framework.

Previously: https://news.ycombinator.com/item?id=46045661