Speaking of "neuroplasticity" the divisions in human society between people who stop thinking new thoughts around age 14 or so, vs the people who keep thinking

Speaking of "neuroplasticity" the divisions in human society between people who stop thinking new thoughts around age 14 or so, vs the people who keep thinking until they die, we'll say age 80, are already very large and would get immensely larger. Everyone has anecdotes about relatives at both ends of the scale, and the scale will probably get wider over time. From an evolutionary fitness standpoint people who stop thinking are not likely to live very long so there would be pressure toward plasticity.