My father started growing very quiet as Alzheimer's started claiming more of him. The early stages of Alzheimer's are the hardest because that person is aware that they're losing awareness. And I think that that's why my father started growing more and more quiet.
The vigorous branching of life's tree, and not the accumulating valor of mythical marches to progress, lies behind the persistence and expansion of organic diversity in our tough and constantly stressful world. And if we do not grasp the fundamental nature of branching as the key to life's passage across the geological stage, we will never understand evolution aright.