Memory cells are one of the main reasons why young children often die of diseases that their parents shake off easily: There are just not enough living memories in their tiny bodies yet, and so even smaller infections can spread and become a mortal danger. Their parents, with an Adaptive Immune System that is remembering thousands of invasions, can just rely on their living memory. And likewise, as we reach old age, more and more Memory Cells stop working as well as when they were younger or just call it quits, leaving us exposed in the last phase of our lives.
