7/14/2026
A few weeks ago I read some research about the functions of human hippocampus. I made a note of the research and wanted to come back to this, because one of my college classmates lost about 90% of the volume of her hippocampus due to some unknown reason. This research suggests that the hippocampus plays a much broader role than neuroscientists once believed.
Neuroscientists have discovered that the hippocampus is involved not only in forming memories but also in imagining the future. Whether we plan tomorrow's activities, picture how an event might unfold, or visualize a place we have never seen, many of these mental simulations depend on the hippocampus. In other words, remembering the past and imagining the future rely on many of the same neural machinery.
Modern neuroscience increasingly suggests that the hippocampus is a simulation engine—a brain system that uses the past to construct possible futures.
From an evolutionary perspective, this makes perfect sense. Remembering the past is valuable because it helps us anticipate the future. Animals that can predict danger, locate food, or choose better actions are more likely to survive and reproduce.
Memory evolved not to preserve yesterday, but to prepare for tomorrow.
A growing body of research suggests that regular physical exercise, mentally stimulating activities such as reading and language learning, music, and rich social engagement are all associated with better hippocampal health and a lower risk of cognitive decline.
Finally, writing serves another valuable purpose. By recording our experiences, we create an external memory that works better at preserving our memory, and with that years later, these memories allow us to revisit the past, reflect on it, and use it to imagine the future once again.
Perhaps that is one reason human beings have always kept diaries, written memoirs, and told stories. Memory allows us to learn from yesterday; writing allows us to preserve those memories long after they begin to fade.
