TOTAL RECALL: What’s Wrong with Our Childhood Memories

Photo by National Cancer Institute on Unsplash

All people «remember themselves» starting from a certain moment. For instance, the earliest memory our mind can usually retrieve dates back to the age of 3 or 4. But everything before that is hidden in impenetrable darkness, unreachable no matter how hard we try. Does this mean, however, that our brain truly retained nothing from that period?

THE MANAGER OF OUR MEMORY

Scientists believe that even if we can’t recall them in adulthood, our early memories are still preserved in an «encoded» form. MRI scans of the brain have shown that in infants and young children, this encoding is managed by the hippocampus. It’s no coincidence that it’s often called the «memory manager.»

The hippocampus is a rather peculiar figure in Greek mythology — a horse with a fish tail, ridden by Poseidon, god of the sea. It likely resembled a real creature from nature — a small fish known as a seahorse.

If you look at this paired structure, located in the temporal lobes of the brain, from the side, you’ll notice a striking resemblance to a seahorse. Because of this similarity, this ancient part of the cerebral cortex was named the hippocampus. It earned the title «memory manager» thanks to its function of transferring short-term memory into long-term memory. In other words, it regulates memory consolidation — encoding and compact storage.

Beyond memory, this «conductor of the brain’s depths» is also responsible for emotions and spatial navigation.

NOTHING LIKE ANIMALS

Maura O’Connor, a star of American science journalism, attempted to summarize everything modern science knows about the hippocampus in her book Wayfinding: The Science and Mystery of How Humans Navigate the World. Based on the data she presents, one clear conclusion emerges: in order to survive, humans had to become extremely mobile.

Evolution continuously «upgraded» our navigational skills, which led to an increase in skull volume and, ultimately, to the development of language and writing. Various forms of super-orientation are widespread in the animal kingdom. While humans were only beginning to invent the compass, animals already had one — built directly into their biology.

Bees, for example, can determine solar azimuth angles with astonishing precision. Spiders in the Namib desert navigate by the stars. Shrimp and squid use polarized light. Almost all animal species are sensitive to the Earth’s magnetic field. But humans are built differently: we clearly lag behind animals when it comes to natural orientation skills.

To navigate successfully, humans had to rely on their intellect. Over time, our brains grew larger, reaching their peak size — about 1800 cm³ — roughly 25,000 years ago. Since then, not only has it stopped growing, but it has even slightly decreased.

THE «EINSTEINS» OF PRIMAL SOCIETIES

Today, most human brains don’t face tasks even remotely as energy-intensive as those encountered by our distant ancestors. Only the minds of the most exceptional scientists come close. Once humans transitioned to a sedentary lifestyle, the need for deep «spatial understanding» diminished — something that was essential to so-called «uncivilized» peoples.

Just imagine the virtuosity with which the hippocampus of an Australian Aboriginal manages information, storing an incredibly detailed system of landmarks that simultaneously includes the sun, moon, constellations, trees, streams, and stones… The people of Oceania navigate by the stars and by types of waves. For instance, a wave reflected from the shore has unique characteristics and can indicate the direction of the nearest landmass even from a considerable distance away.

The Inuit can do nearly the same — but on a sea of ice and snow. Winds blowing from different directions create distinct surface patterns. Add to that the variations in the shape of the horizon — of which they can recognize thousands — and you’ll begin to understand: the average modern person is as far from the «primitive» brain as they are from Einstein’s.

THE HIPPOCAMPUS LEARNS TO «READ THE WORLD»

It appears that brain expansion, along with navigation and communication skills, began developing simultaneously around 2.3 million years ago. This was driven by the need to «read the tracks» of animals, mark out new routes, and share this information with others. The hippocampus played a key role in these processes: if it’s damaged, a person loses the ability to recognize familiar places.

A child, however, does not receive a fully formed hippocampus at birth — it reaches its «design capacity» around the age of six. This development happens through exploration. When children are restricted from discovering their environment and building new paths, their cognitive abilities suffer, including memory and social interaction. But the hippocampus is a highly flexible brain instrument and can adjust its volume throughout life depending on context.

According to recent findings by neuroscientists from Columbia University in New York, infants as young as one year old are already capable of forming memories. If we can’t remember the first few years of life, it’s not because those memories weren’t created or stored. Childhood amnesia is not due to the absence of memories but to the difficulty of retrieving them.

NO CONTEXT — NO MEMORIES

Scientists have proposed that the solution lies somewhere deep in our hippocampus. They formed a group of 26 children aged 4 months to 2 years and used MRI scans while the children performed memory-related tasks. Typically, children spend more time looking at familiar things. The researchers observed that the more active the hippocampus was when a child viewed a new image, the longer the child spent looking at the same image during repeated exposure — meaning they recognized it.

The highest encoding activity was noted in the rear portion of the hippocampus, which is responsible for memory retrieval. This activity was especially pronounced in children over one year old. Even in its immature state, the hippocampus carries out some encoding of episodic memory, though it likely lacks the recall experience characteristic of the adult brain.

Later in life, our brain relies on «cues» to retrieve memories, embedding everything seen and heard into a certain context — such as the pattern of ocean waves, snow formations, the horizon line, or constellation layouts. Infants don’t yet possess such a «reference base,» though they’re already starting to accumulate and encode memories.

However, every «navigation shift» — for instance, transitioning from lying down to crawling, or from crawling to walking — radically changes a baby’s view of the world. As a result, all infant memories encoded by the hippocampus without a stable context remain with us, but we can no longer retrieve them from the depths of our memory.

Original research: