This key ability helps make us human—and we still don’t fully understand it

You can easily picture yourself riding a bicycle across the sky, although that may not be something that can happen. You can imagine doing something you’ve never done before – like water skiing – and maybe even imagine a better way to do it than anyone else.

Imagination involves creating a mental image of something that isn’t there to your senses, or even something that isn’t actually out there somewhere. Imagination is one of the key skills that make us human. But where did it come from?

I’m a neuroscientist studying how children acquire imagination. I am particularly interested in the neurological mechanisms of imagination. Once we’ve figured out what brain structures and connections are necessary to mentally construct new objects and scenes, scientists like me can look back over the course of evolution to see when these brain areas emerged — and possibly the first types of imagination have produced.

From bacteria to mammals

After life appeared on Earth about 3.4 billion years ago, organisms gradually became more complex. About 700 million years ago, neurons organized into simple neural networks, which then evolved into the brain and spinal cord about 525 million years ago.

After all, dinosaurs evolved about 240 million years ago, and mammals appeared a few million years later. While sharing the landscape, dinosaurs were very good at catching and eating small, furry mammals. However, dinosaurs were cold-blooded and, like modern cold-blooded reptiles, could only move during the day and hunt effectively when it was warm. To evade predation by dinosaurs, mammals stumbled upon a solution: hide underground during the day.

However, not much food grows underground. Mammals had to move across the ground to feed – but the safest time to forage was at night, when dinosaurs were less dangerous. Evolution into warm-blooded animals meant that mammals could move at night. However, this solution came with a trade-off: Mammals had to consume far more food per unit weight than dinosaurs to maintain their high metabolism and support their constant internal body temperature of around 37 degrees Celsius.

Our mammalian ancestors had to find ten times more food during their brief waking hours, and they had to find it in the dark of night. How did you accomplish this task?

To optimize their foraging, mammals have evolved a new system to efficiently remember locations where they’ve found food: they connect the part of the brain that records sensory aspects of the landscape — how a place looks or smells — to the Part of the brain that controls navigation. They encoded features of the landscape in the neocortex, the outermost layer of the brain. They encoded navigation in the entorhinal cortex. And the whole system was connected through the brain structure called the hippocampus. Humans still use this memory system to remember objects and past events, e.g. B. Your car and where you parked it.

Groups of neurons in the neocortex encode these memories of objects and past events. The memory of something or an episode reactivates the same neurons that originally encoded it. All mammals can probably remember and re-experience previously encoded objects and events by reactivating these groups of neurons. This neocortex-hippocampus-based memory system, which evolved 200 million years ago, was the first key step toward imagination.

The next building block is the ability to construct a “memory” that didn’t actually happen.

Imagination involves creating a mental image of something that isn’t there to your senses, or even something that isn’t actually out there somewhere. Imagination is one of the key skills that make us human.

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Involuntarily invented “memories”

The simplest form of imagining new objects and scenes is in dreams. These vivid, bizarre involuntary fantasies are associated with the rapid eye movement (REM) phase of sleep in humans.

Scientists assume that species whose rest periods include periods of REM sleep also experience dreams. Marsupials and placental mammals have REM sleep. However, the egg-laying mammal, the echidna, does not, suggesting that this stage of the sleep cycle evolved after these evolutionary lines diverged 140 million years ago. In fact, recordings of specialized neurons in the brain called place cells showed that animals can “dream” about going to places they’ve never been before.

In humans, solutions found while dreaming can help solve problems. There are numerous examples of scientific and technical solutions that are spontaneously visualized during sleep.

Neuroscientist Otto Loewi dreamed of an experiment proving that nerve impulses are transmitted chemically. He immediately went to his laboratory to carry out the experiment – he later received the Nobel Prize for this discovery.

Elias Howe, the inventor of the first sewing machine, claimed that the main innovation, the placement of the threaded hole near the point of the needle, came to him in a dream.

Dmitri Mendeleev described seeing in a dream as “a table where all the elements fit together as needed. When I woke up I immediately wrote it down on a piece of paper.” And that was the periodic table.

These discoveries were made possible by the precise mechanism of involuntary imagination, first acquired by mammals 140 million years ago.

Introduce on purpose

The difference between voluntary and involuntary imagination is analogous to the difference between voluntary muscle control and muscle spasms. Voluntary muscle control allows people to consciously combine muscle movements. The spasm occurs spontaneously and cannot be controlled.

Only humans can voluntarily conjure up new objects and events in our minds through prefrontal synthesis.

Similarly, voluntary imagination allows people to combine thoughts intentionally. When asked to combine two identical right triangles along their long edges, or hypotenuses, imagine a square. If you are asked to mentally cut a round pizza by two vertical lines, imagine four identical slices.

This intentional, engaging, and reliable ability to combine and recombine mental objects is known as prefrontal synthesis. It relies on the ability of the prefrontal cortex, located at the very front of the brain, to control the rest of the neocortex.

When did our species acquire the ability for prefrontal synthesis? Any artifact dated 70,000 years ago could have been made by a creator who lacked this ability. On the other hand, since around this time there have been various archaeological artifacts that clearly indicate his presence: composite figurative objects such as lion-men; eyed bone needles; bows and arrows; musical instruments; built homes; decorated burials denoting belief in life after death, and much more.

Several types of archaeological artifacts clearly associated with the prefrontal synthesis appeared simultaneously in multiple geographic locations around 65,000 years ago. This abrupt change in the imagination has been dubbed the “cognitive revolution” by historian Yuval Harari. Remarkably, it roughly matches the largest homo sapiens Emigration from Africa.

Genetic analysis suggests that some individuals acquired this ability for prefrontal synthesis and then spread their genes far and wide by eliminating other contemporaneous males with an imagination-activating strategy and newly developed weapons.

So it was a journey of many millions of years of evolution for our species to be endowed with imagination. Most non-human mammals have the potential to imagine what doesn’t exist or didn’t happen involuntarily during REM sleep; Only humans can voluntarily conjure up new objects and events in our minds through prefrontal synthesis.

This article was originally published on The Conversation by Andrey Vyshedskiy at Boston University. Read the original article here.

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