The last time I wrote about the second vision of existence — the kinship vision — I described its emergence in largely practical terms. I suggested that it became necessary when our earliest ancestors, having acquired the useful ability to create mental maps of their surroundings in space and time, began to flourish and spread out in all directions.

As the human community expanded, the kinship vision made it possible for the members of different bands to continue perceiving one another as family rather than as strangers. The Neanderthals never managed that trick, but our own ancestors did. I would guess this occurred around 340,000 years ago, when the ending of an ice age had opened up new territories.

Two elements went into the making of the kinship vision. One was the sense of belonging to a larger whole provided by higher knowledge. The other was a structuring of human relationships using the same mental tools that had previously been applied to the natural world. The basic family roles — mothers and fathers, aunts and uncles, grandmothers and grandfathers — were generalized to encompass more distant relatives. People began assembling mental maps of their own family trees and using those as a basis for action.

At least that’s how I accounted for the origins of the kinship vision two years ago. But at the time, I wasn’t factoring in the underground stream — the magical and occult current of thought that adds an element of the unknown and the uncanny to the otherwise rational and mystical materials of every vision.

The most obvious way in which an occult element would have contributed to the development of the kinship vision was through a belief in the spirits of the dead. And that belief could have easily predated the kinship vision itself — because it arises out of dream.

There is a quality to dreams that I think of as progressive rationalization. Dreams may be sparked by vague, unidentifiable images — but they only truly begin when we start to tell ourselves a story that explains what we’re seeing. “I seem to be in a large room full of people. Some kind of lecture hall, perhaps? Oh, I know, I’m back in college. We’re taking a final exam.”

But the more explanatory details you add, the more it contradicts the facts of your waking life. Then you start to wake, something closer to normal consciousness kicks in, and you realize in panic that you haven’t actually been attending classes and have no idea what’s on the test. And at last you wake fully, with a great sense of relief.

The same sequence of thought applies to dreams of the dead. You might identify an image in the dream as a friend or relative and start to interact with them. Then you reach that halfway state and remember that they’re no longer living — and that elicits a strong emotional reaction, along with a frantic attempt to explain what’s happening.

This seems to be especially common with the recently departed. Soon after my grandmother died, I had a dream in which she was nagging me about something, and I thought resentfully, “Why are you still here bugging me? Don’t you know that you’re dead?”

After my cat died a few years back, she appeared in two separate dreams. In the first, I was happy at first that she’d come back to life, but then I became sad, thinking, “She’s still old and sick and is only going to die again.” In the second, I realized I was dreaming but my reaction was, “This may be an illusion, but I don’t care as long as it’s soft and warm and purrs when I pet it.”

I think our remote ancestors had the same kinds of dreams and very similar rationalizations, which led them to believe that the dead could hang around, or come back to life, or appear in the form of an insubstantial spirit. Since Neanderthals and perhaps even Homo heidelbergensis appear to have buried their dead, this belief may be far older than our own species.

So when the proto-humans of 340,000 years ago crafted the kinship vision, they were able to draw upon a well-established belief that the dead continue to engage with the living. And that belief in the power of the Ancestors formed the basis of a unified vision, combining known and unknown, into which they could plug themselves, their grandparents, and their aunts and uncles and cousins.

But although the people of that time were laying the foundation for what we ourselves have since become, they were not yet us. Their brains were nearly as large as ours, and there’s no doubt they were highly intelligent and quick to learn and possessed a fair amount of linguistic fluency. Yet if we could meet them today, we would probably find them oddly unimaginative and lacking in introspection.

The crucial evolutionary leap appears to have occurred between about 300,000 and 200,000 years ago, most likely in Africa. Skulls from that earlier date found in the Middle East, Africa, and Greece have certain characteristics which are consistent with them being our ancestors, but they are still extremely heavy-browed and primitive in appearance. They are considered to belong to the eastern branch of Homo heidelbergensis and not to Homo sapiens.

In contrast, skulls from East Africa dated to 200,000 years ago and later display only a few archaic traits and without question belong to our own species. It seems as though there must have been an abrupt reconfiguration of both skull architecture and brain organization in the interim.

Beyond that the fossil record cannot help us — but various lines of brain research suggest that the change had to do with intuition, imagination, and access to higher knowledge.

It was reported last winter that neuroscientists Randy L. Buckner and Fenna M. Krienen had found that in the brains of most mammals, “the neurons in one region mostly make short connections to a neighboring region,” but that our own brains aren’t like that.

Human brains are different. As they got bigger, their sensory and motor cortices barely expanded. Instead, it was the regions in between, known as the association cortices, that bloomed.

Our association cortices are crucial for the kinds of thought that we humans excel at. Among other tasks, association cortices are crucial for making decisions, retrieving memories and reflecting on ourselves.

Association cortices are also unusual for their wiring. They are not connected in the relatively simple, bucket-brigade pattern found in other mammal brains. Instead, they link to one another with wild abandon. A map of association cortices looks less like an assembly line and more like the Internet, with each region linked to others near and far.

Buckner and Krienen suggest that the change became possible as our brains grew larger, because “some neurons are too far from the signals to follow their commands.” However, the same shift in emphasis away from the sensory and motor cortices does not appear to have occurred with the Neanderthals. Another recent study has determined that “although Neanderthals’ brains were similar in size to their contemporary modern human counterparts, fresh analysis of fossil data suggests that their brain structure was rather different. Results imply that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement.”

In other words, the changes in our brains that made us distinctively human — changes associated with memory, imagination, and introspection — appear to have begun after our own lineage split from that of the Neanderthals. The first phase of that shift may have been responsible for our ability to create mental maps, which requires a high degree of memory and self-awareness. But the transition reached a climax with the second phase, between 300,000 and 200,000 years ago, which probably gave rise to intuition and our ability to access sudden flashes of higher knowledge.

In an early entry at this blog, I quoted a New Scientist article which described the “neuronal avalanches” that occasionally race across the brain. It stated that these “are capable of setting up new connections within the brain” and that we sometimes experience them as “a thought popping into your head as if from nowhere.”

The neuronal avalanches that Beggs investigated, for example, are perfect for transmitting information across the brain. If the brain was in a more stable state, these avalanches would die out before the message had been transmitted. If it was chaotic, each avalanche could swamp the brain. At the critical point, however, you get maximum transmission with minimum risk of descending into chaos. …

Self-organised criticality also appears to allow the brain to adapt to new situations, by quickly rearranging which neurons are synchronised to a particular frequency. “The closer we get to the boundary of instability, the more quickly a particular stimulus will send the brain into a new state,” says Liley.

It seems as though these neural avalanches may be responsible for creating the “wild abandon” of the wiring that connects our association cortices — and also for modifying its pathways as needed. But the real question for me is what it would have felt like to be someone living between 300,000 and 250,000 years ago in the middle of what must have been a wildly disorienting transition from bucket brigade thinking to free-form mental cross-connections.

Did that shift have an immediate evolutionary utility of its own? Or was it something that took us entirely by surprise as our brains grew larger to provide more storage space for our increasingly elaborate mental maps?

I suspect it was the second. In that case, the effect might have been like the entire species going on a 50,000 year acid trip. And the effects of that long, strange passage have shaped us to this day.

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