Book Excerpt: Why the Brain Isn’t the Self
For centuries, humans have sought a vital essence to explain what makes life different from the rest of matter. Therein lies one of the most persistent errors in human thought, and one that has acquired new force in an age when intelligence is increasingly imagined as something separable from biological life.
The accompanying excerpt is adapted from “Alive: The Hidden Intelligence of the Living World” by Melanie Challenger. (Penguin, 352 pages.)
At its Latin roots, consciousness literally meant “knowing with.” This was a borrowing from an earlier Proto-Indo-European verb for splitting or separating something, which gave rise, in turn, to a host of related words for division and distinction.
Consciousness, then, was to know others and thereby to know oneself. Perhaps, too, it was to know what no one else knew. And so, at its post-Aristotelian origins, to be conscious was both a differentiation of knowledge and a knowledge of difference. Potentially, consciousness might be more comprehensible, then, as a form of knowledge of the knowledge of the body.
All organisms have some minimal knowledge of the body, and all qualify as selves. But only some appear to have knowledge of this knowledge. And only humans, as best we can tell at present, also discuss this knowledge with ourselves. The difference here is that we approach matters of experience, thought, feeling, and awareness from the bottom up, from the ethical baseline of a living body, rather than from the top down, from the perceived moral climax of a human mind.
This is not to underplay the curiosity and complexity of the human brain. As Brazilian neuroscientist Suzana Herculano-Houzel noted in her 2009 study on brain statistics and perceived cognitive prowess, both the relative size of the human brain and the absolute numbers of neurons indicate that we occupy a cognitive niche. And yet, she pointed out, humans have the number of neurons expected for a primate of our size. In this way, we have, as Herculano-Houzel put it, a “linearly scaled-up primate brain.”
However, recent studies on neurons have hinted at some unusual ways the human brain saves energy. In 2021, MIT researcher Mark Harnett published cross-species data showing that human cortical neurons have a much lower number of ion channels than you’d expect for their size. This, Harnett’s group explained, cuts down the energy the cells waste through leakage and electrical spikes, enabling greater efficiency.
An earlier study by Harnett and co-authors also found that human dendrites show enhanced electrical compartmentalization, which could mean individual neurons have increased computational power. These studies complement work from several decades ago by British neuroscientist Peter Lennie, who proved that the cost of a single cortical spike is so high that only a small fraction of neurons can be strongly active at once — proof that thinking is effortful.
It is self-evident that we are an animal that specializes in mental prowess and that our brains go a long way to helping us understand why we stand out among the community of life on Earth. That said, appreciating how we have come to dominate the world through the cognitive processes that support complex social collaboration does not mean that our brains should be the default baseline for everything that has significance.
Yet that’s precisely how much of science and society proceeds. Many evolutionary approaches to the nature of intelligence and consciousness have matched this bias towards the human brain perfectly. This is true even of those animals that evidently experience their lives and communicate with us. Having a brain or feelings or communicative capacities isn’t enough; to support exceptionalism we cling to the idea of human consciousness.
This has not always served us well. Type “humans and free will” into a search engine today, for instance, and you will bring up a vast number of pages. But many of them will contain headlines like: “There’s no such thing as free will” or “Is free will an illusion?” Here is the neuroscientist Sam Harris in his book “Free Will”: “How can we be ‘free’ as conscious agents if everything that we consciously intend is caused by events in our brain that we do not intend and of which we are entirely unaware?” These kinds of arguments have proliferated.
To some extent, this perspective rests on definition problems around consciousness. And perhaps also an identity error. As Francis Crick once said, “You’re nothing but a pack of neurons.” It was a playful quip. Nevertheless, it betrays a real and dubious idea that “we” are our minds and not our bodies.
This is not an obligatory position. We might as justifiably argue from the science of life that consciousness is a phenomenon of selfhood. If consciousness is the body’s way of knowing itself, then it is the living form in its entirety that should be taken as selfhood proper, with the brain as an especially feverish region.
Another way to think about the brain is as a concentration of purposeful activity, spooling out from the eyes, which scan the horizon ceaselessly for meaning. As others have said, the brain itself can be thought about as an elaborate eye that witnesses not only the surrounding world but everything the body senses, inside and out.
We are the chemistry of the cosmos bonded in just the right way, in just the right quantities, to look on the world and seek to explore it. The vast darkness of space becomes the mirror of self-recognition.
Yet the brain is also an organ of organization. And it is an organ of exploration, both physically in the world and imaginatively. This is inspiring. We are the chemistry of the cosmos bonded in just the right way, in just the right quantities, to look on the world and seek to explore it. The vast darkness of space becomes the mirror of self-recognition.
Once there were selves capable of generating meaning as part of their own formation, the emergence of something like the brain is not especially surprising, just as the eye was almost foreseeable once the I of the body came to be.
Melanie Challenger is a British writer and natural philosopher whose work explores the history and philosophy of science and humanity’s relationship with the living world. She is the author of “How to Be Animal: A New History of What It Means to Be Human” and “On Extinction: How We Became Estranged from Nature,” and host of the podcast “The Psychosphere.”