by Paul Singh
Who Am I
We like to think of ourselves as being something other than our bodies, but actually, as modern science has shown, we are our bodies. You are your body; you wouldn’t be you without your body wired together with your brain. Without your brain, you wouldn’t be you. Everything about you as a person can be explained by what goes on in your brain. Who you are and what you are like, all of your emotions and every one of your ideas, how you think and what you think about, and your own personal story, come from your brain. You would have no idea of your own existence without your brain. The body you will leave behind when you die will carry your name, because it was your body, and not someone else’s. The very possibility of imagining that you can float free from your body or of fantasizing that your soul can survive the death of your body is conceivable only because it is your brain that thinks these things.
Try a thought experiment. If you really think that you are something over and above your brain and can float free of your body like a pair of ethereal eyeballs or a shadowy ghost drifting around, you are doing so because your brain is thinking these things. Try to imagine some other person, a specific human person with their own personal identity and sense of who they are, who has never had a body or a brain. You can’t do it. If you manage to imagine a mind that has never had a brain, you have only imagined some imaginary mind that can think about things, not a specific person’s mind which thinks only about certain things.
If you think that you really can imagine a specific personality without a body that is only because you are borrowing aspects of real peoples’ personalities you have already known from this life. Imagining a disembodied personality only amounts to combining, for example, a memory of your grandfather’s kindliness with your best friend’s empathy and your teacher’s conscientiousness, and so on. Everything we know about personality and being a personal self comes from our acquaintance with ourselves in this life and the real embodied people we have known in this life. You can keep on imagining some abstract mind thinking abstractly about random things, but that generic mind isn’t a person and it couldn’t be you. If you ever became like that disembodied, depersonalized mind, you would cease to exist. Only you are you. In an infinite universe that has existed for some fourteen billion years or so, or perhaps in a multi-verse that is literally eternal, there will be only one of you. So you are very special indeed. And that means your brain is very special.
What Is a Brain?
The human brain is a three-pound organ that sits inside your skull and extends its wires back and forth into the rest of the body to be able to directly or indirectly affect the function of all 10 trillion cells in your body. It is a wetware, of the consistency of tofu and is made of over 100 billion neurons; each neuron making connections with as many as 100 thousand other neurons. The magic happens when the brain decides to use any combination or permutation of these connections. The total number of unique fingerprints or impressions that are possible approaches the number of particles in the universe. This is a simple mathematical calculation, but it is not very intuitive to the average person. If you understand the power of permutations and combinations, then you have the answer to the question of how the brain can do such amazing things as to make us feel that we have free will, consciousness, and a self.
Nearly half of our human genes are active in the brain at any given moment. The human brain is the most intricate and wondrous thing ever to have emerged in the entire universe. Nothing else yet discovered in the realm of physical or biological sciences compares with the mind-bending complexity of this organ. It is our brain, after all, that has allowed us to understand the universe in the first place. There is absolutely no knowledge about anything without the brain. There would be no science, no art, no literature, no religion, and no philosophy without it. So why not study this most interesting thing in the universe? Perhaps the most complex conundrums of humanity are conundrums because we never bother to look inside our own skull deep enough, but seek answers in the outside world or look for them in an imaginary inner self. Your inner self, your soul, and the god you worship are nothing else but your own brain interconnected with the rest of your body.
Intelligent life with its complex nervous systems is an impressive achievement in itself. Over three billion years and hundreds of millions of generations were needed for natural evolution to develop life from the first single cells into large multi-celled animals probing around and pursuing matters of life and death. Eat fast or be eaten was the new law of life after complex nervous systems allowed creatures to sense each other, size each other up, and figure out whether to put up a fight or flee the scene. Nervous systems are very complex networks of specialized cells called neurons. Neurons were originally the messenger cells linking receptor cells that detected warmth, odors, frictions, and electrical current (sight and hearing features came later on during evolution), with motor cells controlling appendages. Our nervous system still regulates how we behave in response to ongoing matters around us, including what we observe, what we can grab and eat, where we can enjoy ourselves, and who we can communicate with.
One of the best-surviving animals on record, the kind of early arthropods known as trilobites, flourished in the earth’s oceans from the dawning Cambrian age around 520 million years ago until their extinction 250 million years ago, surviving more than 270 million years. Their fossils preserve a distinctive armor covering them, like a horseshoe crab today. But its success was powered by good eyes, sensitive antennae, and a tiny thickening of ganglia, a proto-brain, able to coordinate sensory information with scurrying legs. The next age was ruled by the dinosaurs, which didn’t need large brains, but they did display some clever intelligence. By the time the mammals replaced dinosaurs as the dominant animals on the earth, around 65 million years ago, those mammals had large brains for their body size. Mammals were doing so much more than reptiles could do, and they were learning how to change their habitats to suit them. As mammals diversified to inhabit many environmental niches, so many more than reptiles could inhabit, their bodies and brains grew more complex and intelligent. Most mammals—such as dolphins, whales, elephants, horses, and all of the primates including chimpanzees and humans—have very large brains in proportion to their bodies. Size matters, but complexity matters more.
Primates not only have larger brain sizes than other mammals having about the same body weight, but they are extremely complex, and the part of the brain called the cortex is dramatically more important. The brains of primates, like all mammals, still include simple parts of the brain, located closer to the spinal column and the rest of the body, that resemble the brains of reptiles and ancient mammals now extinct. The evolution of the brain has been a story about how the “oldest” functions of the brain have been preserved and supplemented by additional parts of the brain for performing more complex behaviors. Today’s primate brains have a large cortex, the wrinkled outer part of a brain. The cortex surrounds inner parts of the brain such as the brain stem and the cerebellum (retained from our reptilian ancestry), along with the limbic system’s hippocampus, amygdala, and hypothalamus (retained from the earliest mammals). Early mammals from 200 million years ago had just a little cortex, while later mammals grew much more cortex in stages, so that parts of the cortex gradually emerged, making more complex and intelligent behavior possible.
There has been so much development of the cortex over the past 60 million years that neuroscientists refer to it as the “neocortex” because it is almost like having a ‘new’ brain to use. Mammals became good at taking care of offspring and relatives, strategically avoiding danger, skillfully obtaining food, cooperating with each other for protection, communicating with sounds and gestures, and even making simple tools for getting tasks done. Different parts of the cortex, by working together, became good at remembering lots of details about places, events, and others in the group; at using tactics for aggression, defense, deception, and playing; at organizing activities that benefit the group as well as ind
ividuals; and even at thinking up original ways to accomplish goals using whatever happened to be at hand.
The mammals with the most complex sort of neocortex, the primates, could do all of these things and more, thanks to the newest part of the neocortex, the prefrontal cortex, which is protected by the forehead. The prefrontal cortex is associated with using long-term memory and imagination, applying foresight and judging possibilities, and considering actions before they are taken. Some primates, such as Australopithecus around 3.5 million years ago, left the safety of forests and roamed the grassy savannahs with brains not much larger than those of chimpanzees, their ancestral cousins. Homo habilus had brains twice as large by two million years ago, measuring more than 600 cubic centimeters in volume. Their large brains had developed advanced communication and social skills, adept hunting and scavenging techniques, and notable stone-tool manufacturing. Adaptability was the evolutionary reward. Despite Africa’s fluctuating environment, our hominid ancestors were able to survive and even to journey into Europe and Asia. By the time that Homo sapiens had evolved in stages from Homo erectus, some 200,000 years ago, our brain size reached an average of 1250 cubic centimeters. There was a large prefrontal cortex that gave Homo sapiens the intelligence for going on to create everything we regard as truly human—our cleverness with inventing almost any sort of tool; our creative imagination expressed through the cultural forms of song, dance, storytelling, and art; and our curiosity about the wide world around us from the beckoning seas and tall mountains all the way up to the starry skies.
Our brain is the result of an amazing evolutionary journey. By fortuitous mutation and natural selection, our ancestors—from reptiles to mammals and then to primates—had ever more impressive brains, each good enough to permit survival for a time. The scrambling and re-scrambling of that genetic inheritance, through sexual reproduction and natural selection, has resulted in a human brain that isn’t quite like the brain of any other species. That long development over hundreds of millions of years ensured that brains never stayed the same for long, as the genetic instructions encoded by DNA kept receiving revision after revision from natural selection. The genetic “recipe” for a human brain is unique among all animals. Similarities abound among all brains, of course, but some pretty unique features are only human, special to just us.
A Uniquely Special Brain
By comparing human brains to each other, the brain sciences have revealed how the individualized genetic instructions for growing a brain during fetal pregnancy and infancy are only a part of the story. Those genetic instructions don’t actually specify every precise detail about the brain’s construction and neural interconnections. Plenty of neurons are grown and placed in the right general locations during pregnancy, so that a fetal brain has the same basic components that an adult brain has. However, the number of neurons and the kinds of interconnections in any brain eventually depend on the immediate environment of the fetus during late development and on the surroundings of the infant after birth. New neurons are supplied during infancy as the brain keeps growing during the early years of life, but they don’t all get used in the same way, and the ones that prove useful get put to work depending on what the brain needs to accomplish. In other words, the actual sensing, exploring, and learning that happen during infancy and childhood gradually finish up the job of developing a specific brain after the genetic instructions get a brain started.
Here is an analogy. Suppose a city engineer is assigned the job of ensuring that plenty of roads are built for a new city. But the new city hasn’t taken shape yet, and the final locations of all the buildings and homes haven’t been decided by the other city engineers. There have to be plenty of roads within the city so that people can get to the places where buildings and homes could and should be built, but no one can predict where the most useful roads must be from the start. You can’t build any buildings until there are some roads, and you can’t know where to put roads until the buildings have a place to be. A real conundrum, right?
The practical solution looks like this. The road engineer gives vague instructions for laying down plenty of simple dirt roads going all over the place, so that all places are accessible for some sort of travel. As the locations of useful buildings get settled in a gradual fashion, some of those simple roads get used a lot, some have to be shifted to the left or right or around a corner (not that hard to do for dirt roads), and eventually some get used so much that the road engineer orders their replacement by concrete roads so they get sturdier. Over time, lots of dirt roads hardly get used at all. By the time that half of the roads are hard concrete and serve all the finished buildings, the other half of the dirt roads aren’t used anymore and turn back into grass-covered areas. The final city has a complicated network of concrete roads directly serving the city’s buildings, but no single person planned any of it in advance, and a road map can be drawn up only after the city is finished.
A city built up like that would have a completely unique road map, because every detail was influenced by many decisions only happening over time in a certain unpredictable order. When that road engineer moves on to help with the next new city, she knows that there’s no point to drawing up a detailed road map first, since the new city will develop its own unique road network too. This little story is actually quite realistic. In city after city around the world, every driving experience will be uniquely different, because every city has its own particular environment and a special historical development.
If this analogy between growing cities and developing brains makes its point, then you can see why each person’s brain has to be unique down to the tiniest detail of the way the neurons are interconnected. By the time that a child’s brain reaches a stable developmental stage thanks to good growth and skull expansion, at around five to six years of age, that brain’s unique network of billions of communicating neurons reflects an evolutionary heritage of enormous complexity. It has an individualized genetic code of instructions, a specialized history of a few years’ worth of activities and explorations, and a personalized temperament of mental habits for reacting to the specific situations that have happened before. It also has an intellectual toolbox gathered from everything that could be learned from older persons around to help with guidance and instruction. And additional years of life’s opportunities and events guide some further brain development, which never quite ceases throughout a person’s entire lifespan. There is nothing about you, nothing that you sense, feel, want, think about, hope for, work for, or dream up, that hasn’t been made possible by what your special brain can do. Your brain doesn’t “make” you do any of these things. Your life is your own because you have been a truly special and irreplaceable brain making its own way in the world.
The reason you can’t be like anyone else comes down to the way that your brain couldn’t possibly be just like anyone else’s. Your brain is uniquely your own, and you are your brain.
Minding the Mind
The human brain is powerful enough to become sensitively aware of its own abilities. Brains were shaped during evolution to attend to surrounding matters and bodily needs, not to its own level of performance. As some primates evolved into Homo sapiens, their prefrontal cortex grew dramatically over the course of millions of years, allowing them to pay closer attention to what others were doing and to what they themselves were doing. The fundamental capacities needed for social relationships and the emergence of culture were developing rapidly.
Not only can we pay close attention to what we are doing, we also can become aware of how much thoughtful attention we are directing to our activities. We can think about what we have been doing, and we can think about how well we are thinking about things. Large-brained animals evidently ponder perplexing tasks in front of them, but it is difficult to know if some animals ever get distracted by pondering their own intellectual performance. We humans do spend a lot of time thinking and talking about ourselves and about what we are thinking. We not only have awareness (sen
sing the environment) and sentience (dealing with the environment), but our big brains also permit conscious intelligence and even a degree of self-awareness. Conscious intelligence is displayed in our ability to probe into what is going on and assess alternative courses of action. Self-awareness is our capacity to understand the powers and limitations of conscious intelligence in a personal way, seeing where our own skills of intelligence are different from another person’s, and trying to improve our intellectual skills. Other animals make and use tools but only we humans try to sharpen up our finest tool, our intelligence, by encouraging and instructing each other. The most powerful kind of intelligence is social intelligence, which is responsible for why our species eventually dominated all other species and colonized every continent.
We must realize that a brain usually allows a person to do things without letting the person know how the brain does it. Indeed, that’s the point of having a brain—things can get done in a focused way without the brain also wasting energy on activating an additional part of the brain for generating any awareness of exactly how things are getting accomplished inside the brain.
