Evolution is a scientific fact. Sure, all facts are subject to being proven wrong. But the chance of that happening to evolution is very slim, because the evidence for evolution is so strong.
Since I love to learn about true things, this is why my pre-meditation reading each morning often consists of a science book. I see no reason to pick up a religious book any more, because my eyes have been opened to the falsity of believing in God or other supernatural entities.
A few weeks ago I finished reading Joseph LeDoux's book, "The Deep History of Ourselves: The Four-Billion Year Story of How We Got Conscious Brains."
I'm a habitual highlighter of non-fiction books. I supplement my highlighting with notes in the back blank pages found in most books, where I write down the page numbers of subjects I found most interesting, along with a highly personal system of underlining, circles, question marks, arrows, and other notations that remind me of portions of the book that I considered significant.
Here's some passages from the 432 pages in LeDoux's meaty/tofuy book that garnered significant markings. Before each one I'll briefly explain why I liked them.
I heartily agree with LeDoux that conscious awareness is just the tip of the iceberg when it comes to goings-on within the human brain, and likely every other kind of brain. We simply have no clue about what most of our 100 billion neurons with their trillions of connections are up to. He writes:
Behavior did not arise to serve the subjective mind. It came about and persists to enhance fitness -- to keep organisms alive and well so that reproduction can occur.
This perspective puts the behavior of humans and bacteria, and all organisms in between, on a level playing field, one in which consciousness, in the sense that humans mean by the term in everyday life, has a peripheral role in most of the history of life.
If we commit to the very reasonable assumption that over the long course of evolution behavior has mostly been generated by nonconscious systems, and that behavior, even in humans, should be assumed to be nonconsciously controlled unless proven otherwise, the science of behavior would advance much more smoothly.
And, by the same token, so would the science of consciousness. This is the perspective I will take as I guide you on our ascent of the tree of life in the remainder of this book.
One of the most ridiculous things about religions is that they usually consider humans to have been created by God in God's image. This is clearly not true, given the fact of evolution. Like every species, Homo sapiens is different from other forms of life, but not better or worse than those other forms.
Evolution does not create superior or inferior organs or tissues; it created diversity through divergence (not by accumulation of features).
What works in a given environmental situation is determined by natural selection, but as the environment changes, or the group moves to a new niche, new traits become important and previously useful traits can become detriments.
In trying to understand how changes in brains over the course of vertebrate evolution gave rise to our own behavioral and mental capacities, we thus have to take care to climb the vertebrate tree of life without using Edinger's ladder, and also to be cautious not to overinterpret the differences we encounter.
We are newer and different, but not better.
As I have pointed out, we have to guard against anthropocentric tendencies, but also against anthropomorphic ones. In other words, we sometimes attribute too much to other animals, and sometimes to ourselves. We have to find the right balance, which I strive to do in the coming chapters.
However, we humans do possess a marvelously capable brain that has impressive cognitive powers. Yet as LeDoux notes at the end of this passage, human cognition is an outgrowth of capabilities that our evolutionary ancestors possessed.
Our species has survived and thrived not by being bigger, faster, or stronger, but by being clever. We haven't, like most organisms, simply evolved by adapting our Bauplan to the world as it changes; we have used our cognitive abilities to change the world. We do so because we think it might be advantageous to our bodies and way of life, or that it might simply be interesting to tinker with nature.
No other animal, not even our closest primate relatives, can have an idea like building a skyscraper, finding a cure for a disease, composing an opera, or writing a novel, then describe it to a colleague, plan how to execute it, and carry it out.
That human cognition is unique in no way means we are better or more entitled than our ancestors or animals with which we currently share the planet. It just means we are different. Unique though it may be, human cognition emerged by building on cognitive capabilities possessed by our mammalian ancestors.
There's zero evidence to support the idea of a conscious soul separate from the physical brain. Consciousness is one aspect of the brain in action, not something ethereal or supernatural. Research on split-brain patients proves this, since basically their consciousness is divided into two parts -- which couldn't happen if a unitary soul was the source of consciousness.
Because language is usually controlled by the left hemisphere, split-brain patients are able to give verbal reports about information presented to the right half of visual space, which is preferentially seen by the left hemisphere, but cannot name stimuli in the left half of visual space, which is seen by the right hemisphere
They can, however, respond nonverbally to the stimuli seen by the right hemisphere, by pointing toward or grabbing objects with the left hand, which is preferentially connected to the right hemisphere. Similarly, when blindfolded, these subjects can name objects placed in their right hand, but not objects placed in their left hand.
Such findings showing that conscious experience can be isolated in a specific part of the brain by cutting axonal connections provided compelling evidence for something that scientists long believed but could not prove: namely, that consciousness depends on the brain's neural circuits, and is not, as Descartes had said, associated with a separate, nonphysical, soul.
I'm completely open to the fact that people have religious and mystical experiences, in part because I've had those experiences myself. (This doesn't make those experiences objectively true, of course.) But science teaches us that it is wise to be cautious about trusting the accuracy of accounts of any experience recounted by memory, since the brain engages in top-down reformulations of the memory every time it is remembered.
As Gerald Clore, Daniel Kahneman, and others have noted, the closest we ever come to the truth of experience is when we are in the experience. Everything that happens later is a top-down reinterpretation of the memory of the original experience.
In therapeutic situations, such revisionist histories can be revealing of one's psychological tendencies and proclivities, but they can never be as true to a past experience as the experience itself was in real time. The mere act of retrieving a memory can, through the process of memory reconsolidation, change the nature of the memory (this is a natural process through which memories are changed after retrieval, requiring restorage).
The longer the amount of time that passes between the actual experience and the memory of it, the greater opportunity to revise and reconsolidate it upon retrieval of the remembered narrative.
Here LeDoux repeats his contention that we humans are different, not special. We are part of a four-billion-year process of evolution that continues to this day, and will keep on for as long as life exists on Earth.
Our survival circuits connect us to the survival history of organisms with nervous systems. And the universal survival strategies that survival circuits and behaviors tactically implement connect us to the entire history of life. Separation of the history of emotions and other states of consciousness from the deep history of survival circuits allows us to see our place in this ancient story.
Like all other species, we are special because we are different. Our differences are important to us because they are ours. But they are mere footnotes in a four-billion-year-old saga. Only by knowing the whole story can we truly understand who we are, and how we came to be that way.