Scan barcode
A review by tonyzale
The Deep History of Ourselves: The Four-Billion-Year Story of How We Got Conscious Brains by Joseph LeDoux
3.0
The Deep History of Ourselves sits in an awkward halfway between an abridged biology textbook and a pop science book. Joseph LeDoux's introduction intrigues with a claim that the connection between our behaviors and conscious thought isn't as strong as one might expect. Then, he spends 2/3rds of the book laying the groundwork for these claims, giving a compressed overview of the history of behavior and the biological machinery behind it. The whirlwind tour starts with single-celled organisms and their chemical responses, continues to the development of neurons, and eventually on to the human brain. Initially, I was energized by this; I haven't read anything like it since taking biology in high school. I hadn't considered that bacteria or plants might be able to learn, despite not having a nervous system. Eventually, though, it was just too much. I could only absorb so much scientific jargon before I started flipping a little faster.
Eventually, we reach the author's main thesis: human consciousness is mostly an observer of our behavior. Our emotions are not the drivers of behavior, but instead a byproduct - a higher order brain function that responds to the same stimuli as the circuits driving decision making. Additionally, he asserts that there's little evidence other animals experience conscious thought. He repeatedly calls out other researchers for anthropomorphizing animals by suggesting their facial expressions and behaviors indicate they must have similar conscious thought processes, too. Evolution implies that humans and animals are very similar, but LeDoux thinks many draw the wrong conclusion on the nature of that similarity; in his mind it's not that animals have similar thought processes to us, but instead that most of our behavior is rooted in the deep tree of evolutionary ancestry that existed prior to our complex brain. He backs these claims with descriptions of experiments involving subjects with localized brain damage to areas like the amygdala. These tests show that the subconscious response to a threat like a racing heart can be isolated from the conscious experience of fear if certain connections in the brain are severed. LeDoux is very research-oriented, and rightly insists on strong experimental evidence for theories of consciousness.
Still, the state of brain research is limited, and he can't make many solid claims about what our conscious thought process actually is, or where the dividing line between conscious and nonconscious behavior might be. He makes assertions that are almost non sequiturs, suggesting we can't experience more than one emotion at a time, without any explanation or experimental evidence to back the claim. The biology lessons of the majority of the book mostly only support the arguments at the end by establishing the long history of pre-human behavior - it seems that point could have been established more efficiently. Finally, he does little to present alternate hypotheses - I have very little sense for how his rivals view their own theories, because LeDoux consistently paints them with a reductive anthropomorphic brush.
Overall, this book had several valuable nuggets, but I probably won’t remember many details of the extensive biology lesson that serve as scaffolding for the author’s theories.
Eventually, we reach the author's main thesis: human consciousness is mostly an observer of our behavior. Our emotions are not the drivers of behavior, but instead a byproduct - a higher order brain function that responds to the same stimuli as the circuits driving decision making. Additionally, he asserts that there's little evidence other animals experience conscious thought. He repeatedly calls out other researchers for anthropomorphizing animals by suggesting their facial expressions and behaviors indicate they must have similar conscious thought processes, too. Evolution implies that humans and animals are very similar, but LeDoux thinks many draw the wrong conclusion on the nature of that similarity; in his mind it's not that animals have similar thought processes to us, but instead that most of our behavior is rooted in the deep tree of evolutionary ancestry that existed prior to our complex brain. He backs these claims with descriptions of experiments involving subjects with localized brain damage to areas like the amygdala. These tests show that the subconscious response to a threat like a racing heart can be isolated from the conscious experience of fear if certain connections in the brain are severed. LeDoux is very research-oriented, and rightly insists on strong experimental evidence for theories of consciousness.
Still, the state of brain research is limited, and he can't make many solid claims about what our conscious thought process actually is, or where the dividing line between conscious and nonconscious behavior might be. He makes assertions that are almost non sequiturs, suggesting we can't experience more than one emotion at a time, without any explanation or experimental evidence to back the claim. The biology lessons of the majority of the book mostly only support the arguments at the end by establishing the long history of pre-human behavior - it seems that point could have been established more efficiently. Finally, he does little to present alternate hypotheses - I have very little sense for how his rivals view their own theories, because LeDoux consistently paints them with a reductive anthropomorphic brush.
Overall, this book had several valuable nuggets, but I probably won’t remember many details of the extensive biology lesson that serve as scaffolding for the author’s theories.