The Deep History of Ourselves: The Four-Billion-Year Story of How We Got Conscious Brains

by Joseph E. LeDoux

Longlisted for the PEN/E.O. Wilson Literary Science Writing Award A leading neuroscientist offers a history of the evolution of the brain from unicellular organisms to the complexity of animals and human beings todayRenowned neuroscientist Joseph LeDoux digs into the natural history of life on earth to provide a new perspective on the similarities between us and our ancestors in deep time. This page-turning survey of the whole of terrestrial evolution sheds new light on how nervous systems evolved in animals, how the brain developed, and what it means to be human.In The Deep History of Ourselves, LeDoux argues that the key to understanding human behavior lies in viewing evolution through the prism of the first living organisms. By tracking the chain of the evolutionary timeline he shows how even the earliest single-cell organisms had to solve the same problems we and our cells have to solve each day. Along the way, LeDoux explores our place in nature, how the evolution of nervous systems enhanced the ability of organisms to survive and thrive, and how the emergence of what we humans understand as consciousness made our greatest and most horrendous achievements as a species possible.

Genres: Science, Nonfiction, Psychology, Neuroscience, History, Biology, Evolution

432 pages, Kindle Edition

First published August 27, 2019

Reviews

[Marc Lamot · Rating 3 out of 5]

The controversial British philosopher John Gray has been insisting for years that humans just are mammals, and thus certainly not a unique creature that stands above all others. Judging from this book, Joseph LeDoux (° 1949), an eminent neuroscientist, is more or less on the same page. He does this by very meticulously establishing the close link between mankind and the evolution of life on earth, right from the start. He wants to demonstrate that the human constitution originates from the very beginning of life on earth and that we bear the traces of all subsequent stages. “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.”

This book is, at least for the first 250 pages, a real natural history, a very detailed, yet didactic overview of the evolution of life, with growing complexity as its common thread. LeDoux goes through all the stages and sometimes delves deeper into very specific biological issues, such as how beings transitioned to sexual reproduction, or how they developed a nervous system. Although LeDoux really does his best to explain everything as well as possible, these are pretty tough chunks.

But in the last third, this book turns into a rather different one. LeDoux is now diving into the field that is his own specialization, namely the human brain, and more specific human cognition. You notice that this has a completely different slant, and that LeDoux works more apologetically here, presents his own views, and takes a stand against colleagues. For example, he very extensively defends his thesis that human emotions are a by-product of our cognitive abilities, especially language, and that emotions guide our behavior. Unfortunately, he loses sight of his initial purpose, which is to illustrate how the human "building plan" (the author systematically uses the German term ‘Bauplan’) builds on that of previous beings. So, as many other reviewers noted, these are actually two books in one. Both are fascinating, but especially in the second part you get lost a bit more. Anyway, the great merit of this book certainly is its attempt to synthesize natural history.

[Sense of History]

Great book, that nevertheless did not live up to my expectations. I had hoped that it would uncover the origins of man's cognitive abilities. For several decades now, scientists have been debating about what might have happened, somewhere between 100,000 and 50,000 Before Present, when the homo sapiens species (which had been around for some time) suddenly made a real leap in cognitive abilities. This leap can be empirically deducted from archaeological findings. Earlier I read the bold theory of Steven Mithen (in his The Prehistory of the Mind: The Cognitive Origins of Art, Religion and Science), and the much looser comments of Colin Renfrew (in Prehistory: The Making Of The Human Mind). I now wanted to know what the eminent neuroscientist Joseph LeDoux had to say about this.

His starting point is interesting: namely that the human building plan (including cognition) builds on everything that went before: “core survival requirements were solved by the first successful living organisms billions of years ago, and that they passed their solution on to every organism that followed”. LeDoux therefore sketches in detail the evolution from the first living organisms to homo sapiens, always explaining which leaps (or more neutral: changes) were made. That is certainly relevant and to a great extent enlightening. Unfortunately, when he comes to the emergence of the human species, he ignores the archaeological material that attempts to map human evolution. Instead, he offers a very technical explanation of the composition and functioning of the human brain, which provides only partial clarification. It is disappointing, therefore, that in the end LeDoux has to stick to the observation that our unique cognitive qualities arise mainly from our ability to produce and use language, and from "autonoetic cognition", our ability to reflect on ourselves as subjects. This is certainly an interesting book, but it did not give me the answers I was looking for.

[Peter Tillman]

Nature's long, detailed review, by a fellow neuroscientist: https://www.nature.com/articles/d4158...
Excerpts:

"There is a tradition for scientists of a certain age to write a book tackling grand topics about the human condition. . . . The Deep History of Ourselves offers one grand narrative of how humans got conscious brains. LeDoux surveyed the relevant data and gives us his best take of how things work. Many topics of debate pass unmarked, so every scientist will probably find something to disagree with. . . .

The Deep History of Ourselves is not a comprehensive review of any scientific topic. It is a curated tour: a window into one distinguished scientist’s beliefs about what is important and true. Its scope is broad, yet it contains enough detail for an engaging storyline. It offers thoughtful insights that linger over time. It is, in short, an admirable effort from one of this generation’s most important neuroscientists."

[Peter Herrmann · Rating 5 out of 5]

The 5-stars is mostly my reaction for the first half of the book, which is one of the best renditions I've ever read (clear, concise) of growth and evolution from microbes to metazoa. (There were a few questions [not disagreements; simply questions] which arose in my mind that were unanswered - as best I could tell - but I won't fault the author). The second half of the book was very thorough (about cognition and mind etc etc). The author seems to have delivered a very comprehensive discussion - but I've read so many of these mind/brain elaborations over the years and they now sort of put me to sleep: too much verbiage for me, and no new revelations for me (unless I've missed them). However, if somebody is reading about this topic for the first time, it's probably superb; but I've read about -e.g., Phineas Gage - so many times now that I just tune out. Not the author's fault; indeed, he'd be remiss if he didn't discuss it.

[Stetson · Rating 4 out of 5]

The Deep History of Ourselves is a foray into "Big History" by renowned neuroscientist Joseph LeDoux. The first half of the work is a low resolution recapitulation of metazoan evolution through primates. This part shares a lot of similarities with Max Bennett's A Brief History of Intelligence. The second half explores the cognitive capacities of the human brain with a focus on consciousness.

LeDoux is a bit heterodox on the evolution of consciousness. He argues the capacity is unique to humans. He bases this claims on the fact we can only purportedly demonstrate self-knowledge in humans, and that unwarranted anthropomorphizing occurs when consciousness is projected on animals due to their shared affect (i.e. when a dog is clearly sad or a Dolphin is excited by its own reflection). Perhaps more convincingly, LeDoux also alleges certain circuits that are fundamental to conscious experiences are unique to human beings. I think both these claims rest on shaky ground, but the science of consciousness is quite fraught and thus cannot blame him for venturing interesting ideas. However, I think LeDoux's ideas would do well to take evolution more seriously. I think it is defensible to assume that consciousness was selected for. Our scientific efforts should be focused on confirming whether this is true and finding out exactly how and why it was selected for.

The going theory for both rapid brain evolution and consciousness is the social brain hypothesis (SBH). The model presupposes tensions between individual and group survival/fitness strategies (very game theory-ish). These tension facilitated an arms race between deception (individual) and gossip (group) that drove selection on intelligence/consciousness. This was also enabled energetically by calorie rich environments unlocked through the invention of cooking. It is likely that sexual selection played a role in this dynamic as well, though this is controversial and can still be folded into the larger SBH. I bring this up only to point out this was an omission from the work and I would have liked to see LeDoux address these ideas.

LeDoux also defends his preferred theory of consciousness, higher order theory (HOT). He does so we respect to global workspace theory and predictive processing. He folds some elements of the latter into HOT but generally argues that HOT is the best model for explaining self-awareness. To me, I can often find appealing things in any of the models of consciousness. They all seem to depart from what we can test for and prove, which is perturbing. One has to wonder if we're approaching the question improperly or if the question cannot be answered with scientific approaches (RE: Erik Hoel). Due to the recursive architecture of consciousness and the inaccessibility/murky interpretability of brain activity, I sometimes fear the worst.

Regardless, I obviously think it is worth the effort to learn about these topics and become conversant in them. This is perhaps the tenth or so work I've read on the subject. Keep them coming!

[Richard S · Rating 3 out of 5]

Tough days for scientists, at least those trying to write good science books. It's shocking the need for non-science to make its way into a book for political purposes. In fact it's the worst possible thing. Do scientists also feel that throwing in virtue signaling in Trump bashing and Republican bashing generally is a necessary part of scientific writing? It's sad, ugly, and mars the book far too frequently. I laughed out loud when the author insisted that humans were no "better" than animals (just different!), right after describing all of the reasons why we are.

There were parts of the book which were pretty interesting, particularly the story of how intelligence evolved. I've read extensively on this topic and while the book swallowed current scientific thinking it didn't even acknowledge the existence of problems in the theory and difficulties in explaining certain features of evolution. It's seems close to 100% certain that evolution exists, but we understand about 0.1% of it, 1.0% is still discoverable and 99% is unknowable - the mechanism by which eukaryotes incorporated mitochondria, just one example.

For example I love how he says "life arose on earth 3.8 to 4.0 billion years ago" as if it was a scientific proven fact - I think more because of the scientific consensus that panspermia sounds like "science fiction" and therefore discredits evolutionary theory as a whole. His explanation of how multicellular organisms arose was the best part of the book. Thank you choanoflagellates. I'm a happy father because of your continued existence inside of me.

My other thought towards the end of the book - which is really a completely different book, nothing to do with the first, is how much modern neuroscience sounds like Freud, words, words, words, lots of words and really no science. I love how so much of it is just "brain spotting" - identifying what parts of the brain control what, as if that adds in some way to our understanding of the whole. "The fear emotion does not reside in the amygdyla." So what? It's rather clear - isn't it - that understanding the interactions between billions of neurons is beyond the capacity of science, and all we can do is find different sets of descriptive words to talk about certain of its features. The author admits that the study of consciousness is just beginning. I think we might get to the 1% we can get to on evolution. Eventually a supercomputer might be able to model a human brain, but we are not that supercomputer, scientifically speaking.

Otherwise, the book seems a bit hurried, and has one horrible typo "400,000 1 million" which is unforgivable in science book of all things. The last 20 chapters or so are about Professor LeDoux's real area of study and understanding, but are not at all relevant to the first 45 chapters. He feels the need to go into a very long apology (?) for his prior discussion of fear in other books (was this the point of the book, really?) that is a pointless distraction to his reader. The book should have ended with the differences between chimps and humans under evolutionary theory, not with a very long explanation of how the human brain works. Then it could have been quite an excellent historical study of the evolutionary development of intelligence. Evolution is mentioned maybe a couple times in the last 20 chapters.

Anyway - thank you Professor LeDoux for standing up to the anthropomorphisists. It is brave for scientists to fight against the dear sweet wishes of the progressive animal supporting community with their claims that all species are created equal (even amoebas have "consciousness"!). I only wish you didn't keep dropping "quotes" all the time as if they were "truths". Stick to science - you are a fantastic scientist and an excellent writer - your book is good, if it was cleaned up and focused, it actually could have been a great one.

[Elentarri · Rating 3 out of 5]

The first half of this book is a very broad, somewhat simplistic, natural history overview of the evolution of life with a nervous system.  The remainder of the book deals with the the composition and functioning of the human brain, specifically human cognition.  This section is dense and inundated with technical terms, but provides the more juicy part of the topic, being less an overview of what is know about human cognition and more about the author's particular thesis on the concept.  Needless to say, no definitive answers are forthcoming and more research is required.  The book also includes a plethora of very helpful grey-scale illustrations that help elucidate concepts.  An interesting overview, but uneven writing.

[Joanna Slow · Rating 4 out of 5]

Sięgając po „Historie naszej świadomości” nie spodziewałam się, że dostanę opowieść o kształtowaniu się życia na ziemi. Nie tego szukałam. Ale Joseph LeDoux wiedział lepiej niż ja, czego potrzebuję, by zrozumieć fenomen świadomości i zaakceptować tezę, że związek stanów umysłowych z zachowaniem jest złudzeniem. Autor pokazuje, że wszystkie organizmy niezależnie od poziomu złożoności (nawet te bez układu nerwowego), wykazują podobne zachowania przetrwaniowe, że są to mechanizmy gwarantujące dostosowanie i warunkujące istnienie. I dlatego sensowne wydaje się założenie, że tego typu zachowania kontrolowane są przez systemy nieświadome również u ludzi. Autor przedstawia wspólny rodowód wszystkich organizmów (LUCA) oraz wspólny „bauplan” budowy mózgu przekonując (mnie skutecznie), że wyjątkowość naszej świadomości polega wyłącznie na jej odmienności od narzędzi adaptacyjnych dostępnych innym gatunkom. Po lekturze nabrałam przekonania, że antropomorfizm, do którego mamy skłonność analizując zachowania zwierząt wcale nie jest dowodem humanizmu.
Nie była to łatwa lektura, być może nie da się opisać tego tematu bardziej przystępnie. Wymagała świeżej, niezmęczonej głowy, a nieraz zaakceptowania, że brak mi podstaw, które pozwoliłyby tę wiedzę przyswoić, a już na pewno zapamiętać.

[Mark · Rating 4 out of 5]

I will accept without much argument that the origin of the universe is still “the big mystery” waiting to be fully solved, but as important and fascinating as that topic is, it is still a backward-looking exercise. Human consciousness, however, and all its related intellectual understanding is possibly an even bigger mystery, and in addition to being just as important and fascinating, there is a forward-looking aspect to it that adds more thrill to its solution.

While each new text on the subject answers some questions and poses new ones, Joseph LeDoux’s enormously engaging book, The Deep History of Ourselves: The Four-Billion-Year Story of How We Got Conscious Brains, inches us ever-so closer to ultimate knowledge. The book is lavishly and generously illustrated with informative grayscale artwork, but the labeling and annotating of the artwork is in an italic font small enough to challenge even young readers’ eyes. The font used for page footnotes—of which there are many—is even smaller, making them almost unreadable! Why? Trust me, there are nerdy readers who want to read all diagram labels and all footnotes.

The first half of this meticulously-researched work is a solid account of evolution starting with unicellular organisms and evolving to multi-cellular life. LeDoux explains that the two functions that dominated primitive life (and arguably still does in a very basic way) were survival and reproduction. Survival, in simplest terms, often meant “moving away” from harmful threats and predators, or “moving towards” life-sustaining ambience. With each short chapter, LeDoux moves along the timeline chronicling the evolution of various species, finally reaching homo sapiens.

It is fair to note that the writing becomes quite dense at times, and the penalty for readers’ attention wandering even for a moment will be some re-reading. As an example, when LeDoux is making a point about goal-directed responses and habits, he says, “…during Pavlovian conditioning, the reinforcing unconditioned stimulus alters the ability of the conditioned stimulus to activate neurons to which it is synaptically connected. In instrumental conditioning, the reinforcing unconditioned stimulus establishes a relation between neurons that process a stimulus and a response, making it more likely that in the presence of the stimulus the response will occur. If the responses depend on the unconditioned stimulus being a valuable outcome at the moment, then the response is goal directed; otherwise, it is a habit.”

Despite such challenging density, LeDoux minimizes the chances of overwhelming readers by adopting Edward O. Wilson’s style in The Meaning of Human Existence of expressing one thought or idea in one concise chapter. This reduces chapter size to between 1500-2000 words, but results in a large number of chapters, albeit helpfully grouped under common headings. I think—or rather, hope—that the structural format will be more widely adopted by other science writers.

There are several critical sections and chapters in LeDoux’s evolving (no pun intended) story. For example, “…And Then Animals Invented Neurons,” “The Beginning of Cognition,” and “Creeping up on Consciousness.” LeDoux is clear with important definitions, especially when they counter mainstream ideas. “Cognition,” he says, “will refer to processes that underlie the acquisition of knowledge by creating internal representations of external events and storing them as memories that can later be used in thinking, reminiscing, and musing, and when behaving. Its dependence on internal representations of things or events, in the absence of the external referent of the representation, is what makes cognition different from noncognitive forms of information processing.”

The Deep History of Ourselves is not for the faint-hearted, but more tenacious readers will be rewarded with a fabulous, sweeping narrative that does indeed successfully address the book’s subtitle of how humans got conscious brains, with ample coverage and analysis of current thinking on the subject.

[Tony Zale · Rating 3 out of 5]

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.

[Stuart · Rating 3 out of 5]

A Neuroscientist Traces the Development of Complex Organisms, Animals, Primates, and Humans, and then Dives Deep into the Functioning of the Brain and the Conscious/Subconscious Mind
Basically this is a pretty technical read, and as I did it via audiobook it was pretty hard to grasp a lot of the scientific details, especially the final third of the book that discusses the complex working of the brain and which parts are responsible for projecting our unconscious and conscious minds, giving birth to "consciousness", which he argues is unique to humans.

The early parts are quite interesting, and if you are a student of evolutionary biology, medicine, or neuroscience, this might be a very interesting book (though actually not detailed enough for a serious student), but pitched a bit too difficult for the lay reader or science enthusiast. I don't blame the book for being too difficult - just too difficult for me to grasp and appreciate other than in a very broad sense. I did learn a lot about how early inorganic life and single cell organisms gradually evolved into multicellular organisms and eukaryotes and fungi and a host of other creatures. It is pretty mind-expanding stuff, so if you are keen to know more about these things, it's not a bad book to read.

[Sophia · Rating 1 out of 5]

Yeah, like, I see what he's saying. And I agree with some of it. But I also disagree with a lot of how he's organizing data. I think it's actually just really a lot more complicated than he wants to accept. He talks a lot about anthropocentrism but then his theory is extremely anthropocentric. It's not like including a discussion on non-human animals going back to the beginning of time is going to unroot the engrained bias that humans are ✨special✨. Also when he talks about animal consciousness, I understand what he's saying about what science can or cannot know.... I'm on that train as a religious studies scholar.... But the way he talks about it is sraight out of the mouth of one of those neo-behaviorist incel science bros who mansplain anthropology to me (yeah I have a few people in mind). He grants the existence of a mind and of cognitive processes but then denies any semblance of these evolutionary processes to animals because the human brain is completely different. I'm gonna side with Frans de Waal here. I line how he just dismisses all of these other researches who he disagrees with as not really understanding all of these theories he understands based on absolutely nothing. #unnecessary. If we can't know that animals have any tiny bit of consciousness then how can you mindread that all of these animal researchers heart don't know the same theories as you do??? Awkward

He promises in the book title to get through the whole evolutionary history and then just kinda stops at some point after multi cellelar organisms and jumps straight to talking about modern animals such as dogs and cats. I don't think that's very comprehensive and thought out and I'm not impressed. As an physical anthropology student i did have to go back through the entire evolutionary tree and low the branches (as it pertained to humans) and that did a hot second so I understand why that might be a thick book. But I also think if he wants to talk about the thoroughness of science then hij moet het ook zelf doen. Where are the 4billion years you promised?

[SJ L · Rating 3 out of 5]

Deep History of Ourselves

I listened to LeDoux on the Joe Rogan podcast (https://www.youtube.com/watch?v=Tnr4E...) and then read the book. The book is good, interesting, pretty informative, but the interview is awesome and you’ll learn almost as much as you would reading this book.

Anyhow, life evolved. This is a story of how the cognitive life evolved. I learned a lot of cool things about how animal shapes influence their behaviors. LeDoux’s big thing is that we can’t infer animals have emotions. Humans are probably the only ones that have complex emotions because they require pretty complex thought to make happen. Complex emotions and mental life, humans only. Emotion as causing behavior, nonsense (he says the emotion arises with the behavior). “The connection of behaviors to mental life, like mental life itself, is an evolutionary afterthought.”

Quotes
There are three types of animal bodies. Asymmetrical (all sides grow equally, like sponges), radial bodies (vertical, but no front or back, like jellyfish), horizontal and upright organisms (most animals and humans) 139
Consciousness is the remembered present. 289

[Vitalijus Gafurovas · Rating 4 out of 5]

Pradžioje labai daug biologijos, evoliucinės biologijos: nuo pačių paprasčiausių vienaląsčių, gyvenusių prieš milijardus metų iki žmogaus su galingom smegenim, ką gana sunku sekti ir suprasti, jei turi mažai ryšio su tuo. Vis dėlto, antroje knygos dalyje daugiau kalbama apie tai, kaip vystėsi mūsų protas, kas buvo visai įdomu. Kas esate susipažinę bent minimaliai su LeDoux, tai jis visur kiša savo teoriją, kad jei bijom, tai elgiamės ne dėl to, kad bijom. Tai ir čia ji bandyta įkišti. Turiu pasakyti, kad teorija visai intriguojanti ir įdomi, nors nėra lengvai suprantama ir nutolsta nuo bendro visų žmonių suvokimo, kad baimė sukelia elgesį.

[Robert · Rating 4 out of 5]

I read this as someone with no background in biology or neuroscience and I was generally impressed by how accessible it is.

I also LOVED his decision to use many short chapters (most about 6 pages long). It made the the material feel much less daunting. More non-fiction books should try this, especially science books. (Marvin Minsky's "Society of Mind" is another book that does this.)

One weird thing though is how he spends 40 chapters tracing the entire history of how life evolved on Earth and then in the remaining chapters he completely switches topic to consciousness and never once refers to the earlier chapters! It kind of felt like two unrelated books, but fortunately I enjoyed both of them.

Some aspects that particularly struck me in his discussion of consciousness:

(1) He makes a convincing case that animals (even apes, cats and dogs) probably don't have the necessary neural equipment to be conscious in the same way that humans are. It is hypothesized that humans only developed this capacity between 50,000-200,000 years ago and that this was the KEY event that led us to where we are today.

(2) He make a good case that emotions are COGNITIVE events and NOT automatic unconscious responses, as a lot of people tend to think.

[Tobias Johnson · Rating 1 out of 5]

Could have been SO great. But was kind of unfriendly to the casual reader. I wasn't looking for a slog, and this reads like a textbook. Tonnes of lonely facts about neurophysiology that no one will ever remember. There may have been some great ideas in here, but they were clustered within a word salad of latin brain areas, and protozoa archaea etc.......I just missed them.

Idk, I think I need myself mentally for dry book, reading this was like going into a Marvel movie and a biochemistry lecture starts playing instead.

Also I've realised that consciousness research is fractionated into:

1. scientists who define consciousness as "what it's like to be something" AKA the felt experience of being you, that would not be there if you were a rock, table or lamppost.

2. scientists who think conscioiusness is synonymous with "self-awareness"

I find the first type of scientist fascinating and I think they're studying the most interesting and mysterious idea known to man.

I find the second type far less interesting and lump them in with scientists who study questions like "how does the visual system work?"

and I'd NEVER read a book titled "how does the visual system work?"

[Eliza K · Rating 2 out of 5]

DNF. Started to lose my interest at the spinal cord and lost my confidence in the science the way the author opened chapter 42:

“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.”

Well that still comes off as entitled ignorance to me.

Despite the mild qualifier, this was a huge claim to make. I disagree that no other animals have formed a complex idea, communicated it, and carried it out. So much of this claim relies on humans being able to detect what is spawned from novel thought and what isn’t in an animal, and give it fair value at that. Wtf. Have you seen termite structures? That’s a whole damn metropolis with community-made HVAC better than what we have.

Anyway, I liked the first half and felt like it was solid. But the second half getting into more modern theories (cough mostly the author’s cough) around cognition felt real hoity-toity and I lost trust. Also, for being over halfway through the book, he only referenced TWO female scientists compared to dozens of men. Don’t tell me it’s a male-dominated field when it’s just been about sexism and being admitted into the fancy special club (Western thoughts only). The first female mention was a one-sentence one-off and the other he felt the need to immediately qualify that her later work wasn’t accepted by science, for no literary effect. So two sentences for her!! Yet he freely cites and gives lots of airtime to 20th century male scientists that altered their EVIDENCE-BASED theories - to keep up with a scientific TREND, not because they went back and found different conclusions - and comments boo on that.

[Jacob · Rating 4 out of 5]

This book talks about how a neurologist by the name Joseph LeDoux digs deeper into the understanding of us. He goes into the natural history of life and talks about our similarities of us and our ancestors and many more. This book also talks about how in animals their brains have evolved over time. Also how the brain is developed and the big question what it means to be human. They also describe our similarities of human brain and an animals brain and how both have evolved. My experience in this book was good. It showed me many different perspectives on natural human history. Also showed me what it means to be human. It wasn’t a difficult book to read it was very interesting to think about. I do recommend this book to other people who have fascinations about human nature and evolution of our consciousness. I recommend it to them because it’s a great read to learn more about it and u see a different perspective since it’s from a neurologist.

[Sheeraz · Rating 3 out of 5]

This was just alright for me, partly because of the mismatch between my expectations and what the book actually covers. I thought there'll be more of a flair of philosophy, but the book is roughly half biology (the first half), and half (mostly fundamental) psychology. The writing style is also a little too riddled with redundancies, with repeated mentions of the same ideas -- usually the ones the author believed to be the right ones. A more consolidated view of insights from cognitive science, parallels between machine learning and human learning, and inquiry into the nature of consciousness is what I would have loved to see. But again, maybe that's just wishful thinking based on my own research interests, and not the focus the author intended for the book. Still an interesting read.

[Alan Eyre · Rating 3 out of 5]

Finished. I held on for dear life for the first half, covering evolution of life to Homo sapiens, but when he went into the human brain and different models of consciousness, I was being dragged on the ground by the stirrups as the author went god knows where. When I regained my own consciousness I was black and blue on the final page.

[John Majerle · Rating 5 out of 5]

Very informative treatment of the subject. The author was able to describe very technical topics for a laymen reader without dimming down the material. I often found myself searching online for more information as I read which is always a good sign when teading science books.

[Jessica Linville · Rating 2 out of 5]

Took me a year to get through. 2/3 of the book was about the history of evolution which I found informative, but all of that was the lead up to his theory which was never explained well. I have a masters and like to read about the brain so this book is likely inaccessible to most readers.

[Maciek · Rating 4 out of 5]

4.5 stars. Good book. Not an easy read but definitely worth it, leaves you thinking about many things!

[Josh Fischer · Rating 3 out of 5]

Interesting, but much more in the weeds of biology than anticipated.

[Petter Wolff · Rating 3 out of 5]

I have tremendous respect for LeDoux ever since I read The Emotional Brain, but The Deep History did not really meet my high expectations. Maybe it's related to the question LeDoux received from a friend when told about the endeavour - "Why would YOU do that?", and that I'm more interested in specifics from LeDoux regarding brain-behaviour that I don't want "the whole story" from the beginning of evolution.
I really got most out of the last part "Emotional Subjectivity" and the chapter on "Thoughtful Feelings", which seems to be solid home turf for LeDoux. Here, it's all laid out in a way that seems to make it possible to integrate with the ideas on Attention Schema Theory from Graziano, and with Butz' paper "Toward a Unified Sub-symbolic Computational Theory of Cognition" (these two of which are my current go-to sources of understanding). Some work to be done there, which I hope to find the time and energy for. If something good comes out of that, LeDoux would have provided much material with this single chapter, and credit should be given for that.
And the book in its entirety is not bad, and the subject as a whole is of course immensely interesting. But the ground has been covered in various ways before (Damasio, Sapolsky, Dawkins to mention a few) and I'm just not sure that LeDoux brought anything really new to the table.
The long reading time was due to reading bits and pieces now and then, not digesting the book from start to finish, and for reading other stuff in between.

[George · Rating 3 out of 5]

The most insightful portion of this book is early on. He presents the first animal (sponge) in chapter 26 spending the first 25 on evolutionary biology of cells and geological manifestations of that; trying to explain the origin of life (before Archaea & Bacteria) .

Then he proceeds into the first phyla with a nervous system (but no brain) the cnidarians which we often call The Thing About Jellyfish . Spending a lot of time on the evolutionary conversion of asymmetric bodies first into oceans and then on land (about 380 M BC).

He dismisses this bilateral symmetry path as somehow being axiomatic in the development of the cox gene sometime before 580M years BC. He earlier postulates the Earth it self is 6B years old., and that `animals` left the sea for land around 400M years BC after the Cambrian explosion for which he admits we have little (or only) Hard evidence since soft tissue is done gone.

Another place he brings to fore is the origins of genetics in discussing which came first DNA or RNA. He even suggests the COX gene might be responsible for asymmetric animals becoming bilateral [Bauplan]. My takeaway is the 2 methods of reproduction i. replication ii. sexual are symbiotic and sexual allows the randomness in traits creating more heritable mutations than replication alone can.

He admits that something like a great flood acted to prune the species tree at 45M years BC (extinguishing large reptiles). For the origin of cellular life he seems to follow Nick Lane Theories that proceed the development of Prokaryotes

it is with the Neo-Bauplan vertebrae that brain functionality precursor humanoid [Chapter 33] first appears.

*alerte spoiler** Creationists won't like this book much except maybe the 2nd half.

Around chapter 40 he begins to examine mammalian brain physiology, and its implications toward human psychology (show me a The Disordered Mind: What Unusual Brains Tell Us About Ourselves or of this genre that doesn't highlight Phineas Gage ?); and it's implication. He seems to sidestep the memory issue by using terms like Semantic, and Episodic memory. What other authors refer to as working memory he seems to couch in something called schema.

Later when he introduces Global Workspace theory contrasting that to his favored HOT (David Rosenthal's higher order theory 2011) or even Horror (Richard Brown see Table 52.1 page 273) [a further layer of abstract perception encasing the more abstract coding of HOT]. Pointing out that both GWT & HOT incorporate data from the visual cortex BEFORE other sensory data comes into play (the crunch of the apple since there are green apples). A rather innocuous statement appears earlier:

"... with even bigger hotter brains .. especially prefrontal cortex ... cognitive capacity increased "--- page 259 which doesn't explain why AD the human brain size has been continually decreasing. This energy analysis of emotion was something author Lisa Feldman-Barrett also did in her book(s); so viewed in this way deterioration in Broca's or Wernicke's area does begin to explain afflictions like aphasia using an energy conservation model. Feldman claims minimizing energy consumption is one of the key features of emotion.

LeDoux does seem to be spinning towards defending his other book [thesis work] "the Integrated Mind" he co-wrote with his advisor Gazzaniga. He does admit (part 13) that language is a key component of memory formation and (emotional) memory retrieval for learning, so even if animals speak would that mean they experience emotion ? [if a lion could speak we would not understand him -- Ludwig Wittgenstein ]. So do plants fungi etc exemplify rudimentary consciousness ?. LeDoux is very good at highlighting unanswerable questions !.

"gratuitous anthropomorphism is distinctly unhelpful" -- Frans de Waal [page 200]

in this introduction to consciousness he makes some leading edge statements contrasting cognitive sciences with behaviorism (\[ ]] introducing the term non-conscious to describe the Freudian unconscious). Even contrasting "weak AI" to human consciousness. Memory formation seems to be where real learning has occurred.

The issue of emotion in non-humans begins with Charles Darwin The Expression of the Emotions in Man and Animals, but he then mentions The Ego and the Id and The Writings of William James: A Comprehensive Edition as key scholars.

Another researcher he mentions (but minimizes) is How Emotions Are Made: The Secret Life of the Brain perhaps postulating emotions are the work product of schema rather than the other way around (as Feldman-Barrett proposes). Emotions would seem to be a shortcut for somatic data reporting if not the prediction error itself.

Overall this book might have been way too ambitious with it's 15 parts in 66 chapters. I liked that the chapters (the earlier ones) were short and stood alone (somewhat) since the academic density seemed to increase as the book went on. In his own field Parts 12,13,14 i think he doesn't understand that his audience might not agree with various sublime points of academic histology he takes as granted or givens. As Dr Feldman astutely observes in her review of this book, academics love to speculate outside their specialty. Biologist play neurologists, neurologists play psychologist etc.

[Ginger Griffin · Rating 4 out of 5]

If you had to throw 20 heads in a row to advance to the next stage of the game, you wouldn't like your chances. But what if you had millions of tries? Then the odds would get a lot better. That's been the story of life's evolution from the beginning, as this book recounts in detail.

Many of evolution's trickiest parts happened in the oceans, where tiny life forms could float freely and widely, bumping into potential nutrients (and one another) along the way. The earliest forms reproduced quickly (often several times a day), mostly by simple cell division -- each one another roll of the evolutionary dice.
 
The few winners used their advantage to propagate their kind, and the next round of the game began. Even so, it took billions of years for multi-cellular organisms to emerge. Once that happened, things sped up (from hundreds of millions to mere tens of millions of years between major steps). 

We've inherited only from the winners (because the losers died out). So we got the parts that were proven to work. But it takes evolution a while to work out the bugs in any system. And humans are a relatively young species. Our cell structure and basic body plans evolved hundreds of millions of years ago, and have had plenty of time to hone their operation. Our brains? Not so much.

Human brains are large, of course, but that's not really the interesting part. The most important aspect is how they're wired. The neurons in our prefrontal cortex (where much of the conscious action happens) are strongly interconnected with one another and with other parts of the brain -- and the genes within them are expressed in unique ways. That's led one researcher to describe the human prefrontal cortex as "rewired and running hot." So it's not surprising that humans are so vulnerable to brain-related conditions (autism, bi-polar disorder, schizophrenia, and many others). Our brains may still be in the beta-testing stage.
 
Nonetheless, we've managed to invent nuclear weapons and produce rapid climate change. Flipping the coin again! Just hope we don't need 20 heads in a row to survive this stage of our evolution.  

[Dariusz · Rating 3 out of 5]

Książka jakby dwuczęściowa - najpierw ewolucja stworzeń i rozwój ich układów nerwowych, bardzo sprawnie napisana, sporo przystępnej wiedzy. Druga część to rozważania o naszym umyśle, dużo słabsza bo autor wielokrotnie forsuje swoje przemyślenia o tym że skoro tylko człowiek ma świadomość to tylko człowiek może mieć uczucia. Hipoteza dobra jak każda inna ale podana w innych słowach dziesiąty raz już tylko męczyła.

[Peter Farago · Rating 4 out of 5]

LeDoux's The Deep History of Ourselves is a broad and careful examination of the complex genesis of human consciousness. It begins 4 billion years ago by detailing the emergence of earth's simplest forms of life, and proceeds gradually, over its 66 short pithy chapters, to guide the reader forward, explaining in great detail, the vast biological complexity we humans have inherited. I can now say with relative assurance that I fully comprehend the important differences between Protostomes and Deuterostomes!

It's timely, technically current, and one learns a lot of what has been discovered (and disputed) in the last few decades.

In chapter 42 Cognition, LeDoux makes a rather curious and defensive argument that AI will never achieve human-like consciousness.

“My view is thus that cognition is a product of biological evolution, and as such, requires biological information processing.”

Perhaps his view will ultimately be proven true, but frankly mainstream AI research considers this issue irrelevant. As Stuart Russell and Peter Norvig observe, most AI researchers don't care whether you call it a simulation of intelligence or real intelligence.

In any case, one does not need to agree with all of LeDoux's positions, and I, for one, agree with nearly all of his conjectures. I greatly admire the depth, readability, and simplicity of this achievement and have happily recommended it to many of my friends.

[Harriet · Rating 4 out of 5]

As others have noted, this feels like two distinct books crammed into one. The first two-thirds of the book takes us on a fabulous journey through the evolution of multicellular organisms, and lays the groundwork for a historical and multifaceted understanding of where humans have come from. The last third reads like an apologia for a particular neuroscientific view of human development. The problem is that these are two distinct audiences. As a fairly well-educated layperson I wound up skimming most of the last third of the book, much of which felt so arcane to me that I couldn't make sense of it. Nor did I want to. Worth reading for that first two-thirds, and don't beat yourself up if you get lost in the last third.