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Oct 27, 2019

Joseph LeDoux is a celebrated neuroscientist whose latest book is a work of quite staggering ambition - it traces the ‘Four Billion Year Story of How We Got Conscious Brains’. He reveals the profound similarities between us and bacteria, as well as offering a brilliant, overarching account of what makes us unique in the animal kingdom; how we developed the capacity for emotion and self-consciousness.


2:27 LeDoux describes his career path – from a small town in Louisiana, via business administration to the legendary studies on split-brain patients he undertook with Michael Gazzaniga.  

 9:11 What are ‘split brain’ patients and why are they so intriguing? LeDoux describes one of the pioneering experiments he was involved with in the 70s and what they reveal.

The split brain experiments may be tricky to understand from the audio alone! Here’s the experimental set up and results we’re describing...

RIGHT hemisphere sees: SNOW SCENE

LEFT hemisphere sees: a CHICKEN 

*Then* participant then asked: pick the object associated with the image.

Right hand (controlled by LEFT hemisphere) picks a CHICKEN CLAW

Left hand (controlled by RIGHT hemisphere) picks a SNOW SHOVEL

BUT the left hemisphere offers a surprising explanation for the behaviour of the left hand…

12:48 Why do we need a ‘deep’ history that covers 4 billion years of evolution? LeDoux explains how his research kept drawing him deeper and deeper into evolutionary history as he traced the origins of the molecular mechanisms at work in our own brains.  

 22.16 We discuss the staggering fact that even bacteria have a basic capacity for learning and memory

24:16 What do we have in common with the mother of all organisms - LUCA - (the Last Universal Common Ancestor). LeDoux argues that a lot of behaviour is driven by impulses related to survival, rather than the mental states (the thoughts and feelings) which accompany behaviour. Consciousness

26:10 Do we feel emotion because of action, or do we act because of emotion? LeDoux takes issue with William James.

29:00 Darwin was not such a great psychologist. LeDoux cautions against the tempting assumption that animals are conscious, while admitting tends to assume his cat is conscious.

32:26 “Behaviour is not a tool of the mind, it’s a tool of survival.” This falls out of a deep history of the mind.

36:25 To what extent we are still at the mercy of ancient instincts and impulses – how much more control does cognition afford us?

What kind of consciousness might other animals have? LeDoux describes ‘autonoetic consciousness’, the ability for the self to be part of an experience, as distinctively human. He traces the evidence for different forms of consciousness in other animals and discusses brai based differences.

 39:56 LeDoux sets out the Higher Order theory of consciousness which he defends. Is it really just a search for the neural correlates of consciousness, or an explanation for phenomenal consciousness?  

42:36 “Once we understand consciousness, we get emotions for free

44:30 What elements are required to have an emotion? LeDoux explains why he got a T-shirt printed with “No self, no fear”. 

46:43 Are our conscious minds in the driving seat, or are they just monitoring the auto-pilot? LeDoux admits he’s ‘kinda waffley’ on free will (49:23) so I let it go… 

49:41 What brain features are associated with having a developed self-schema, which other primates don’t?

54.14 LeDoux surprises me with the suggestion that maybe emotion did not arise through natural selection!

58:21 We discuss the book’s epilogue, starting with LeDoux’s evocative statement, “While autonoetic self-awareness is the enabler of our deepest problems, it is also our sole hope for a future.” The deep history tells us that species come and go. Bacteria will definitely make it through environmental catastrophe, but will we? 


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

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