52 in 52 Book Summaries

Book Summary: Human: The Science Behind What Makes Your Brain Unique by Michael Gazzaniga

Human: The Science Behind What Makes Your Brain Unique by Michael Gazzaniga


The Essence

Humans are animals. But we are particular interesting due to our niche on the evolutionary tree. While our biological systems function just as many living organism do, we have set of mental faculties that make us unique. Neuroscientist Michael Gazzaniga’s book Human is a tour de force, exploring how certain mental tools available to only humans help explain why our thinking, emotions, perceptions, and memory are different from our predecessors. For instance, consider how we can create states that simulate the past, and the future, or simulate what animals and even objects intentions and feelings are; our simulation capabilities are outmatched in complexity and power. When sensory information fails to provide enough incoming information, we as humans fill in the gaps with what has been and what can be. Simulations is only one of the many psychological mechanism reviewed by Gazzaniga has he explores a number of issues related to human consciousness, language, aesthetics, and emotions.

Human Journal Entry Notes:

This is my book summary of Human. My notes are a reflection of the journal write up above. Written informally, the notes contain a mesh and mix of quotes and my own thoughts on the book. Sometimes, to my own fault, quotes are interlaced with my own words. Though rest assured, I am not attempting to take any credit for the main ideas below. The Journal write up includes important messages and crucial passages from the book.

  • Consciousness is an emergent property and not a process in and of itself.
  • The human brain is a bizarre device, set in place through natural selection for one main purpose-to make decisions that enhance reproductive success.
  • The ability to simulate emotions from language and imagination, to alter our simulations by using perspective, and project ourselves into the future and past enrich our social world and make our simulations more powerful and complex than those of other species.
  • Much information that we use from our memories or past experiences is highly colored by our non-reflective intuitive beliefs, and some of it can be wrong. It is a challenge to separate the intuitive from the verifiable.
  • Evolutionary Psychology: Attempts to explain mental traits, such as memory, perception, or language, as adaptations-products of natural or sexual selection.
    Distinct systems may have evolved for these negative emotions (e.g. fear, disgust, anger) in order to detect and coordinate flexible responses to different ecological threats.
    Our world has changed too fast for evolution to keep up with it. More types of information are going in, but the mental modules are still triggered in the same old ways.
  • Cognition has a functional structure that has a genetic bases.
  • We have genes that code for certain adaptions, but in order to realize their full potential certain exterior conditions need to be met. “Innate ideas are incomplete ideas… Out evolved inheritance is very rich compared to a blank slate, but impoverished compared to a fully realized person.”
  • Modular brain theory: The concept of a brain with specialized circuits for specific for specific problems.
  • Our social behavior has biological origins. To survive and prosper, we had to become social.
  • Reciprocal Altruism: Selfless favors that are returned at a later date. Hunting and gathering become more efficient, providing protection from predators… larger brains meant we band together in social groups.
  • Gossip: THE social grooming tool. It fosters relationships, elicits information, maintains and reforms facial norms, and builds reputation.
  • Social behaviors correlated with neocortex size in primates:
    Grooming clique size

    Tactical deception (influence without force)
    Social Play
    Social skills in male mating strategy
    Group size. (Dunbar’s Number)


  • Agency taking: We reflexively build models in our minds about intentions, feelings, and goals of others, including animals and objects. We can’t help it.
  • Many of the systems that function nonconsciously in the human brain function similarly in the brain of other animals, there is considerable overlap among species in the nonconscious aspects of the self.
  • Everyone is a hypocrite. It apparently is just easier to see from outside than the inside.
  • Most people use anecdotal evidence.
  • People don’t use information in an analytical manner.
  • Reappraise>Suppress: Reappraisal can change your physiological response, while suppression does not, and suppression decreases the experience of positive behavior.
  • Imagination: Crucial for social learning. Helps us reappraise a situation, it allows us to simulate our past emotions and learn from those experiences.
  • Our self-centered perception can lead to errors in social judgement. We need to be able to separate ourselves form others. Inhibition of our own perspective will help take others perspective.
  • Children may be born believing in essences; not taught. Does this mean our innate inference systems are made to judge?
  • The left-hemisphere: Makes sense out of all the other processes it takes in all the input and puts together a story that ‘makes sense’ (though it may be wrong).
  • Self is a byproduct. The self is a knowledge structure, not a mystical entity. Information is integrated in a unique coherent way that creates our habitualized belief of an entity known as self.
  • The ability to imitate must be innate.
  • Our agency-detection device combined with our need to explain and teleological thinking is the basis of creationism.
  • Negativity Bias: Through Natural selection, humans have been optimized for identifying the negatives of life over the positives. This is optimal for a few reason:
    Negative events are complex.
    Negative events can be contagious.
    Negative events can happen suddenly.
    Negative events are potent.
  • Our ability to use contingently true information is unique. This allowed us to be very flexible and adapt to various environments. We break out of the rigid behavioral patterns that other animals are subject to.
  • Humans are natural taxonomist.
  • Reason made the list of options, but emotion made the choice. Pure reason is not enough to make decisions. Scientist have found somatic markers for tasks that are commonly correlated with rational decision making.
  • Theory of Mind: The ability to observe behavior and then infer the unobservable mental states causing it.
  • We sit on a branch of an evolutionary tree, not on the top of a ladder.

If you liked what you saw. Here are 3 titles that I recommend based on what was discussed in Humans.

  1. The Emotional Brain: The Mysterious Underpinnings of Emotional Life by Joseph Ledoux
  2. How Emotions Are Made by Lisa Barrett
  3. The Blank Slate: The Modern Denial of Human Nature by Steven Pinker

Find the book on Amazon: Print

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