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  • BOOK REVIEW

A tour of the evolution of minds

Male Satin Bowerbird tends his bower decorated with blue plastic

A male bowerbird creates an intricate arrangement of found objects to attract a mate.Credit: Martin Willis/Nature Picture Library

Journey of the Mind: How Thinking Emerged from Chaos Ogi Ogas and Sai Gaddam W. W. Norton & Company (2022)

Look through a microscope at a macrophage cell pursuing, engulfing and consuming a bacterium, and it is hard not to impose a narrative: one is trying to catch the other, which is in turn trying to escape. In Journey of the Mind, neuroscientists Ogi Ogas and Sai Gaddam imply that this interpretation is not fanciful. They argue that minds of a sort have existed since the first archaea colonized the planet, billions of years ago.

Ogas and Gaddam’s tour of the evolution of minds starts with the first cells on Earth and continues from flatworms to insects, reptiles and mammals. Along the way, biological brains amass sophisticated functions and capabilities, from navigation to memory, pattern recognition and sociality. The story doesn’t end with humans: the authors argue that civilizations represent a kind of collective super-mind, augmented with wholly artificial AI minds. The narrative is enjoyable and illuminating, but it is flawed by a failure to separate fact from speculation.

The book offers an admirable survey of how minds might comprise modules that control simple operations, which are combined to solve complex problems of survival. For instance, a bacterium can move towards food sources thanks to motor systems that switch between directional swimming and random tumbling, depending on how it senses nutrient concentrations changing in its environment. In this way, a spatial problem acquires a temporal solution — how does the situation now compare with a moment ago? — and the microbe acquires a memory of sorts.

A rat finding food in a maze breaks down a visual scene into component features of edges, foreground and so on. And there’s more: the rat mind holds a complex internal representation of the world against which to compare sensory input; it is constantly checking this inner map. The authors lean here towards the ‘free-energy minimization’ model proposed by neuroscientist Karl Friston and others, in which organisms strive to shrink the mismatch between expectation and experience.

Ogas and Gaddam take a very broad view of mind as “a physical system that converts sensations into action”. At face value, this grants a mind to thermostats and robots as much as to living entities. “A mind responds. A mind transforms. A mind acts,” they write. But the same is true of many machines. What, then, distinguishes a mind? If it’s sentience or awareness, the authors give a confusing picture. They say the “self-awareness” of an amoeba is “piddling” — and later seem to deny this quality to all organisms except vertebrates.

Many assertions go beyond the facts. The discussion of consciousness rests on the belief that the problem has been solved by cognitive scientist Stephen Grossberg (whom the authors thank for “guidance and support”). Since the late 1960s, Grossberg has developed the idea that consciousness arises from ‘resonance’ between specific modules of the brain. Ogas and Gaddam are vague about what resonance means here, beyond saying that the modules amplify and prolong each other’s outputs, and they give the reader little indication of what empirical evidence exists to support the idea. Grossberg’s theory is provocative and stimulating, but, couched in the abstract mathematical framework of dynamical systems theory, it remains contingent on his supposition that “all conscious states are resonant states”. I’m not convinced it amounts to the revolution that the authors assert.

There are many other proposals for what consciousness is and how it arises. Better-known is global workspace theory, championed in the past three decades by Bernard Baars, Stanislas Dehaene and others. They present consciousness as a phenomenon of information exchange in the brain, positing that awareness simply ‘ignites’ once certain criteria in the interaction of brain circuits are satisfied. Their corollary is that this would apply to any information-processing circuits with the correct architecture. Others, including neuroscientist Anil Seth, suspect that consciousness might be supported by only certain kinds of entities — as far as we know right now, ones that are alive. Ogas and Gaddam jump the gun, in my view, when they suggest that Grossberg has all the answers.

There are other instances in which they present contentious ideas with certainty. For all of the minds they discuss, much remains open. They write that birds didn’t develop language “because they don’t have hands”, but in fact it’s still debated whether gestures helped lead to the origin of language. They state that insects have no consciousness, when there is good reason to suppose that bees, at least, have many of the mental attributes associated with consciousness, such as foresight and the ability to imagine. Even bacteria are not the simple automata portrayed here; other researchers describe bacterial behaviours in the language of cognition.

The structure of a progression from the seemingly simple minds of bacteria and amoebas to the complex ones of primates makes narrative sense, but recalls the outdated image of evolution with humans at the apex. Our minds do excel in certain respects, most obviously in developing language and complex culture — but in dexterity, vision, navigation and more, other species eclipse us. There is more than a hint that evolution is striving to a particular end in Ogas and Gaddam’s suggestion that, once early single-celled organisms acquired the ability to sense and move, “the royal road to consciousness beckoned”.

The authors deploy some unedifying metaphors to tell their tale. One is the story of the nineteenth-century US anti-slavery campaigner Frederick Douglass, offered (I think) in an attempt to illustrate the social construction of the self. And they trivialize a pivotal social moment when they compare the mind’s attentive focus to the media presentation of the murder of George Floyd in Minneapolis in 2020.

There is plenty to like in Journey of the Mind. It is so often informative and entertaining that it feels mean to cavil. But the book exemplifies a persistent problem in popular science, in which pet theories are presented with too much confidence and too little context. Readers deserve the full picture — less definitive and satisfying, perhaps, but ultimately more honest and illuminating.

Nature 603, 221-222 (2022)

doi: https://doi.org/10.1038/d41586-022-00652-z

Competing Interests

The author declares no competing interests.

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