杏吧原创

NO ONE disputes the complex role of imagination in everything from science and art to daily life. Its origins, however, remain elusive.

The Evolution of Imagination, one of the latest attempts to grapple with it, focuses on improvisation, characterising this as spontaneous creativity and arguing it is the fundamental process behind the artistic and scientific imagination.

It鈥檚 hard to disagree with philosopher Stephen Asma鈥檚 view that imagination is good for us, individually and as a society. But should we really let it 鈥渙ff the leash鈥� to run free in the uncertain future we face? Donald Trump鈥檚 impromptu tweets suggest such behaviour is best avoided for the sake of world peace.

While Asma does cover politics towards the end of his book, his touchstone is jazz improvisation. Having played with some great musicians, Asma has fascinating insights into how improvisation works. He also weaves together ideas from Eastern and Western philosophy, neuroscience, anthropology, archaeology and everyday life, often drawing on his experiences of having lived in a variety of cultures.

On Eastern philosophy, I can only take Asma at his word. But in my own area of expertise 鈥� prehistoric archaeology and human evolution 鈥� I fear his imagination has run riot. My main worry is Asma鈥檚 allegiance to the idea of the 鈥渢riune brain鈥�: the notion that our brain evolved in distinct layers, beginning with an ancient, motivational 鈥渞eptilian鈥� brain to which evolution added an 鈥渆motional鈥� brain (the limbic system) and then a 鈥渞ational鈥� brain (the neocortex).

As Lisa Feldman Barrett鈥檚 How Emotions Are Made and other books make clear, neuroscientists have long rejected the idea that emotion and rationality can be easily separated in the brain, while accepting that evolution has involved reorganisation of core circuits, rather than simply the addition of new layers.

Asma believes that early humans (by which I think he means any prior to Homo sapiens, although the Neanderthals are left hanging) lived by their emotional brain alone. They relied on 鈥渉ot cognition鈥�, their imaginations unconstrained by rationality, the 鈥渃old cognition鈥� provided by the expanded neocortex of modern humans. Those early hotheads were unable to control their imaginations, leaving minds fixed in what we would see as a dream-like state.

If so, one wonders how Homo erectus and the rest could have searched for carcasses on the savannah, made symmetrical stone tools or built social alliances. Also, how much cortex does it take before cold cognition kicks in? Early humans had relatively large neocortices compared with other primates, as do living non-human primates compared with other animals. The idea that imagination evolved from the dream-like and uncontrolled to being domesticated by the rationality provided by an expanded neocortex is imaginative but lacking in credibility.

鈥淓volution has reorganised core circuits in the brain, rather than simply adding new layers鈥�

Equally unsubstantiated is Asma鈥檚 idea that spoken language might have evolved around the time of the first Upper Palaeolithic cave painting, serving to decouple hot from cold cognition. And the evidence simply doesn鈥檛 support his assertion that children鈥檚 artistic development recapitulates that of graphic art in the archaeological record.

Elsewhere, Asma鈥檚 imagination seems to fail him. Drawing on his experience of safaris in Tanzania and Rwanda, he suggests that early life on the savannah would have been one of constant fear. My own imagination suggests those who grew up there most probably loved it and would have feared our urban environment.

Whether it deals with the role of imagination in education, politics or jazz, much of Asma鈥檚 book is compelling. So while I profoundly disagree with his view of how the imagination evolved, I greatly appreciate how his imagination fuelled and helped shape my own, and I feel much better for that.

This article appeared in print under the headline 鈥淓volution, jazzed up鈥�