Thursday, January 20

Conscious review – in the realm of the senses | Science and Nature Books


WWhat can a ballet dancer learn from doing pirouettes on the ground by studying the fastest mammal on earth? And why did the United States Navy investigate owl feathers in their search for stealthier submarines? These are questions that Jackie Higgins, a filmmaker and author who studied zoology as a student of Richard Dawkins, addresses in Sensitive, which intertwines scientific research in the animal kingdom with new insights into the ways in which our senses work.

It was once thought that there are only five senses, but neurobiologists like Colin Blakemore now believe there could be more than 30, each with its own dedicated receptors. Each chapter in the book addresses a different sense through an exploration of a particular animal’s specialized ability, one that has emerged from a unique anatomy, and then explores what we can learn about humans from this.

In the chapter on the circadian sense, Higgins shows how almost all forms of life, including humans, march to the rhythm of an internal timekeeper, even when deprived of external signals of light and dark. For example, trashline orbweaver spiders They have an internal biological clock so extraordinarily versatile that scientists study them to find out if they can help us overcome jet lag. Evidence for the human body clock emerged in 1962 when French geologist Michel Siffre cut himself off from the world in a deep cavern beneath the Alps. He remained underground for two months in total isolation, only alerting his followers on the surface when he woke up, ate and slept. The diary showed that he had maintained a regular sleep / wake cycle despite having no way of knowing the passage of time.

Higgins keeps the lay reader engaged with his lyrical and lucid style, despite describing complex science (often at the molecular level), and skillfully incorporates individual human stories. In a chapter on touch, we learn that the swamp-dwelling star-nosed mole has 22 tiny tentacles on its wonderful snout. This unique feature allows it to savor its prey underwater using air bubbles and consume it at an impressive speed. It also means that it has “the most sensitive tactile organ of all mammals discovered so far.” The tentacles of the star-nosed mole harbor a dense network of tiny receptors, known as Merkel cells, that can detect the slightest touch and then send signals to the brain. We have Merkel cells at our fingertips. Deafblind author Helen Keller learned to communicate by lightly touching her partner’s lips and throat. Feeling its movement and vibration allowed Keller to understand the speech that he could neither hear nor see.

Like Oliver Sacks, whom Higgins refers to, she is adept at describing how people with rare genetic disorders or life-altering injuries shed light on our understanding of the standard human senses. When theologian John Hull lost his sight, his descent into depression was prevented by his refocused hearing, allowing him to use bat-like echo localization to navigate his darkened world.

In the penultimate chapter, we learn how octopuses are the most flexible animals known on the planet, allowing them to be the Houdinis of research laboratory aquariums. With tens of thousands of sensory receptors on all of their tentacles, their brains are just one part of their intelligence, they are masters of proprioception, the sixth sense of self-movement, and body position awareness. Higgins compares his virtuosity to the fascinating and complex story of Ian Waterman, a young man from Portsmouth who was struck by a rare neurological disease. He destroyed the nerve fibers that told his brain where his body was: he could move but he couldn’t control his limbs. But with great concentration, he trained himself to control his body by observing each individual muscle as he moved, using his sight instead of his lost proprioception.

As a producer of natural history documentaries, Higgins makes popular science accessible: Sensitive it is a dizzying display of the evolutionary ingenuity not only of life forms, but also of zoologists, neuroscientists and biologists who have drawn new frontiers of knowledge. You may finish reading it and wish that humans could use that intelligence to stop the destruction of the habitats we all live in.

Sentient: What animals reveal about our senses by Jackie Higgins is published by Picador (£ 20). To support the guardian Y Observer order your copy at guardianbookshop.com. Shipping charges may apply


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