Diving Seals and Meditating Yogis
Strategic Metabolic Retreats
Diving Seals and Meditating Yogis
Strategic Metabolic Retreats
As Elsner reveals, survival in extreme conditions such as those faced by seals is often not about running for cover or coming up for air, but rather about working within the confines of an environment and suppressing normal bodily function. Animals in this withdrawn state display reduced resting metabolic rates and are temporarily less dependent upon customary levels of oxygen. For diving seals—creatures especially well-adapted to prolonged submergence in the ocean’s cold depths—such periods of rest lengthen dive endurance. But while human divers share modest, brief adjustments of suppressed metabolism with diving seals, it is the practiced response achieved during deep meditation that is characterized by metabolic rates well below normal levels, sometimes even approaching those of non-exercising diving seals. And the comparison does not end here: hibernating animals, infants during birth, near-drowning victims, and clams at low tide all also display similarly reduced metabolisms.
By investigating these states—and the regulatory functions that help maintain them—across a range of species, Elsner offers suggestive insight into the linked biology of survival and well-being.
“Physiological responses to breath-hold diving are relevant to all placental eutherian mammals (including humans) since the first major event in our independent lives is the breath-hold dive we make during birth. This slender book gradually builds up to a final chapter discussion of this fact and its many important implications. Along the way, it provides a logically constructed, carefully thought out, interesting, and thought-provoking review and commentary on many aspects of the broad subject of the patterns, mechanisms, and controls underlying the reductions of metabolic rate that occur as normal parts of the life histories of many kinds of animals faced with a range of significant environmental challenges. . . . Elegant, literary, clear, and understated.”
Malcolm S. Gordon, University of California Los Angeles | Physiologist
“A timely and detailed exploration broader than even the title suggests, including, among others, sections on hibernation and resistance to asphyxia in foetuses and neonates. Elsner's erudite mind, testament to more than half a century of research into mammalian divers, is unleashed onto the page to the benefit of all who desire a near-definitive text on metabolic downregulation in mammals. His close acquaintance with the topic over a protracted period and his intimate collaborations with some of the world's great respiratory physiologists are etched into his writing, which conveys many insights into the history of physiological research. . . . No doubt many physiologists will frequently refer to this book for enlightenment on a host of important metabolic concepts.”
Lewis G. Halsey, University of Roehampton | Trends in Ecology & Evolution
“There are so few books dealing specifically with diving in animals, and such a book is overdue. There is no question that Elsner has the longest term association with diving physiology of any other living physiologist or person. Diving Seals and Meditating Yogis is an opportunity to get the written word and perspective from one of the seasoned masters of this small and eclectic field of researchers.”
Gerald L. Kooyman, Scripps Institution of Oceanography, University of California, San Diego | author of "Diverse Divers: Physiology and Behavior" and "Weddell Seal: Consummate Diver"
“One of the most fascinating books I have read in a long time. Elsner’s papers on metabolic regulation in diving seals, meditating yogis, and diving ama are considered individual classics; a book that compiles this work into central unifying themes is indeed exciting. I found each of the topics addressed amazing, from the seals and yogis, to the concepts of metabolic retreats, pre- and post-conditioning of organs, and comparative aspects of hypoxia tolerance, and more. The book is surprising in the range of topics explored. Written by a well-respected scientist who is considered the premier researcher on the topic of metabolic suppression in mammals, Diving Seals and Meditating Yogis is intriguing, timely, and potentially of broad interest to the general public as well as scientists. The combination of amazing science with human health implications makes this book a natural for engaging students across biology, medicine, and beyond. I feel much wiser for having read it.”
Terrie Williams, University of California, Santa Cruz | author of "The Hunter’s Breath: On Expedition with the Weddell Seals of the Antarctic"
“Elsner, a founding father of seal physiology, discovered many of the fascinating adaptations that allow marine mammals to dive very deep and for long periods of time. He taught these marvels to a host of young scientists around the world. This book is a treasure trove of fundamental concepts and insights into the control of metabolic rate in animals and humans. Elsner explores the special adaptations that allow certain well adapted animals to live and thrive in extreme or hostile environments, often drawing on the fruits of his own research expeditions from India to the Arctic and Antarctic. Elsner’s comparisons between the diverse survival strategies of these animals, and his insightful description of their unifying similarities help us appreciate and understand these extraordinary physiological achievements. In a fascinating segment, Elsner includes an inquiry into the strategies humans have developed for slowing down their metabolic rate. Elsner prods us to consider that the control of metabolic rate achieved by meditating yogis, while poorly understood, is worthy of being studied alongside the better-known strategies for slowing metabolic rate, notably those used by long-diving seals. Elsner pulls together a broad spectrum of solid physiological science in an accessible and engaging form; his book should appeal not only to students of comparative biology but also to students of yoga, and generally to any reader who is curious about the wonders of the natural world.”
Warren M. Zapol, Massachusetts General Hospital and Harvard Medical School, US Arctic Research Commission
Table of Contents
1 Strategic metabolic retreats
2 Marine mammal divers
3 Meditating yogis
4 Cardiovascular and metabolic interactions in diving seals
5 Regulatory mechanisms in the seal’s dives
6 The conditioning phenomenon
7 Hibernation and diving
8 Human divers
9 Resistances to asphyxia