Ed Young’s latest book ‘An Immense World’ explores how different animals perceive the world through their senses. We all live in a sensory bubble, what we see as the world is what is perceived through our senses. If that is true how do the animals that share the planet perceive the world? The idea that what we perceive is always limited by our senses is something eastern philosophers have talked about for a long time. In recent years there have been tremendous scientific experiments to understand how in reality various animals perceive the world.
This book uses this research and provides a holistic account of the different senses and how different animals use it in radically different ways. As we read this book, we are filled with a sense of wonder, we are constantly surprised by the radically different sensory perceptions that various animals experience.
Take for instance smell, humans use the faculty of smell in a very limited fashion, whereas animals like dogs and elephants use it extensively. A dog for instance can make a mental map of its surroundings only through smell. Dogs have dedicated channels through which they can continuously smell, unlike humans who cannot smell while exhaling air. This provides dogs tremendous advantages, they can smell the past, they can identify fellow dogs, their age and sex, etc only by smelling other dogs’ urine. Ed Young lists down various experiments and ways in which scientists study the sense perception of various animals. For instance, when a jeep containing a Masai tribe who hunt elephants was taken via the forest the elephants never came close to the jeep. Even when the person was removed and a fabric worn by the person was placed in the jeep, the elephants remained at a distance. In a similar manner, elephants can identify elephants from the same group from the smell of urine.
Eyes are central to humans, our eyes point to the front hence we always walk into the world in front of us. For many birds, for instance, the eyes are on the sides, hence their worlds are circular and surround them. Our eyes are highly sensitive in the middle, hence we focus the middle of our eyes to get a clear vision, for birds this too is at the sides, hence they turn their head sideways to see clearly something right in front of them. Our eyes possess three cones red, blue, and green hence we see certain colors, but dogs have only two cones they sense colors completely differently. A blue whale for instance is monochromatic hence the ocean is actually grey to a blue whale and not blue. Certain animals have four cones and their eyes are sensitive to exceedingly different colors. Eyes also vary in their sensitivity, we are blessed with extremely sharp eyes, but animals such as the lion have less sharp eyes but they can see better during the night. Hence a zebra that looks sharp to us in its white and black stripes will look grey like a donkey to a lion. Eagles have extremely sharp eyes but they have a blind spot right behind their eyes which when they glide down to hunt becomes right in front of it, making them susceptible to crashing into airplanes. For millions of years, the eagle didn’t have to deal with objects flying into it.
Sometimes sense organs are evolutionary accidents, in a specific species of frog their ears are sensitive to a particular frequency, and a particular set of frogs started taking advantage of this peculiarity by using this frequency as a mating signal. Hence they got selected by natural selection, which made them also vulnerable to prey which started copying this frequency to hunt. Peacocks crest feathers in females resonate when male rattles its feather. Hence its a sensory organ used in mating.
The extraordinary diversity of the sensory experience of various animals is incredible in itself, but animals also have unique sensory organs which we humans completely lack. For instance whales and elephants can produce infrasonic sound waves, especially whales can use it communicate across distances separated by oceans. Many insects such as bees can see ultraviolet rays, for example the sunflower which is predominantly yellow to a human eye contains a center ultraviolet core which a bee can see. Bats can use echolocation they release sound waves and from the reflection it can make an accurate map of the surroundings. The book explains in detail how the bats use it, by continously emitting sounds and finding the target with greater accuracy. This has been used by visually challenged people also to move around. Fish have capacity to emit electric fields which help them navigate the seas. Birds posses magnetic sensors that can always detect the north. Young provides details on how they were discovered and the ways these are used by these animals.
The book concludes by providing details on how human activities contribute towards sensory pollution. The use of bright lights even during nights, the loud music and sounds, the bright lights emitted from cars affect animals in myriad different ways. It has been found out that birds which use melodic sounds to communicate amongst them usually move out of noisy neighbourhoods, these inturn affect the natural tree growth in an envrionment as they carry the seeds. Birds also get confused during their long migratory flights especially by powerful lights emitted from skyscrappers etc.
Understanding this multifaceted sensory experience that each animal shares is enriching and also makes us understand the harmful effects that we can bring to our environment. This book is a timely read.
Ashok 