Subtitled Nature's Engine and the Order of Life, this book seeks to show us in terms of energy, mass and volume how and why forms of animal life past and present differ from one another.
A simple illustration is used to introduce geometric principles: a melon twice the length of an orange has a surface area four times that of the orange, but it also has eight times the volume and eight times as much juice. Hence a 4cm fish only has to grow 1cm longer to double its weight.
These principles explain such matters as why ostriches can't grow large enough wings to support them in flight, why large animals conserve heat better than a number of smaller animals of the same total weight, and what benefits may fall to light creatures in certain environments and heavy creatures in others.
Fascinating information is presented which the reader may not have previously considered. The giraffe, for instance, has a blood pressure of 300mm, in order to pump blood up to its head. But how does this not explode the fragile capillaries in its lungs? The division of mammal hearts solves this problem, as the right half pumps blood to the lungs and thence to the left half of the heart, which has thicker walls of muscle and thus pumps blood at a much stronger pressure around the body. Coldblood hearts are differently structured.
The author is a lecturer at the University of Nottingham. He points out that, among large creatures, warmbloods chiefly inhabit land, with a very few species of coldblood such as Komodo dragons: whereas freshwater is dominated by coldbloods such as crocodiles, with a very few species such as manatees representing warmbloods. If a preserved dinosaur heart could be found, that would prove once and for all whether they were warm or cold blooded. The author puts forward both sides of the argument and explains the differing metabolic engines dinosaurs would have had in either case.
I differ with the author over a couple of points. He says that Grevy's zebra is the heaviest equine, followed by the horse. Even the largest zebra cannot weigh more than an eighteen-hand Clydesdale. However in general I would recommend this book for those interested in biology of all sorts or in the loss of biodiversity in today's threatened environment.
Or for those who enjoy fascinating facts - there is one cold-blooded mammal, the naked mole rat of Africa, living entirely underground with its body heat at the air temperature of its tunnels. The amazing variety of poisonous plants and invertebrates in Australia may be directly related to the low soil fertility level. Birds conduct breath through their hollow bones. The smallest warmbloods - Kitti's hognosed bat, Cuban bee hummingbird and Etruscan shrew - weigh two grams, though reptiles and amphibians are commonly smaller.
And the answer to the query in the title is that, given the ear size of ice-age mammoths compared to elephants and their respective environments, the elephant's big ears are heat radiators.