A biologist's inquiry into the science of size in creation

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Nidhi Mathur

Why Size Matters, John Bonner, Princeton, Pp 176 (PB) $ 12.95

When we look around us, we find there is hardly anything in life which we do not measure it by its size, be it done consciously or unconsciously. We can see it in English literature also, be it Gulliver’s Travels or Grimms’ Fairy Tales or Alice in Wonderland.

In the 17th century, it was believed that the human sperm contained a minute human being – a homunculus – that was implanted in the womb. The process of growth and development led to the enlargement of the homunculus and passing through birth to reach maturity.

This book, by an eminent biologist, provides a completely new perspective, arguing that size is a supreme and universal determinant to what an organism can be or do. For instance, tiny creatures are subject primarily to forces of cohesion and larger beasts to gravity, therefore, for instance, a fly can walk up a wall with considerable ease but not a human being. Many examples are cited to support the correlations in which various properties of organisms vary with size. It is these correlations that provide the foundation, the underpinning for the contention that size rules life. The correlations are stated in the form of five rules which are as follows:

*    Strength varies with size

*    Surfaces that permit diffusion of oxygen, of food and of heart in and out of the body, vary with size

*    The division of labour (complexity) varies with size

*    The rate of various living processes varies with size, such as metabolism, generation time, longevity and the speed of locomotion

*    The abundance of organisms in Nature varies with their size

We have always been fascinated by thing big and small. So, why do scientists normally consider the size of a creature only when studying something else, such as its running speed or metabolism? In clear and unambiguous terms, Bonnner introduces the layman to the importance of size in the lives of the giants and dwarfs of human species, animals and plant history. He explores questions like the biological effects of the physics of size, the evolution of size over geological time and the role of size in the function and longevity of living things.

(Princeton University Press, 41 William Street, Princeton, New Jersey 08540; www.press.princeton.edu)