Animals are one of the most familiar and ubiquitous mental categories. They surround all of us, whether they are minuscule flies or oversize pets, and the human history would have been unimaginably different without our oversize reliance on animals. Aside from our daily experience, we learn about animals in school, but unless we end up majoring in biology very few of us go through the trouble of learning about these creatures on a deeper and more systematic level.

In “The Animal Kingdom: A Very Short Introduction” Peter Holland takes us on a journey of rediscovery of animals in all of their fascinating glory. This book can challenge and radically transform one’s understanding of what is meant by the word “animal.” It turns out that animals are much more diverse and heterogeneous than what most of us suspect. There are estimated millions of species of animals out there, and we’ll probably never get a full catalog of them. Like with all other branches of the tree of life, most animals are extremely small or microscopic, live in regions far away from human habitats, and engage in lifestyles that make them extremely hard to detect and study. Even with the known species of animals, the process of categorization and classification can be extremely daunting. For the most of human history, including the past couple of centuries of rapid scientific progress, animals had been categorized in terms of their gross physiological features. This sort of classification worked more or less well for the larger species, but for some smaller ones it created a lot of puzzles. All of this has changed with the advent of DNA analysis which has put the task of animal classification on a much more rigorous footing. DNA analysis has brought about many interesting surprises, and it has shed the new light on the evolution of animals. Thanks to the combination of DNA analysis and some older techniques today we can classify animals into about 33 different phyla. Most of these phyla are completely unknown to anyone but the specialized biologists, and this very short introduction tries to shed some light on at least some of them.

One of the most wonderful aspects of this little book is that it always tries to keep the big picture in mind. Its aim is to offer understanding, and not just a dry recitation of various animals, species, and phyla. This approach is invaluable and makes even a book that is filled with recondite classification jargon extremely accessible and even fun to read. The evolution of animal life is one of the nature’s greatest adventure stories, and Holland manages to convey much of its excitement. It was very hard for me to put this book down, and I found myself reaching for Wikipedia more often than not in order to find out more about some truly amazing animal species. This is definitely one of the best very short introduction books, and one of my favorite overall popular science books. Anyone who has a desire to understand the diversity of animal life will greatly benefit from going through this short and accessible resource.