Dance of the Dung Beetles Their Role in Our Changing World

Having just reviewed The Mosquito, I am continuing the theme of small things running the world. Here is another overlooked insect that literally moves mountains, doing the dirty job that nobody wants to do: the dung beetle. Entomologist Marcus Byrne has teamed up with popular science writer Helen Lunn for Dance of the Dung Beetles, a captivating and charming introduction to their cultural history, their role in the history of biology as a discipline, and some really funky contemporary research.

Dance of the Dung Beetles is really a book in three parts. Any book that wants to give a complete introduction to the cultural and biological history of dung beetles – or scarabs – has to begin in Ancient Egypt. With its habit of moulding excrement into neat little balls being interpreted as an act of creation, and the rolling of the ball as the daily passage of the sun, dung beetles entered the Egyptian pantheon as the scarab-faced deity Khepri.

Subsequent religions held no such fascination for the dung beetle, so the authors pick up the historical thread in the Middle Ages. Here, the first naturalists started noticing them again, in particular the Italian scholar Ulisse Aldrovandi, whose 1602 book De Animalibus Insectis (for short) described their nesting behaviour. Colonialism and trade brought vast quantities of unknown flora and fauna back to Europe, feeding a craze for curiosity cabinets to display these. A knowledge vacuum became apparent and naturalists mostly busied themselves describing and cataloguing all this diversity. It was Linneaus who would ultimately stamp his mark on this era with his binomial naming system introduced in his book Systema Naturae. Byrne & Lunn discuss how dung beetles pop up in this period in books and paintings, showing a renewed awareness and interest in them.

This cultural history spans a good 40% of the book before the authors turn to the dung beetle’s role in the history of biological disciplines. The boom of agriculture in North America after the American Civil War in the 1860s saw a surging interest in biological pest control and the birth of the discipline of economic entomology. Although dung beetles do not attack insect pests directly, they do limit their breeding grounds by rapidly burying animal dung. Dung beetles were subsequently imported into Hawai’i and later Australia, and scientists learned important lessons on the particular habitat and food requirements of each beetle species when introductions failed. Not all dung is created equally, it seems. But where they were successful, the positive effect of dung beetles on soil health has not gone unnoticed, as witnessed by the ongoing work of, for example, Dung Beetle Solutions Australia (see also Dung Down Under).

This leads into a very interesting if slightly off-topic chapter on elephants. Byrne & Lunn provide a short but pointed introduction to the trade in ivory (initially indigenous, then boosted by the desires of colonial powers) and the establishment of game parks. Especially on the latter, they have some interesting and outspoken opinions. A rinderpest pandemic sweeping through Africa at the end of the 19th century emptied many areas of livestock, leading to a spike in tsetse flies and accompanying sleeping sickness. Colonial governments responded by relocating whole populations, often turning the abandoned areas into game reserves, without ever considering if these areas were fit for animal populations. Byrne & Lunn highlight the clashes between newly minted and haughty conservation ecologists who had limited knowledge of, for example, elephants lording over these reserves, and the game wardens and naturalists on the ground. It is an interesting aside before they get to the link with dung beetles. It was studies in Tsavo National Park, Kenya, on dung beetles and dung producers (elephants) that moved research from single species towards ecosystems, made famous by further work by the late Ilkka Hanski (see Dung Beetle Ecology).

Not until the last two chapters do the authors finally talk about the topics I really came here for: the fantastic contemporary research on beetle behaviour. There is the huge variety in dung processing, for not all dung beetles roll balls. There is the wild divergence in mating tactics, which is what the dung ball rolling is all about: brood provisioning. Males roll balls which are gifted to females who will lay an egg in it, providing a safe and nutritious cradle for their offspring. Some males have horns with which they defend their dung balls, others do not and engage in sneaky copulations (the topic of my own PhD research, see also Alternative Reproductive Tactics). This allows Byrne and Lunn to talk about sexual selection, evolution, and genetics and casually give some of the best concise explanations of epigenetics and gene translation and regulation I have read in a popular science book.

And then there are the experiments that catapulted dung beetles into fame in 2013 when it turned out that some species orient themselves at night by the light of the Milky Way. This involved delightful experiments observing dung beetles rolling balls in planetariums, using polarised light filters in the field, and fitting beetles with mini-hats to prevent them from seeing the sky. I would have loved to read more about these and other experiments, and this part of the book felt too short – there must be more unusual research that could have been covered. Rather than reducing the interesting sections on cultural history, I would not have minded had the authors expanded the book as a whole, adding a few more chapters on specific biology topics.

As far as I can tell, the only similar popular book with which Dance of the Dung Beetles competes for your attention at the moment is Call of Nature, which delights in dung more generally. That book has line drawings of many of the insect species discussed, something which this book could have profited from, though there is an extended colour plate section with excellent photos here to make up for that. For readers such as myself who want to dig deeper into the biology, there are always the edited collections Ecology and Evolution of Dung Beetles and Evolutionary Biology and Conservation of Dung Beetles. For general readers, though, this book offers a wide-ranging introduction to the fascinating dung beetle that is very hard to put down.