Aquaculture for all

Dark Side of Evolution: Animal Cannibalism

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UK - In an exclusive interview, author David Soulsby talks about his new book "Animal Cannibalism" and the impetus for his research which resulted in this book.

What is your background?

After gaining a B.Sc. Honours in Geology from the University of Manchester in 1970 I travelled to Africa to work as a mining and exploration geologist. Living for almost three years in remote bush camps, this offered the opportunity to observe wildlife at close quarters. I continued working as a geologist in the commercial, environmental, and humanitarian spheres on contracts in many different parts of the world. I have always had broad interests in the natural sciences, and in fact was never really interested in directing my career along one particular specialized path.

Why did you decide to publish this book now?

During one job in Zimbabwe I came across a large swarm of ground crickets on a road. Many of the insects had been killed by passing vehicles, others were cannibalistically scavenging upon the bodies. This set me wondering about the phenomenon of animals eating their own kind in nature. At this stage I had not thought of producing a book, and only after researching the subject for some years did I decide to try writing about it in my spare time. Then, around the year 2000 the possibility of publishing arose in my mind. My researches have also extended into human cannibalism, for which books are currently being prepared.

What is your target audience for the book?

The target audience for 'Animal Cannibalism' are biologists, zoologists, researchers in animal behaviour, animal breeders, and anyone else fascinated by natural history. Cannibalism is a real phenomenon found in thousands of species, both in the wild and in captivity, but one which has received very little study.

Which species are most prolific in terms of cannibalism?

Animal groups most cannibalistically prolific in purely numerical terms are beetles, spiders, and bony fishes (especially the perch-like species such as groupers and cichlids).

In evolutionary terms how important is this behaviour?

All aspects of an animal’s body design and behaviour are the result of evolution. This must include cannibalism, which in many species is directed at increasing the chances of survival and procreation, even if their young are predominantly the victims. Offspring may be sacrificed and consumed to improve the chances of later broods. Survival and procreation constitute the definition of ‘fitness’. Nature dictates that only the fittest (or luckiest!) survive to spread their genes. An example is the development of ‘cannibal morphs’ among young of many amphibians. These forms prey upon ‘normal young’ of their own kind and may be the only ones to survive (and reproduce) if the body of water in which they are growing dries up.

Is infanticide a common behaviour in most animal species?

Infanticide probably occurs in some form in most animal species, including, of course, humans.

During your research, what was the most surprising reason for cannibalism you encountered?

Cannibalism takes many forms, most of which exploit either eggs or post-natal young as the victims.

The most surprising phenomenon to me is the occurrence of matriphagy - young consuming their own mother. This has been observed in certain species of nematodes, insects, scorpions, and spiders. Another amazing case, and one difficult to explain in terms of its origin, is that of a small parasitic isopod around Taiwan which infects some fresh-water fish. It burrows into the body cavity, often as sexual pairs. While inside the fish the isopods reproduce and the male may consume the female, or vice versa.

Other surprising, and slightly disturbing incidents include cannibalism by shark embryos while in utero, and two events in which Sumatran orang-utan mothers fed on the bodies of their own dead infants.

To find out more about this book or to order a copy, visit

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