WHEN THE EGYPTIA NS ELEVATED the humble dung beetle to a symbol of transformation, they were part of a long process of change in the course of human beliefs. We moved from being animists (where each object was imbued with its own spirit) to being theists, where power was held by a limited number of deities and brokered by a priesthood that mediated access to those gods. That journey (from imagining how the earth came into being, to accepting that all life is composed of the same genetic material) has brought us to the point of understanding that we share a common origin with dung beetles and every other living organism on this earth. How that common ancestor has evolved into a myriad different creatures is a fascinating and constantly expanding field of enquiry, and our indomitable little friends are helping us to find the answers to some of those questions.

Dung beetles have become one of the pivotal species’ groups in modern evolutionary studies because, small though they are, they are helping us to begin understanding how variation within a species (in horn size, for instance), could promote speciation, which has resulted in so many diverse species in this case. Those 6 000-plus species are found in at least 257 genera (the plural for genus, the next grouping in the classification hierarchy in which species are nested); compare this to humans, where we are only one species (sapiens), sitting alone in our solitary genus (Homo), with all of our relatives extinct. The transformation dung beetles are now helping us to understand is one of speciation: in other words, how one species can give rise to another.

These recent findings go a long way to resolving Charles Darwin's issues with his own theory of evolution. Darwin had Mendel's discoveries of the mechanisms of inheritance on his own bookshelf, unread; if he had read them, he could have explained the problem of the blending of parental characteristics in their offspring (that over time, this would remove variation from any population, thereby leaving natural selection nothing to work on). In the same way, Darwin came tantalisingly close to an explanation of how new species could arise when he used dung beetle horns as examples of a sexually selected characteristic in The Descent of Man, and Selection in Relation to Sex (1871).