The missing metric: speculations on tusk curvature

Abstract

As weight is the criterion of commercial value, elephant tusks have been weighed in their millions across the centuries. More recently, it has been shown that weight, length and circumference-at-lip of the African savannah elephant (Loxodonta africana) are predictive of one another and, at the population level, related to age. Missing altogether are data on the curvature created by helical tusk growth. Describing this in population terms would require large sample sizes of tusks from both sexes of all ages. While natural mortality of elephants of known ages could, in due course provide sufficient data for such an analysis, at present none are available. To partially fill this knowledge gap, this paper considers available evidence to suggest how the shape of the male savannah elephant tusk changes with age and how its changing curvature may influence behaviour.