Rhinos: Horning in on evolutionary assumptions

Elephants aren’t the only animals targeted by black-market trade. Rhinoceroses also live in the crosshairs of hunters and poachers greedy for their horns (made of a keratin material, which is ground up and sold for use in traditional medicines). Naturally, poachers and hunters want to bag the rhinos with the longest horns, but decades of hunting have left a mark on these iconic creatures.

A recent study searched over 100 years of photographic rhino records, measuring the horns of 80 rhinos between 1886 and 2018. Researchers discovered that the average length of rhino horns have shortened, relative to their body length, most likely because of intense hunting. By targeting rhinos with the longest horns, hunters and poachers have left the shorter-horned rhinos to pass on their shorter schnoz to future generations.

According to the researchers in this study, this horn reduction represents “an evolutionary change.” But what’s at play here isn’t evolution. No new structures are forming; the average length of horns is simply shrinking due to artificial selection (a loss of genetic variety caused by human interference).

Rhinos use their horns for defending young, digging for water, and foraging. Thankfully, another recent study by the University of Bristol Vet School in Namibia discovered that rhinos suffered no negative effects on reproduction or survival when their horns were removed to discourage poaching. Sadly, in our fallen world, we might have to get used to seeing rhinos without their iconic headgear, but at least these majestic creatures will be around for years to come.

This article is from Answers magazine, April–June, 2023, p. 18.