Rhino horns are getting smaller and smaller

About the episode

New research would show that rhino horns have become smaller over the past century. And the reason is most likely (and not entirely surprising): hunting.

This research was made possible by a huge database of rhinos. Collected by Dutch researcher Kees Rookmaker. He was aiming for this
the Rhino Resource Center on. Here you will find, among other things, a huge amount of images of rhinos – photos but also drawings and paintings – from past centuries.

Because you can’t just study horns, and observations in the wild only say something about their current appearance, they thought in this University of Cambridge study: Let’s use this huge data set.

By examining photos, they found that horn length had decreased in all five species. Something which, according to the researchers, could have negative consequences for the animal. The reason for the decrease is most likely hunting. The more big-horned animals were hunted, the more short-horned animals remained. They breed again and on average you get more little horns.

They also saw something positive in looking at all the images together: it also shows how our relationship with the rhinoceros has changed over the centuries. From “wow, what a curiosity”, to something that has been hunted, to something that needs to be protected.

In this audio you can hear researcher Oscar Wilson, who is currently working at the University of Helsinki. Read more about research here: Photos suggest rhino horns have shrunk over the past century, likely due to hunting. The paper is here: Image-based analyzes from an online repository provide rich insights into long-term changes in rhino morphology and human perceptions.